Speciation of mercury in sediments of the Seine estuary (France)

Mikac, Nevenka; Niessen, Sylvie; Ouddane, Baghdad; Wartel, M.

doi:10.1002/(sici)1099-0739(199910)13:10<715::aid-aoc918>3.0.co;2-4

Cited by 86 publications

(37 citation statements)

References 39 publications

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“…Mercury was detected by cold vapour atomic fluorescence spectroscopy (CV AFS) after SnCl 2 reduction. The configuration includes a vapour generator (PSA 10.003), a gold platinum trap (PSA 10.501 Galahad) and fluorescence detector (PSA 10.023 Merlin) and is described in detail elsewhere [18,19]. The accuracy of the method used was verified by the analysis of the certified reference materials PACS-1 (marine sediment, National research Council Canada) and IAEA-405 (estuarine sediment, International Atomic Energy Agency).…”

Section: Analysessupporting

confidence: 37%

Extractability of HgS (cinnabar and metacinnabar) by hydrochloric acid

Mikac

Foucher

Niessen

et al. 2002

Analytical and Bioanalytical Chemistry

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In this work we investigated the behaviour of pure HgS during extraction with dilute HCl to establish its extractability in 1 and 6 M HCl at the concentration level close to those occurring in natural sediments and soils. We found that neither cinnabar nor metacinnabar were soluble in 1 M HCl, whereas both were partially extracted by 6 M HCl. Metacinnabar precipitated in the laboratory was most prone to dissolution in 6 M HCl (up to 90%), followed by crystalline (commercial) metacinnabar (up to 70%) and cinnabar (up to 15%). Solubility of HgS in 6 M HCl was found to be dependent on its concentration, and an exponential relationship between quantity of HgS added to 20 mL of 6 M HCl (the range of 0.1-10 mg was used) and the solubility in 6 M HCl was established. For higher concentrations of HgS (10 mg in 20 mL of acid), a similarly low solubility of cinnabar was obtained as found in the literature. A study of dissolution kinetics of HgS in 6 M HCl indicated that it was a fairly slow process. Unexpected oxidation of HgS in water or 1 M HCl was found for extractions performed in Teflon vials previously used for the digestion of residual undissolved HgS by aqua regia. We presumed that the Teflon material could preserve some oxidising gases (presumably Cl(2)) developed during digestion with aqua regia which can then oxidise HgS during extraction with water or 1 M HCl. Regarding the extraction of Hg from natural sediments, we concluded that 6 M HCl could not be used to extract reactive Hg and predict bioavailability of mercury in sediments containing HgS and that experiments with model compounds should not be done at a concentration level several orders of magnitude higher than in natural samples.

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Section: Analysessupporting

confidence: 37%

Extractability of HgS (cinnabar and metacinnabar) by hydrochloric acid

Mikac

Foucher

Niessen

et al. 2002

Analytical and Bioanalytical Chemistry

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“…The MeHg and Hg(II) diffusive fluxes estimated in this study were at the lower range of those calculated for the southern New England continental shelf (Hammerschmidt and Fitzgerald 2006), Mediterranean Sea (Ogrinc et al 2007), San Francisco Bay (Choe et al 2004), Boston Harbor (Benoit et al 2009), and Chesapeake Bay (Hollweg et al 2009), with similar methods, and more than an order of magnitude lower than those estimated at other sites (Mikac et al 1999;Hammerschmidt and Fitzgerald 2008), as outlined in Table 8. The differences in flux estimations were primarily driven by differences in measured pore-water concentrations across sites, as the diffusive flux coefficients (D w ) used in these other studies were similar to or lower than what was used in this study.…”

Section: Discussionmentioning

confidence: 99%

Mercury and methylmercury cycling in sediments of the mid‐Atlantic continental shelf and slope

Hollweg

Gilmour

Mason

2010

Limnology & Oceanography

101

115

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We present a detailed study of the biogeochemical factors controlling mercury (Hg) distribution, methylmercury (MeHg) production, and MeHg efflux in sediments of the mid-Atlantic continental shelf and slope. The mildly reduced surface sediments of the shelf and slope provide ideal conditions for MeHg production. They are sufficiently reduced to support microbial sulfate reduction, but contain very low dissolved sulfide concentrations. The redox zonation of sediments determined the depth distribution of MeHg production, whereas the bioavailability of inorganic Hg for methylation appeared to be the dominant driver of spatial patterns across the shelf and slope. Sediment total Hg concentrations were well predicted by sediment organic matter (SOM) content, with the highest concentrations of Hg and MeHg in the fine-grained organic clays of the slope. However, SOM-normalized Hg concentrations decreased with distance from shore. The changing character of organic matter with distance from shore appeared to affect Hg partitioning and bioavailability for methylation. The percentage of Hg in sediments as MeHg was well predicted by measured methylation rates, but not by demethylation rates. On the basis of measured concentrations in bottom waters and surficial pore waters, the average diffusive efflux of Hg(II) and MeHg from sediments to coastal waters was estimated to be 26 and 0.8 pmol m 22 d 21 , respectively. Extrapolated globally, the diffusive input of MeHg from shelf and slope sediments is estimated to be 0.01 Mmol per year. As the actual fluxes can be substantially higher than diffusive fluxes, we suggest that shelf and upper slope sediments are a major source of MeHg to the coastal ocean.

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“…Higher CH 3 Hg + concentrations are found in zooplankton from lakes with lower pH and higher DOC (Watras et al, 1998). Sediment-dwelling invertebrates are also exposed to Hg bound to particulates, most of which is inorganic (Kannan et al, 1998;Mikac et al, 1999).…”

Section: Aquatic Invertebratesmentioning

confidence: 95%