Mercury concentrations, speciation, and isotopic composition in sediment from a cold seep in the northern Gulf of Mexico

Brown, Garry; Sleeper, K.; Johnson, Marcus W.; Cizdziel, James V.

doi:10.1016/j.marpolbul.2013.09.030

Cited by 17 publications

(7 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Second, these records imply that the isotopic signatures observed in modern marine sediments and associated with terrestrial runoff and atmospheric Hg 2+ deposition can hold even in a world with potentially high levels of volcanic Hg in the environment. For instance, the slight positive D 199 Hg values that are present throughout the Buchanan Lake section are similar to those measured in modern and pre-anthropogenic oceanic sediments that do not receive significant continental runoff (Gehrke et al, 2009;Brown et al, 2013;Mil-Homens et al, 2013;Yin et al, 2015). Similar Hg-MIF signatures have also been measured in Hg anomalies from deep-water sequences spanning the Cretaceous-Paleogene transition (e.g., the Neuquén Basin, Argentina; see Sial et al, 2016).…”

supporting

confidence: 66%

Do mercury isotopes record the signature of massive volcanism in marine sedimentary records?

Thibodeau

Bergquist

2017

Geology

View full text Add to dashboard Cite

show abstract

supporting

confidence: 66%

Do mercury isotopes record the signature of massive volcanism in marine sedimentary records?

Thibodeau

Bergquist

2017

Geology

View full text Add to dashboard Cite

show abstract

“… , These depths overlap with the depths where the highest MeHg is found in Southern Ocean near the Antarctic margin. , The possible sources of MeHg at these depths include residual MeHg that sank from the surface, in situ microbial methylation and mobilization of MeHg produced in coastal marine sediments. , The MeHg from marine sediments is unlikely a major source of MeHg for seals because, based on the current knowledge, the MIF of MeHg from marine sediments is incompatible with the MIF of the seal feces. Although there are no direct measurements of Hg MIF in coastal marine sediments in Antarctica, most marine sediments from other locations of the world exhibit very small MIF for the THg (Δ 199 Hg within ∼ ± 0.2 ‰), ,,− and the MIF of MeHg produced in marine sediments is likely similar to that of THg in marine sediments. If the marine sediment MeHg was an important contributor to the MeHg bioaccumulated by seals, then the Δ 199 Hg values in seal feces would be expected to be diluted compared to the penguin guano (which records surface ocean MeHg) due to the likely low MIF of MeHg produced in marine sediments.…”

Section: Resultsmentioning

confidence: 99%

Mercury Stable Isotopes in Ornithogenic Deposits As Tracers of Historical Cycling of Mercury in Ross Sea, Antarctica

Zheng

Xie

Bergquist

2015

Environ. Sci. Technol.

View full text Add to dashboard Cite

Production of methylmercury (MeHg) in ocean waters and its bioaccumulation in marine organisms are critical processes controlling the fate and toxicity of mercury (Hg). However, these processes are not well understood in the Antarctic, where high levels of MeHg are observed in the subsurface ocean (100-1000 m). We explored the use of Hg stable isotope compositions in historical and modern biological deposits as a new approach for discerning Hg sources and tracing MeHg cycling in the ocean and bioaccumulation in marine biota. We found similar mass independent isotope fractionation (MIF) of Hg between a sediment profile containing historical penguin and seal feces deposits from coastal Antarctica and modern penguin and seal feces, suggesting that penguin and seal feces were the dominant sources of Hg to the sediments at different time periods. Furthermore, sediments dominated by seal feces displayed a significantly lower MIF slope (Δ(199)Hg/Δ(201)Hg) than those dominated by penguin feces despite similar extents of MIF. Since seals forage at greater depths (>400 m) than penguins (<100 m), the high MIF values and lower Δ(199)Hg/Δ(201)Hg in seal feces suggest that a significant fraction of MeHg accumulated by seals was produced in situ in the subsurface ocean from residual inorganic Hg(II) that sank from the euphotic zone after partial photoreduction. Our results suggest that in situ Hg methylation can be an important source of MeHg for marine biota, and Hg isotope compositions in biological archives can be valuable tracers of MeHg cycling.

show abstract

“…Sulfate-reducing bacteria, methanogens, and anaerobic methane oxidation archaea (ANME) in sea oor cold seeps may play an important role to induce Hg(II) methylation or MeHg demethylation 22,23 . One study of sediment Hg geochemistry in the northern Gulf of Mexico 24 , reported that no obvious differences in Hg concentrations and isotopic compositions were observed between the cold seep and surrounding reference environments. However, this might not the case for cold seep systems in other geological settings.…”

Section: Introductionmentioning

confidence: 99%

Deep sea cold seep is an atmospheric Hg sink and MeHg source

Li¹,

Dong²,

Tang³

et al. 2022

Preprint

View full text Add to dashboard Cite

Mercury (Hg) is an important element in seafloor cold seeps that might govern methane emission. However, so far, the knowledge of biogeochemical Hg cycle in it remains poorly understood. In this study, Hg geochemical characteristics and microorganisms involved in Hg biogeochemical cycling were examined in three (active, inactive seep vs reference) different types of sediments sampled from the Haima cold seep in the South China Sea. Sediments in the active seep area were significantly enriched in mercury and methylmercury (MeHg) compared to the reference. Accordingly, abundant genes related to Hg methylation (hgcAB), demethylation (merB) and reduction (merA) were detected in the active seep sediments, phylogenetically associated with various bacterial and archaeal linages (e.g. Desulfobacterota, Gammaproteobacteria and Halobacteriota). Hg odd-mass number isotopes (Δ199Hg and Δ201Hg) pointed to their source from the upper ocean and the occurrence of abiotic dark oxidation. The δ202Hg values indicate Hg mass fractionation, migration and transformation in the active seep sediments. These geochemical and microbial data highlight active Hg biogeochemical cycles in seafloor cold seeps, functioning as important Hg-sinks and MeHg sources in the deep ocean.

show abstract

Mercury concentrations, speciation, and isotopic composition in sediment from a cold seep in the northern Gulf of Mexico

Cited by 17 publications

References 41 publications

Do mercury isotopes record the signature of massive volcanism in marine sedimentary records?

Do mercury isotopes record the signature of massive volcanism in marine sedimentary records?

Mercury Stable Isotopes in Ornithogenic Deposits As Tracers of Historical Cycling of Mercury in Ross Sea, Antarctica

Deep sea cold seep is an atmospheric Hg sink and MeHg source

Contact Info

Product

Resources

About