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Korak JA, McKay G. Critical review of fluorescence and absorbance measurements as surrogates for the molecular weight and aromaticity of dissolved organic matter. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2024; 26:1663-1702. [PMID: 39058291 DOI: 10.1039/d4em00183d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/28/2024]
Abstract
Dissolved organic matter (DOM) is ubiquitous in aquatic environments and challenging to characterize due to its heterogeneity. Optical measurements (i.e., absorbance and fluorescence spectroscopy) are popular characterization tools, because they are non-destructive, require small sample volumes, and are relatively inexpensive and more accessible compared to other techniques (e.g., high resolution mass spectrometry). To make inferences about DOM chemistry, optical surrogates have been derived from absorbance and fluorescence spectra to describe differences in spectral shape (e.g., E2:E3 ratio, spectral slope, fluorescence indices) or quantify carbon-normalized optical responses (e.g., specific absorbance (SUVA) or specific fluorescence intensity (SFI)). The most common interpretations relate these optical surrogates to DOM molecular weight or aromaticity. This critical review traces the genesis of each of these interpretations and, to the extent possible, discusses additional lines of evidence that have been developed since their inception using datasets comparing diverse DOM sources or strategic endmembers. This review draws several conclusions. More caution is needed to avoid presenting surrogates as specific to either molecular weight or aromaticity, as these physicochemical characteristics are often correlated or interdependent. Many surrogates are proposed using narrow contexts, such as fractionation of a limited number of samples or dependence on isolates. Further study is needed to determine if interpretations are generalizable to whole-waters. Lastly, there is a broad opportunity to identify why endmembers with low abundance of aromatic carbon (e.g., effluent organic matter, Antarctic lakes) often do not follow systematic trends with molecular weight or aromaticity as observed in endmembers from terrestrial environments with higher plant inputs.
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Affiliation(s)
- Julie A Korak
- Department of Civil, Environmental, and Architectural Engineering, USA.
- Environmental Engineering Program, University of Colorado, Boulder, CO, USA
| | - Garrett McKay
- Zachry Department of Civil & Environmental Engineering, Texas A&M University, College Station, TX 77843, USA.
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2
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Du R, Wen J, Huang J, Zhang Q, Shi X, Wang B, Deng S, Yu G. Dissolved organic matter isolates obtained by solid phase extraction exhibit higher absorption and lower photo-reactivity: Effect of components. WATER RESEARCH 2024; 256:121604. [PMID: 38640562 DOI: 10.1016/j.watres.2024.121604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 03/24/2024] [Accepted: 04/10/2024] [Indexed: 04/21/2024]
Abstract
Notable differences in photo-physical and chemical properties were found between bulk water and solid phase extraction (SPE) isolates for dissolved organic matter (DOM). The moieties extracted using modified styrene divinylbenzene cartridges, which predominantly consist of conjugated aromatic molecules like humic acids, contribute mainly to light absorption but exhibit lower quantum yields of fluorescence and photo-produced reactive intermediates (PPRIs). Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) revealed lignin as the moieties displaying most significant variance in abundance. In Van Krevelen-Spearman plot, we observed molecules positively or negatively correlated with DOM's optical and photochemical properties (including SUVA254, steady-state concentrations of ·OH, 1O2 quantum yield, etc.) were confined to specific regions, which can be delineated using a threshold modified aromaticity index (AImod) of 0.3. Based on the relationships between optical properties and PPRI production, it is suggested that the energy gap between ground state and excited singlet state (△ES1→S0), governing the inner conversion rate, serves as a determinant for apparent quantum yield of PPRIs in DOM, with intra-molecular charge transfer (CT) interactions potentially playing a pivotal role. Regarding DOM's photoreactivity with pollutants, this study has revealed, for the first time, that protein/amino sugars/amino acids could act as antioxidant groups in addition to phenols on the photolysis of sulfadiazine. These findings provide valuable insights into DOM photochemistry and are expected to stimulate further research in this area.
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Affiliation(s)
- Roujia Du
- State Key Joint Laboratory of Environmental Simulation and Pollution Control (SKLESPC), Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Jiaqi Wen
- State Key Joint Laboratory of Environmental Simulation and Pollution Control (SKLESPC), Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Jun Huang
- State Key Joint Laboratory of Environmental Simulation and Pollution Control (SKLESPC), Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Qianxin Zhang
- State Key Joint Laboratory of Environmental Simulation and Pollution Control (SKLESPC), Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Xiaoyu Shi
- State Key Joint Laboratory of Environmental Simulation and Pollution Control (SKLESPC), Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Bin Wang
- State Key Joint Laboratory of Environmental Simulation and Pollution Control (SKLESPC), Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Shubo Deng
- State Key Joint Laboratory of Environmental Simulation and Pollution Control (SKLESPC), Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Gang Yu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control (SKLESPC), Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China; Advanced Interdisciplinary Institute of Environmental and Ecology, Beijing Normal University, Zhuhai, 519087, China.
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3
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Buckley S, McKay G, Leresche F, Rosario-Ortiz F. Inferring the Molecular Basis for Dissolved Organic Matter Photochemical and Optical Properties. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:9040-9050. [PMID: 38743693 DOI: 10.1021/acs.est.3c10881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Despite the widespread use of photochemical and optical properties to characterize dissolved organic matter (DOM), a significant gap persists in our understanding of the relationship among these properties. This study infers the molecular basis for the optical and photochemical properties of DOM using a comprehensive framework and known structural moieties within DOM. Utilizing Suwannee River Fulvic Acid (SRFA) as a model DOM, carboxylated aromatics, phenols, and quinones were identified as dominant contributors to the absorbance spectra, and phenols, quinones, aldehydes, and ketones were identified as major contributors to radiative energy pathways. It was estimated that chromophores constitute ∼63% w/w of dissolved organic carbon in SRFA and ∼47% w/w of overall SRFA. Notably, estimations indicate the pool of fluorescent compounds and photosensitizing compounds in SRFA are likely distinct from each other at wavelengths below 400 nm. This perspective offers a practical tool to aid in the identification of probable chemical groups when interpreting optical and photochemical data and challenges the current "black box" thinking. Instead, DOM photochemical and optical properties can be closely estimated by assuming the DOM is composed of a mixture of individual compounds.
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Affiliation(s)
- Shelby Buckley
- Environmental Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Garrett McKay
- Zachry Department of Civil & Environmental Engineering, Texas A&M University, College Station, Texas 77845, United States
| | - Frank Leresche
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Fernando Rosario-Ortiz
- Environmental Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
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4
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Korak JA, McKay G. Meta-Analysis of Optical Surrogates for the Characterization of Dissolved Organic Matter. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:7380-7392. [PMID: 38640357 PMCID: PMC11064222 DOI: 10.1021/acs.est.3c10627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 03/28/2024] [Accepted: 03/29/2024] [Indexed: 04/21/2024]
Abstract
Optical surrogates, derived from absorbance and fluorescence spectra, are widely used to infer dissolved organic matter (DOM) composition (molecular weight, aromaticity) and genesis (autochthonous vs allochthonous). Despite the broad adoption of optical surrogates, several limitations exist, such as context- and sample-specific factors. These limitations create uncertainty about how compositional interpretations based on optical surrogates are generalized across contexts, specifically if there is duplicative or contradictory information in those interpretations. To explore these limitations, we performed a meta-analysis of optical surrogates for DOM from diverse sources, both from natural systems and after water treatment processes (n = 762). Prior to analysis, data were screened using a newly developed, standardized methodology that applies systematic quality control criteria before reporting surrogates. There was substantial overlap in surrogate values from natural and treated samples, suggesting that the gradients governing the surrogate variability can be generated in both contexts. This overlap provides justification for using optical surrogates originally developed in the context of natural systems to describe DOM changes in engineered systems, although the interpretations may change. Absorbance-based surrogates that describe the amount of spectral tailing (e.g., E2:E3 and S275-295) had a high frequency of strong correlations with one another but not to specific absorbance (SUVA254) or absorbance slope ratio (SR). The fluorescence index (FI) and biological index (β/α) were strongly correlated with one another and to the peak emission wavelength but not to the humification index (HIX). Although SUVA254 and FI have both been correlated to DOM aromaticity in prior research, there was a lack of reciprocity between these optical surrogates across this data set. Additionally, there were patterns of deviations in the wastewater subset, suggesting that effluent organic matter may not follow conventional interpretations, urging caution in the use of optical surrogates to track DOM in water reuse applications. Finally, the meta-analysis highlights that three aspects should be captured when optical spectra are used for DOM interpretation: specific absorbance, absorbance tailing, and the extent of red-shifted fluorescence. We recommend that SUVA254, E2:E3, and FI or β/α be prioritized in future DOM studies to capture these aspects, respectively.
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Affiliation(s)
- Julie A. Korak
- Department
of Civil, Environmental, and Architectural Engineering, University of Colorado, Boulder, Colorado 80309-0428, United States
- Environmental
Engineering Program, University of Colorado, Boulder, Colorado 80303, United States
| | - Garrett McKay
- Zachry
Department of Civil & Environmental Engineering, Texas A&M University, College
Station, Texas 77843, United States
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5
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Allen A, Cheng K, McKay G. Evaluating the pH-dependence of DOM absorbance, fluorescence, and photochemical production of singlet oxygen. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2023; 25:1974-1985. [PMID: 37971490 DOI: 10.1039/d3em00316g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
The protonation state of dissolved organic matter (DOM) impacts its structure and function in natural and engineered environmental systems, including DOM's ability to absorb light and form photochemically produced reactive intermediates (PPRI). However, the impacts of pH on DOM optical properties and PPRI formation have largely been evaluated separately, with less information being available on their interrelationship as a function of pH for the same set of samples. It is also unclear whether the impact of pH on optical spectra and associated optical surrogates for molecular size (e.g., E2 : E3) of DOM isolates is representative of the behavior of whole water samples. To address these knowledge gaps, spectral pH titrations were performed for seven humic substance and natural organic matter isolates, three whole water samples, and three model compounds. Comparison of the fractional and differential absorption and fluorescence spectra between DOM isolates, whole water samples, and model compounds revealed similar spectral features between all samples. The results show that spectral features observed for DOM isolates also occur for whole water samples, which suggests that there is overlap in the types of chromophores present in DOM isolates and whole waters. Although results from model compounds overlapped with DOM, especially in the ultraviolet region of the spectrum, no model compound replicated DOM's pH dependence perfectly. By measuring apparent quantum yields of singlet oxygen (ΦΔ), we show that aquatic DOM isolates exhibit a different pH-dependence (ΦΔ ∝ pH-1) than soil-derived humic acid isolates (ΦΔ ∝ pH). For aquatic DOM isolates, ΦΔ values measured at different pH were not correlated to apparent fluorescence quantum yields (Φf), suggesting that pH impacts singlet and triplet excited state DOM dynamics in different ways. In contrast, the proportional relationship between Φf and ΦΔ with increasing pH for soil humic acid isolates suggests that pH impacts singlet and triplet excited DOM in these samples in a similar fashion.
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Affiliation(s)
- Anya Allen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
- Zachry Department of Civil & Environmental Engineering, Texas A&M University, College Station, TX 77843, USA.
| | - Kai Cheng
- Zachry Department of Civil & Environmental Engineering, Texas A&M University, College Station, TX 77843, USA.
| | - Garrett McKay
- Zachry Department of Civil & Environmental Engineering, Texas A&M University, College Station, TX 77843, USA.
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6
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Zhang C, Mo S, Liu Z, Chen B, Korshin G, Hertkorn N, Ni J, Yan M. Interpreting pH-Dependent Differential UV/VIS Absorbance Spectra to Characterize Carboxylic and Phenolic Chromophores in Natural Organic Matter. WATER RESEARCH 2023; 244:120522. [PMID: 37660469 DOI: 10.1016/j.watres.2023.120522] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 08/15/2023] [Accepted: 08/23/2023] [Indexed: 09/05/2023]
Abstract
Natural organic matter (NOM) is critical for the biogeochemical cycles of energy and many elements in terrestrial and aquatic ecosystems, and protonation-active functional groups in NOM molecules, notably carboxylic and phenolic groups often mediate these critical environmental functions. Molecular heterogeneity, polydispersity and dynamic behavior of NOM complicate achieving an unambiguous description of its molecular properties and reactivity. This study demonstrates that differential ultraviolet-visible (UV/VIS) absorbance spectra (DAS) of NOM acquired at varying pH values exhibit several distinct features associated with the deprotonation of NOM molecules, independent of the environmental provenance of NOM (e.g., surface water, seawater, sediment, and wastewater). The protonation-active functionalities that contribute to the Gaussian distribution bands present in the DAS were identified here by comparing characteristic properties of the bands with the stoichiometries of NOM molecules ascertained by Ultrahigh-Resolution Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS). The protonation-active individual chromophores universally present in NOM molecules were identified by a genetic molecular network analysis. The observed DAS features were closely modeled via superimposing DAS spectra of 51 individual protonation-active chromophores. Molecular orbital theory was applied to further interpret the deprotonation of these chromophores, their molecular structure, electron distribution, and electron transitions measured using DAS. The high sensitivity and easy implementation of the DAS approach allows using it as a powerful tool to quantify the molecular properties and reactivity of NOM at environmental concentrations.
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Affiliation(s)
- Chenyang Zhang
- College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.; The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China
| | - Shansheng Mo
- College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.; The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China
| | - Zhongli Liu
- College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.; The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China
| | - Bingya Chen
- College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.; The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China
| | - Gregory Korshin
- Department of Civil and Environmental Engineering, University of Washington, Box 352700, Seattle, WA 98195-2700, United States
| | - Norbert Hertkorn
- Helmholtz-Centre Munich, German Research Center for Environmental Health, Research Unit Analytical Biogeochemistry (BGC), Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - Jinren Ni
- College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.; The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China
| | - Mingquan Yan
- College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.; The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China..
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7
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Wang Y, Ma J. Charge transfer interactions exist in extracellular polymeric substances: Comparison with natural organic matter. CHEMOSPHERE 2023:139030. [PMID: 37236282 DOI: 10.1016/j.chemosphere.2023.139030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 05/23/2023] [Accepted: 05/24/2023] [Indexed: 05/28/2023]
Abstract
Extracellular polymeric substances (EPS) and natural organic matter (NOM) are widely present in the environment. While the molecular basis of NOM's optical properties and reactivity after treatment with sodium borohydride (NaBH4) has been successfully explained by the charge transfer (CT) model, the corresponding structure basis and properties of EPS remain poorly understood. In this work, we investigated the reactivity and optical properties of EPS after NaBH4 treatment, comparing them to the corresponding changes in NOM. After reduction, EPS exhibited optical properties and a reactivity with Au3+ similar to NOM, manifesting an irreversible loss of visible absorption (≥70%) associated with blue-shifted fluorescence emission (8-11 nm) and a lower rate of gold nanoparticles formation (decreasing by ≥ 32%), which can be readily explained by the CT model as well. Furthermore, the absorbance and fluorescence spectra of EPS were solvent polarity dependent, contrary to the superposition model. These findings contribute to an original understanding of the reactivity and optical properties of EPS and facilitate further cross-disciplinary studies.
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Affiliation(s)
- Ya Wang
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China; State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Jiahai Ma
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
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8
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Zhang T, Cheng F, Chen X, Zhang YN, Qu J, Chen J, Peijnenburg WJGM. Dark repair of sunlight-inactivated tetracycline-resistant bacteria: Mechanisms and important role of bacteria in viable but non-culturable state. JOURNAL OF HAZARDOUS MATERIALS 2023; 454:131560. [PMID: 37148796 DOI: 10.1016/j.jhazmat.2023.131560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 04/19/2023] [Accepted: 05/01/2023] [Indexed: 05/08/2023]
Abstract
The spread of antibiotic resistant bacteria (ARB) in the environment poses a potential threat to human health, and the reactivation of inactivated ARB accelerated the spread of ARB. However, little is known about the reactivation of sunlight-inactivated ARB in natural waters. In this study, the reactivation of sunlight-inactivated ARB in dark conditions was investigated with tetracycline-resistant E. coli (Tc-AR E. coli) as a representative. Results showed that sunlight-inactivated Tc-AR E. coli underwent dark repair to regain tetracycline resistance with dark repair ratios increasing from (0.124 ± 0.012)‱ within 24 h dark treatment to (0.891 ± 0.033)‱ within 48 h. The presence of Suwannee River fulvic acid (SRFA) promoted the reactivation of sunlight-inactivated Tc-AR E. coli and tetracycline inhibited their reactivation. The reactivation of sunlight-inactivated Tc-AR E. coli is mainly attributed to the repair of the tetracycline-specific efflux pump in the cell membrane. Tc-AR E. coli in a viable but non-culturable (VBNC) state was observed and dominated the reactivation as the inactivated ARB remain present in the dark for more than 20 h. These results explained the reason for distribution difference of Tc-ARB at different depths in natural waters, which are of great significance for understanding the environmental behavior of ARB.
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Affiliation(s)
- Tingting Zhang
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China
| | - Fangyuan Cheng
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China
| | - Xiaobing Chen
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China
| | - Ya-Nan Zhang
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China.
| | - Jiao Qu
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China.
| | - Jingwen Chen
- Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Willie J G M Peijnenburg
- Institute of Environmental Sciences, Leiden University, Leiden, the Netherlands; National Institute of Public Health and the Environment (RIVM), Center for Safety of Substances and Products, Bilthoven, the Netherlands
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9
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Li H, McKay G. Fluorescence Quenching of Humic Substances and Natural Organic Matter by Nitroxide Free Radicals. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:719-729. [PMID: 36547376 DOI: 10.1021/acs.est.2c02220] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Fluorescence spectroscopy is one of the most frequently used techniques for studying dissolved organic matter (DOM) in natural and engineered systems. However, the spatial distribution and fluorophores, including local and interacting states, within DOM's larger structure remains poorly understood. In this study, we used two nitroxide fluorescence quenchers to evaluate the chemical and spatial heterogeneity of DOM fluorophores. Several results from quenching experiments with cationic 4-amino-TEMPO (tempamine), including downward-curving Stern-Volmer plots and spectral dependent quenching, show that multiple emitting species contribute to the observed emission even at a single excitation wavelength. Furthermore, for DOM isolates of diverse geographic origins (soil vs aquatic) and isolation procedures (reverse osmosis vs humic substances), the maximum extent of quenching occurs on the red edge of the emission spectra. For soil humic substance isolates, the spectral dependent quenching was significant enough to affect a blue shift in the average emission wavelength. The same soil humic substance isolates whose emission spectra were blue shifted by tempamine quenching were also blue shifted by decreasing solution pH and decreasing solvent polarity, which suggests a role for anionic fluorophores (e.g., hydroxybenzoic acids) in long wavelength fluorescence. Finally, curvature in Stern-Volmer plots indicate that between 10 and 50% of emitting species detected by steady-state fluorescence are inaccessible to quenching by tempamine, suggesting that this fraction of fluorophores may be inaccessible to water solvent. Results from this study provide an assessment of the spatial distribution of fluorophores within DOM and help to reconcile prior studies on the role of solvent polarity and pH on DOM fluorescence.
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Affiliation(s)
- Hang Li
- Zachry Department of Civil & Environmental Engineering, Texas A&M University, College Station, Texas77845, United States
| | - Garrett McKay
- Zachry Department of Civil & Environmental Engineering, Texas A&M University, College Station, Texas77845, United States
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10
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Alves MR, Coward EK, Gonzales D, Sauer JS, Mayer KJ, Prather KA, Grassian VH. Changes in light absorption and composition of chromophoric marine-dissolved organic matter across a microbial bloom. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2022; 24:1923-1933. [PMID: 36169554 DOI: 10.1039/d2em00150k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Marine chromophoric dissolved organic matter (m-CDOM) mediates many vital photochemical processes at the ocean's surface. Isolating m-CDOM within the chemical complexity of marine dissolved organic matter has remained an analytical challenge. The SeaSCAPE campaign, a large-scale mesocosm experiment, provided a unique opportunity to probe the in situ production of m-CDOM across phytoplankton and microbial blooms. Results from mass spectrometry coupled with UV-VIS spectroscopy reveal production of a chemodiverse set of compounds well-correlated with increases in absorbance after a bacterial bloom, indicative of autochthonous m-CDOM production. Notably, many of the absorbing compounds were found to be enriched in nitrogen, which may be essential to chromophore function. From these results, quinoids, porphyrins, flavones, and amide-like compounds were identified via structural analysis and may serve as important photosensitizers in the marine boundary layer. Overall, this study demonstrates a step forward in identifying and characterizing m-CDOM using temporal mesocosm data and integrated UV-VIS spectroscopy and mass spectrometry analyses.
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Affiliation(s)
- Michael R Alves
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA.
| | - Elizabeth K Coward
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA.
| | - David Gonzales
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA.
| | - Jon S Sauer
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA.
| | - Kathryn J Mayer
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA.
- Department of Chemistry, Colorado State University, Fort Collins, Colorado, 80523, USA
| | - Kimberly A Prather
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA.
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, USA
| | - Vicki H Grassian
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA.
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11
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Couch K, Leresche F, Farmer C, McKay G, Rosario-Ortiz FL. Assessing the source of the photochemical formation of hydroxylating species from dissolved organic matter using model sensitizers. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2022; 24:102-115. [PMID: 34908096 DOI: 10.1039/d1em00345c] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Dissolved organic matter (DOM) is ubiquitous in natural waters and can facilitate the chemical transformation of many contaminants through the photochemical production of reactive intermediates, such as singlet oxygen (1O2), excited triplet state DOM (3DOM*), and hydroxylating species (˙OH and other intermediates of similar reaction chemistry). The formation mechanism of most reactive intermediates is well understood, but this is not the case for the formation of hydroxylating species from DOM. To investigate this chemistry, DOM model sensitizers were irradiated with two different probe compounds (benzene and benzoic acid) at two irradiation wavelengths (254 and 320 nm). The ability of DOM model sensitizers to hydroxylate these arene probes was assessed by measuring rates of formation of the hydroxylated probe compounds (phenol and salicylic acid). Multiple classes of model sensitizers were tested, including quinones, hydroxybenzoic acids, aromatic ketones, and other triplet forming species. Of these classes of model sensitizers, only quinones and hydroxybenzoic acids had a hydroxylating capacity. Methanol quenching experiments were used to assess the reactivity of hydroxylating species. These results have several implications for the systems tested. First, they suggest that the hydroxylating intermediate produced from hydroxybenzoic acid photolysis may not be hydroxyl radical, but a different hydroxylating species. Also, these data prompted investigation of whether quinone photoproducts have a hydroxylating capacity. These results confirm that hydroxybenzoic acids and quinones are important to the photochemical production of hydroxylating species from DOM, but the mechanism by which this occurs for these classes of sensitizers is still elusive.
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Affiliation(s)
- Kylie Couch
- Department of Civil, Environmental, and Architectural Engineering, Environmental Engineering Program, University of Colorado Boulder, 607 UCB, CO 80309, USA.
| | - Frank Leresche
- Department of Civil, Environmental, and Architectural Engineering, Environmental Engineering Program, University of Colorado Boulder, 607 UCB, CO 80309, USA.
| | - Claire Farmer
- Department of Civil, Environmental, and Architectural Engineering, Environmental Engineering Program, University of Colorado Boulder, 607 UCB, CO 80309, USA.
| | - Garrett McKay
- Zachry Department of Civil and Environmental Engineering, Texas A&M University, 3136 TAMU, College Station, TX 77843, USA.
| | - Fernando L Rosario-Ortiz
- Department of Civil, Environmental, and Architectural Engineering, Environmental Engineering Program, University of Colorado Boulder, 607 UCB, CO 80309, USA.
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12
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Leresche F, Vialykh EA, Rosario-Ortiz FL. Computational Calculation of Dissolved Organic Matter Absorption Spectra. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:491-500. [PMID: 34905334 DOI: 10.1021/acs.est.1c06252] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The absorption spectrum of dissolved organic matter (DOM) is a topic of interest to environmental scientists and engineers as it can be used to assess both the concentration and physicochemical properties of DOM. In this study, the UV-vis spectra for DOM model compounds were calculated using time-dependent density functional theory. Summing these individual spectra, it was possible to re-create the observed exponential shape of the DOM absorption spectra. Additionally, by predicting the effects of sodium borohydride reduction on the model compounds and then calculating the UV-vis absorbance spectra of the reduced compounds, it was also possible to correctly predict the effects of borohydride reduction on DOM absorbance spectra with a relatively larger decrease in absorbance at longer wavelengths. The contribution of charge-transfer (CT) interactions to DOM absorption was also evaluated, and the calculations showed that intra-molecular CT interactions could take place, while inter-molecular CT interactions were proposed to be less likely to contribute.
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Affiliation(s)
- Frank Leresche
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Environmental Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Elena A Vialykh
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Environmental Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Fernando L Rosario-Ortiz
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Environmental Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
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13
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Vione D, Minero C, Carena L. Fluorophores in surface freshwaters: importance, likely structures, and possible impacts of climate change. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2021; 23:1429-1442. [PMID: 34490433 DOI: 10.1039/d1em00273b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Fluorescence spectroscopy is one of the most useful techniques currently available for the characterisation of organic matter in natural water samples, because it combines easy availability of instrumentation, high sensitivity and limited requirements for sample treatment. The main fluorophores that can be found in natural waters are usually proteins (and/or free amino acids) and humic substances (humic and fulvic acids). The identification of these fluorescent compounds in water samples helps to obtain information about, among others, biological activity in the water body, possible transport of organic matter from soil, and the phenomenon of photobleaching that decreases both the absorbance and (usually) the fluorescence of natural organic matter. Interestingly, all these phenomena can be affected by climate change, which could alter to different extents the ratio between aquagenic and pedogenic fluorophores. Several events induced by warming in natural waters (and especially lake water) could enhance algal growth, thereby also enhancing the production of aquagenic organic matter. Intense precipitation events could increase the export of pedogenic material to surface waters, while photobleaching would be enhanced in the epilimnion of lakes when summer stratification becomes longer and more stable because of higher temperatures. Interestingly, photobleaching affects humic substances to a higher extent compared to protein-like material, thus protein fluorescence signals could be more preserved in stratified waters.
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Affiliation(s)
- Davide Vione
- Dipartimento di Chimica, Università di Torino, Via P. Giuria 5, 10125 Torino, Italy.
| | - Claudio Minero
- Dipartimento di Chimica, Università di Torino, Via P. Giuria 5, 10125 Torino, Italy.
| | - Luca Carena
- Dipartimento di Chimica, Università di Torino, Via P. Giuria 5, 10125 Torino, Italy.
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14
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Song F, Li T, Shi Q, Guo F, Bai Y, Wu F, Xing B. Novel Insights into the Molecular-Level Mechanism Linking the Chemical Diversity and Copper Binding Heterogeneity of Biochar-Derived Dissolved Black Carbon and Dissolved Organic Matter. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:11624-11636. [PMID: 34197711 DOI: 10.1021/acs.est.1c00083] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Biochar-derived dissolved black carbon (DBC) varies in chemical composition and significantly affects the environmental fate of metal ions. However, the intrinsic molecular composition of DBC fractions and their molecular interaction mechanisms with metal ions remain unclear. We propose a novel, molecular-level covariant binding mechanism to comparatively interpret the heterogeneities, active sites, and sequential responses of copper binding with molecular compounds in DBC and natural dissolved organic matter (DOM). Relatively large proportions of lipid/aliphatic/peptide-like compounds with low mass distributions and lignin-like compounds with oxidized/unsaturated groups existed in acidic- and alkaline-extracted DBC, respectively. A larger percentage of tannin-like/condensed aromatic compounds and higher average conditional stability constants (logK̅Cu) of visible fluorescent components were found for DOM than for DBC. Overall, 200-320 Da and 320-480 Da molecular components contributed significantly to the logK̅Cu values of UVA and visible fluorescent components, respectively, in DBC/DOM. Nitrogenous groups likely exhibited stronger binding affinities than phenolic/carboxylic groups. The sequential copper-binding responses of molecular compounds in DBC/DOM generally followed the order lipid/aliphatic/peptide-like compounds → tannin-like compounds → condensed aromatic compounds. These insights will improve the prediction of the potential effects of DBC on various contaminants and the risks of biochar application to ecosystems.
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Affiliation(s)
- Fanhao Song
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 10012, China
- College of Water Sciences, Beijing Normal University, Beijing 100875, China
| | - Tingting Li
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 10012, China
| | - Quan Shi
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China
| | - Fei Guo
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 10012, China
| | - Yingchen Bai
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 10012, China
| | - Fengchang Wu
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 10012, China
| | - Baoshan Xing
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, Massachusetts 01003, United States
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15
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Li H, McKay G. Relationships between the Physicochemical Properties of Dissolved Organic Matter and Its Reaction with Sodium Borohydride. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:10843-10851. [PMID: 34291922 DOI: 10.1021/acs.est.1c01973] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The reaction of dissolved organic matter (DOM) with sodium borohydride has been used to understand the geographic origin of DOM and investigate the photophysical model underlying DOM's optical properties. However, the physicochemical properties of DOM (e.g., molecular size and charge) that influence the kinetics and ultimate reducibility of DOM by borohydride remain poorly characterized. Herein, we studied the kinetics of DOM-borohydride reactions by recording absorbance and fluorescence spectra at a high temporal frequency (every ∼10 min for 24 h) for a diverse set of DOM isolates of aquatic and soil origin. The reducibility of DOM by sodium borohydride (as judged by relative removal of initial absorbance) varied appreciably among the DOM samples studied, with soil humic substances being less reducible than aquatic humic substances and natural organic matter. While statistically significant correlations were found between the reducibility of DOM and descriptors of molecular size, these descriptors were not able to differentiate the reducibility of soil versus aquatic DOM isolates that had similar bulk properties. Thus, it appears that the extent of absorbance removal by borohydride is largely driven by the origin of the humic substance isolate (aquatic vs soil) instead of molecular size or charge. Borohydride reduction resulted in increased fluorescence emission across UV and visible excitation wavelengths. However, the enhanced emission at visible excitation decreased over a time period of hours to days, suggesting that reduction of an important subset of DOM chromophores is reversible. This reversibility in fluorescence emission is consistent with the small role of quinones in the absorbance of DOM but suggests a more important role for quinone-containing charge-transfer contacts in the fluorescence of DOM, particularly at visible excitation wavelengths.
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Affiliation(s)
- Hang Li
- Zachry Department of Civil & Environmental Engineering, Texas A&M University, College Station, Texas 77845, United States
| | - Garrett McKay
- Zachry Department of Civil & Environmental Engineering, Texas A&M University, College Station, Texas 77845, United States
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16
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Yakimov BP, Rubekina AA, Budylin GS, Zherebker AY, Kompanets VO, Chekalin SV, Vainer YG, Fadeev VV, Gorbunov MY, Perminova IV, Shirshin EA. Ultrafast Energy Transfer Determines the Formation of Fluorescence in DOM and Humic Substances. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:10365-10377. [PMID: 34260209 DOI: 10.1021/acs.est.1c00998] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Humification is a ubiquitous natural process of biomass degradation that creates multicomponent systems of nonliving organic matter, including dissolved organic matter (DOM) and humic substances (HS) in water environments, soils, and organic rocks. Despite significant differences in molecular composition, the optical properties of DOM and HS are remarkably similar, and the reason for this remains largely unknown. Here, we employed fluorescence spectroscopy with (sub)picosecond resolution to elucidate the role of electronic interactions within DOM and HS. We revealed an ultrafast decay component with a characteristic decay lifetime of 0.5-1.5 ps and spectral diffusion originating from excitation energy transfer (EET) in the system. The rate of EET was positively correlated to the fraction of aromatic species and tightness of aromatic species packing. Diminishing the number of EET donor-acceptor pairs by reduction with NaBH4 (decrease of the acceptor number), decrease of pH (decrease of the electron-donating ability), or decrease of the average particle size by filtration (less donor-acceptor pairs within a particle) resulted in a lower impact of the ultrafast component on fluorescence decay. Our results uncover the role of electronic coupling among fluorophores in the formation of DOM and HS optical properties and provide a framework for studying photophysical processes in heterogeneous systems of natural fluorophores.
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Affiliation(s)
- Boris P Yakimov
- Faculty of Physics, M.V. Lomonosov Moscow State University, 1-2 Leninskie Gory, 119991 Moscow, Russia
- World-Class Research Center "Digital Biodesign and Personalized Healthcare", Sechenov First Moscow State Medical University, Trubetskaya Street, 8-2, 119048 Moscow, Russia
| | - Anna A Rubekina
- Faculty of Physics, M.V. Lomonosov Moscow State University, 1-2 Leninskie Gory, 119991 Moscow, Russia
| | - Gleb S Budylin
- Institute of Spectroscopy of the Russian Academy of Sciences, Fizicheskaya Street, 5, Troitsk, 108840 Moscow, Russia
| | - Alexander Y Zherebker
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Skolkovo, 143026 Moscow, Russia
| | - Victor O Kompanets
- Institute of Spectroscopy of the Russian Academy of Sciences, Fizicheskaya Street, 5, Troitsk, 108840 Moscow, Russia
| | - Sergey V Chekalin
- Institute of Spectroscopy of the Russian Academy of Sciences, Fizicheskaya Street, 5, Troitsk, 108840 Moscow, Russia
| | - Yuri G Vainer
- Institute of Spectroscopy of the Russian Academy of Sciences, Fizicheskaya Street, 5, Troitsk, 108840 Moscow, Russia
| | - Victor V Fadeev
- Faculty of Physics, M.V. Lomonosov Moscow State University, 1-2 Leninskie Gory, 119991 Moscow, Russia
| | - Maxim Y Gorbunov
- Environmental Biology and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, 57 US Highway 1, New Brunswick, New Jersey 08901-8554, United States
| | - Irina V Perminova
- Faculty of Chemistry, M.V. Lomonosov Moscow State University, 1-3 Leninskie Gory, 119991 Moscow, Russia
| | - Evgeny A Shirshin
- Faculty of Physics, M.V. Lomonosov Moscow State University, 1-2 Leninskie Gory, 119991 Moscow, Russia
- World-Class Research Center "Digital Biodesign and Personalized Healthcare", Sechenov First Moscow State Medical University, Trubetskaya Street, 8-2, 119048 Moscow, Russia
- Institute of Spectroscopy of the Russian Academy of Sciences, Fizicheskaya Street, 5, Troitsk, 108840 Moscow, Russia
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17
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Zhou Y, Cheng F, He D, Zhang YN, Qu J, Yang X, Chen J, Peijnenburg WJGM. Effect of UV/chlorine treatment on photophysical and photochemical properties of dissolved organic matter. WATER RESEARCH 2021; 192:116857. [PMID: 33517044 DOI: 10.1016/j.watres.2021.116857] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 01/15/2021] [Accepted: 01/17/2021] [Indexed: 06/12/2023]
Abstract
Dissolved organic matter (DOM) is a ubiquitous component in effluents, DOM discharged with an effluent can affect the composition and properties of natural DOM in the receiving waters. As the photophysical and photochemical properties of effluent DOM can be changed by wastewater treatment processes, the effect of UV/chlorine treatment on the photophysical and photochemical properties of DOM was investigated using Suwannee River fulvic acid (SRFA) and Suwannee River natural organic matter (SRNOM) as representatives. Results showed that the absorbance of the two DOM was significantly decreased. The evolution trends of three representative photophysical parameters upon increase of chlorine dosages were observed. Also, a decrease in DOM aromaticity, molecular weight and electron-donating capacity was observed upon increasing chlorine dosage. Quantum yields of excited triplet state of DOM (3DOM*), singlet oxygen (1O2) and hydroxyl radicals (·OH) first decreases and then increased in the UV/chlorine systems upon increasing chlorine dosages due to the different reaction pathways of the two DOM. Moreover, 3DOM* can not only be regarded as a "controller" of other reactive intermediates, but also effectively promote the photodegradation of bezafibrate, which is classified as a persistent organic contaminant. This study gives deep insights into effects of UV/chlorine on the photophysical and photochemical properties of DOM, and is helpful for understanding the dynamic roles of DOM in the photodegradation of micropollutants.
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Affiliation(s)
- Yangjian Zhou
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China; School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Fangyuan Cheng
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China
| | - Dongyang He
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China
| | - Ya-Nan Zhang
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China.
| | - Jiao Qu
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China.
| | - Xin Yang
- School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Jingwen Chen
- Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Willie J G M Peijnenburg
- Institute of Environmental Sciences, Leiden University, Leiden, the Netherlands; National Institute of Public Health and the Environment (RIVM), Center for Safety of Substances and Products, Bilthoven, the Netherlands
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18
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Ossola R, Jönsson OM, Moor K, McNeill K. Singlet Oxygen Quantum Yields in Environmental Waters. Chem Rev 2021; 121:4100-4146. [PMID: 33683861 DOI: 10.1021/acs.chemrev.0c00781] [Citation(s) in RCA: 87] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Singlet oxygen (1O2) is a reactive oxygen species produced in sunlit waters via energy transfer from the triplet states of natural sensitizers. There has been an increasing interest in measuring apparent 1O2 quantum yields (ΦΔ) of aquatic and atmospheric organic matter samples, driven in part by the fact that this parameter can be used for environmental fate modeling of organic contaminants and to advance our understanding of dissolved organic matter photophysics. However, the lack of reproducibility across research groups and publications remains a challenge that significantly limits the usability of literature data. In the first part of this review, we critically evaluate the experimental techniques that have been used to determine ΦΔ values of natural organic matter, we identify and quantify sources of errors that potentially explain the large variability in the literature, and we provide general experimental recommendations for future studies. In the second part, we provide a qualitative overview of known ΦΔ trends as a function of organic matter type, isolation and extraction procedures, bulk water chemistry parameters, molecular and spectroscopic organic matter features, chemical treatments, wavelength, season, and location. This review is supplemented with a comprehensive database of ΦΔ values of environmental samples.
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Affiliation(s)
- Rachele Ossola
- Institute of Biogeochemistry and Pollutant Dynamics (IBP), Department of Environmental Systems Science, ETH Zürich, 8092 Zürich, Switzerland
| | - Oskar Martin Jönsson
- Institute of Biogeochemistry and Pollutant Dynamics (IBP), Department of Environmental Systems Science, ETH Zürich, 8092 Zürich, Switzerland
| | - Kyle Moor
- Utah Water Research Laboratory, Department of Civil and Environmental Engineering, Utah State University, 84322 Logan, Utah, United States
| | - Kristopher McNeill
- Institute of Biogeochemistry and Pollutant Dynamics (IBP), Department of Environmental Systems Science, ETH Zürich, 8092 Zürich, Switzerland
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19
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Wünsch UJ, Murphy K. A simple method to isolate fluorescence spectra from small dissolved organic matter datasets. WATER RESEARCH 2021; 190:116730. [PMID: 33348069 DOI: 10.1016/j.watres.2020.116730] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/06/2020] [Accepted: 12/05/2020] [Indexed: 06/12/2023]
Abstract
Dissolved organic matter (DOM) is a complex pool of compounds with a key role in the global carbon cycle. To understand its role in natural and engineered systems, efficient approaches are necessary for tracking DOM quality and quantity. Fluorescence spectroscopy combined with parallel factor analysis (PARAFAC) is very widely used to identify and quantify different fractions of DOM as proxies of DOM source, concentration and biogeochemical processing. A major limitation of the PARAFAC approach is the requirement for a large data set containing many variable samples in which the fractions vary independently. This severely curtails the possibilities to study fluorescence composition and behavior in small or unique datasets. Herein, we present a simple and inexpensive experimental procedure that makes it possible to mathematically decompose a small dataset containing only highly-correlated fluorescent fractions. The approach, which uses widely-available commercial extraction sorbents and previously established protocols to expand the original dataset and inject the missing chemical variability, can be widely implemented at low cost. A demonstration of the procedure shows how a robust six-component PARAFAC model can be extracted from even a river-water dataset with only five bulk samples. Widespread adoption of the procedure for analyzing small fluorescence datasets is needed to confirm the suspected ubiquity of certain DOM fluorescence fractions and to create a shared inventory of ubiquitous components. Such an inventory could greatly simplify and improve the use of fluorescence as a tool to investigate biogeochemical processing of DOM in diverse water sources.
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Affiliation(s)
- Urban J Wünsch
- Technical University of Denmark, National Institute of Aquatic Resources, Kemitorvet, 2800 Kgs. Lyngby, Denmark; Chalmers University of Technology, Architecture and Civil Engineering, Water Environment Technology, Sven Hultins Gata 6, 41296 Gothenburg, Sweden
| | - Kathleen Murphy
- Chalmers University of Technology, Architecture and Civil Engineering, Water Environment Technology, Sven Hultins Gata 6, 41296 Gothenburg, Sweden.
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20
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Chen W, Yu HQ. Advances in the characterization and monitoring of natural organic matter using spectroscopic approaches. WATER RESEARCH 2021; 190:116759. [PMID: 33360618 DOI: 10.1016/j.watres.2020.116759] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 12/16/2020] [Accepted: 12/16/2020] [Indexed: 06/12/2023]
Abstract
Natural organic matter (NOM) is ubiquitous in environment and plays a fundamental role in the geochemical cycling of elements. It is involved in a wide range of environmental processes and can significantly affect the environmental fates of exogenous contaminants. Understanding the properties and environmental behaviors of NOM is critical to advance water treatment technologies and environmental remediation strategies. NOM is composed of characteristic light-absorbing/emitting functional groups, which are the "identification card" of NOM and susceptive to ambient physiochemical changes. These groups and their variations can be captured through optical sensing. Therefore, spectroscopic techniques are elegant tools to track the sources, features, and environmental behaviors of NOM. In this work, the most recent advances in molecular spectroscopic techniques, including UV-Vis, fluorescence, infrared, and Raman spectroscopy, for the characterization, measurement, and monitoring of NOM are reviewed, and the state-of-the-art innovations are highlighted. Furthermore, the limitations of current spectroscopic approaches for the exploration of NOM-related environmental processesand how these weaknesses/drawbacks can be addressed are explored. Finally, suggestions and directions are proposed to advance the development of spectroscopic methods in analyzing and elucidating the properties and behaviors of NOM in natural and engineered environments.
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Affiliation(s)
- Wei Chen
- School of Metallurgy and Environment, Central South University, Changsha410083, China
| | - Han-Qing Yu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei230026, China.
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21
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Vialykh EA, McKay G, Rosario-Ortiz FL. Computational Assessment of the Three-Dimensional Configuration of Dissolved Organic Matter Chromophores and Influence on Absorption Spectra. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:15904-15913. [PMID: 33269593 DOI: 10.1021/acs.est.0c05860] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The three-dimensional configuration of dissolved organic matter (DOM) is an important factor in determining the role of DOM in natural and engineered systems, yet there is still considerable uncertainty regarding the formation and potential stability of molecular aggregates within DOM. In this paper, we describe a computational assessment of the three-dimensional configuration of DOM. Specifically, we were interested in evaluating the hypothesis that DOM forms thermodynamically stable molecular aggregates that as a result were potentially shielded from water solvent molecules. Molecular dynamics simulations of DOM model compounds carefully selected based on ultrahigh-resolution mass spectrometry data revealed that, while DOM does indeed form molecular aggregates, the large majority of molecules (especially, O-atom bearing molecules) are solvent accessible. Additionally, these computations revealed that molecular aggregates are weak and dissociate when placed in organic solvents (tetrahydrofuran, methyl tert-butyl ether). Time-dependent density functional theory calculations demonstrated long-wavelength absorbance for both model DOM chromophores and their molecular aggregates. This study has important implications for determining the origin of DOM optical properties and for enhancing our collective understanding of DOM three-dimensional structures.
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Affiliation(s)
- Elena A Vialykh
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Garrett McKay
- Zachry Department of Civil & Environmental Engineering, Texas A&M University, College Station, Texas 77843, United States
| | - Fernando L Rosario-Ortiz
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Environmental Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
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22
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Zhang YN, Zhang T, Liu H, Qu J, Li C, Chen J, Peijnenburg WJGM. Simulated sunlight-induced inactivation of tetracycline resistant bacteria and effects of dissolved organic matter. WATER RESEARCH 2020; 185:116241. [PMID: 32777596 DOI: 10.1016/j.watres.2020.116241] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/22/2020] [Accepted: 07/27/2020] [Indexed: 06/11/2023]
Abstract
The transmission of antibiotic resistance in surface water has attracted much attention due to its increasing threat to human health. The role of sunlight irradiation and the effect of dissolved organic matter (DOM) on the transmission of antibiotic resistance are still unclear. In this study, photo-inactivation of antibiotic resistant bacteria (ARB) was investigated using antibiotic resistant E. coli (AR E. coli) that contained the tetracycline resistance gene (Tc-ARG) as a representative. The results showed that AR E. coli underwent significant photo-inactivation due to the membrane damage induced by direct irradiation and by the generated reactive oxygen species. Simulated sunlight irradiation specifically suppressed the expression of tetracycline resistance, which is attributed to the destruction of tetracycline-specific efflux pump. Tetracycline inhibited the photo-inactivation of AR E. coli due to its selective pressure on tetracycline resistant E. coli and competitive light absorption effect. Suwannee River fulvic acid (SRFA), a representative DOM, promoted the inactivation of AR E. coli and further inhibited the expression of tetracycline resistance gene due to the generation of its excited triplet state, singlet oxygen, and hydroxyl radical. The extracellular Tc-ARG also underwent fast photodegradation under light irradiation and in the presence of SRFA, which leads to the decrease of its transformation efficiency. This study provided insight into the sunlight-induced inactivation of ARB, which is of significance for understanding the transmission of tetracycline resistance in surface water.
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Affiliation(s)
- Ya-Nan Zhang
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China
| | - Tingting Zhang
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China
| | - Haiyang Liu
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China
| | - Jiao Qu
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China.
| | - Chao Li
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China
| | - Jingwen Chen
- Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Willie J G M Peijnenburg
- Institute of Environmental Sciences, Leiden University, Leiden, the Netherlands; National Institute of Public Health and the Environment (RIVM), Center for Safety of Substances and Products, Bilthoven, the Netherlands
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23
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Chen Y, Liu J, Zhang X, Blough NV. Time-Resolved Fluorescence Spectra of Untreated and Sodium Borohydride-Reduced Chromophoric Dissolved Organic Matter. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:12109-12118. [PMID: 32845124 DOI: 10.1021/acs.est.0c03135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Time-resolved fluorescence spectra of chromophoric dissolved organic matter (CDOM) from different sources were acquired using UV (280 and 375 nm) and visible light (440 and 640 nm) excitation to probe the structural basis of the emission properties of CDOM. Emission decays were faster at the blue and red edges, particularly at the red edge, relative to those acquired from 480 to 550 nm. Based on the lifetime distribution and multiexponential analysis of the emission decays recorded at different time resolution, current findings demonstrate that the components recovered based on a superposition model have no defined physical meaning. A substantial increase in steady-state fluorescence intensity and only small changes (<30%) of amplitude-weighted average lifetime caused by sodium borohydride reduction suggest that intramolecular fluorescence quenching occurs mainly through formation of ground state charge-transfer interactions. Short-lived species (lifetime < 100 ps) dominate the emission decays over wavelengths from 400 to 800 nm, particularly under excitation at long wavelengths (440 and 640 nm). Compared to locally excited (LE) states, the contribution of charge-transfer excited (ECT) states and other short-lived species to the steady-state emission is small because of their very rapid nonradiative relaxation. This study suggests that a careful choice of observation wavelength is needed to distinguish LE states from ECT states.
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Affiliation(s)
- Yuan Chen
- Department of Environmental Science, School of Resources and Environmental Science, Wuhan University, Wuhan 430079, P. R. China
| | - Juan Liu
- Department of Environmental Science, School of Resources and Environmental Science, Wuhan University, Wuhan 430079, P. R. China
| | - Xu Zhang
- Department of Environmental Science, School of Resources and Environmental Science, Wuhan University, Wuhan 430079, P. R. China
| | - Neil V Blough
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
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Goffin A, Vasquez-Vergara LA, Guérin-Rechdaoui S, Rocher V, Varrault G. Temperature, turbidity, and the inner filter effect correction methodology for analyzing fluorescent dissolved organic matter in urban sewage. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:35712-35723. [PMID: 32601876 DOI: 10.1007/s11356-020-09889-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Accepted: 06/25/2020] [Indexed: 06/11/2023]
Abstract
Dissolved organic matter (DOM) will be increasingly monitored by means of in situ fluorescence spectroscopy devices in order to supervise wastewater treatment plant efficiency, due to their ease of implementation and high-frequency measurement capacity. However, fluorescence spectroscopy measurements are reported to be sensitive to the sample matrix effects of temperature, the inner filter effect (IFE), and turbidity. Matrix effect estimation tests and signal correction have been developed for DOM (tyrosine-like, tryptophan-like, and humic substances-like fluorescent compounds) fluorescence measurements in unfiltered urban sewage samples. All such tests are conducted in temperature, absorbance, and turbidity ranges representative of urban sewage. For all fluorophores studied, an average of 1% fluorescence intensity decrease per degree (°C) of temperature increase could be observed. Protein-like fluorescent compound signals were found to be significantly affected by turbidity (0 to 210 NTU) and IFE (absorbance 254 nm > 0.200). Only temperature needs to be corrected for humic substances-like fluorescent compounds since other effects were not observed over the studied ranges of absorbance and turbidity. The fluorescence intensity correction method was applied first to each matrix effect separately and then combined by using a sequential mathematical correction methodology. An efficient methodology for determining the matrix effect correction equations for DOM fluorescence analysis into unfiltered urban sewage samples has been highlighted and could be used for in situ fluorescence measurement devices.
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Affiliation(s)
- Angélique Goffin
- LEESU, Universite Paris Est Créteil, F-94010, Créteil, France.
- SIAAP, Direction Innovation, Colombes, France.
| | | | | | | | - Gilles Varrault
- LEESU, Universite Paris Est Créteil, F-94010, Créteil, France
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25
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Zherebker A, Yakimov B, Rubekina A, Kharybin O, Fedoros EI, Perminova IV, Shirshin E, Nikolaev EN. Photoreactivity of humic-like polyphenol material under irradiation with different wavelengths explored by FTICR MS and deuteromethylation. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2020; 26:292-300. [PMID: 32264711 DOI: 10.1177/1469066720917067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The goal of this study was to establish reactivity of lignin-derived synthetic polyphenolic material under irradiation by ultraviolet (254 nm) and visible (460 and 525 nm) light in order to deeper examine relationships between the optical properties of this complex mixture and its individual constituents. In all photoirradiation experiments, blue shift of the fluorescence spectrum was observed. We aimed at understanding whether these changes could be explained on the basis of the chromophore interactions hypothesis, which implies destruction of electron-acceptor pairs via free radical transformations to be responsible for the alteration of optical properties. For this, changes in molecular composition were explored by Fourier transform ion cyclotron resonance mass spectrometry. Irradiation with UV resulted in a pronounced oxidation of polyphenols, which was manifested in the van Krevelen diagram by the formation of components with higher O/C ratio. At the same time, irradiation by visible light had led to the appearance of more condensed molecules depleted of oxygen. Consideration of changes in relative contribution of 500 most abundant components in polyphenol materials revealed higher transformation yields under UV light as compared to the visible light. Further studies using deuteromethylation followed by Fourier transform ion cyclotron resonance mass spectrometry enabled to enumerate the number of carboxylic groups in individual components of the parent polyphenol material. It was shown that at all wavelengths irradiation mainly impacted carboxylic-rich unsaturated and aromatic compounds, which can be considered as strong electron-acceptors. We suggest that their transformation is responsible for the blue shift of fluorescence spectrum, thus emphasizing the role of chromophore interaction mechanism of the optical properties formation.
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Affiliation(s)
- Alexander Zherebker
- Skolkovo Institute of Science and Technology, Moscow, Russia
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia
| | - Boris Yakimov
- Department of Physics, Lomonosov Moscow State University, Moscow, Russia
| | - Anna Rubekina
- Department of Physics, Lomonosov Moscow State University, Moscow, Russia
| | - Oleg Kharybin
- Skolkovo Institute of Science and Technology, Moscow, Russia
| | - Elena I Fedoros
- N.N. Petrov National Medical Research Center of Oncology, Saint-Petersburg, Russia
- Nobel LTD, Saint-Petersburg, Russia
| | - I V Perminova
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia
| | - Evgeny Shirshin
- Department of Physics, Lomonosov Moscow State University, Moscow, Russia
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26
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McKay G. Emerging investigator series: critical review of photophysical models for the optical and photochemical properties of dissolved organic matter. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2020; 22:1139-1165. [PMID: 32270849 DOI: 10.1039/d0em00056f] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Optical measurements (absorbance and fluorescence) are widely used to track dissolved organic matter (DOM) quantity and quality in natural and engineered systems. Despite many decades of research on the optical properties of DOM, there is a lack of understanding with regards to the underlying photophysical model that is the basis for these optical properties. This review both summarizes advances to date on the photophysical properties of DOM and seeks to critically evaluate the photophysical models for DOM optical properties. Recent studies have refined the quantitative understanding of DOM photophysical properties such as excited state lifetimes and energies, rates of different photophysical processes, and quantum yields. Considering fundamental models, more clarity is needed on whether DOM photophysical processes are due to a superposition of non-interacting components (superposition model), or whether a portion of optical signals can be ascribed to electronically interacting moieties, for example in the form of electron donor-acceptor complexes (charge transfer model). Multiple studies over more than two decades have provided evidence for the charge transfer model. Questions have been raised, however, about the broad applicability of the charge transfer model. The charge transfer and superposition model are critically reviewed in light of this current research. Recommendations are given for future studies to help clarify the accuracy of these competing photophysical models.
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Affiliation(s)
- Garrett McKay
- Zachry Department of Civil and Environmental Engineering, Texas A&M University, College Station, TX 77843, USA.
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27
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Ike IA, Karanfil T, Ray SK, Hur J. A comprehensive review of mathematical models developed for the estimation of organic disinfection byproducts. CHEMOSPHERE 2020; 246:125797. [PMID: 31918104 DOI: 10.1016/j.chemosphere.2019.125797] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 12/24/2019] [Accepted: 12/29/2019] [Indexed: 06/10/2023]
Abstract
In this review, we present comparative and comprehensive views on the foundations, potentials and limitations of the previously reported mathematical models for the estimation of the concentration of disinfection byproducts (DBPs) generated during the chlor(am)ination of water. To this end, DBPs models were divided into two major categories: static variable (SV) and dynamic variable (DV) or differential models. In SV models, variables remain in their original form throughout a chlor(am)ination modelling period while DV models consider the changes driven by a chlor(am)ination treatment as the variables. This classification and the comparative study of the two types of models led to a better understanding of the assumptions, potentials, and limitations of the existing DBP models. In opposition to several claims in the literature, certain DV models based on UV absorbance/fluorescence failed to selectively track the chromophores responsible for DBP formation. In this critical review, a conceptual model for the photophysics of dissolved organic matter (DOM) based on the theory of electron delocalization was proposed to explain some inconsistent spectroscopic properties of DOM following chlor(am)ination and several unique photophysical properties of DOM. New insights for the development and deployment of mathematical models were also provided to estimate DBPs in various settings.
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Affiliation(s)
- Ikechukwu A Ike
- Department of Environment and Energy, Sejong University, 209, Neungdong-ro, Gwangjin-gu, Seoul, 05006, South Korea
| | - Tanju Karanfil
- Environmental Engineering and Earth Sciences, Clemson University, 342 Computer Court, Anderson, SC, 29625, USA
| | - Schindra Kumar Ray
- Department of Environment and Energy, Sejong University, 209, Neungdong-ro, Gwangjin-gu, Seoul, 05006, South Korea
| | - Jin Hur
- Department of Environment and Energy, Sejong University, 209, Neungdong-ro, Gwangjin-gu, Seoul, 05006, South Korea.
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28
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McKay G, Hohner AK, Rosario-Ortiz FL. Use of optical properties for evaluating the presence of pyrogenic organic matter in thermally altered soil leachates. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2020; 22:981-992. [PMID: 32065181 DOI: 10.1039/c9em00413k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The increased frequency and severity of wildfires in forested watersheds has the potential to significantly impact the quantity and quality of water extractable organic matter (WEOM) exported from these ecosystems. This study examined the optical properties of WEOM from laboratory heated soil in order to understand physicochemical changes occurring in the organic matter as a result of heating, as well as test the usefulness of optical parameters for assessing the presence of pyrogenic organic matter. WEOM absorbance and fluorescence spectral shape and intensity varied systematically as a function of soil heating temperature. Notably, absorbance and fluorescence intensity, specific ultraviolet absorbance, apparent fluorescence quantum yield, specific fluorescence emission intensity, and maximum fluorescence emission wavelength exhibited consistent changes with heating temperature and indicated that WEOM in heated soil leachates was lower in molecular weight and more aromatic than in unheated samples. The lower molecular weight in heated soil WEOM was corroborated with size-exclusion chromatography measurements. This work increases the understanding of the molecular changes occurring in WEOM as a result of wildfire and indicates that optical measurements (i.e., absorbance and fluorescence) could be used for watershed monitoring of post-fire pyrogenic organic matter.
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Affiliation(s)
- Garrett McKay
- Zachry Department of Civil and Environmental Engineering, Texas A&M University, College Station, TX, USA.
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29
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Xu J, Kralles ZT, Hart CH, Dai N. Effects of Sunlight on the Formation Potential of Dichloroacetonitrile and Bromochloroacetonitrile from Wastewater Effluents. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:3245-3255. [PMID: 32068383 DOI: 10.1021/acs.est.9b06526] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Sunlight plays an important role in transforming effluent organic matter as wastewater effluents travel downstream, but the corresponding effects on the formation of haloacetonitriles (HANs), a group of toxic disinfection byproducts, in wastewater-impacted surface water have not been thoroughly investigated. In this study, we observed that sunlight preferentially attenuated the formation potential of bromochloroacetonitrile (BCAN-FP) over that of dichloroacetonitrile (DCAN-FP) in chlorine- and UV-disinfected secondary effluents. For four effluent samples from different plants, 36 h of irradiation by simulated sunlight removed 28-33% of DCAN-FP and 41-48% of BCAN-FP. Across a larger set of effluent samples (n = 18), 8 h of irradiation (equivalent to 2-3 d of natural sunlight) decreased the calculated cytotoxicity contributed by dihaloacetonitrile-FP in most samples. Similar behavior was observed for a mixture of wastewater and surface water (volume ratio 1:1). For UV-disinfected effluents, the higher the UV dose, the more likely was there a reduction in DCAN-FP and BCAN-FP in the subsequent sunlight irradiation. Experiments with model compounds showed that fulvic acid and UV photoproducts of tryptophan yield excited triplet-state organic matters during sunlight irradiation and play an important role in promoting the attenuation of HAN precursors.
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Affiliation(s)
- Jiale Xu
- Department of Civil, Structural and Environmental Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Zachary T Kralles
- Department of Civil, Structural and Environmental Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Christine H Hart
- Department of Civil, Structural and Environmental Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Ning Dai
- Department of Civil, Structural and Environmental Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
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30
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Ghigo G, Vione D, Berto S. Experimental and theoretical study of the fluorescence emission of ferulic acid: Possible insights into the fluorescence properties of humic substances. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020; 228:117587. [PMID: 31707022 DOI: 10.1016/j.saa.2019.117587] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 07/26/2019] [Accepted: 09/30/2019] [Indexed: 06/10/2023]
Abstract
Ferulic acid ((E)-3-(4-hydroxy-3-methoxy-phenyl)prop-2-enoic acid, hereinafter FA) is a building block of plant cell walls that is commonly found in lignocellulose. As such, it is a potential component of humic substances produced by microbial degradation of plant spoils. The fluorescence excitation-emission matrix spectra of FA have an interesting humic-like shape, with bands that can be assimilated to the A and C regions of humic substances. Therefore, the study of FA photoluminescence might provide interesting insight into the still unknown processes that lay behind the fluorescence properties of humic compounds. FA is a weak diprotic acid that occurs in three different forms in aqueous solution (neutral H2FA, singly deprotonated HFA- and doubly deprotonated FA2-), which have slightly different absorption and emission properties. The "A-like" fluorescence emission of the FA species is accounted for by excitation from the ground singlet state S0 to singlet excited states higher than the first (S4 for H2FA, S5 for HFA-, and a state higher than S2 for FA2-), followed by radiationless deactivation to the first excited singlet state (S1), and by fluorescence emission according to the S1 → S0 transition. In contrast, the "C-like" emission is mainly caused by S0 → S1 excitation combined with S1 → S0 emission, but there is also a minor contribution from the S0 → S2 excitation that becomes significant for HFA-. The uneven variations with pH of the wavelengths of the maximum FA radiation absorption and fluorescence emission can be rationalised in the framework of the energy levels of the frontier (HOMO and LUMO) molecular orbitals of the different FA species. These levels are affected by charge interaction between the relevant electrons and the neutral (protonated) or negative (deprotonated) groups of each species.
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Affiliation(s)
- Giovanni Ghigo
- Department of Chemistry, University of Torino, Via Pietro Giuria 5,7, 10125, Torino, Italy
| | - Davide Vione
- Department of Chemistry, University of Torino, Via Pietro Giuria 5,7, 10125, Torino, Italy.
| | - Silvia Berto
- Department of Chemistry, University of Torino, Via Pietro Giuria 5,7, 10125, Torino, Italy.
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31
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Zherebker A, Shirshin E, Rubekina A, Kharybin O, Kononikhin A, Kulikova NA, Zaitsev KV, Roznyatovsky VA, Grishin YK, Perminova IV, Nikolaev EN. Optical Properties of Soil Dissolved Organic Matter Are Related to Acidic Functions of Its Components as Revealed by Fractionation, Selective Deuteromethylation, and Ultrahigh Resolution Mass Spectrometry. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:2667-2677. [PMID: 32045519 DOI: 10.1021/acs.est.9b05298] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The goal of this study was to establish a relationship between the optical properties of soil dissolved organic matter (DOM) and acidic functions carried out by its individual constituents. We obtained 12 fractions of DOM samples using sequential solid phase extraction on nonionic sorbent at steadily lowered pH values: 7, 5, 3, 2, which correspond to low bounds of pKa values of phenols, aliphatic, and aromatic carboxylic acids, and ketoacids. The structural studies were conducted with the use of NMR and selective deuteromethylation of isolated fractions coupled to ultrahigh resolution mass spectrometry. First, a gradual shift of molecular compositions was observed from reduced components to aromatic oxidized compounds isolated at pH 7 and 2, respectively. Changes in molecular compositions were accompanied by a red shift of fluorescence spectra. Further application of deuteromethylation enabled us to distinguish DOM constituents with different amounts of carboxylic groups. Moreover, identification of structural isomers in a single DOM sample was achieved. Statistical analysis revealed that red shift of fluorescence is facilitated by the increase of a contribution of aromatic poly(carboxylic acid)s with high conjugation lengths. Additionally, analysis of the labeled fractionated permafrost thaw DOM directly showed carboxyl-rich alicyclic molecules, while the same components from lower-latitude DOM were assigned to lignin-like species.
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Affiliation(s)
- Alexander Zherebker
- Skolkovo Institute of Science and Technology, Skolkovo, Moscow Region 143025, Russia
- Department of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Evgeny Shirshin
- Department of Physics, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Anna Rubekina
- Department of Physics, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Oleg Kharybin
- Skolkovo Institute of Science and Technology, Skolkovo, Moscow Region 143025, Russia
| | - Alexey Kononikhin
- Skolkovo Institute of Science and Technology, Skolkovo, Moscow Region 143025, Russia
| | - Natalia A Kulikova
- Department of Soil Science, Lomonosov Moscow State University, Moscow, 119991, Russia
- Federal Research Center "Fundamentals of Biotechnology", Bakh Institute of Biochemistry, Russian Academy of Sciences, Moscow, 119071, Russia
| | - Kirill V Zaitsev
- Department of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
| | | | - Yuri K Grishin
- Department of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Irina V Perminova
- Department of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Evgeny N Nikolaev
- Skolkovo Institute of Science and Technology, Skolkovo, Moscow Region 143025, Russia
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32
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Ulliman SL, Korak JA, Linden KG, Rosario-Ortiz FL. Methodology for selection of optical parameters as wastewater effluent organic matter surrogates. WATER RESEARCH 2020; 170:115321. [PMID: 31877555 DOI: 10.1016/j.watres.2019.115321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 10/29/2019] [Accepted: 11/17/2019] [Indexed: 06/10/2023]
Abstract
Absorbance- and fluorescence-based optical parameters are commonly used as surrogates in engineered systems, but there is no systematic approach for selecting robust parameters. This study develops a methodology that is applied to a case study of differentiating wastewater effluent organic matter from naturally-derived organic matter. The methodology defines criteria to identify optical parameters that could detect statistically significant compositional differences in organic matter, independent of organic matter concentration, and measure fluorescence-based parameters with low susceptibility to inner filter effects. The criteria were applied to 26 parameters that were measured for 11 pairs of source water and conventionally-treated wastewater samples collected from sites with varied spatial and temporal conditions. Only two parameters, apparent fluorescence quantum yield measured at excitation 370 nm and fluorescence peak ratio A:T, met the criteria across all sites. These results demonstrate and encourage an objective and robust process for selecting optical surrogates for organic matter characterization.
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Affiliation(s)
- Sydney L Ulliman
- Department of Civil, Environmental and Architectural Engineering, Environmental Engineering Program, University of Colorado Boulder, Colorado, 80309, United States
| | - Julie A Korak
- Department of Civil, Environmental and Architectural Engineering, Environmental Engineering Program, University of Colorado Boulder, Colorado, 80309, United States.
| | - Karl G Linden
- Department of Civil, Environmental and Architectural Engineering, Environmental Engineering Program, University of Colorado Boulder, Colorado, 80309, United States
| | - Fernando L Rosario-Ortiz
- Department of Civil, Environmental and Architectural Engineering, Environmental Engineering Program, University of Colorado Boulder, Colorado, 80309, United States.
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33
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Carstea EM, Popa CL, Baker A, Bridgeman J. In situ fluorescence measurements of dissolved organic matter: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 699:134361. [PMID: 31683216 DOI: 10.1016/j.scitotenv.2019.134361] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 08/20/2019] [Accepted: 09/07/2019] [Indexed: 05/22/2023]
Abstract
There is a need for an inexpensive, reliable and fast monitoring tool to detect contaminants in a short time, for quick mitigation of pollution sources and site remediation, and for characterization of natural dissolved organic matter (DOM). Fluorescence spectroscopy has proven to be an excellent technique in quantifying aquatic DOM, from autochthonous, allochthonous or anthropogenic sources. This paper reviews the advances in in situ fluorescence measurements of DOM and pollutants in various water environments. Studies have demonstrated, using high temporal-frequency DOM fluorescence data, that marine autochthonous production of DOM is highly complex and that the allochthonous input of DOM from freshwater to marine water can be predicted. Furthermore, river measurement studies found a delayed fluorescence response of DOM following precipitation compared to turbidity and discharge, with various lags, depending on season, site and input of dissolved organic carbon (DOC) concentration. In addition, research has shown that blue light fluorescence (λemission = 430-500 nm) can be a good proxy for DOC, in environments with terrestrial inputs, and ultraviolet fluorescence (λemission = UVA-320-400 nm) for biochemical oxygen demand, and also E. coli in environments with sanitation issues. The correction of raw fluorescence data improves the relationship between fluorescence intensity and these parameters. This review also presents the specific steps and parameters that must be considered before and during in situ fluorescence measurement session for a harmonized qualitative and quantitative protocol. Finally, the strengths and weaknesses of the research on in situ fluorescence are identified.
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Affiliation(s)
- Elfrida M Carstea
- National Institute of R&D for Optoelectronics, Atomistilor 409, 077125 Magurele, Romania.
| | - Cristina L Popa
- National Institute of R&D for Optoelectronics, Atomistilor 409, 077125 Magurele, Romania.
| | - Andy Baker
- Connected Waters Initiative Research Centre, UNSW Sydney, Sydney, NSW 2052, Australia.
| | - John Bridgeman
- Faculty of Engineering and Informatics, University of Bradford, Richmond Road, Bradford BD7 1DP, UK.
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Yan M, Luo T, Li N, Korshin GV. Monitoring the kinetics of reactions between natural organic matter and Al(III) ions using differential absorbance spectra. CHEMOSPHERE 2019; 235:220-226. [PMID: 31260862 DOI: 10.1016/j.chemosphere.2019.06.072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 06/05/2019] [Accepted: 06/10/2019] [Indexed: 06/09/2023]
Abstract
This study examined the kinetics of the binding of Al(III) ions by natural organic matter (NOM) exemplified by Suwannee River humic acid (SRHA). This processes was studied for a 5-8 pH range and environmentally relevant concentrations of the system components. Al(III)-NOM interactions were quantified using differential absorbance spectra whose intensity and shape depended on pH and reaction time. In all cases the differential spectra had four bands with maxima located at 245, 275, 320, 380 nm. These bands were assigned to the engagement of the carboxylic-like and/or phenolic-like groups, as well as electrostatic gel in NOM. Several parameters of the absorbance spectra (e.g., spectral slopes of log-transformed spectra in wavelength range 260-270 and 350-400 nm, ΔS260-270 and ΔS350-400 respectively) were linearly correlated (R2 = 0.98) with concentrations of carboxylic-like groups and total NOM-bound Al(III) ions predicted based on the NICA-Donnan model. The binding of Al(III) ion by NOM at all pHs was modeled assuming the presence of three kinetically distinct sites. This study demonstrates that differential absorbance spectroscopy can be used to quantify the kinetics and mechanisms of NOM-metal ions interactions and monitor them in practically important system including water treatment operations.
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Affiliation(s)
- Mingquan Yan
- Department of Environmental Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, 100871, China.
| | - Tingting Luo
- School of Resources and Materials, Northeastern University at Qinhuangdao, No. 143, Taishan Road, Qinhuangdao, Hebei, 066004, China
| | - Na Li
- School of Resources and Materials, Northeastern University at Qinhuangdao, No. 143, Taishan Road, Qinhuangdao, Hebei, 066004, China
| | - Gregory V Korshin
- Department of Civil and Environmental Engineering, University of Washington, Box 352700, Seattle, WA, 98195-2700, United States
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35
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Xiao X, Xi BD, He XS, Zhang H, Li YH, Pu S, Liu SJ, Yu MD, Yang C. Redox properties and dechlorination capacities of landfill-derived humic-like acids. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 253:488-496. [PMID: 31330341 DOI: 10.1016/j.envpol.2019.07.044] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 06/20/2019] [Accepted: 07/09/2019] [Indexed: 05/26/2023]
Abstract
Electron transfer capacities (ETC) of humic-like acids (HLA) and their effects on dechlorination are dependent on their redox-active properties. Aging and minerals can affect the chemical compositions and structures of HLA. However, the underlying mechanism and the impacts on the dechlorination capacities of HLA are poorly understood. We investigated how redox properties change in association with the intrinsic chemical natures and exterior minerals of the HLA extracted from landfilled solid wastes. Furthermore, the ETC of the landfill-derived HLA could be strengthened by increasing landfill age and demineralization, thereby facilitating the dechlorination of pentachlorophenol (PCP). The HLA molecules started to polymerize aromatic macromolecules during landfilling, leading to an increase in ETC and dechlorination capacities. Macromolecular HLA were dissociated to smaller molecules and exposed more aromatic and carboxyl groups when separated from minerals, which enhanced the ETC and the dechlorination abilities of the HLA. Microbial-mediated dechlorination was an effective way to degrade PCP, and almost 80% of the PCP was transformed after 40 days of demineralized HLA and Shewanella oneidensis MR-1 incubation. The demineralization and aging further facilitated the microbial-mediated PCP dechlorination. The findings provide a scientific base for improving in-situ bioremediation of chlorinated compound-contaminated soils using freshly synthesized HLA.
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Affiliation(s)
- Xiao Xiao
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Bei-Dou Xi
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541006, China
| | - Xiao-Song He
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
| | - Hui Zhang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Yan-Hong Li
- College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541006, China
| | - Shengyan Pu
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Si-Jia Liu
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541006, China
| | - Min-Da Yu
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Chao Yang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
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Yan S, Liu Y, Lian L, Li R, Ma J, Zhou H, Song W. Photochemical formation of carbonate radical and its reaction with dissolved organic matters. WATER RESEARCH 2019; 161:288-296. [PMID: 31202115 DOI: 10.1016/j.watres.2019.06.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Revised: 05/28/2019] [Accepted: 06/01/2019] [Indexed: 05/27/2023]
Abstract
The carbonate radical (CO3•-) is a strong oxidative radical that is generated via the reactions of HCO3-/CO32- with hydroxyl radical (HO•) or triplet states of dissolved organic matter (3DOM∗) in sunlit surface water. The bimolecular reaction rate constants of CO3•- with various DOM isolates ( [Formula: see text] ) were calculated as 15-239 (mg of C/L)-1 s-1 and were correlate to the bulk DOM properties, such as the content of phenolic moieties, the specific UV absorbance (SUVA), the E2/E3 value, and the fluorescence index (FI). The spectroscopic E2/E3 values was found to strongly correlated (R2 = 0.93) with [Formula: see text] , and an empirical equation was established. Our results also demonstrate that CO3•- is involved in the photobleaching of dissolved organic matter (DOM) and in particular reacts with electron-donor moieties, leading to faster decay rates at long wavelengths of UV-vis absorption. Furthermore, a model was developed to calculate the steady-state concentrations of CO3•- during DOM photobleaching. These results allow us to estimate the reactivity of DOM with CO3•- and to evaluate the role of CO3•- in sunlit surface water. It will also allow a better assessment of the concentration and utilization of CO3•- during the application of advanced oxidation processes.
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Affiliation(s)
- Shuwen Yan
- Department of Environmental Science & Engineering, Fudan University, Shanghai, 200433, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, PR China
| | - Yingjie Liu
- Department of Environmental Science & Engineering, Fudan University, Shanghai, 200433, PR China
| | - Lushi Lian
- Department of Environmental Science & Engineering, Fudan University, Shanghai, 200433, PR China
| | - Rui Li
- Department of Environmental Science & Engineering, Fudan University, Shanghai, 200433, PR China
| | - Jianzhong Ma
- Department of Environmental Science & Engineering, Fudan University, Shanghai, 200433, PR China
| | - Huaxi Zhou
- Department of Environmental Science & Engineering, Fudan University, Shanghai, 200433, PR China
| | - Weihua Song
- Department of Environmental Science & Engineering, Fudan University, Shanghai, 200433, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, PR China.
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37
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Schendorf TM, Del Vecchio R, Bianca M, Blough NV. Combined Effects of pH and Borohydride Reduction on Optical Properties of Humic Substances (HS): A Comparison of Optical Models. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:6310-6319. [PMID: 31063364 DOI: 10.1021/acs.est.9b01516] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The combined effects of pH and borohydride reduction on the optical properties of a series of humic substances and a lignin model were examined to probe the molecular moieties and interactions that give rise to the observed optical properties of these materials. Increasing the pH from 2 to 12 produced significantly enhanced absorption across the spectra of all samples, with distinct spectral responses observed over pH ranges attributable to the deprotonation of carboxylic acids and phenols. Borohydride reduction substantially attenuated the broadband absorption enhancements with pH, clearly indicating that the loss of absorption due to ketone/aldehyde reduction is coupled with the pH-dependent increase in absorption due to deprotonation of carboxylic acids and phenols. These results cannot be easily explained by a superposition of the spectra of independently absorbing chromophores (superposition model) but are readily interpretable within a charge transfer (CT) model. Changes of fluorescence emission with pH for both untreated and borohydride reduced samples suggest that a pH-dependent structural reorganization of the HS may also be influencing the fluorescence emission. Independent of optical model, these results demonstrate that chemical tests targeted to specific moieties can identify distinct structural differences among HS sources as well as provide insight into the molecular moieties and interactions that produce the observed optical and photochemical properties.
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Leresche F, McKay G, Kurtz T, von Gunten U, Canonica S, Rosario-Ortiz FL. Effects of Ozone on the Photochemical and Photophysical Properties of Dissolved Organic Matter. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:5622-5632. [PMID: 31022348 DOI: 10.1021/acs.est.8b06410] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
This study focused on the effects of ozonation on the photochemical and photophysical properties of dissolved organic matter (DOM). Upon ozonation, a decrease in DOM absorbance was observed in parallel with an increase in singlet oxygen (1O2) and fluorescence quantum yields (Φ1O2 and ΦF). The increase in Φ1O2 was attributed to the formation of quinone-like moieties during ozonation of the phenolic moieties of DOM, while the increase in ΦF can be explained by a significant decrease in the internal conversion rate of the first excited singlet state of the DOM (1DOM*). It is a consequence of an increase in the average energy of the first electronic transition (S1 → S0) that was assessed using the wavelength of maximum fluorescence emission (λF,max). Furthermore, ozonation did not affect the ratio of the apparent steady-state concentrations of excited triplet DOM (3DOM*) and 1O2, indicating that ozonation does not affect the efficiency of 1O2 production from 3DOM*. The consequences of these changes for the phototransformation rates of micropollutants in surface waters were examined using photochemical model calculations. The decrease in DOM absorbance caused by ozonation leads to an enhancement of direct photolysis rates due to the increased transparency of the water. Rates of indirect photooxidation induced by 1O2 and 3DOM* slightly decrease after ozonation.
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Affiliation(s)
- Frank Leresche
- Department of Civil, Environmental and Architectural Engineering , University of Colorado , Boulder , Colorado 80309 , United States
| | - Garrett McKay
- Department of Civil, Environmental and Architectural Engineering , University of Colorado , Boulder , Colorado 80309 , United States
| | - Tyler Kurtz
- Department of Civil, Environmental and Architectural Engineering , University of Colorado , Boulder , Colorado 80309 , United States
| | - Urs von Gunten
- Eawag, Swiss Federal Institute of Aquatic Science and Technology , Überlandstrasse 133 , CH-8600 Dübendorf , Switzerland
- School of Architecture, Civil and Environmental Engineering (ENAC) , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland
| | - Silvio Canonica
- Eawag, Swiss Federal Institute of Aquatic Science and Technology , Überlandstrasse 133 , CH-8600 Dübendorf , Switzerland
| | - Fernando L Rosario-Ortiz
- Department of Civil, Environmental and Architectural Engineering , University of Colorado , Boulder , Colorado 80309 , United States
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39
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Gu L, Huang B, Han F, Xu Z, Ren D, He H, Pan X, Dionysiou DD. Intermittent light and microbial action of mixed endogenous source DOM affects degradation of 17β-estradiol day after day in a relatively deep natural anaerobic aqueous environment. JOURNAL OF HAZARDOUS MATERIALS 2019; 369:40-49. [PMID: 30769326 DOI: 10.1016/j.jhazmat.2019.02.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 12/29/2018] [Accepted: 02/05/2019] [Indexed: 06/09/2023]
Abstract
All kinds of wastewaters containing steroid estrogens (SEs) and mixed endogenous source dissolved organic matter (DOM) enter natural water environments with intermittent illumination where microbial action occurs in a relatively deep natural aqueous environment. The role of mixed endogenous source DOM in SEs' biodegradation and photochemical degradation in such environments was studied using 17β-estradiol (E2) in laboratory experiments under anaerobic conditions. The experimental results show that microbial action can improve the optical properties and electron transfer capability of mixed endogenous source DOM, promoting photodegradation and biodegradation. Intermittent illumination attenuates DOM's electron transfer capacity and its chromophore groups, but it improves the bioavailability of low molecular weight dissolved organic matter which promotes microbial growth under anaerobic conditions. DOM-mediated co-degradation by light and microbial action over three days was better than either individually. The presence of Fe(III) promoted electron transfer, and Fe(III)-DOM complexes accelerated energy transfer under irradiation, enhancing photodegradation. Any remaining estrogens will continue to degrade, most effectively in well-aerated waters with sufficient illumination.
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Affiliation(s)
- Lipeng Gu
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, China; Beijing Key Laboratory of Farmland Soil Pollution Prevention and Remediation, College of Resources and Environmental Science, China Agricultural University, Beijing, 100193, China
| | - Bin Huang
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, China.
| | - Fengxia Han
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, China
| | - Zhixiang Xu
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, China
| | - Dong Ren
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, China; College of Environmental Science and Engineering, China West Normal University, Nanchong, 637009, China
| | - Huan He
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, China
| | - Xuejun Pan
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, China
| | - Dionysios D Dionysiou
- Environmental Engineering and Science Program, Department of Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, OH, 45221, USA.
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40
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Perminova IV, Shirshin EA, Konstantinov AI, Zherebker A, Lebedev VA, Dubinenkov IV, Kulikova NA, Nikolaev EN, Bulygina E, Holmes RM. The Structural Arrangement and Relative Abundance of Aliphatic Units May Effect Long-Wave Absorbance of Natural Organic Matter as Revealed by 1H NMR Spectroscopy. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:12526-12537. [PMID: 30296078 DOI: 10.1021/acs.est.8b01029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The objective of this study was to shed light on structural features which underlay intensity of long wave absorbance of natural organic matter (NOM) using 1H NMR spectroscopy. For this purpose, a set of the NOM samples was assembled from arctic and nonarctic sampling sites (the Kolyma river basin and Moscow region, respectively). It was to ensure a substantial difference in the humification degree of the isolated organic matter-the biogeochemical proxy of the long-wave absorbance of NOM. The assembled NOM set was analyzed using solution-state 1H NMR spectroscopy. The distribution of both backbone and exchangeable protons was determined using acquisition of spectra in three different solvents. The substantially higher contribution of nonfunctionalized aliphatic moieties CHn (e.g., materials derived from linear terpenoids, MDLT) in the arctic NOM samples was revealed as compared to the nonarctic ones. The latter were characterized with the higher content of CHα protons adjacent to electron-withdrawing groups which belong to carboxyl rich alicyclic moieties (CRAMs) or to aromatic constituents of NOM. We have calculated a ratio of CHn to CHα protons as a structural descriptor which showed significant inverse correlation to intensity of long wave absorbance assessed with a use of E4/ E6 ratio and the slope of absorption spectrum. The steric hindrance of aromatic chromophoric groups of the NOM ensemble by bulky nonfunctionalized aliphatic moieties (e.g., MDLT) was set as a hypothesis for explanation of this phenomenon. The bulky aliphatics might increase a distance between the interacting groups resulting in inhibition of electronic (e.g., charge-transfer) interactions in the NOM ensemble. The obtained relationships were further explored using Fourier transform mass spectrometry as complementary technique to 1H NMR spectroscopy. The data obtained on correlation of molecular composition of NOM with 1H NMR data and optical properties were very supportive of our hypothesis that capabilities of NOM ensemble of charge transfer interactions can be dependent on structural arrangement and relative abundance of nonabsorbing aliphatic moieties.
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Affiliation(s)
- I V Perminova
- Department of Chemistry , Lomonosov Moscow State University , Leninskie Gory 1-3 , 119991 Moscow , Russia
| | - E A Shirshin
- Department of Physics , Lomonosov Moscow State University , Leninskie Gory 1-2 , 119991 Moscow , Russia
| | - A I Konstantinov
- Department of Chemistry , Lomonosov Moscow State University , Leninskie Gory 1-3 , 119991 Moscow , Russia
| | - A Zherebker
- Department of Chemistry , Lomonosov Moscow State University , Leninskie Gory 1-3 , 119991 Moscow , Russia
- Skolkovo Institute of Science and Technology , 143025 Skolkovo, Moscow region , Russia
- Institute for Energy Problems of Chemical Physics of RAS , Leninskij pr. 38-2 , 119334 Moscow , Russia
| | - V A Lebedev
- Department of Chemistry , Lomonosov Moscow State University , Leninskie Gory 1-3 , 119991 Moscow , Russia
- Department of Materials Science , Lomonosov Moscow State University , Leninskie Gory 1-73 , 199991 Moscow , Russia
| | - I V Dubinenkov
- Department of Chemistry , Lomonosov Moscow State University , Leninskie Gory 1-3 , 119991 Moscow , Russia
| | - N A Kulikova
- Department of Chemistry , Lomonosov Moscow State University , Leninskie Gory 1-3 , 119991 Moscow , Russia
- Department of Soil Science , Lomonosov Moscow State University , Leninskie Gory 1-12 , 199991 Moscow , Russia
- Bach Institute of Biochemistry of RAS , Federal Research Center "Biotechnology" , Leninskij pr. 33-2 , 119071 Moscow , Russia
| | - E N Nikolaev
- Skolkovo Institute of Science and Technology , 143025 Skolkovo, Moscow region , Russia
- Institute for Energy Problems of Chemical Physics of RAS , Leninskij pr. 38-2 , 119334 Moscow , Russia
| | - E Bulygina
- Woods Hole Research Center , 149 Woods Hole Rd , Falmouth , Massachusetts 02540 , United States
| | - R M Holmes
- Woods Hole Research Center , 149 Woods Hole Rd , Falmouth , Massachusetts 02540 , United States
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41
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Önnby L, Salhi E, McKay G, Rosario-Ortiz FL, von Gunten U. Ozone and chlorine reactions with dissolved organic matter - Assessment of oxidant-reactive moieties by optical measurements and the electron donating capacities. WATER RESEARCH 2018; 144:64-75. [PMID: 30014980 DOI: 10.1016/j.watres.2018.06.059] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 06/08/2018] [Accepted: 06/24/2018] [Indexed: 06/08/2023]
Abstract
Oxidation processes are impacted by the type, concentration and reactivity of the dissolved organic matter (DOM). In this study, the reactions between various types of DOM (Suwannee River fulvic acid (SRFA), Nordic Reservoir NOM (NNOM) and Pony Lake fulvic acid (PLFA)) and two oxidants (ozone and chlorine) were studied in the pH range 2-9 by using a combination of optical measurements and electron donating capacities. The relationships between residual electron donating capacity (EDC) and residual absorbance showed a strong pH dependence for the ozone-DOM reactions with phenolic functional groups being the main reacting moieties. Relative EDC and absorbance abatements (UV254 or UV280) were similar at pH 2. At pH 7 or 9, the relative abatement of EDC was more pronounced than for absorbance, which could be explained by the formation of UV-absorbing products such as benzoquinone from the transformation of phenolic moieties. An increase in fluorescence abatement with increasing pH was also observed during ozonation. The increase in fluorescence quantum yields could not be attributed to formation of benzoquinone, but related to a faster abatement of phenolic moieties relative to fluorophores with low ozone reactivity. The overall •OH yields as a result of DOM-induced ozone consumption increased significantly with increasing pH, which could be related to the higher reactivity of phenolic moieties at higher pH. The •OH yields for SRFA and PLFA were proportional to the phenolic contents, whereas for NNOM, the •OH yield was about 30% higher. During chlorination of DOM at pH 7 an efficient relative EDC abatement was observed whereas the relative absorbance abatement was much less pronounced. This is due to the formation of chlorophenolic moieties, which exert a significant absorbance, and partly lose their electron donating capacity. Pre-ozonation of SRFA leads to a decrease of chloroform and haloacetic acid formation, however, only after a threshold of > ∼50% abatement of the EDC and under conditions which are not precursor limited. The decrease in chloroform and haloacetic acid formation after the threshold EDC abatement was proportional to the relative residual EDC.
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Affiliation(s)
- Linda Önnby
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Elisabeth Salhi
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Garrett McKay
- Department of Civil, Environmental and Architectural Engineering, Environmental Engineering Program, University of Colorado, Boulder, CO 80309, USA
| | - Fernando L Rosario-Ortiz
- Department of Civil, Environmental and Architectural Engineering, Environmental Engineering Program, University of Colorado, Boulder, CO 80309, USA
| | - Urs von Gunten
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; Institute of Biogeochemistry and Pollutant Dynamics, Swiss Federal Institute of Technology (ETH) Zürich, 8092 Zürich, Switzerland; School of Architecture, Civil & Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
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42
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McKay G, Korak JA, Rosario-Ortiz FL. Temperature Dependence of Dissolved Organic Matter Fluorescence. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:9022-9032. [PMID: 30028602 DOI: 10.1021/acs.est.8b00643] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The temperature dependence of organic matter fluorescence apparent quantum yields (Φf) was measured for a diverse set of organic matter isolates (i.e., marine aquatic, microbial aquatic, terrestrial aquatic, and soil) in aqueous solution and for whole water samples to determine apparent activation energies ( Ea) for radiationless decay processes of the excited singlet state. Ea was calculated from temperature dependent Φf data obtained by steady-state methods using a simplified photophysical model and the Arrhenius equation. All aquatic-derived isolates, all whole water samples, and one soil-derived fulvic acid isolate exhibited temperature dependent Φf values, with Ea ranging from 5.4 to 8.4 kJ mol-1 at an excitation wavelength of 350 nm. Conversely, soil humic acid isolates exhibited little or no temperature dependence in Φf. Ea varied with excitation wavelength in most cases, typically exhibiting a decrease between 350 and 500 nm. The narrow range of Ea values observed for these samples when compared to literature Ea values for model fluorophores (∼5-30 kJ mol-1) points to a similar photophysical mechanism for singlet excited states nonradiative inactivation across organic matter isolates of diverse source and character. In addition, this approach to temperature dependent fluorescence analysis provides a fundamental, physical basis, in contrast to existing empirical relationships, for correcting online fluorescence sensors for temperature effects.
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Affiliation(s)
- Garrett McKay
- Department of Civil, Environmental, and Architectural Engineering , University of Colorado , Boulder , Colorado 80309 , United States
| | - Julie A Korak
- Department of Civil, Environmental, and Architectural Engineering , University of Colorado , Boulder , Colorado 80309 , United States
| | - Fernando L Rosario-Ortiz
- Department of Civil, Environmental, and Architectural Engineering , University of Colorado , Boulder , Colorado 80309 , United States
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43
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Chen Y, Zhang X, Feng S. Contribution of the Excited Triplet State of Humic Acid and Superoxide Radical Anion to Generation and Elimination of Phenoxyl Radical. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:8283-8291. [PMID: 29916697 DOI: 10.1021/acs.est.8b00890] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Contributions of excited triplet state of humic acid (3HA*) and superoxide radical anion (O2•-), which is mainly generated via the reaction of O2 with HA-derived reducing intermediates (HA•-), to phenol transformation were revealed using acetaminophen, 2,4,6-trimethylphenol and tyrosine as probe molecules. Phenol transformation was initiated by 3HA*, leading to the formation of the phenoxyl radical (PhO•), but the distribution of transformation intermediates was codetermined by 3HA* and HA•-. The influence of HA•- essentially resulted from the production of O2•-, which affected the fate of PhO•. PhO• could undergo dimerization, or react with O2•-, leading to either phenol peroxide formation (radical addition) or phenol regeneration (electron transfer). In addition, PhO• could bind to HA or react with HA radicals, particularly in the absence of O2 and O2•-. These PhO• reactions were dependent on the reduction potential and structure of PhO•. This study also proved that the reaction of phenol with 1O2 and the reaction of PhO• with O2•- lead to the same oxidation product. The contributions of 3HA* and its generated 1O2, HA•- and its generated O2•- to phenol transformation were pH-dependent.
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Affiliation(s)
- Yuan Chen
- Department of Environmental Science , School of Resources and Environmental Science, Wuhan University , Wuhan 430079 , P.R. China
| | - Xu Zhang
- Department of Environmental Science , School of Resources and Environmental Science, Wuhan University , Wuhan 430079 , P.R. China
| | - Shixiang Feng
- Department of Environmental Science , School of Resources and Environmental Science, Wuhan University , Wuhan 430079 , P.R. China
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44
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Blough NV, Del Vecchio R. Comment on The Case Against Charge Transfer Interactions in Dissolved Organic Matter Photophysics. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:5512-5513. [PMID: 29659267 DOI: 10.1021/acs.est.8b01189] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Affiliation(s)
- Neil V Blough
- Department of Chemistry and Biochemistry , University of Maryland , College Park , Maryland 20742 , United States
| | - Rossana Del Vecchio
- Earth System Science Interdisciplinary Center , University of Maryland , College Park , Maryland 20770 , United States
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45
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McKay G, Korak JA, Erickson PR, Latch DE, McNeill K, Rosario-Ortiz FL. Response to Comment on The Case Against Charge Transfer Interactions in Dissolved Organic Matter Photophysics. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:5514-5516. [PMID: 29659265 DOI: 10.1021/acs.est.8b01807] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Affiliation(s)
- Garrett McKay
- Department of Civil, Environmental and Architectural Engineering , University of Colorado , Boulder , Colorado 80309 , United States
| | - Julie A Korak
- Department of Civil, Environmental and Architectural Engineering , University of Colorado , Boulder , Colorado 80309 , United States
- Bureau of Reclamation , Department of the Interior , PO Box 25007, Denver , Colorado 80225 , United States
| | - Paul R Erickson
- Institute of Biogeochemistry and Pollutant Dynamics , ETH Zurich , 8092 Zurich , Switzerland
| | - Douglas E Latch
- Department of Chemistry , Seattle University , Seattle , Washington 98122 , United States
| | - Kristopher McNeill
- Institute of Biogeochemistry and Pollutant Dynamics , ETH Zurich , 8092 Zurich , Switzerland
| | - Fernando L Rosario-Ortiz
- Department of Civil, Environmental and Architectural Engineering , University of Colorado , Boulder , Colorado 80309 , United States
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