Studies of mercury bioaccumulation in fish continue to be an important scientific discipline for ... more Studies of mercury bioaccumulation in fish continue to be an important scientific discipline for understanding the bioavailability and fate of mercury and for monitoring environmental levels of mercury in natural aquatic ecosystems. Many recent studies have utilized mercury stable isotope ratios in fish to monitor mercury sources and biogeochemical processes in diverse aquatic ecosystems. More experimental studies are however needed to precisely quantify the degree and mechanism(s) governing internal isotope fractionation of two mercury species, methylmercury (MMHg) and inorganic mercury (IHg), in fish. In order to better trace environmental sources of mercury using fish, we performed controlled experiments by raising Paralichthys olivaceus in captivity for 3 months and feeding them food pellets spiked with either MMHg or IHg (0.4 and 1.6 ug/g). Total mercury (THg) and MMHg concentrations and mercury isotope ratios (δ202Hg, Δ199Hg) were measured in the muscle, liver, kidney, and intestine tissues of fish. Fish fed with food pellets spiked with varying concentrations of MMHg equilibrated to the isotopic composition of the food regardless of the tissue type and MMHg concentration. In contrast, fish fed with food pellets spiked with varying concentrations of IHg showed a tissue specific variation. Kidney and muscle tissues with relatively large proportions of MMHg from THg (>60%) exhibited small isotopic shifts toward the IHg food pellets after 3 months. The mercury isotope ratios of intestine comprised mostly of IHg (>90%) equilibrated to the isotopic composition of the food. Interestingly, liver tissues comprised mostly of MMHg (~100%) showed δ202Hg value that is ~0.7 permil higher than the IHg food pellet, suggesting the presence of significant mass-dependent fractionation (MDF) in the fish liver. Our study demonstrates how the isotope ratios of different mercury species behave in the internal system of fish and that the mechanism responsible for MDF needs to be elucidated particularly for using fish tissues to monitor sites contaminated with IHg.
Mercury isotope ratios in fish tissues have been used to infer sources and biogeochemical process... more Mercury isotope ratios in fish tissues have been used to infer sources and biogeochemical processes of mercury in aquatic ecosystems. More experimental studies are however needed to understand the internal dynamics of mercury isotopes and to further assess the feasibility of using fish mercury isotope ratios as a monitoring tool. We exposed Olive flounder (Paralichthys olivaceus) to food pellets spiked with varying concentrations (400, 1600 ng/g) of methylmercury (MeHg) and inorganic mercury (IHg) for 10 weeks. Total mercury (THg), MeHg concentrations, and mercury isotope ratios (d 202 Hg, D 199 Hg, D 200 Hg) were measured in the muscle, liver, kidney, and intestine of fish. Fish fed mercury unamended food pellets and MeHg amended food pellets showed absence of internal d 202 Hg and D 199 Hg fractionation in all tissue type. For fish fed IHg food pellets, the d 202 Hg and D 199 Hg values of intestine equilibrated to those of the IHg food pellets. Kidney, muscle, and liver exhibited varying degrees of isotopic mixing toward the IHg food pellets, consistent with the degree of IHg bioaccumulation. Liver showed additional positive d 202 Hg shifts (~0.63‰) from the binary mixing line between the unamended food pellets and IHg food pellets, which we attribute to redistribution or biliary excretion of liver IHg with a lower d 202 Hg to other tissues. Significant d 202 Hg fractionation in the liver and incomplete isotopic equilibration in the muscle indicate that these tissues may not be suitable for source monitoring at sites heavily polluted by IHg. Instead, fish intestine appears to be a more suitable proxy for identifying IHg sources. The results from our study are essential for determining the appropriate fish tissues for monitoring environmental sources of IHg and MeHg.
Studies of mercury bioaccumulation in fish continue to be an important scientific discipline for ... more Studies of mercury bioaccumulation in fish continue to be an important scientific discipline for understanding the bioavailability and fate of mercury and for monitoring environmental levels of mercury in natural aquatic ecosystems. Many recent studies have utilized mercury stable isotope ratios in fish to monitor mercury sources and biogeochemical processes in diverse aquatic ecosystems. More experimental studies are however needed to precisely quantify the degree and mechanism(s) governing internal isotope fractionation of two mercury species, methylmercury (MMHg) and inorganic mercury (IHg), in fish. In order to better trace environmental sources of mercury using fish, we performed controlled experiments by raising Paralichthys olivaceus in captivity for 3 months and feeding them food pellets spiked with either MMHg or IHg (0.4 and 1.6 ug/g). Total mercury (THg) and MMHg concentrations and mercury isotope ratios (δ202Hg, Δ199Hg) were measured in the muscle, liver, kidney, and intestine tissues of fish. Fish fed with food pellets spiked with varying concentrations of MMHg equilibrated to the isotopic composition of the food regardless of the tissue type and MMHg concentration. In contrast, fish fed with food pellets spiked with varying concentrations of IHg showed a tissue specific variation. Kidney and muscle tissues with relatively large proportions of MMHg from THg (>60%) exhibited small isotopic shifts toward the IHg food pellets after 3 months. The mercury isotope ratios of intestine comprised mostly of IHg (>90%) equilibrated to the isotopic composition of the food. Interestingly, liver tissues comprised mostly of MMHg (~100%) showed δ202Hg value that is ~0.7 permil higher than the IHg food pellet, suggesting the presence of significant mass-dependent fractionation (MDF) in the fish liver. Our study demonstrates how the isotope ratios of different mercury species behave in the internal system of fish and that the mechanism responsible for MDF needs to be elucidated particularly for using fish tissues to monitor sites contaminated with IHg.
Mercury isotope ratios in fish tissues have been used to infer sources and biogeochemical process... more Mercury isotope ratios in fish tissues have been used to infer sources and biogeochemical processes of mercury in aquatic ecosystems. More experimental studies are however needed to understand the internal dynamics of mercury isotopes and to further assess the feasibility of using fish mercury isotope ratios as a monitoring tool. We exposed Olive flounder (Paralichthys olivaceus) to food pellets spiked with varying concentrations (400, 1600 ng/g) of methylmercury (MeHg) and inorganic mercury (IHg) for 10 weeks. Total mercury (THg), MeHg concentrations, and mercury isotope ratios (d 202 Hg, D 199 Hg, D 200 Hg) were measured in the muscle, liver, kidney, and intestine of fish. Fish fed mercury unamended food pellets and MeHg amended food pellets showed absence of internal d 202 Hg and D 199 Hg fractionation in all tissue type. For fish fed IHg food pellets, the d 202 Hg and D 199 Hg values of intestine equilibrated to those of the IHg food pellets. Kidney, muscle, and liver exhibited varying degrees of isotopic mixing toward the IHg food pellets, consistent with the degree of IHg bioaccumulation. Liver showed additional positive d 202 Hg shifts (~0.63‰) from the binary mixing line between the unamended food pellets and IHg food pellets, which we attribute to redistribution or biliary excretion of liver IHg with a lower d 202 Hg to other tissues. Significant d 202 Hg fractionation in the liver and incomplete isotopic equilibration in the muscle indicate that these tissues may not be suitable for source monitoring at sites heavily polluted by IHg. Instead, fish intestine appears to be a more suitable proxy for identifying IHg sources. The results from our study are essential for determining the appropriate fish tissues for monitoring environmental sources of IHg and MeHg.
Journal of Korean Society of Environmental Engineers
Mercury is a globally distributed toxic trace metal, which can travel long distances in the atmos... more Mercury is a globally distributed toxic trace metal, which can travel long distances in the atmosphere and bioaccumulate to elevated levels in ecosystem food webs. Since 2013, various parts of the mercury life cycle, including the production, use, emissions, releases, as well as the environmental and ecosystem fate, have been governed via the global treaty on mercury, the Minamata Convention of Mercury. The convention also calls attention to the application of mercury stable isotopes for distinguishing between various mercury sources in environmental media and for identifying sources, which require targeted risk management. Here, we introduce ways in which mercury stable isotopes can be applied in the field of environmental forensics to identify sources responsible for local contamination and global cycling that require international governance. This review is divided into: 1) the general overview on the mercury speciation and cycling, 2) the nomenclature of mercury stable isotope s...
Nearshore systems play an important role as mercury (Hg) sources to the open ocean and to human h... more Nearshore systems play an important role as mercury (Hg) sources to the open ocean and to human health via fish consumption. The nearshore system along East Asia is of particular concern given the rapid industrialization, which contributes to significant anthropogenic Hg emissions and releases. We used Hg stable isotopes to characterize Hg sources in the sediment and fish along the west coast of Korea, located at the northeast of the East China Sea. The Hg isotope ratios of the west coast sediments (δ202Hg; -0.89 to -0.27‰, Δ199Hg; -0.04 to 0.14‰) were statistically similar with other nearshore sediments (δ202Hg; -0.99 to -0.30‰, Δ199Hg; -0.04 to 0.19‰) and overlapped with the industrial Hg source end-member (δ202Hg; -0.5‰, Δ199Hg; 0.01‰) estimated from the Chinese marginal seas. Using a ternary mixing model, we estimated that industrial Hg sources contributes 83-97% in the west coast of Korea, and riverine and atmospheric Hg sources play minor roles in the Korean west coast and the Chinese marginal seas. The comparison between Hg isotope ratios of the sediment and nearshore fish revealed that the fish in the most west coast sites are exposed to MeHg produced in the sediment. At a few southwest coast sites, external MeHg produced in rivers and the open ocean water column appears to be more important as a source in fish. This is supported by much higher δ202Hg (0.74‰; similar to oceanic fish) and lower δ202Hg (-0.71‰; similar to riverine sources) compared to fish collected from other west coast sites influenced by sedimentary MeHg. The substantial Hg contributions from industrial activities suggest the national policies regulating anthropogenic Hg releases can directly mitigate human Hg exposure originating via local fish consumption. This study contributes to the growing regional and global inventories of Hg fluxes and sources exported into coastal oceans.
Studies of mercury bioaccumulation in fish continue to be an important scientific discipline for ... more Studies of mercury bioaccumulation in fish continue to be an important scientific discipline for understanding the bioavailability and fate of mercury and for monitoring environmental levels of mercury in natural aquatic ecosystems. Many recent studies have utilized mercury stable isotope ratios in fish to monitor mercury sources and biogeochemical processes in diverse aquatic ecosystems. More experimental studies are however needed to precisely quantify the degree and mechanism(s) governing internal isotope fractionation of two mercury species, methylmercury (MMHg) and inorganic mercury (IHg), in fish. In order to better trace environmental sources of mercury using fish, we performed controlled experiments by raising Paralichthys olivaceus in captivity for 3 months and feeding them food pellets spiked with either MMHg or IHg (0.4 and 1.6 ug/g). Total mercury (THg) and MMHg concentrations and mercury isotope ratios (δ202Hg, Δ199Hg) were measured in the muscle, liver, kidney, and intestine tissues of fish. Fish fed with food pellets spiked with varying concentrations of MMHg equilibrated to the isotopic composition of the food regardless of the tissue type and MMHg concentration. In contrast, fish fed with food pellets spiked with varying concentrations of IHg showed a tissue specific variation. Kidney and muscle tissues with relatively large proportions of MMHg from THg (>60%) exhibited small isotopic shifts toward the IHg food pellets after 3 months. The mercury isotope ratios of intestine comprised mostly of IHg (>90%) equilibrated to the isotopic composition of the food. Interestingly, liver tissues comprised mostly of MMHg (~100%) showed δ202Hg value that is ~0.7 permil higher than the IHg food pellet, suggesting the presence of significant mass-dependent fractionation (MDF) in the fish liver. Our study demonstrates how the isotope ratios of different mercury species behave in the internal system of fish and that the mechanism responsible for MDF needs to be elucidated particularly for using fish tissues to monitor sites contaminated with IHg.
Mercury isotope ratios in fish tissues have been used to infer sources and biogeochemical process... more Mercury isotope ratios in fish tissues have been used to infer sources and biogeochemical processes of mercury in aquatic ecosystems. More experimental studies are however needed to understand the internal dynamics of mercury isotopes and to further assess the feasibility of using fish mercury isotope ratios as a monitoring tool. We exposed Olive flounder (Paralichthys olivaceus) to food pellets spiked with varying concentrations (400, 1600 ng/g) of methylmercury (MeHg) and inorganic mercury (IHg) for 10 weeks. Total mercury (THg), MeHg concentrations, and mercury isotope ratios (d 202 Hg, D 199 Hg, D 200 Hg) were measured in the muscle, liver, kidney, and intestine of fish. Fish fed mercury unamended food pellets and MeHg amended food pellets showed absence of internal d 202 Hg and D 199 Hg fractionation in all tissue type. For fish fed IHg food pellets, the d 202 Hg and D 199 Hg values of intestine equilibrated to those of the IHg food pellets. Kidney, muscle, and liver exhibited varying degrees of isotopic mixing toward the IHg food pellets, consistent with the degree of IHg bioaccumulation. Liver showed additional positive d 202 Hg shifts (~0.63‰) from the binary mixing line between the unamended food pellets and IHg food pellets, which we attribute to redistribution or biliary excretion of liver IHg with a lower d 202 Hg to other tissues. Significant d 202 Hg fractionation in the liver and incomplete isotopic equilibration in the muscle indicate that these tissues may not be suitable for source monitoring at sites heavily polluted by IHg. Instead, fish intestine appears to be a more suitable proxy for identifying IHg sources. The results from our study are essential for determining the appropriate fish tissues for monitoring environmental sources of IHg and MeHg.
Studies of mercury bioaccumulation in fish continue to be an important scientific discipline for ... more Studies of mercury bioaccumulation in fish continue to be an important scientific discipline for understanding the bioavailability and fate of mercury and for monitoring environmental levels of mercury in natural aquatic ecosystems. Many recent studies have utilized mercury stable isotope ratios in fish to monitor mercury sources and biogeochemical processes in diverse aquatic ecosystems. More experimental studies are however needed to precisely quantify the degree and mechanism(s) governing internal isotope fractionation of two mercury species, methylmercury (MMHg) and inorganic mercury (IHg), in fish. In order to better trace environmental sources of mercury using fish, we performed controlled experiments by raising Paralichthys olivaceus in captivity for 3 months and feeding them food pellets spiked with either MMHg or IHg (0.4 and 1.6 ug/g). Total mercury (THg) and MMHg concentrations and mercury isotope ratios (δ202Hg, Δ199Hg) were measured in the muscle, liver, kidney, and intestine tissues of fish. Fish fed with food pellets spiked with varying concentrations of MMHg equilibrated to the isotopic composition of the food regardless of the tissue type and MMHg concentration. In contrast, fish fed with food pellets spiked with varying concentrations of IHg showed a tissue specific variation. Kidney and muscle tissues with relatively large proportions of MMHg from THg (>60%) exhibited small isotopic shifts toward the IHg food pellets after 3 months. The mercury isotope ratios of intestine comprised mostly of IHg (>90%) equilibrated to the isotopic composition of the food. Interestingly, liver tissues comprised mostly of MMHg (~100%) showed δ202Hg value that is ~0.7 permil higher than the IHg food pellet, suggesting the presence of significant mass-dependent fractionation (MDF) in the fish liver. Our study demonstrates how the isotope ratios of different mercury species behave in the internal system of fish and that the mechanism responsible for MDF needs to be elucidated particularly for using fish tissues to monitor sites contaminated with IHg.
Mercury isotope ratios in fish tissues have been used to infer sources and biogeochemical process... more Mercury isotope ratios in fish tissues have been used to infer sources and biogeochemical processes of mercury in aquatic ecosystems. More experimental studies are however needed to understand the internal dynamics of mercury isotopes and to further assess the feasibility of using fish mercury isotope ratios as a monitoring tool. We exposed Olive flounder (Paralichthys olivaceus) to food pellets spiked with varying concentrations (400, 1600 ng/g) of methylmercury (MeHg) and inorganic mercury (IHg) for 10 weeks. Total mercury (THg), MeHg concentrations, and mercury isotope ratios (d 202 Hg, D 199 Hg, D 200 Hg) were measured in the muscle, liver, kidney, and intestine of fish. Fish fed mercury unamended food pellets and MeHg amended food pellets showed absence of internal d 202 Hg and D 199 Hg fractionation in all tissue type. For fish fed IHg food pellets, the d 202 Hg and D 199 Hg values of intestine equilibrated to those of the IHg food pellets. Kidney, muscle, and liver exhibited varying degrees of isotopic mixing toward the IHg food pellets, consistent with the degree of IHg bioaccumulation. Liver showed additional positive d 202 Hg shifts (~0.63‰) from the binary mixing line between the unamended food pellets and IHg food pellets, which we attribute to redistribution or biliary excretion of liver IHg with a lower d 202 Hg to other tissues. Significant d 202 Hg fractionation in the liver and incomplete isotopic equilibration in the muscle indicate that these tissues may not be suitable for source monitoring at sites heavily polluted by IHg. Instead, fish intestine appears to be a more suitable proxy for identifying IHg sources. The results from our study are essential for determining the appropriate fish tissues for monitoring environmental sources of IHg and MeHg.
Journal of Korean Society of Environmental Engineers
Mercury is a globally distributed toxic trace metal, which can travel long distances in the atmos... more Mercury is a globally distributed toxic trace metal, which can travel long distances in the atmosphere and bioaccumulate to elevated levels in ecosystem food webs. Since 2013, various parts of the mercury life cycle, including the production, use, emissions, releases, as well as the environmental and ecosystem fate, have been governed via the global treaty on mercury, the Minamata Convention of Mercury. The convention also calls attention to the application of mercury stable isotopes for distinguishing between various mercury sources in environmental media and for identifying sources, which require targeted risk management. Here, we introduce ways in which mercury stable isotopes can be applied in the field of environmental forensics to identify sources responsible for local contamination and global cycling that require international governance. This review is divided into: 1) the general overview on the mercury speciation and cycling, 2) the nomenclature of mercury stable isotope s...
Nearshore systems play an important role as mercury (Hg) sources to the open ocean and to human h... more Nearshore systems play an important role as mercury (Hg) sources to the open ocean and to human health via fish consumption. The nearshore system along East Asia is of particular concern given the rapid industrialization, which contributes to significant anthropogenic Hg emissions and releases. We used Hg stable isotopes to characterize Hg sources in the sediment and fish along the west coast of Korea, located at the northeast of the East China Sea. The Hg isotope ratios of the west coast sediments (δ202Hg; -0.89 to -0.27‰, Δ199Hg; -0.04 to 0.14‰) were statistically similar with other nearshore sediments (δ202Hg; -0.99 to -0.30‰, Δ199Hg; -0.04 to 0.19‰) and overlapped with the industrial Hg source end-member (δ202Hg; -0.5‰, Δ199Hg; 0.01‰) estimated from the Chinese marginal seas. Using a ternary mixing model, we estimated that industrial Hg sources contributes 83-97% in the west coast of Korea, and riverine and atmospheric Hg sources play minor roles in the Korean west coast and the Chinese marginal seas. The comparison between Hg isotope ratios of the sediment and nearshore fish revealed that the fish in the most west coast sites are exposed to MeHg produced in the sediment. At a few southwest coast sites, external MeHg produced in rivers and the open ocean water column appears to be more important as a source in fish. This is supported by much higher δ202Hg (0.74‰; similar to oceanic fish) and lower δ202Hg (-0.71‰; similar to riverine sources) compared to fish collected from other west coast sites influenced by sedimentary MeHg. The substantial Hg contributions from industrial activities suggest the national policies regulating anthropogenic Hg releases can directly mitigate human Hg exposure originating via local fish consumption. This study contributes to the growing regional and global inventories of Hg fluxes and sources exported into coastal oceans.
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