1
|
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.
Collapse
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
| |
Collapse
|
2
|
Li SA, Wang Q, Ma H, Cao X, Song Y, Cui F, Tanentzap AJ. Photochemical processes transform dissolved organic matter differently depending on its initial composition. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 923:171465. [PMID: 38453086 DOI: 10.1016/j.scitotenv.2024.171465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 03/01/2024] [Accepted: 03/02/2024] [Indexed: 03/09/2024]
Abstract
Dissolved organic matter (DOM) is one of the most important fluxes in the global carbon cycle but its response to light exposure remains unclear at a molecular-level. The chemical response of DOM to light should vary with its molecular composition and environmental conditions while some basic hypotheses are still unclear, such as the balance between photobleaching and photo-humification and the question of oxidative properties. Here we exposed aquatic DOM from diverse freshwaters impacted by different levels of anthropogenic activity and algal exudates to environmentally-realistic light conditions. We found that photobleaching occurred in DOM with relatively high initial humic content producing low H/C molecules, whereas DOM with low initial humic content was humified. DOM pools with relatively high initial saturation and low aromaticity were prone to transform towards more unsaturated molecular formulae and high H/C molecules with a distinct decrease of bioavailability. Photo-transformation was mainly influenced by reactive intermediates, with reactive oxygen species (ROS) playing a dominant role in humification when the initial humus content of DOM was high. In contrast, for algal DOM with high protein content, it was likely that the autoxidation of excited state DOM was more important than indirect oxidation involving ROS. Our results reveal how photo-transformation patterns depend on the initial composition of DOM and provide new insights into the role of photochemical processes in biogeochemical cycling of DOM.
Collapse
Affiliation(s)
- Sheng-Ao Li
- College of Environment and Ecology, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Qianru Wang
- College of Environment and Ecology, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Hua Ma
- College of Environment and Ecology, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China.
| | - Xinghong Cao
- College of Environment and Ecology, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Yingyue Song
- College of Environment and Ecology, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Fuyi Cui
- College of Environment and Ecology, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Andrew J Tanentzap
- Ecosystems and Global Change Group, School of the Environment, Trent University, Peterborough, Ontario K9L 0G2, Canada
| |
Collapse
|
3
|
Xu Y, Wang X, Ou Q, Zhou Z, van der Hoek JP, Liu G. Appearance of Recalcitrant Dissolved Black Carbon and Dissolved Organic Sulfur in River Waters Following Wildfire Events. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:7165-7175. [PMID: 38597176 PMCID: PMC11044583 DOI: 10.1021/acs.est.4c00492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 03/29/2024] [Accepted: 04/01/2024] [Indexed: 04/11/2024]
Abstract
Increasing wildfire frequency, a consequence of global climate change, releases incomplete combustion byproducts such as aquatic pyrogenic dissolved organic matter (DOM) and black carbon (DBC) into waters, posing a threat to water security. In August 2022, a series of severe wildfires occurred in Chongqing, China. Samples from seven locations along the Yangtze and Jialing Rivers revealed DBC, quantified by the benzene poly(carboxylic acid) (BPCA) method, comprising 9.5-19.2% of dissolved organic carbon (DOC). High concentrations of BPCA-DBC with significant polycondensation were detected near wildfire areas, likely due to atmospheric deposition driven by wind. Furthermore, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) revealed that wildfires were associated with an increase in condensed aromatics, proteins, and unsaturated hydrocarbons, along with a decrease in lignins. The condensed aromatics primarily consisted of dissolved black nitrogen (DBN), contributing to abundant high-nitrogen-containing compounds in locations highly affected by wildfires. Meanwhile, wildfires potentially induced the input of recalcitrant sulfur-containing protein-like compounds, characterized by high oxidation, aliphatic nature, saturation, and low aromaticity. Overall, this study revealed the appearance of recalcitrant DBC and dissolved organic sulfur in river waters following wildfire events, offering novel insights into the potential impacts of wildfires on water quality and environmental biogeochemistry.
Collapse
Affiliation(s)
- Yanghui Xu
- Key
Laboratory of Drinking Water Science and Technology, Research Centre for Eco-Environmental Sciences, Chinese Academy of
Sciences, Beijing 100085, China
- Section
of Sanitary Engineering, Department of Water Management, Faculty of
Civil Engineering and Geosciences, Delft
University of Technology, Stevinweg 1, 2628 CN Delft, The Netherlands
| | - Xintu Wang
- Key
Laboratory of Drinking Water Science and Technology, Research Centre for Eco-Environmental Sciences, Chinese Academy of
Sciences, Beijing 100085, China
- College
of Environmental Science and Engineering, Guilin University of Technology, Guangxi 541004, China
| | - Qin Ou
- Key
Laboratory of Drinking Water Science and Technology, Research Centre for Eco-Environmental Sciences, Chinese Academy of
Sciences, Beijing 100085, China
- Section
of Sanitary Engineering, Department of Water Management, Faculty of
Civil Engineering and Geosciences, Delft
University of Technology, Stevinweg 1, 2628 CN Delft, The Netherlands
| | - Zhongbo Zhou
- College
of Resources and Environment, Southwest
University, Chongqing 400715, China
| | - Jan Peter van der Hoek
- Section
of Sanitary Engineering, Department of Water Management, Faculty of
Civil Engineering and Geosciences, Delft
University of Technology, Stevinweg 1, 2628 CN Delft, The Netherlands
- Waternet,
Department Research & Innovation,
P.O. Box 94370, 1090 GJ Amsterdam, The Netherlands
| | - Gang Liu
- Key
Laboratory of Drinking Water Science and Technology, Research Centre for Eco-Environmental Sciences, Chinese Academy of
Sciences, Beijing 100085, China
- Section
of Sanitary Engineering, Department of Water Management, Faculty of
Civil Engineering and Geosciences, Delft
University of Technology, Stevinweg 1, 2628 CN Delft, The Netherlands
- University
of Chinese Academy of Sciences, Beijing 101408, China
| |
Collapse
|
4
|
Li M, Zhang X, Zhang Y, Xu X, Liu Y, Zhang Y, He Z, Wang J, Liang Y. Effect of interaction between dissolved organic matter and iron/manganese (hydrogen) oxides on the degradation of organic pollutants by in-situ advanced oxidation techniques. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 918:170351. [PMID: 38307288 DOI: 10.1016/j.scitotenv.2024.170351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 12/26/2023] [Accepted: 01/19/2024] [Indexed: 02/04/2024]
Abstract
Iron and manganese (hydrogen) oxides (IMHOs) exhibit excellent redox capabilities for environmental pollutants and are commonly used in situ chemical oxidation (ISCO) technologies for the degradation of organic pollutants. However, the coexisting dissolved organic matter (DOMs) in surface environments would influence the degradation behavior and fate of organic pollutants in IMHOs-based ISCO. This review has summarized the interactions and mechanisms between DOMs and IMHOs, as well as the properties of DOM-IMHOs complexes. Importantly, the promotion or inhibition impact of DOM was discussed from three perspectives. First, the presence of DOMs may hinder the accessibility of active sites on IMHOs, thus reducing their efficiency in degrading organic pollutants. The formation of compounds between DOMs and IMHOs alters their stability and activity in the degradation process. Second, the presence of DOMs may also affect the generation and transport of active species, thereby influencing the oxidative degradation process of organic pollutants. Third, specific components within DOMs also participate and affect the degradation pathways and rates. A comprehensive understanding of the interaction between DOMs and IMHOs helps to better understand and predict the degradation process of organic pollutants mediated by IMHOs in real environmental conditions and contributes to the further development and application of IMHO-mediated ISCO technology.
Collapse
Affiliation(s)
- Mengke Li
- Department of Environmental Science and Engineering, College of Environment and Resources, Xiangtan University, Xiangtan 411105, China
| | - Xin Zhang
- Department of Environmental Science and Engineering, College of Environment and Resources, Xiangtan University, Xiangtan 411105, China
| | - Yan Zhang
- Department of Environmental Science and Engineering, College of Environment and Resources, Xiangtan University, Xiangtan 411105, China
| | - Xin Xu
- Department of Environmental Science and Engineering, College of Environment and Resources, Xiangtan University, Xiangtan 411105, China
| | - Yun Liu
- Department of Environmental Science and Engineering, College of Environment and Resources, Xiangtan University, Xiangtan 411105, China.
| | - Yaoyao Zhang
- Chinese Academy of Geological Sciences, Beijing 100037, China.
| | - Zhiguo He
- School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China
| | - Jieyi Wang
- School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China
| | - Yuting Liang
- School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China
| |
Collapse
|
5
|
Armstrong G, Janssen SE, Poulin BA, Tate MT, Krabbenhoft DP, Hurley JP. Competition between Dissolved Organic Matter and Freshwater Plankton Control Methylmercury Isotope Fractionation during Uptake and Photochemical Demethylation. ACS EARTH & SPACE CHEMISTRY 2023; 7:2382-2392. [PMID: 38148993 PMCID: PMC10749477 DOI: 10.1021/acsearthspacechem.3c00154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 11/20/2023] [Accepted: 11/21/2023] [Indexed: 12/28/2023]
Abstract
Isotope fractionation related to photochemical reactions and planktonic uptake at the base of the food web is a major uncertainty in the biological application of mercury (Hg) stable isotopes. In freshwater systems, it is unclear how competitive interactions among methylmercury (MeHg), dissolved organic matter (DOM), and phytoplankton govern the magnitude of mass-dependent and mass-independent fractionation. This study investigated how DOM alters rates of planktonic MeHg uptake and photodegradation and corresponding Hg isotope fractionation in the presence of freshwater phytoplankton species, Raphidocelis subcapitata. Outdoor sunlight exposure experiments utilizing R. subcapitata were performed in the presence of different DOM samples using environmentally relevant ratios of MeHg-DOM thiol groups. The extent of Δ199Hg in phytoplankton incubations (2.99‰ St. Louis River HPOA, 1.88‰ Lake Erie HPOA) was lower compared to paired abiotic control experiments (4.29 and 2.86‰, respectively) after ∼30 h of irradiation, resulting from cell shading or other limiting factors reducing the extent of photodemethylation. Although the Δ199Hg/Δ201Hg ratio was uniform across experiments (∼1.4), Δ199Hg/δ202Hg slopes varied dramatically (from -0.96 to 15.4) across incubations with R. subcapitata and DOM. In addition, no evidence of Hg isotope fractionation was observed within R. subcapitata cells. This study provides a refined examination of Hg isotope fractionation markers for key processes occurring in the lower food web prior to bioaccumulation, critical for accurately accounting for the photochemical processing of Hg isotopes across a wide spectrum of freshwater systems.
Collapse
Affiliation(s)
- Grace
J. Armstrong
- U.S.
Geological Survey Upper Midwest Water Science Center, Madison, Wisconsin 53726, United States
- Environmental
Chemistry and Technology Program, University
of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Sarah E. Janssen
- U.S.
Geological Survey Upper Midwest Water Science Center, Madison, Wisconsin 53726, United States
| | - Brett A. Poulin
- Department
of Environmental Toxicology, University
of California Davis, Davis, California 95616 United States
| | - Michael T. Tate
- U.S.
Geological Survey Upper Midwest Water Science Center, Madison, Wisconsin 53726, United States
| | - David P. Krabbenhoft
- U.S.
Geological Survey Upper Midwest Water Science Center, Madison, Wisconsin 53726, United States
| | - James P. Hurley
- Environmental
Chemistry and Technology Program, University
of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- University
of Wisconsin Aquatic Sciences Center, Madison, Wisconsin 53706, United States
| |
Collapse
|