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Park SY, Zhang Y, Kwon JS, Kwon MJ. Multi-approach assessment of groundwater biogeochemistry: Implications for the site characterization of prospective spent nuclear fuel repository sites. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 926:171918. [PMID: 38522553 DOI: 10.1016/j.scitotenv.2024.171918] [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: 01/06/2024] [Revised: 03/10/2024] [Accepted: 03/21/2024] [Indexed: 03/26/2024]
Abstract
The disposal of spent nuclear fuel in deep subsurface repositories using multi-barrier systems is considered to be the most promising method for preventing radionuclide leakage. However, the stability of the barriers can be affected by the activities of diverse microbes in subsurface environments. Therefore, this study investigated groundwater geochemistry and microbial populations, activities, and community structures at three potential spent nuclear fuel repository construction sites. The microbial analysis involved a multi-approach including both culture-dependent, culture-independent, and sequence-based methods for a comprehensive understanding of groundwater biogeochemistry. The results from all three sites showed that geochemical properties were closely related to microbial population and activities. Total number of cells estimates were strongly correlated to high dissolved organic carbon; while the ratio of adenosine-triphosphate:total number of cells indicated substantial activities of sulfate reducing bacteria. The 16S rRNA gene sequencing revealed that the microbial communities differed across the three sites, with each featuring microbes performing distinctive functions. In addition, our multi-approach provided some intriguing findings: a site with a low relative abundance of sulfate reducing bacteria based on the 16S rRNA gene sequencing showed high populations during most probable number incubation, implying that despite their low abundance, sulfate reducing bacteria still played an important role in sulfate reduction within the groundwater. Moreover, a redundancy analysis indicated a significant correlation between uranium concentrations and microbial community compositions, which suggests a potential impact of uranium on microbial community. These findings together highlight the importance of multi-methodological assessments in better characterizing groundwater biogeochemical properties for the selection of potential spent nuclear fuel disposal sites.
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Affiliation(s)
- Su-Young Park
- Department of Earth and Environmental Sciences, Korea University, Seoul, Republic of Korea
| | - Yidan Zhang
- Department of Earth and Environmental Sciences, Korea University, Seoul, Republic of Korea
| | - Jang-Soon Kwon
- Korea Atomic Energy Research Institute, Daejeon, Republic of Korea
| | - Man Jae Kwon
- Department of Earth and Environmental Sciences, Korea University, Seoul, Republic of Korea.
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2
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Xu L, Hu Q, Liu Z, Jian M, Peng Y, Shen R, Liao W, Zhong A. Hydrological alteration drives chemistry of dissolved organic matter in the largest freshwater lake of China (Poyang Lake). WATER RESEARCH 2024; 251:121154. [PMID: 38271743 DOI: 10.1016/j.watres.2024.121154] [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: 11/09/2023] [Revised: 01/15/2024] [Accepted: 01/16/2024] [Indexed: 01/27/2024]
Abstract
As the largest reactive organic carbon pool, dissolved organic matter (DOM) plays an important role in various biogeochemical processes in lake ecosystems. Recently, climate change-induced extreme events (e.g., floods and droughts) have significantly modified the hydrological patterns of lakes worldwide, and regulated the quality and quantity of DOM. However, the responses of DOM chemistry to hydrological alteration in lakes remain poorly understood. Here we investigated the influences of hydrological alteration on sources, composition, and characteristics of DOM in Poyang Lake, the largest freshwater lake in China, using a combination of bulk chemical, optical and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) techniques. Results show various sources of DOM (autochthonous, allochthonous, and anthropogenic inputs) and significant variations in DOM chemistry across four hydrological periods (the retreating, dry, rising, and flooding periods) in Poyang Lake. During the retreating, rising, and flooding periods, DOM was characterized by higher aromaticity, humification degree, and recalcitrance, and exhibited pronounced allochthonous signatures. In contrast, DOM contained more S-containing molecules and aliphatic compounds during the dry period, displaying relatively stronger autochthonous features. Terrestrial inputs and the lignin-CHOS formation process are likely the primary underlying mechanisms shaping the differences in DOM chemistry in Poyang Lake. Our research demonstrates the significant impacts of hydrological alteration on DOM dynamics, and provides an improved understanding of DOM biogeochemical cycles and carbon cycling in large aquatic systems under global climate change.
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Affiliation(s)
- Lei Xu
- Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang 332900, China
| | - Qian Hu
- Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang 332900, China
| | - Zetian Liu
- Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang 332900, China
| | - Minfei Jian
- College of Life Science, Jiangxi Provincial Key Laboratory of Protection and Utilization of Subtropical Plant Resources, Jiangxi Normal University, Nanchang, 330022, China
| | - Yansong Peng
- Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang 332900, China
| | - Ruichang Shen
- Jiangxi Province Key Laboratory of Watershed Ecosystem Change and Biodiversity, Center for Watershed Ecology, School of Life Science, Nanchang University, Nanchang 330031, China; Jiangxi Poyang Lake Wetland Conservation and Restoration National Permanent Scientific Research Base, National Ecosystem Research Station of Jiangxi Poyang Lake Wetland, Nanchang University, Nanchang 330031, China
| | - Wei Liao
- Wetland Research Center, Jiangxi Academy of Forestry, Nanchang, 330032, China.
| | - Aiwen Zhong
- Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang 332900, China.
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Cheng H, You J, Ma S, Liao K, Hu H, Ren H. 2-Hydroxy-1,4-Naphthoquinone: A Promising Redox Mediator for Minimizing Dissolved Organic Nitrogen and Eutrophication Effects of Wastewater Effluent. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:2870-2880. [PMID: 38181504 DOI: 10.1021/acs.est.3c07261] [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: 01/07/2024]
Abstract
Researchers and engineers are committed to finding effective approaches to reduce dissolved organic nitrogen (DON) to meet more stringent effluent total nitrogen limits and minimize effluent eutrophication potential. Here, we provided a promising approach by adding specific doses of 2-hydroxy-1,4-naphthoquinone (HNQ) to postdenitrification bioreactors. This approach of adding a small dosage of 0.03-0.1 mM HNQ effectively reduced the concentrations of DON in the effluent (ANOVA, p < 0.05) by up to 63% reduction of effluent DON with a dosing of 0.1 mM HNQ when compared to the control bioreactors. Notably, an algal bioassay indicated that DON played a dominant role in stimulating phytoplankton growth, thus effluent eutrophication potential in bioreactors using 0.1 mM HNQ dramatically decreased compared to that in control bioreactors. The microbe-DON correlation analysis showed that HNQ dosing modified the microbial community composition to both weaken the production and promote the uptake of labile DON, thus minimizing the effluent DON concentration. The toxic assessment demonstrated the ecological safety of the effluent from the bioreactors using the strategy of HNQ addition. Overall, HNQ is a promising redox mediator to reduce the effluent DON concentration with the purpose of meeting low effluent total nitrogen levels and remarkably minimizing effluent eutrophication effects.
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Affiliation(s)
- Huazai Cheng
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 Jiangsu, China
| | - Jiaqian You
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 Jiangsu, China
| | - Sijia Ma
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 Jiangsu, China
| | - Kewei Liao
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 Jiangsu, China
| | - Haidong Hu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 Jiangsu, China
| | - Hongqiang Ren
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 Jiangsu, China
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Gao Z, Guo H, Chen D, Yu C, He C, Shi Q, Qiao W, Kersten M. Transformation of dissolved organic matter and related arsenic mobility at a surface water-groundwater interface in the Hetao Basin, China. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 334:122202. [PMID: 37453683 DOI: 10.1016/j.envpol.2023.122202] [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: 05/16/2023] [Revised: 06/26/2023] [Accepted: 07/12/2023] [Indexed: 07/18/2023]
Abstract
Porewater arsenic mobility above the groundwater table has been recognized as a potential cause of arsenic-rich groundwater, but the processing pathways of dissolved organic matter (DOM) in that hyporheic zone and their effect on porewater arsenic release remain poorly understood. To address these issues, two porewater profiles were sampled in a surface water-groundwater interaction zone from the Hetao Basin, China, to monitor the porewater geochemistry and DOM molecular characteristics. The results show that the porewater arsenic, Fe(II), and DOC concentrations were all significantly higher than those of the intruding pond water, and were located above the conservative mixing model lines. This indicates a net release of these solutes from the sediment. By comparing the porewater with pond water DOM, we found that the carboxyl-rich alicyclic molecules (CRAM) were selectively preserved, carbohydrates and aliphatics/proteins were preferentially consumed, and low O/C-ratio compounds with high bioproduction index (I_bioprod) and terrestrial index (I_terr) were produced. The transformation of CHO to CHOS compounds also represented a pathway of recalcitrant DOM production. The produced recalcitrant organic compounds mostly contributed to the elevated porewater DOC concentrations, but their contribution decreased along the filtration path. The consumption of labile DOM compounds would be responsible for Fe(III) hydroxide reduction and arsenic release. The generated recalcitrant DOM may also be a driver of porewater arsenic mobility by acting as electron shuttles. This study highlights the importance of the hyporheic zone in shaping shallow groundwater DOM composition and the potential contribution to arsenic enrichment.
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Affiliation(s)
- Zhipeng Gao
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Beijing), Beijing, 100083, PR China; MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, and School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, 100083, PR China
| | - Huaming Guo
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Beijing), Beijing, 100083, PR China; MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, and School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, 100083, PR China.
| | - Dou Chen
- MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, and School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, 100083, PR China
| | - Chen Yu
- MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, and School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, 100083, PR China
| | - Chen He
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing, 102249, PR China
| | - Quan Shi
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing, 102249, PR China
| | - Wen Qiao
- China Institute of Geo-Environment Monitoring, China Geological Survey, Beijing, 100081, PR China
| | - Michael Kersten
- Environmental Geochemistry Group, Institute of Geosciences, Johannes Gutenberg-University, Mainz, 55099, Germany
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Kong Q, Ye L, Pan Y, Zhou Y, Lei Y, Zeng Z, Chen S, Yao L, Zhang X, Westerhoff P, Yang X. Photochemical Transformation of Free Chlorine Induced by Triplet State Dissolved Organic Matter. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023. [PMID: 37428984 DOI: 10.1021/acs.est.3c02458] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/12/2023]
Abstract
Photolysis of free chlorine is an increasingly recognized approach for effectively inactivating microorganisms and eliminating trace organic contaminants. However, the impact of dissolved organic matter (DOM), which is ubiquitous in engineered water systems, on free chlorine photolysis is not yet well understood. In this study, triplet state DOM (3DOM*) was found to cause the decay of free chlorine for the first time. By using laser flash photolysis, the scavenging rate constants of triplet state model photosensitizers by free chlorine at pH 7.0 were determined to be in the range of (0.26-3.33) × 109 M-1 s-1. 3DOM*, acting as a reductant, reacted with free chlorine at an estimated reaction rate constant of 1.22(±0.22) × 109 M-1 s-1 at pH 7.0. This study revealed an overlooked pathway of free chlorine decay during UV irradiation in the presence of DOM. Besides the DOM's light screening ability and scavenging of radicals or free chlorine, 3DOM* played an important role in the decay of free chlorine. This reaction pathway accounted for a significant proportion of the decay of free chlorine, ranging from 23 to 45%, even when DOM concentrations were below 3 mgC L-1 and a free chlorine dose of 70 μM was present during UV irradiation at 254 nm. The generation of HO• and Cl• from the oxidation of 3DOM* by free chlorine was confirmed by electron paramagnetic resonance and quantified by chemical probes. By inputting the newly observed pathway in the kinetics model, the decay of free chlorine in UV254-irradiated DOM solution can be well predicted.
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Affiliation(s)
- Qingqing Kong
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Lei Ye
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Yanheng Pan
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Yangjian Zhou
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Yu Lei
- Key Laboratory of Photochemistry, Institute of Chemistry Chinese Academy of Sciences, Beijing National Laboratory for Molecular Sciences, Beijing 100190, China
| | - Zihan Zeng
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Siqi Chen
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Liaoliao Yao
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Xinran Zhang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Paul Westerhoff
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85287-3005, United States
| | - Xin Yang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
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Lopez-Fernandez M, Westmeijer G, Turner S, Broman E, Ståhle M, Bertilsson S, Dopson M. Thiobacillus as a key player for biofilm formation in oligotrophic groundwaters of the Fennoscandian Shield. NPJ Biofilms Microbiomes 2023; 9:41. [PMID: 37349512 DOI: 10.1038/s41522-023-00408-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Accepted: 06/09/2023] [Indexed: 06/24/2023] Open
Abstract
Biofilm formation is a common adaptation for microbes in energy-limited conditions such as those prevalent in the vast deep terrestrial biosphere. However, due to the low biomass and the inaccessible nature of subsurface groundwaters, the microbial populations and genes involved in its formation are understudied. Here, a flow-cell system was designed to investigate biofilm formation under in situ conditions in two groundwaters of contrasting age and geochemistry at the Äspö Hard Rock Laboratory, Sweden. Metatranscriptomes showed Thiobacillus, Sideroxydans, and Desulforegula to be abundant and together accounted for 31% of the transcripts in the biofilm communities. Differential expression analysis highlighted Thiobacillus to have a principal role in biofilm formation in these oligotrophic groundwaters by being involved in relevant processes such as the formation of extracellular matrix, quorum sensing, and cell motility. The findings revealed an active biofilm community with sulfur cycling as a prominent mode of energy conservation in the deep biosphere.
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Affiliation(s)
- Margarita Lopez-Fernandez
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Stuvaregatan 4, 392 31, Kalmar, Sweden.
- Department of Microbiology, Faculty of Sciences, University of Granada, Avenida Fuentenueva s/n, 18071, Granada, Spain.
| | - George Westmeijer
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Stuvaregatan 4, 392 31, Kalmar, Sweden
| | - Stephanie Turner
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Stuvaregatan 4, 392 31, Kalmar, Sweden
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Box 7026, 75007, Uppsala, Sweden
| | - Elias Broman
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Stuvaregatan 4, 392 31, Kalmar, Sweden
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Svante Arrhenius väg 20 A, 106 91, Stockholm, Sweden
| | - Magnus Ståhle
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Stuvaregatan 4, 392 31, Kalmar, Sweden
| | - Stefan Bertilsson
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, SE75007, Uppsala, Sweden
| | - Mark Dopson
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Stuvaregatan 4, 392 31, Kalmar, Sweden
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An S, Mao Z, Chen M, Huang X, Shi L, Xing P, Kong L, Zhou Y, Du Y, Zhang Y. Sunlight irradiation promotes both the chemodiversity of terrestrial DOM and the biodiversity of bacterial community in a subalpine lake. ENVIRONMENTAL RESEARCH 2023; 227:115823. [PMID: 37004851 DOI: 10.1016/j.envres.2023.115823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 03/28/2023] [Accepted: 03/30/2023] [Indexed: 05/08/2023]
Abstract
Alpine lake habitats are evolving into subalpine lakes under the scenario of climate change, where the vegetation are promoted due to increasing temperature and precipitation. The abundant terrestrial dissolved organic matter (TDOM) leached from watershed soil into subalpine lakes would undergo strong photochemical reaction due to the high altitude, with the potential to alter DOM composition and affect the bacterial communities. To reveal the transformation of TDOM by both photochemical and microbial processes in a typical subalpine lake, Lake Tiancai (located 200 m below the tree line) was chosen. TDOM was extracted from the surrounding soil of Lake Tiancai and then subjected to the photo/micro-processing for 107 days. The transformation of TDOM was analyzed by Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and fluorescence spectroscopy, and the shift of bacterial communities was analyzed using 16s rRNA gene sequencing technology. Dissolved organic carbon and light-absorbing components (a350) decay accounted for approximately 40% and 80% of the original, respectively, in the sunlight process, but both less than 20% in the microbial process for 107 days. The photochemical process promoted the chemodiversity as there were ∼7000 molecules after sunlight irradiation, compared to ∼3000 molecules in the original TDOM. Light promoted the production of highly unsaturated molecules and aliphatics, which were significantly associated with Bacteroidota, suggesting that light may influence bacterial communities by regulating the DOM molecules. Carboxylic-rich alicyclic molecules were generated in both photochemical and biological processes, suggesting TDOM was converted to a stable pool over time. Our finding on the transformation of terrestrial DOM and the alternation of bacterial community under the simultaneously photochemical and microbial processes will help to reveal the response of the carbon cycle and lake system structure to climate change for high-altitude lakes.
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Affiliation(s)
- ShiLin An
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - ZhenDu Mao
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Meilian Chen
- Department of Geosciences & Natural Resources, Western Carolina University, Cullowhee, NC 28723, United States
| | - XiuLin Huang
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China; School of Environmental and Chemical Engineering, Chongqing Three Gorges University, Chongqing, 404020, China
| | - LiMei Shi
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Peng Xing
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - LingYang Kong
- Yunnan Key Laboratory of Plateau Geographical Processes and Environmental Changes, Yunnan Normal University, Kunming, 650500, China
| | - YongQiang Zhou
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - YingXun Du
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - YunLin Zhang
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing, 100049, China
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Hu T, Luo M, Qi Y, He D, Chen L, Xu Y, Chen D. Molecular evidence for the production of labile, sulfur-bearing dissolved organic matter in the seep sediments of the South China Sea. WATER RESEARCH 2023; 233:119732. [PMID: 36801578 DOI: 10.1016/j.watres.2023.119732] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 02/05/2023] [Accepted: 02/11/2023] [Indexed: 06/18/2023]
Abstract
Cold seeps with methane-rich fluids leaking out of the seafloor usually support massive biomass of chemosynthetic organisms and associated fauna. A substantial amount of methane is converted to dissolved inorganic carbon by microbial metabolism, and this process also releases dissolved organic matter (DOM) into pore water. Here, pore water samples from "Haima cold seeps" sediments and the non-seep reference sediments in the northern South China Sea were analyzed for optical properties and molecular compositions of pore water DOM. Our results showed that the relative abundance of protein-like DOM, H/Cwa and molecular lability boundary percentage (MLBL%) in the seep sediments were significantly higher than those in the reference sediments, indicating that more labile DOM related to unsaturated aliphatic compounds is produced in the seep sediments. Spearman's correlation of the fluoresce and molecular data suggested that the humic-like components (C1 and C2) mainly constituted the refractory compounds (CRAM, highly unsaturated and aromatics compounds). In contrast, the protein-like component (C3) had high H/C ratios featuring high degree of DOM lability. The amount of S-containing formulas (CHOS and CHONS) was greatly elevated in the seep sediments, likely caused by abiotic and biotic sulfurization of DOM in the sulfidic environment. Although the abiotic sulfurization was proposed to have a stabilizing effect on organic matter, our results implied that the biotic sulfurization in the cold seep sediments would increase DOM lability. Overall, the labile DOM accumulated in the seep sediments is closely linked to methane oxidation, which not only support heterotrophic communities and but also likely have an impact on carbon and sulfur cycling in the sediments and the ocean.
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Affiliation(s)
- Tingcang Hu
- College of Geography and Environment, Liaocheng University, Liaocheng, China
| | - Min Luo
- Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China; Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China.
| | - Yulin Qi
- Institute of Surface-Earth System Science, College of Earth System Science, Tianjin University, Tianjin, China
| | - Ding He
- Department of Ocean Science and Hong Kong Branch of the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), The Hong Kong University of Science and Technology, Hong Kong, China
| | - Linying Chen
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
| | - Yunping Xu
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
| | - Duofu Chen
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China.
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Yi B, Liu J, He W, Lü X, Cao X, Chen X, Zeng X, Zhang Y. Optical variations of dissolved organic matter due to surface water - groundwater interaction in alpine and arid Datonghe watershed. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 864:161036. [PMID: 36563761 DOI: 10.1016/j.scitotenv.2022.161036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 12/14/2022] [Accepted: 12/15/2022] [Indexed: 06/17/2023]
Abstract
The direction and quantity of surface water - groundwater interaction (SGI) in alpine-arid zones can be tracked using multiple tracers. However, few studies have examined whether the optical indices of dissolved organic matter (DOM) can also track SGI. This study used excitation-emission matrix spectroscopy combined with parallel factor analysis (EEM-PARAFAC) to reveal the optical variations in dissolved organic matter (DOM) in groundwater and surface water with various SGIs in the Datonghe watershed. The results showed that the absorbance spectral indices of DOM did not vary with SGI, whereas DOM fluorescence varied with SGI. PARAFAC indicated that groundwater predominantly recharged by precipitation had significantly lower humic-like (C2 and C3) fluorescence than groundwater predominantly recharged by riverine water. Since humic-like substances were more likely to be retained in the aqueous phase than protein-like substances, significantly fewer protein-like substances (C4) were introduced when surface water was recharged to groundwater. This suggests that C4 can be used as an effective indicator to identify the SGI process from surface water to groundwater. Based on the principal component analysis of DOM and hydrochemical indicators, it was concluded that traditional chemical tracers were significantly and positively correlated with humic-like substances C2 and C3. Given that C3 is more stable and persistent in the environment, it could be used to track SGI processes midstream of the watershed. The findings of this study will assist in accurately identifying the processes and mechanisms of SGI on a regional scale and provide a basis for future water resource management and the protection of water ecosystems.
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Affiliation(s)
- Bing Yi
- Beijing Key Laboratory of Water Resources & Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, China; Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang 050061, China
| | - Jingtao Liu
- Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang 050061, China
| | - Wei He
- Beijing Key Laboratory of Water Resources & Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, China.
| | - Xiaoli Lü
- China Institute of Geo-Environmental Monitoring, Beijing 100081, China
| | - Xu Cao
- Beijing Key Laboratory of Water Resources & Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, China
| | - Xiaorui Chen
- Beijing Key Laboratory of Water Resources & Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, China
| | - Xianjiang Zeng
- Beijing Key Laboratory of Water Resources & Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, China
| | - Yuxi Zhang
- Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang 050061, China
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