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Goranov AI, Sørmo E, Hagemann N, Cornelissen G, Zimmerman AR, Hatcher PG. Using the benzenepolycarboxylic acid (BPCA) method to assess activated biochars and their PFAS sorption abilities. Chemosphere 2024; 355:141750. [PMID: 38522671 DOI: 10.1016/j.chemosphere.2024.141750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 02/05/2024] [Accepted: 03/16/2024] [Indexed: 03/26/2024]
Abstract
Activated carbon (AC) has important industrial and environmental applications as it has excellent abilities to sorb contaminants such as per- and polyfluoroalkyl substances (PFAS). Current research aims to develop activated biochars (AB) from renewable biomass to replace AC that is produced from fossil feedstock. Both AC and AB are primarily comprised of condensed aromatic carbon (ConAC), the component that is the focus of this study. ConAC is characterized to determine its relationship with biochar activation conditions and PFAS sorption, which are understudied at present. Benzenepolycarboxylic acid (BPCA) markers for ConAC were quantified in steam-activated biochars (AB-Steam) and carbon dioxide-activated biochars (AB-CO2) prepared from waste timber at different temperatures (800, 850, 900 °C) and molar ratios of feedstock-carbon:steam (0.50 - 1.25). A non-activated biochar was also included as a reference. ConAC relative to total organic carbon content was higher in AB-Steam than in AB-CO2 (92 ± 2 % vs. 81 ± 11%). The ratio of benzenehexa- (B6CA) to benzenepentacarboxylic (B5CA) acids revealed that AB-Steam also had larger ConAC clusters than AB-CO2. These findings provide novel evidence that steam activation is more effective than CO2 activation in creating ConAC. To assess how ConAC impacts AB sorption abilities, AB-Steam were used to remediate PFAS from contaminated soils. The observed strong correlations between ConAC content and sorption of long-chain PFAS suggest the importance of hydrophobic interactions between PFAS tails and ConAC. Poor correlations for short-chain PFAS, on the other hand, indicated the existence of electrostatic repulsion interactions between PFAS head groups and ConAC. Collectively, these results explain the great ability of AB-Steam to sorb PFAS from contaminated soils (up to 100% remediation). More broadly, this work demonstrates that the BPCA method can be a valuable tool to assess the quality of biochars and other carbonaceous sorbents in relation to their production conditions or contaminant sorption abilities.
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Affiliation(s)
- Aleksandar I Goranov
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA, USA.
| | - Erlend Sørmo
- Department of Environmental Chemistry, Norwegian Geotechnical Institute (NGI), Oslo, Norway; Faculty of Environmental Science and Natural Resource Management (MINA), University of Life Sciences (NMBU), Ås, Norway
| | - Nikolas Hagemann
- Agroscope, Reckenholz, Switzerland; Ithaka Institute for Carbon Strategies, Arbaz, Switzerland and Goldbach, Germany
| | - Gerard Cornelissen
- Department of Environmental Chemistry, Norwegian Geotechnical Institute (NGI), Oslo, Norway; Faculty of Environmental Science and Natural Resource Management (MINA), University of Life Sciences (NMBU), Ås, Norway
| | - Andrew R Zimmerman
- Department of Geological Sciences, University of Florida, Gainesville, FL, USA
| | - Patrick G Hatcher
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA, USA.
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2
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Sørmo E, Lade CBM, Zhang J, Asimakopoulos AG, Åsli GW, Hubert M, Goranov AI, Arp HPH, Cornelissen G. Stabilization of PFAS-contaminated soil with sewage sludge- and wood-based biochar sorbents. Sci Total Environ 2024; 922:170971. [PMID: 38408660 DOI: 10.1016/j.scitotenv.2024.170971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Revised: 02/12/2024] [Accepted: 02/12/2024] [Indexed: 02/28/2024]
Abstract
Sustainable and effective remediation technologies for the treatment of soil contaminated with per- and polyfluoroalkyl substances (PFAS) are greatly needed. This study investigated the effects of waste-based biochars on the leaching of PFAS from a sandy soil with a low total organic carbon content (TOC) of 0.57 ± 0.04 % impacted by PFAS from aqueous film forming foam (AFFF) dispersed at a former fire-fighting facility. Six different biochars (pyrolyzed at 700-900 °C) were tested, made from clean wood chips (CWC), waste timber (WT), activated waste timber (aWT), two digested sewage sludges (DSS-1 and DSS-2) and de-watered raw sewage sludge (DWSS). Up-flow column percolation tests (15 days and 16 pore volume replacements) with 1 % biochar indicated that the dominant congener in the soil, perfluorooctane sulphonic acid (PFOS) was retained best by the aWT biochar with a 99.9 % reduction in the leachate concentration, followed by sludge-based DWSS (98.9 %) and DSS-2 and DSS-1 (97.8 % and 91.6 %, respectively). The non-activated wood-based biochars (CWC and WT) on the other hand, reduced leaching by <42.4 %. Extrapolating this to field conditions, 90 % leaching of PFOS would occur after 15 y for unamended soil, and after 1200 y and 12,000 y, respectively, for soil amended with 1 % DWSS-amended and aWT biochar. The high effectiveness of aWT and the three sludge-based biochars in reducing PFAS leaching from the soil was attributed largely to high porosity in a pore size range (>1.5 nm) that can accommodate the large PFAS molecules (>1.02-2.20 nm) combined with a high affinity to the biochar matrix. Other factors like anionic exchange capacity could play a contributing role. Sorbent effectiveness was better for long-chain than for short-chain PFAS, due to weaker, apolar interactions between the biochar and the latter's shorter hydrophobic CF2-tails. The findings were the first to demonstrate that locally sourced activated wood-waste biochars and non-activated sewage sludge biochars could be suitable sorbents for the ex situ stabilization and in situ remediation of PFAS-contaminated soil, bringing this technology one step closer to full-scale field testing.
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Affiliation(s)
- Erlend Sørmo
- Norwegian Geotechnical Institute (NGI), 0484 Oslo, Norway; Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences (NMBU), 1430 Ås, Norway
| | - Clara Benedikte Mader Lade
- Norwegian Geotechnical Institute (NGI), 0484 Oslo, Norway; Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences (NMBU), 1430 Ås, Norway
| | - Junjie Zhang
- Department of Chemistry, Norwegian University of Science and Technology (NTNU), 7024 Trondheim, Norway
| | | | - Geir Wold Åsli
- Norwegian Geotechnical Institute (NGI), 0484 Oslo, Norway
| | - Michel Hubert
- Norwegian Geotechnical Institute (NGI), 0484 Oslo, Norway
| | - Aleksandar I Goranov
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA, USA
| | - Hans Peter H Arp
- Norwegian Geotechnical Institute (NGI), 0484 Oslo, Norway; Department of Chemistry, Norwegian University of Science and Technology (NTNU), 7024 Trondheim, Norway
| | - Gerard Cornelissen
- Norwegian Geotechnical Institute (NGI), 0484 Oslo, Norway; Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences (NMBU), 1430 Ås, Norway.
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Carneiro Barreto MS, Wani RP, Goranov AI, Sowers TD, Fischel M, Douglas TA, Hatcher PG, Sparks DL. Carbon Fate, Iron Dissolution, and Molecular Characterization of Dissolved Organic Matter in Thawed Yedoma Permafrost under Varying Redox Conditions. Environ Sci Technol 2024; 58:4155-4166. [PMID: 38385246 DOI: 10.1021/acs.est.3c08219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Permafrost soils store ∼50% of terrestrial C, with Yedoma permafrost containing ∼25% of the total C. Permafrost is undergoing degradation due to thawing, with potentially hazardous effects on landscape stability and water resources. Complicating ongoing efforts to project the ultimate fate of deep permafrost C is the poorly constrained role of the redox environment, Fe-minerals, and its redox-active phases, which may modulate organic C-abundance, composition, and reactivity through complexation and catalytic processes. We characterized C fate, Fe fractions, and dissolved organic matter (DOM) isolates from permafrost-thaw under varying redox conditions. Under anoxic incubation conditions, 33% of the initial C was lost as gaseous species within 21 days, while under oxic conditions, 58% of C was lost. Under anoxic incubation, 42% of the total initial C was preserved in a dissolved fraction. Lignin-like compounds dominated permafrost-thaw, followed by lipid- and protein-like compounds. However, under anoxic incubation conditions, there was accumulation of lipid-like compounds and reduction in the nominal oxidation state of C over time, regardless of the compound classes. DOM dynamics may be affected by microbial activity and abiotic processes mediated by Fe-minerals related to selective DOM fractionation and/or its oxidation. Chemodiversity DOM signatures could serve as valuable proxies to track redox conditions with permafrost-thaw.
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Affiliation(s)
| | - Rucha P Wani
- Department of Plant & Soil Sciences, University of Delaware, Newark, Delaware 19716, United States
- Department of Earth Sciences, Spatial Sciences Institute, University of Southern California, Los Angeles, California 90089, United States
| | - Aleksandar I Goranov
- Department of Chemistry and Biochemistry, Old Dominion University, 4501 Elkhorn Avenue, Norfolk, Virginia 23529, United States
| | - Tyler D Sowers
- Department of Plant & Soil Sciences, University of Delaware, Newark, Delaware 19716, United States
- Center for Environmental Measurement and Modeling, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, Durham, North Carolina 27711, United States
| | - Matthew Fischel
- Department of Plant & Soil Sciences, University of Delaware, Newark, Delaware 19716, United States
- USDA-ARS: Sustainable Agriculture Systems Lab, Beltsville, Maryland 20705, United States
| | - Thomas Alexander Douglas
- U.S. Army Cold Regions Research & Engineering Laboratory, Fort Wainwright, Fairbanks, Alaska 99703, United States
| | - Patrick G Hatcher
- Department of Chemistry and Biochemistry, Old Dominion University, 4501 Elkhorn Avenue, Norfolk, Virginia 23529, United States
| | - Donald L Sparks
- Department of Plant & Soil Sciences, University of Delaware, Newark, Delaware 19716, United States
- Hagler Institute Fellow, Texas A&M University, College Station, Texas 77840, United States
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Goranov AI, Chen H, Duan J, Myneni SCB, Hatcher PG. Potentially Massive and Global Non-Pyrogenic Production of Condensed "Black" Carbon through Biomass Oxidation. Environ Sci Technol 2024; 58:2750-2761. [PMID: 38294931 PMCID: PMC10867845 DOI: 10.1021/acs.est.3c05448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 02/02/2024]
Abstract
With the increased occurrences of wildfires worldwide, there has been an increase in scientific interest surrounding the chemistry of fire-derived "black" carbon (BC). Traditionally, wildfire research has assumed that condensed aromatic carbon (ConAC) is exclusively produced via combustion, and thus, ConAC is equated to BC. However, the lack of correlations between ConAC in soils or rivers and wildfire history suggests that ConAC may be produced non-pyrogenically. Here, we show quantitative evidence that this occurs during the oxidation of biomass with environmentally ubiquitous hydroxyl radicals. Pine wood boards exposed to iron nails and natural weather conditions for 12 years yielded a charcoal-like ConAC-rich material. ConAC was also produced during laboratory oxidations of pine, maple, and brown-rotted oak woods, as well as algae, corn root, and tree bark. Back-of-the-envelope calculations suggest that biomass oxidation could be producing massive non-pyrogenic ConAC fluxes to terrestrial and aquatic environments. These estimates (e.g., 163-182 Tg-ConAC/year to soils) are much higher than the estimated pyrogenic "BC" fluxes (e.g., 128 Tg-ConAC/year to soils) implying that environmental ConAC is primarily non-pyrogenic. This novel perspective suggests that wildfire research trajectories should shift to assessing non-pyrogenic ConAC sources and fluxes, developing new methods for quantifying true BC, and establishing a new view of ConAC as an intermediate species in the biogeochemical processing of biomass during soil humification, aquatic photochemistry, microbial degradation, or mineral-organic matter interactions. We also advise against using BC or pyrogenic carbon (pyC) terminologies for ConAC measured in environmental matrices, unless a pyrogenic source can be confidently assigned.
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Affiliation(s)
- Aleksandar I. Goranov
- Department
of Chemistry and Biochemistry, Old Dominion
University, Norfolk, Virginia 23529 United States
| | - Hongmei Chen
- Department
of Chemistry and Biochemistry, Old Dominion
University, Norfolk, Virginia 23529 United States
| | - Jianshu Duan
- Department
of Geosciences, Princeton University, Princeton, New Jersey 08544 United States
| | - Satish C. B. Myneni
- Department
of Geosciences, Princeton University, Princeton, New Jersey 08544 United States
| | - Patrick G. Hatcher
- Department
of Chemistry and Biochemistry, Old Dominion
University, Norfolk, Virginia 23529 United States
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Goranov AI, Sleighter RL, Yordanov DA, Hatcher PG. TEnvR: MATLAB-based toolbox for environmental research. Anal Methods 2023; 15:5390-5400. [PMID: 37807701 DOI: 10.1039/d3ay00750b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
With the advancements in science and technology, datasets become larger and more multivariate, which warrants the need for programming tools for fast data processing and multivariate statistical analysis. Here, the MATLAB-based Toolbox for Environmental Research "TEnvR" (pronounced "ten-ver") is introduced. This novel toolbox includes 44 open-source codes for automated data analysis from a multitude of techniques, such as ultraviolet-visible, fluorescence, and nuclear magnetic resonance spectroscopies, as well as from ultrahigh resolution mass spectrometry. Provided are codes for processing data (e.g., spectral corrections, formula assignment), visualization of figures, calculation of metrics, multivariate statistics, and automated work-up of large datasets. TEnvR allows for efficient data analysis with minimal "by-hand" manual work by the user, which allows scientists to do research more efficiently. This manuscript is supplemented with a detailed tutorial, example data, and screenshots, which collectively provide instructions on how to use all codes. TEnvR is novice-friendly and experience in programming with MATLAB is not required. TEnvR fulfills the need for a concise MATLAB-based toolbox for working with environmental data and will be updated annually to keep pace with the latest advances and needs for computational work in the environmental sciences.
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Affiliation(s)
- Aleksandar I Goranov
- Department of Chemistry and Biochemistry, Old Dominion University, 4501 Elkhorn Avenue, Norfolk, VA 23529, USA.
| | - Rachel L Sleighter
- Department of Chemistry and Biochemistry, Old Dominion University, 4501 Elkhorn Avenue, Norfolk, VA 23529, USA.
- FBSciences, Inc. R&D Laboratory, 349 Southport Circle, Suite 102, Virginia Beach, VA 23452, USA
| | | | - Patrick G Hatcher
- Department of Chemistry and Biochemistry, Old Dominion University, 4501 Elkhorn Avenue, Norfolk, VA 23529, USA.
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Goranov AI, Tadini AM, Martin-Neto L, Bernardi ACC, Oliveira PPA, Pezzopane JRM, Milori DMBP, Mounier S, Hatcher PG. Comparison of Sample Preparation Techniques for the (-)ESI-FT-ICR-MS Analysis of Humic and Fulvic Acids. Environ Sci Technol 2022; 56:12688-12701. [PMID: 35969691 DOI: 10.1021/acs.est.2c01125] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Soil organic matter (SOM) plays a key role in the global carbon and nitrogen cycles. Soil biogeochemistry is regularly studied by extracting the base-soluble fractions of SOM: acid-insoluble humic acid (HA) and acid-soluble fulvic acid (FA). Electrospray ionization-Fourier transform-ion cyclotron resonance-mass spectrometry (ESI-FT-ICR-MS) is commonly utilized for molecularly characterizing these fractions. Different sample preparation techniques exist for the analysis of HA and FA though questions remain regarding data comparability following different preparations. Comparisons of different sample preparation techniques here revealed that the negative-mode ESI-FT-ICR-MS analytical window can be skewed to detect different groups of molecules, with primary differences in oxygenation, aromaticity, and molecular weight. It was also observed that HA and FA from soils versus an aquatic matrix behaved very differently. Thus, we conclude that sample preparation techniques determined to be "most optimal" in our study are in no way universal. We recommend that future studies of HA and FA involve similar comparative studies for determining the most suitable sample preparation technique for their particular type of HA or FA matrices. This will enhance data comparability among different studies and environmental systems and ultimately allow us to better understand the complex composition of environmental matrices.
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Affiliation(s)
- Aleksandar I Goranov
- Department of Chemistry and Biochemistry, Old Dominion University, 4501 Elkhorn Avenue, Norfolk, Virginia 23529, United States
| | - Amanda M Tadini
- Department of Chemistry and Biochemistry, Old Dominion University, 4501 Elkhorn Avenue, Norfolk, Virginia 23529, United States
- Embrapa Instrumentação, Brazilian Agricultural Research Corporation - Embrapa, Street XV de Novembro, 1452, São Carlos, São Paulo 13560-970, Brazil
| | - Ladislau Martin-Neto
- Embrapa Instrumentação, Brazilian Agricultural Research Corporation - Embrapa, Street XV de Novembro, 1452, São Carlos, São Paulo 13560-970, Brazil
| | - Alberto C C Bernardi
- Embrapa Pecuária Sudeste, Brazilian Agricultural Research Corporation - Embrapa, Rodovia Washington Luiz, Km 234 s/n°, Fazenda Canchim São Carlos, São Paulo 13560-970, Brazil
| | - Patricia P A Oliveira
- Embrapa Pecuária Sudeste, Brazilian Agricultural Research Corporation - Embrapa, Rodovia Washington Luiz, Km 234 s/n°, Fazenda Canchim São Carlos, São Paulo 13560-970, Brazil
| | - José R M Pezzopane
- Embrapa Pecuária Sudeste, Brazilian Agricultural Research Corporation - Embrapa, Rodovia Washington Luiz, Km 234 s/n°, Fazenda Canchim São Carlos, São Paulo 13560-970, Brazil
| | - Débora M B P Milori
- Embrapa Instrumentação, Brazilian Agricultural Research Corporation - Embrapa, Street XV de Novembro, 1452, São Carlos, São Paulo 13560-970, Brazil
| | - Stéphane Mounier
- Unité mixte 110, Mediterranean Institute of Oceanography (MIO), Université de Toulon, Avenue de l'Université - Bat. R, Toulon 83041, France
- Unité mixte 110, MIO, Aix Marseille Université, 163 Avenue de Luminy, Marseille 13288, France
- Unité mixte 110, MIO, Institut de la Recherche et du Développement, 163 Avenue de Luminy, Marseille 13288, France
- Unité mixte 110, MIO, Institut des Sciences de l'Univers, Centre National de la Recherche Scientifique, 163 Avenue de Luminy, Marseille 13288, France
| | - Patrick G Hatcher
- Department of Chemistry and Biochemistry, Old Dominion University, 4501 Elkhorn Avenue, Norfolk, Virginia 23529, United States
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Tadini AM, Goranov AI, Martin-Neto L, Bernardi ACC, Oliveira PPA, Pezzopane JRM, Hatcher PG. Structural characterization using 2D NMR spectroscopy and TMAH-GC × GC-MS: Application to humic acids from soils of an integrated agricultural system and an Atlantic native forest. Sci Total Environ 2022; 815:152605. [PMID: 34971684 DOI: 10.1016/j.scitotenv.2021.152605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 12/15/2021] [Accepted: 12/18/2021] [Indexed: 06/14/2023]
Abstract
Understanding the chemical make-up of soils and their structure is critical for constraining the role of soil organic matter (SOM) into the global biogeochemical cycles, as well as to understand the capability of SOM to sequester carbon and mitigate greenhouse gas emissions. Here, we use two-dimensional 1H-13C heteronuclear single quantum coherence nuclear magnetic resonance (2D 1H-13C HSQC NMR) spectroscopy to structurally characterize the most refractory component of SOM, the humic acid (HA). The observations from 2D 1H-13C HSQC NMR were coupled with lignin phenol and fatty acid measurements using tetramethylammonium hydroxide (TMAH) thermochemolysis - two-dimensional gas chromatography - mass spectrometry (TMAH-GC × GC-MS). We studied humic acids extracted from an integrated Crop - Livestock - Forest System (CLFS) agricultural area and an undisturbed Atlantic Native Forest (NF) area. We evaluated soils from two different depths: the topsoil (0-20 cm) and subsoil (60-100 cm) layers, and reveal the presence of oxidized ligninaceous phenols as we had previously hypothesized. Collectively, our results indicate that there are significant oxidative processes with increasing soil depth which are more pronounced in the CLFS relative to the NF area. Degradation of stearic acid with increasing depth in the CLFS soils indicated that the CLFS is more microbiologically active than NF. Therefore, CLFS is less biochemically stable than we originally perceived. The enhanced bio-reactivity of CLFS is likely driving the enhanced carbon sequestration in the CLFS soils. This is perhaps due to the diversity of biomass remnants available at the CLFS soil rhizosphere which allows for more different types of biomass to be sequestered as oxidized ligninaceous phenols. Our results employing structural characterization with 2D 1H-13C HSQC NMR and TMAH-GC × GC-MS provide a new layer of knowledge about the practice of integrated agricultural systems and allow us to understand the structure and fate of sequestered carbon in soils from different soil environments.
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Affiliation(s)
- Amanda M Tadini
- Embrapa Instrumentação, São Carlos, SP, Brazil; Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA, USA.
| | - Aleksandar I Goranov
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA, USA
| | | | | | | | | | - Patrick G Hatcher
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA, USA
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Bostick KW, Zimmerman AR, Goranov AI, Mitra S, Hatcher PG, Wozniak AS. Photolability of pyrogenic dissolved organic matter from a thermal series of laboratory-prepared chars. Sci Total Environ 2020; 724:138198. [PMID: 32272404 DOI: 10.1016/j.scitotenv.2020.138198] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 03/10/2020] [Accepted: 03/23/2020] [Indexed: 06/11/2023]
Abstract
While pyrogenic dissolved organic matter (pyDOM) is known to be photolabile, the rates and components of pyDOM that are lost via photochemical degradation, and how these vary with pyrogenic source, are poorly understood. Thus, pyDOM was leached from an oak thermal series and a grass chars (250-650 °C) and photoirradiated in a solar simulator. About 10-20% of oak char leachate organic C was mineralized over five days, with greater proportions lost from leachates of higher temperature parent chars. Ultraviolet and fluorescence spectroscopy suggested that mainly aromatic components (e.g., fulvic-, humic-, aromatic-like) were lost. Quantification of benzenepolycarboxylic acids (BPCAs), molecular markers indicated that 75-94% of condensed aromatic C was lost during the first five days of photoincubation, with preferential loss of larger aromatic clusters. Using a 2-component exponential decay model, this most photolabile fraction was calculated to have experimental half-lives of about 1 day. It represented 16 to 23% of the dissolved C, was primarily condensed aromatics, and was likely lost through primary photoreactions. A non-condensed component was lost at half-lives of about 1-2 d, likely through radical-driven propagation reactions. Using the same model, about 43% of pyrogenic C was predicted to be photomineralized over the course of 1 year. These results highlight the contrasting reactivity of condensed and non-condensed portions of pyDOM, and both should be considered when evaluating the potential of pyDOM to alter aquatic ecology and the environmental mobility of priority pollutants.
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Affiliation(s)
- Kyle W Bostick
- Department of Geological Sciences, University of Florida, Gainesville, FL, United States
| | - Andrew R Zimmerman
- Department of Geological Sciences, University of Florida, Gainesville, FL, United States.
| | - Aleksandar I Goranov
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA, United States
| | - Siddhartha Mitra
- Department of Geological Sciences, East Carolina University, Greenville, NC, United States
| | - Patrick G Hatcher
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA, United States
| | - Andrew S Wozniak
- School of Marine Science and Policy, College of Earth, Ocean, and Environment, University of Delaware, Lewes, DE, United States
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