Mercury transformations in resuspended contaminated sediment controlled by redox conditions, chemical speciation and sources of organic matter

Zhu, Wei; Song, Yu; Adediran, Gbotemi A.; Jiang, Tao; Reis, Ana Teresa; Pereira, Eduarda; Skyllberg, Ulf; Björn, Erik

doi:10.1016/j.gca.2017.09.045

Cited by 81 publications

(33 citation statements)

References 116 publications

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“…For example, abiotic nonphotochemical reduction of Hg(II) by DOM has been experimentally shown to produce negative MIF in residual Hg(II) (27). However, this reduction pathway has been well demonstrated to be significantly inhibited under sulfidic conditions due to the strong complexation of Hg(II) to sulfide and thiols (28)(29)(30)(31). Second, the slope of the linear regression between Δ 199 Hg and Δ 201 Hg provides further evidence against this reduction pathway.…”

Section: Resultsmentioning

confidence: 99%

“…The experimentally determined rate of Hg(0) oxidation in the presence of thiols has been shown to be comparable to many other major redox pathways of Hg in natural aquatic systems (e.g., photooxidation and photoreduction) (29,40), making it a potentially significant oxidation pathway during PZE. In addition, once Hg(0) was oxidized to Hg(II), the complexation of Hg(II) to thiols and sulfide has been shown to inhibit or slow down the reduction of Hg(II) (hence the reemission) (28)(29)(30)(31).…”

Section: Resultsmentioning

confidence: 99%

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Mercury isotope signatures record photic zone euxinia in the Mesoproterozoic ocean

Zheng

Gilleaudeau

Kah

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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Photic zone euxinia (PZE) is a condition where anoxic, H2S-rich waters occur in the photic zone (PZ). PZE has been invoked as an impediment to the evolution of complex life on early Earth and as a kill mechanism for Phanerozoic mass extinctions. Here, we investigate the potential application of mercury (Hg) stable isotopes in marine sedimentary rocks as a proxy for PZE by measuring Hg isotope compositions in late Mesoproterozoic (∼1.1 Ga) shales that have independent evidence of PZE during discrete intervals. Strikingly, a significantly negative shift of Hg mass-independent isotope fractionation (MIF) was observed during euxinic intervals, suggesting changes in Hg sources or transformations in oceans coincident with the development of PZE. We propose that the negative shift of Hg MIF was most likely caused by (i) photoreduction of Hg(II) complexed by reduced sulfur ligands in a sulfide-rich PZ, and (ii) enhanced sequestration of atmospheric Hg(0) to the sediments by thiols and sulfide that were enriched in the surface ocean as a result of PZE. This study thus demonstrates that Hg isotope compositions in ancient marine sedimentary rocks can be a promising proxy for PZE and therefore may provide valuable insights into changes in ocean chemistry and its impact on the evolution of life.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Mercury isotope signatures record photic zone euxinia in the Mesoproterozoic ocean

Zheng

Gilleaudeau

Kah

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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“…It is suspected that these results mainly derived from the poor management and low exchange or limited circulation rate of water in the wild areas. Of course, the transportation and transformations of selenium and mercury in aquatic environments involve a large number of complex biotic and abiotic processes (Liang et al., ; Zhu et al., ). All these changes in environmental conditions would have important impacts on their existing forms, distributions, and correlations.…”

Section: Resultsmentioning

confidence: 99%

Species and correlations between selenium and mercury in fishpond ecosystems

Wang

Nan

et al. 2019

Water Environment Research

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The chemical species and contents of selenium and mercury in water, sediments, and crucian carps collected from three wild and three aquaculture fishponds in Tianjin, China, were determined, and the interaction between selenium and mercury in water was also investigated by the calorimetry method. The results revealed that the average contents of total selenium (TSe) and total mercury (THg) in each item of the wild areas were higher than in those of the aquaculture areas, and significant differences (95% confidence) were presented for THg both in the sediments and crucian carps. The molar ratios between TSe and THg in all investigated fishponds were far higher than 1, indicating good protective effects of selenium on mercury toxicity. Obviously, negative correlations (r > 0.9993) were found between TSe and THg in water. The antagonism of selenium on mercury in water was confirmed to mainly result from the reaction between selenate and Hg2+ to form an insoluble selenium–mercury oxygenated compound, by which the addition of selenate into the water of fishponds would reduce the environmental risk of mercury. Practitioner points Se and Hg in different fishpond ecosystems were investigated and compared. Direct evidence was provided for the interaction between Se and Hg in water. The addition of Se(VI) into fishpond ecosystems would reduce the environmental risk of Hg.

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“…While mobile Hg species have been shown to be present, to what extent mobilization from the canal sediment in fact occurs depends on many factors. Zhu et al (2018) recommended that changes in redox potential, Hg chemical speciation and the source and nature of OM all must be considered when assessing mobilization. Even following release from sediment, whether Hg will remain solvated, become associated with suspended particulate matter, or precipitate depends on numerous factors such as pH, composition and redox conditions of the water.…”

Section: Resultsmentioning

confidence: 99%

Assessing Mercury Mobility in Sediment of the Union Canal, Scotland, UK by Sequential Extraction and Thermal Desorption

Cook

Davidson

Keenan

et al. 2019

Arch Environ Contam Toxicol

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The mobility of mercury (Hg) was assessed in sediment from the Union Canal, Scotland, UK. Samples collected from the vicinity of a former munitions factory that manufactured mercury fulminate detonators were subjected to sequential extraction followed by cold vapor atomic absorption spectrometry (CVAAS) and direct analysis using thermal desorption (TD). The sequential extraction indicated that >75% of mercury (up to 429 mg kg-1) was in mobile forms, with <12% semi-mobile and <23% non-mobile species. In the TD method, >67% of the total Hg content was desorbed in the temperature range 100-250 °C consistent with species weakly attached to the mineral matrix (tentatively identified as an iron (oxy)hydroxideassociated species). This predominance of mobile mercury species may arise from a lack of association between Hg and either organic matter or sulfur in the sediments. Further investigation of Hg mobilization, transport and assimilation/biomagnification is required both to determine whether there is a need for remediation of the sediment and to improve understanding of the biogeochemical cycling of Hg in shallow, oxic, freshwater systems.

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Mercury transformations in resuspended contaminated sediment controlled by redox conditions, chemical speciation and sources of organic matter

Cited by 81 publications

References 116 publications

Mercury isotope signatures record photic zone euxinia in the Mesoproterozoic ocean

Mercury isotope signatures record photic zone euxinia in the Mesoproterozoic ocean

Species and correlations between selenium and mercury in fishpond ecosystems

Assessing Mercury Mobility in Sediment of the Union Canal, Scotland, UK by Sequential Extraction and Thermal Desorption

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