Bioaccumulation of methylmercury in a marine copepod

Lee, Cheng‐Shiuan; Fisher, Nicholas S.

doi:10.1002/etc.3660

Cited by 38 publications

(32 citation statements)

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“…We suggest the Δ 199 Hg value in surface zooplankton represents the isotopic composition of photodegraded MMHg in phytoplankton or particle‐associated MMHg that has been photodemethylated before entering the food web. Elevated Δ 199 Hg values of small zooplankton relative to the other size fractions are attributed to a tight linkage between zooplankton (0.06–0.2 and 0.2–0.5 mm) and primary productivity in surface waters at Station ALOHA, because surface water small zooplankton (e.g., copepods) obtain most of their MMHg from an algal dietary source (Lee & Fisher, ). Larger zooplankton may also exploit large POM as a dietary source resulting in lower Δ 199 Hg values (Figure ; Hannides et al, ), because the Δ 199 Hg values associated with POM are very low.…”

Section: Discussionmentioning

confidence: 99%

Mercury Cycling in the North Pacific Subtropical Gyre as Revealed by Mercury Stable Isotope Ratios

Motta

Blum

Johnson

et al. 2019

Global Biogeochemical Cycles

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The oceans are an important global reservoir for mercury (Hg), and marine fish consumption is the dominant human exposure pathway for its toxic methylated form. A more thorough understanding of the global biogeochemical cycle of Hg requires additional information on the mechanisms that control Hg cycling in pelagic marine waters. In this study, Hg isotope ratios and total Hg concentrations are used to explore Hg biogeochemistry in oligotrophic marine environments north of Hawaii. We present the first measurements of the vertical water column distribution of Hg concentrations and the Hg isotopic composition in precipitation, marine particles, and zooplankton near Station ALOHA (22°45′N, 158°W). Our results reveal production and demethylation of methylmercury in both the euphotic (0–175 m) and mesopelagic zones (200–1,000 m). We document a strong relationship between Hg isotopic composition and depth in particles, zooplankton, and fish in the water column and diurnal variations in Δ199Hg values in zooplankton sampled near the surface (25 m). Based on these observations and stable Hg isotope relationships in the marine food web, we suggest that the Hg found in large pelagic fish at Station ALOHA was originally deposited largely by precipitation, transformed into methyl‐Hg, and bioaccumulated in situ in the water column. Our results highlight how Hg isotopic compositions reflect abiotic and biotic production and degradation of methyl‐Hg throughout the water column and the importance of particles and zooplankton in the vertical transport of Hg.

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Section: Discussionmentioning

confidence: 99%

Mercury Cycling in the North Pacific Subtropical Gyre as Revealed by Mercury Stable Isotope Ratios

Motta

Blum

Johnson

et al. 2019

Global Biogeochemical Cycles

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“…The gamma‐emitting radioisotope, 203 Hg (half‐life = 46.6 d), was used in this study to trace the transformation of Hg species between dissolved and gaseous phases. Previously, this isotope was used in experiments to quantify bioaccumulation and trophic transfer of mercury in marine plankton assemblages exposed to environmentally realistic mercury concentrations (Lee and Fisher , ). A solution of 203 Hg(II) in 1 M HCl was obtained from Eckert and Ziegler Isotope Products (Valencia, California) with a specific activity of 185 GBq g −1 and was further converted to methyl‐ 203 Hg (Me 203 Hg) in the lab following established methods (Rouleau and Block ; Lee and Fisher ).…”

Section: Methodsmentioning

confidence: 99%

Microbial generation of elemental mercury from dissolved methylmercury in seawater

Lee

Fisher

2018

Limnology & Oceanography

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Elemental mercury (Hg0) formation from other mercury species in seawater results from photoreduction and microbial activity, leading to possible evasion from seawater to overlying air. Microbial conversion of monomethylmercury (MeHg) to Hg0 in seawater remains unquantified. A rapid radioassay method was developed using gamma‐emitting 203Hg as a tracer to evaluate Hg0 production from Hg(II) and MeHg in the low pM range. Bacterioplankton assemblages in Atlantic surface seawater and Long Island Sound water were found to rapidly produce Hg0, with production rate constants being directly related to bacterial biomass and independent of dissolved Hg(II) and MeHg concentrations. About 32% of Hg(II) and 19% of MeHg were converted to Hg0 in 4 d in Atlantic surface seawater containing low‐bacterial biomass, and in Long Island Sound water with higher bacterial biomass, 54% of Hg(II) and 8% of MeHg were transformed to Hg0. Decreasing temperatures from 24°C to 4°C reduced Hg0 production rates cell−1 from Hg(II) 3.3 times as much as from a MeHg source. Because Hg0 production rates were linearly related to microbial biomass and temperature, and microbial mercuric reductase was detected in our field samples, we inferred that microbial metabolic activities and enzymatic reactions primarily govern Hg0 formation in subsurface waters where light penetration is diminished.

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“…The third is the amount of Hg II produced by MeHg through reductive demethylation processes caused by the activity of bacteria in contaminated environments. The rate constants of the three reaction terms are fixed according to previous works (Monperrus et al, 2007b, a;Lehnherr et al, 2011;Batrakova et al, 2014;Melaku Canu et al, 2015).…”

Section: The Advection-diffusion-reaction Model For the Hg Species Inmentioning

confidence: 99%

HR3DHG version 1: modeling the spatiotemporal dynamics of mercury in the Augusta Bay (southern Italy)

et al. 2020

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Abstract. The biogeochemical dynamics of Hg, and specifically of its three species Hg0, HgII, and MeHg (elemental, inorganic, and organic, respectively), in the marine coastal area of Augusta Bay (southern Italy) have been explored by the high-resolution 3D Hg (HR3DHG) model, namely an advection–diffusion–reaction model for dissolved mercury in the seawater compartment coupled with a diffusion–reaction model for dissolved mercury in the pore water of sediments in which the desorption process for the sediment total mercury is taken into account. The spatiotemporal variability of the mercury concentration in both seawater ([HgD]) and the first layers of bottom sediments ([HgDsed] and [HgTsed]), as well as the Hg fluxes at the boundaries of the 3D model domain, have been theoretically reproduced, showing acceptable agreement with the experimental data collected in multiple field observations during six different oceanographic cruises. Also, the spatiotemporal dynamics of the total mercury concentration in seawater have been obtained by using both model results and field observations. The mass balance of the total Hg species in seawater has been calculated for the Augusta Harbour, improving previous estimations. The HR3DHG model could be used as an effective tool to predict the spatiotemporal distributions of dissolved and total mercury concentrations, while contributing to better assessing hazards for the environment and therefore for human health in highly polluted areas.

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Bioaccumulation of methylmercury in a marine copepod

Cited by 38 publications

References 38 publications

Mercury Cycling in the North Pacific Subtropical Gyre as Revealed by Mercury Stable Isotope Ratios

Mercury Cycling in the North Pacific Subtropical Gyre as Revealed by Mercury Stable Isotope Ratios

Microbial generation of elemental mercury from dissolved methylmercury in seawater

HR3DHG version 1: modeling the spatiotemporal dynamics of mercury in the Augusta Bay (southern Italy)

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