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Huang C, Zeng Y, Jiang Y, Zhang Y, Lu Q, Liu YE, Guo J, Wang S, Luo X, Mai B. Comprehensive exploration of the anaerobic biotransformation of polychlorinated biphenyls in Dehalococcoides mccartyi CG1: Kinetics, enantioselectivity, and isotope fractionation. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 346:123650. [PMID: 38402932 DOI: 10.1016/j.envpol.2024.123650] [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: 11/08/2023] [Revised: 02/18/2024] [Accepted: 02/22/2024] [Indexed: 02/27/2024]
Abstract
Anaerobic microbial transformation is a key pathway in the natural attenuation of polychlorinated biphenyls (PCBs). Much less is known about the transformation behaviors induced by pure organohalide-respiring bacteria, especially kinetic isotope effects. Therefore, the kinetics, pathways, enantioselectivity, and carbon and chlorine isotope fractionation of PCBs transformation by Dehalococcoides mccartyi CG1 were comprehensively explored. The results indicated that the PCBs were mainly dechlorinated via removing their double-flanked meta-chlorine, with their first-order kinetic constants following the order of PCB132 > PCB174 > PCB85 > PCB183 > PCB138. However, PCBs occurred great loss of stoichiometric mass balance during microbial transformation, suggesting the generation of other non-dehalogenation products and/or stable intermediates. The preferential transformation of (-)-atropisomers and generation of (+)-atropisomers were observed during PCB132 and PCB174 biotransformation with the enantiomeric enrichment factors of -0.8609 ± 0.1077 and -0.4503 ± 0.1334 (first half incubation times)/-0.1888 ± 0.1354 (second half incubation times), respectively, whereas no enantioselectivity occurred during PCB183 biotransformation. More importantly, although there was no carbon and chlorine isotope fractionation occurring for studied substrates, the δ13C values of dechlorination products, including PCB47 (-28.15 ± 0.35‰ ∼ -27.77 ± 0.20‰), PCB91 (-36.36 ± 0.09‰ ∼ -34.71 ± 0.49‰), and PCB149 (-28.08 ± 0.26‰ ∼ -26.83 ± 0.10‰), were all significantly different from those of their corresponding substrates (PCB85: -30.81 ± 0.02‰ ∼ -30.22 ± 0.21‰, PCB132: -33.57 ± 0.15‰ ∼ -33.13 ± 0.14‰, and PCB174: -26.30 ± 0.09‰ ∼ -26.01 ± 0.07‰), which further supported the generation of other non-dehalogenation products and/or stable intermediates with enrichment or depletion of 13C. These findings provide deeper insights into the anaerobic microbial transformation behaviors of PCBs.
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Affiliation(s)
- Chenchen Huang
- China University of Mining & Technology, School of Environmental Science & Spatial Informatics, Xuzhou 221116, Jiangsu, China; State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Hangzhou, 310015, China
| | - Yanhong Zeng
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-MaCao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
| | - Yiye Jiang
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-MaCao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Yanting Zhang
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-MaCao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Qihong Lu
- School of Environmental Science and Engineering, Sun Yat-sen University, China
| | - Yin-E Liu
- China University of Mining & Technology, School of Environmental Science & Spatial Informatics, Xuzhou 221116, Jiangsu, China; State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Jian Guo
- Guangdong University of Petrochemical Technology, Maoming 525000, China
| | - Shanquan Wang
- School of Environmental Science and Engineering, Sun Yat-sen University, China
| | - Xiaojun Luo
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-MaCao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Bixian Mai
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-MaCao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
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Huang C, Zeng Y, Hu K, Jiang Y, Zhang Y, Lu Q, Liu YE, Gao S, Wang S, Luo X, Mai B. Anaerobic biotransformation of two novel brominated flame retardants: Kinetics, isotope fractionation and reaction mechanisms. WATER RESEARCH 2023; 243:120360. [PMID: 37481998 DOI: 10.1016/j.watres.2023.120360] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 07/12/2023] [Accepted: 07/14/2023] [Indexed: 07/25/2023]
Abstract
1,2,5,6-tetrabromocyclooctane (TBCO) and 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE), as safer alternatives to traditional brominated flame retardants, have been extensively detected in various environmental media and pose emerging risks. However, much less is known about their fate in the environment. Anaerobic microbial transformation is a key pathway for the natural attenuation of contaminants. This study investigated, for the first time, the microbial transformation behaviors of β-TBCO and DPTE by Dehalococcoides mccartyi strain CG1. The results indicated that both β-TBCO and DPTE could be easily transformed by D. mccartyi CG1 with kobs values of 0.0218 ± 0.0015 h-1 and 0.0089 ± 0.0003 h-1, respectively. In particular, β-TBCO seemed to undergo dibromo-elimination and then epoxidation to form 4,5-dibromo-9-oxabicyclo[6.1.0]nonane, while DPTE experienced debromination at the benzene ring (ortho-bromine being removed prior to para-bromine) rather than at the carbon chain. Additionally, pronounced carbon and bromine isotope fractionations were observed during biotransformation of β-TBCO and DPTE, suggesting that C-Br bond breaking is the rate-limiting step of their biotransformation. Finally, coupled with identified products and isotope fractionation patterns, β-elimination (E2) and Sn2-nucleophilic substitution were considered the most likely microbial transformation mechanisms for β-TBCO and DPTE, respectively. This work provides important information for assessing the potential of natural attenuation and environmental risks of β-TBCO and DPTE.
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Affiliation(s)
- Chenchen Huang
- School of Environmental Science & Spatial Informatics, China University of Mining & Technology, Xuzhou, Jiangsu 221116, China; State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Hangzhou 310015, China
| | - Yanhong Zeng
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-MaCao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
| | - Keqi Hu
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-MaCao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Yiye Jiang
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-MaCao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Yanting Zhang
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-MaCao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Qihong Lu
- School of Environmental Science and Engineering, Sun Yat-sen University, China
| | - Yin-E Liu
- School of Environmental Science & Spatial Informatics, China University of Mining & Technology, Xuzhou, Jiangsu 221116, China; State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Shutao Gao
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-MaCao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Shanquan Wang
- School of Environmental Science and Engineering, Sun Yat-sen University, China
| | - Xiaojun Luo
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-MaCao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Bixian Mai
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-MaCao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
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Wang G, Liu Y, Wang X, Dong X, Jiang N, Wang H. Application of dual carbon-bromine stable isotope analysis to characterize anaerobic micro-degradation mechanisms of PBDEs in wetland bottom-water. WATER RESEARCH 2022; 208:117854. [PMID: 34800854 DOI: 10.1016/j.watres.2021.117854] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 11/05/2021] [Accepted: 11/06/2021] [Indexed: 06/13/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs), one kind of persistent organic pollutants, were widely detected in coastal wetlands. Microbial reductive debromination is one of the most important attenuation processes for PBDEs in anaerobic environment, whereas the underlying reaction mechanisms remain elusive. Dual-element stable isotope analysis was recently recognized to distinguish different reaction mechanism for degradation of organic pollutants. In this study, the dual carbon-bromine isotope effects associated with the anaerobic microbial degradation were first investigated to characterize the reaction mechanisms for BDE-47 and BDE-153. Presence of lower brominated congeners indicated stepwise debromination as the main degradation pathway, with the preferential removal of bromine in para position > meta/ortho position. The pronounced isotope fractionation was observed for both carbon and bromine, with similar carbon (εC) and bromine isotope enrichment factor (εBr) between BDE-47 (εC = -5.98‰, εBr = -2.44‰) and BDE-153 (εC = -5.57‰, εBr = -2.06‰) during the microbial degradation. Compared to εC and εBr, the correlation of carbon and isotope effects (ΛC/Br = Δδ81Br/Δδ13C) was almost the same between BDE-47 (0.436) and BDE-153 (0.435), indicating the similar reaction mechanism. The calculated carbon and bromine apparent kinetic isotope effects (AKIEC and AKIEBr) were 1.0773 and 1.0098 for BDE-47 and 1.0716 and 1.0125 for BDE-153, within range reported for degradation of halogenated compounds following nucleophilic substitution. Combination analysis of degradation products, ΛC/Br and AKIE, all the results pointed to that the anaerobic reductive debromination of BDE-47 and BDE-153 followed the nucleophilic aromatic substitution, with the addition of cofactor to the benzene ring concomitant with dissociation of carbon-bromine bond via the inner-sphere electron transfer, and the cleavage of C-Br bond was the rate-determining step. This study contributed to the development of dual carbon-bromine isotope analysis as a robust approach to probe the fate of PBDEs in contaminated sites.
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Affiliation(s)
- Guoguang Wang
- College of Environmental Science and Engineering, Dalian Maritime University, Dalian 116026, China
| | - Yu Liu
- College of Environmental Science and Engineering, Dalian Maritime University, Dalian 116026, China; Environmental Information Institute, Dalian Maritime University, Dalian 116026, China.
| | - Xu Wang
- College of Environmental Science and Engineering, Dalian Maritime University, Dalian 116026, China
| | - Xu Dong
- College of Environmental Science and Engineering, Dalian Maritime University, Dalian 116026, China
| | - Na Jiang
- College of Environmental Science and Engineering, Dalian Maritime University, Dalian 116026, China
| | - Haixia Wang
- Navigation College, Dalian Maritime University, Dalian 116026, China
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Tang C, Tan J, Tang C, Liu D, Zhang P, Peng X. Are chlorine isotopologues of polychlorinated organic pollutants binomially distributed? Theoretical evaluation, numerical simulation, experimental evidences and implications for chlorine isotope analysis and source identification. CHEMOSPHERE 2021; 282:131099. [PMID: 34119735 DOI: 10.1016/j.chemosphere.2021.131099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 05/25/2021] [Accepted: 06/01/2021] [Indexed: 06/12/2023]
Abstract
Relative abundances of chlorine isotopologues of polychlorinated organic compounds (POCs) are commonly recognized to comply with binomial distribution. This study investigated whether chlorine isotopologue distributions of polychlorinated organic pollutants are binomial and evaluated implications of the distributions to relevant analytical and environmental research by theoretical derivation, numerical simulation and experiment. Chlorine kinetic isotope effects and equilibrium isotope effects vary in stepwise chlorination reactions, leading to inconsistent chlorine isotope ratios on different reaction positions of products, which results in non-binomial chlorine isotopologue distributions of the products. After physical changes and dechlorination, chlorine isotopologues of POCs are unlikely binomially distributed. The experimental results demonstrated that the chlorine isotopologue distributions of perchloroethylene, trichloroethylene, methyl-triclosan, and 2,3,7,8-tetrachlorodibenzofuran in standards and four polychlorinated biphenyls in both standard solutions and sediments were non-binomial. The patterns of chlorine isotope ratios derived from pairs of neighboring chlorine isotopologues of POCs from different sources were different, implying different isotopologue distributions, which might cause biases in compound-specific isotope analysis of chlorine (CSIA-Cl) and source identification. A complete-isotopologue scheme for isotope ratio calculation is recommended to CSIA-Cl for obtaining accurate data. Gas chromatography-double focusing magnetic-sector high resolution mass spectrometry is a promising instrument for CSIA-Cl that uses the complete-isotopologue scheme due to its excellent sensitivity, selectivity and ruggedness. This study yields new insights into chlorine isotopologue distributions of polychlorinated organic pollutants and proposes practicable solutions to improve CSIA-Cl that uses gas chromatography-mass spectrometry and facilitate source identification of polychlorinated organic pollutants.
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Affiliation(s)
- Caiming Tang
- Laboratory of Advanced Analytical Chemistry and Detection Technology, Research Center for Eco-Environmental Engineering, Dongguan University of Technology, Dongguan, 523808, China; State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.
| | - Jianhua Tan
- Guangzhou Quality Supervision and Testing Institute, Guangzhou, 510110, China
| | - Caixing Tang
- The Third Affiliated Hospital of Sun Yat-sen University, Lingnan Hospital, Guangzhou, 510630, China
| | - Deyun Liu
- Guangzhou Quality Supervision and Testing Institute, Guangzhou, 510110, China
| | - Peilin Zhang
- Guangzhou Quality Supervision and Testing Institute, Guangzhou, 510110, China
| | - Xianzhi Peng
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.
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Wang X, Li C, Wu D, Shen J, Wei Y, Wang C. Enrichment of polychlorinated biphenyls in river water by using magnetic adsorbents with high selectivity to nonplanar aromatic compounds and their analysis with gas chromatography–mass spectrometry. J CHIN CHEM SOC-TAIP 2021. [DOI: 10.1002/jccs.202100102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Xuesong Wang
- Department of Analytical Science, Synthetic and Natural Functional Molecule Chemistry of Ministry of Education Key Laboratory, College of Chemistry and Materials Science Northwest University Xi'an China
| | - Chunyan Li
- Department of Analytical Science, Synthetic and Natural Functional Molecule Chemistry of Ministry of Education Key Laboratory, College of Chemistry and Materials Science Northwest University Xi'an China
| | - Dan Wu
- Department of Solid Phase Materials Sunresin New Materials Co., Ltd. Xi'an China
| | - Jiwei Shen
- Department of Analytical Science, Synthetic and Natural Functional Molecule Chemistry of Ministry of Education Key Laboratory, College of Chemistry and Materials Science Northwest University Xi'an China
| | - Yinmao Wei
- Department of Analytical Science, Synthetic and Natural Functional Molecule Chemistry of Ministry of Education Key Laboratory, College of Chemistry and Materials Science Northwest University Xi'an China
| | - Chaozhan Wang
- Department of Analytical Science, Synthetic and Natural Functional Molecule Chemistry of Ministry of Education Key Laboratory, College of Chemistry and Materials Science Northwest University Xi'an China
- Instrumental Analysis Lab National Demonstration Center for Experimental Chemistry Education (Northwest University) Xi'an China
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Tang C, Tan J, Tang C, Liu H, Zhang P, Liu D, Peng X. Chlorine isotope analysis of polychlorinated organic pollutants using gas chromatography-high resolution mass spectrometry and evaluation of isotope ratio calculation schemes by experiment and numerical simulation. J Chromatogr A 2021; 1651:462311. [PMID: 34146960 DOI: 10.1016/j.chroma.2021.462311] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/28/2021] [Accepted: 05/29/2021] [Indexed: 11/28/2022]
Abstract
Compound-specific isotope analysis of chlorine (CSIA-Cl) is a practicable and high-performance approach for revelation of transformation processes and source identification of chlorinated organic pollutants. This study conducted CSIA-Cl for typical polychlorinated organic pollutants using gas chromatography-high resolution mass spectrometry (GCHRMS) with an alternate injection mode using perchloroethylene (PCE) and trichloroethylene (TCE) as model analytes. PCE and TCE standards from two manufacturers were employed for method development, and chlorine isotope ratio calculation schemes were evaluated by experiment and numerical simulation. The achieved precision (standard deviation of isotope ratios) was up to 0.21‰ for PCE and 0.43‰ for TCE. The limits of detection for CSIA-Cl of were 0.05 μg/mL (0.05 ng on column), and the linearities were 0.05-1 μg/mL. Two isotope ratio calculation schemes, i.e., one using complete molecular isotopologues and another using the first pair of neighboring chlorine isotopologues of each analyte, were evaluated in terms of accuracy and precision. The complete-isotopologue scheme showed evidently higher precision and was more competent to reflect trueness than the isotopologue-pair scheme and the two schemes could present completely different outcomes. The method has been successfully applied to PCE and TCE reagents from different suppliers, a trichloromethane reagent, and a plastic material. The relative isotope ratio variations (Δ37Cl) of PCE and TCE in the reagents and plastic material were from -1.84±0.7‰ to 15.12±0.85‰. The analytes from different sources could mostly be discerned from each other by chlorine isotope ratios. This study will be conducive to transformation process elucidation and source identification of for PCE and TCE, and facilitate CSIA-Cl using GC-MS for more polychlorinated organic pollutants, particularly in selection and optimization of isotope ratio calculation schemes.
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Affiliation(s)
- Caiming Tang
- Laboratory of Advanced Analytical Chemistry and Detection Technology, Research Center for Eco-Environmental Engineering, Dongguan University of Technology, Dongguan 523808, China; State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
| | - Jianhua Tan
- Guangzhou Quality Supervision and Testing Institute, Guangzhou 510110, China
| | - Caixing Tang
- The Third Affiliated Hospital of Sun Yat-sen University, Lingnan Hospital, Guangzhou 510630, China
| | - Huachun Liu
- Guangzhou Center for Disease Control and Prevention, Guangzhou 510440, China
| | - Peilin Zhang
- Guangzhou Quality Supervision and Testing Institute, Guangzhou 510110, China
| | - Deyun Liu
- Guangzhou Quality Supervision and Testing Institute, Guangzhou 510110, China
| | - Xianzhi Peng
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
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Huang C, Zeng Y, Cao Y, Zhu C, Ren Z, Liu YE, Gao S, Tian Y, Luo X, Mai B. Mechanistic Aspects Regarding the Ultraviolet Degradation of Polychlorinated Biphenyls in Different Media: Insights from Carbon and Chlorine Isotope Fractionation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:7731-7740. [PMID: 34003641 DOI: 10.1021/acs.est.1c00726] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
In this study, the carbon and chlorine isotope fractionation during ultraviolet-photolysis of polychlorinated biphenyls (PCBs, including PCB18, PCB77, PCB110, and PCB138) in n-hexane (Hex), methanol/water (MeOH/H2O), and silica gel was first investigated to explore their mechanistic processes. We observed a significant variation in ΛCl-C (εCl/εC) for the same PCBs in different photochemical systems, implying that PCB degradation processes in various photoreaction systems could differ. Although all substrates showed normal apparent carbon/chlorine kinetic isotope effects (C-/Cl-AKIE >1), the putative inverse C-AKIE of nondechlorinated pathways was suggested by 13C depletion of the average carbon isotope composition of PCB138 and corresponding dechlorinated products in MeOH/H2O, which might originate from the magnetic isotope effect. Significant negative correlations were found between C-AKIE and relative disappearance quantum yields ("Φ") of ortho-dechlorinated substrates (PCB18, PCB110, and PCB138) in Hex and MeOH/H2O. However, the C-AKIE and "Φ" of PCB77 (meta/para-dechlorinated congener) obviously deviated from the above correlations. Furthermore, significantly different product-related carbon isotope enrichment factors of PCB77 in Hex were found. These results demonstrated the existence of dechlorination position-specific and masking effects in carbon isotope fractionations.
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Affiliation(s)
- Chenchen Huang
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanhong Zeng
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Ya Cao
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chuhong Zhu
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zihe Ren
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yin-E Liu
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shutao Gao
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Yankuan Tian
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Xiaojun Luo
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Bixian Mai
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
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