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He M, Lv S, Yin R, Zhang Y, Lin K, Wang S, Guo H, Chen H, Huang S. Continuous Flow-Double Purge and Trap Method for Preconcentrating Mercury in Large Volumes of Seawater for Stable Isotope Analysis. Anal Chem 2024. [PMID: 38324752 DOI: 10.1021/acs.analchem.3c01657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Mercury (Hg) isotopes provide a useful tool to understand Hg sources and processes in the environment. The Hg isotopic composition of seawater remains poorly constrained due to the lack of an efficient method to process large volumes of low-Hg-concentration seawater samples. Here, we develop a continuous flow-double purge and trap device for the in situ preconcentration of Hg in seawater. This method yielded a good Hg recovery of 91.7 ± 3.3% (n = 4, 1SD) for spiked seawater samples and gave reasonably similar Hg isotope ratios of NIST 8610, indicating a limited matrix effect and limited Hg isotope fractionation during processing of seawater. NIST 8610 δ202Hg (-0.55 ± 0.09‰, n = 4, 1SD) and Δ199Hg (0.07 ± 0.02‰, n = 4, 1SD) were similar to previously published data. The method was successfully applied to seawater collected from the Xiamen Bay and the South China Sea. The seawater samples showed a Hg recovery of 91.6 ± 5.4% (n = 12, 1SD). Seawater Δ199Hg (-0.04 ± 0.05‰, n = 7, 1SD) in the Xiamen Bay was different from seawater Δ199Hg (0.05 ± 0.07‰, n = 5, 1SD) in the South China Sea, which implies distinct Hg sources to coastal and open ocean areas and highlights the robustness of our method in understanding the Hg isotopic composition of seawater.
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Affiliation(s)
- Meijiao He
- Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, Fujian 361005, China
| | - Supeng Lv
- Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, Fujian 361005, China
| | - Runsheng Yin
- State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, Guizhou 550081, China
| | - Yuanbiao Zhang
- Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, Fujian 361005, China
| | - Kunning Lin
- Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, Fujian 361005, China
| | - Sainan Wang
- State Environmental Protection Key Laboratory of Coastal Ecosystem, National Marine Environmental Monitoring Center, Dalian, Liaoning 116023, China
| | - Huige Guo
- Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, Fujian 361005, China
| | - Hongzhe Chen
- Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, Fujian 361005, China
| | - Shuyuan Huang
- Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, Fujian 361005, China
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Yin H, Yao H, Yuan W, Lin CJ, Fu X, Yin R, Meng B, Luo J, Feng X. Determination of the Isotopic Composition of Aqueous Mercury in a Paddy Ecosystem Using Diffusive Gradients in Thin Films. Anal Chem 2023; 95:12290-12297. [PMID: 37605798 DOI: 10.1021/acs.analchem.3c01356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
Measuring the isotopic composition of Hg in natural waters is challenging due to the ultratrace level of aqueous Hg (ng L-1). At least 5 ng of Hg mass is required for Hg isotopic analysis. Given the low Hg concentration in natural waters, a large volume of water (>10 L) is typically needed. The conventional grab sampling method is time-consuming, laborious, and prone to contamination during transportation and preconcentration steps. In this study, a DGT (diffusive gradients in thin films) method based on aminopropyl and mercaptopropyl bi-functionalized SBA-15 nanoparticles was developed and extended to determine the concentration and isotopic composition of aqueous Hg for the first time. The results of laboratory analysis showed that Hg adsorption by DGT induces ∼ -0.2‰ mass-dependent fractionation (MDF) and little mass-independent fractionation (MIF). The magnitude of MDF exhibits a dependence on the diffusion-layer thickness of DGT. Since Hg-MDF can occur in a broad range of environmental processes, monitoring the δ202Hg of aqueous Hg using the DGT method should be performed with caution. Field results show consistent MIF signatures (Δ199Hg) between the DGT and conventional grab sampling method. The developed DGT method serves as a passive sampling method that effectively characterizes the MIF of Hg in waters to understand the biogeochemical cycle of Hg at contaminated sites.
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Affiliation(s)
- Hongqian Yin
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Heng Yao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Wei Yuan
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Che-Jen Lin
- Center for Advances in Water and Air Quality, Lamar University, Beaumont, Texas 77710, United States
| | - Xuewu Fu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Runsheng Yin
- State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Jun Luo
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210023, China
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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Yang S, Li P, Sun K, Wei N, Liu J, Feng X. Mercury isotope compositions in seawater and marine fish revealed the sources and processes of mercury in the food web within differing marine compartments. WATER RESEARCH 2023; 241:120150. [PMID: 37269625 DOI: 10.1016/j.watres.2023.120150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 05/25/2023] [Accepted: 05/28/2023] [Indexed: 06/05/2023]
Abstract
Anthropogenic activities and climate change have significantly increased mercury (Hg) levels in seawater. However, the processes and sources of Hg in differing marine compartments (e.g. estuary, marine continental shelf (MCS) or pelagic area) have not been well studied, which makes it difficult to understand Hg cycling in marine ecosystems. To address this issue, the total Hg (THg) concentration, methylmercury (MeHg) concentration and stable Hg isotopes were determined in seawater and fish samples collected from differing marine compartments of the South China Sea (SCS). The results showed that the estuarine seawater exhibited substantially higher THg and MeHg concentrations than those in the MCS and pelagic seawater. Significantly negative δ202Hg (-1.63‰ ± 0.42‰) in estuarine seawater compared with that in pelagic seawater (-0.58‰ ± 0.08‰) may suggest watershed input and domestic sewage discharge of Hg in the estuarine compartment. The Δ199Hg value in estuarine fish (0.39‰ ± 0.35‰) was obviously lower than that in MCS (1.10‰ ± 0.54‰) and pelagic fish (1.15‰ ± 0.46‰), which showed that relatively little MeHg photodegradation occurred in the estuarine compartment. The Hg isotope binary mixing model based on Δ200Hg revealed that approximately 74% MeHg in pelagic fish is derived from atmospheric Hg(II) deposition, and over 60% MeHg in MCS fish is derived from sediments. MeHg sources for estuarine fish may be highly complex (e.g. sediment or riverine/atmospheric input) and further investigations are warranted to clarify the contribution of each source. Our study showed that Hg stable isotopes in seawater and marine fish can be used to identify the processes and sources of Hg in different marine compartments. This finding is of great relevance to the development of marine Hg food web models and the management of Hg in fish.
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Affiliation(s)
- Shaochen Yang
- Hubei Key Laboratory of Critical Zone Evolution, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China
| | - Ping Li
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Kaifeng Sun
- South China Institute of Environmental Sciences, Ministry of Ecology and Environment of the People's Republic of China, Guangzhou 510655, China
| | - Nan Wei
- South China Institute of Environmental Sciences, Ministry of Ecology and Environment of the People's Republic of China, Guangzhou 510655, China
| | - Jinling Liu
- Hubei Key Laboratory of Critical Zone Evolution, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China.
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
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Zhou Z, Wang H, Li Y. Mercury stable isotopes in the ocean: Analytical methods, cycling, and application as tracers. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 874:162485. [PMID: 36858226 DOI: 10.1016/j.scitotenv.2023.162485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 02/22/2023] [Accepted: 02/22/2023] [Indexed: 06/18/2023]
Abstract
Mercury (Hg) has seven stable isotopes that can be utilized to trace the sources of Hg and evaluate the importance of transport and transformation processes in the cycling of Hg in the environment. The ocean is an integral part of the Earth and plays an important role in the global mercury cycle. However, there is a lack of a systematic review of Hg stable isotopes in marine environments. This review is divided into four sections: a) advances in Hg stable isotope analysis, b) the isotope ratios of Hg in various marine environmental matrices (seawater, sediment, and organisms), c) processes governing stable Hg isotope ratios in the ocean, and d) application of Hg stable isotopes to understand biotic uptake and migration. Mercury isotopes have provided much useful information on marine Hg cycling that cannot be given by Hg concentrations alone. This includes (i) sources of Hg in coastal or estuarine environments, (ii) transformation pathways and mechanisms of different forms of Hg in marine environments, (iii) trophic levels and feeding guilds of marine fish, and (iv) migration/habitat changes of marine fish. With the improvement of methods for seawater Hg isotope analysis (especially species-specific methods) and the measurement of Hg isotope fractionation during natural biogeochemical processes in the ocean, Hg stable isotopes will advance our understanding of the marine Hg cycle in the future, e.g., mercury exchange at the sea-atmosphere interface and seawater-sediment interface, contributions of different water masses to Hg in the ocean, fractionation mechanisms of Hg and MeHg transformation in seawater.
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Affiliation(s)
- Zhengwen Zhou
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education and College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China
| | - Huiling Wang
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education and College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China
| | - Yanbin Li
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education and College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China.
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