Competing ligand exchange-solid phase extraction method for the determination of the complexation of dissolved inorganic mercury (II) in natural waters

Black, Frank J.; Bruland, Kenneth W.; Flegal, A. Russell

doi:10.1016/j.aca.2007.07.043

Cited by 47 publications

(68 citation statements)

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“…The relationship is so strong that it was recently suggested that DOC (or even better the UV absorption of DOC) can be used as a proxy for total Hg concentrations in streams (Dittman et al, 2009). The last decade Hg, L IIIedge EXAFS studies (Xia et al, 1999;Hesterberg et al, 2001;Qian et al, 2002;Yoon et al, 2005;Skyllberg et al, 2006) and binding affinity studies (Lovgren and Sjoberg, 1989;Hintelmann et al, 1997;Skyllberg et al, 2000;Karlsson and Skyllberg, 2003;Black et al, 2007;Gasper et al, 2007) have revealed that the bonding of Hg and MeHg to NOM pertaining to solid and aqueous phases is due to the complexation with thiol groups. 7.5.1.1 Inorganic Mercury.…”

Section: Complex Formation With Natural Organic Mattermentioning

confidence: 99%

Chemical Speciation of Mercury in Soil and Sediment

Skyllberg

2011

Environmental Chemistry and Toxicology of Mercury

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Section: Complex Formation With Natural Organic Mattermentioning

confidence: 99%

Chemical Speciation of Mercury in Soil and Sediment

Skyllberg

2011

Environmental Chemistry and Toxicology of Mercury

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“…Recent studies have shown that complexation between Hg and DOM is not instantaneous, [3,9,10] and this kinetic effect may contribute to the variability in measured Hg-DOM binding constants. Slow reactions between Hg and DOM or rearrangements of the complexed Hg within DOM over time are particularly important to systems receiving fresh sources of Hg.…”

Section: Introductionmentioning

confidence: 99%

“…[8] Recent work has demonstrated that the formation of Hg-DOM complexes is kinetically controlled in both laboratory studies and natural aquatic systems. [3,9,10] Changes in the complexation of Hg and DOM may account for differences in behaviour between freshly added Hg and mercury that has been equilibrated with water. For example, mercuric (Hg II ) isotopes freshly added to lake mesocosms were reported to undergo reduction more readily than Hg already present in the system.…”

Section: Introductionmentioning

confidence: 99%

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Competitive ligand exchange reveals time dependant changes in the reactivity of Hg–dissolved organic matter complexes

Miller

Liang

2012

Environ. Chem.

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Environmental context. Mercury, a globally important pollutant, undergoes transformations in the environment to form methylmercury that is toxic to humans. Naturally occurring dissolved organic matter is a controller in these transformations, and we demonstrate that its strength of interaction with mercury is time dependent. These changes in complexation with dissolved organic matter are likely to affect mercury's reactivity in aquatic systems, thereby influencing how mercury is methylated and bioaccumulated.Abstract. Mercury interactions with dissolved organic matter (DOM) are important in aquatic environments but the kinetics of Hg binding to and repartitioning within the DOM remain poorly understood. We examined changes in Hg-DOM complexes using glutathione (GSH) titrations, coupled with stannous-reducible Hg measurements during Hg equilibration with DOM. In laboratory prepared DOM solutions and in water from a Hg-contaminated creek, a fraction of the Hg present as Hg-DOM complexes did not react to GSH addition. This unreactive Hg fraction increased with time from 13 % at 1 h to 74 % after 48 h of equilibration with a Suwannee River DOM. In East Fork Poplar Creek water in Oak Ridge, Tennessee, ,58 % of the DOM-complexed Hg was unreactive with GSH 1 h after the sample was collected. This timedependent increase in unreactive Hg suggests that Hg forms stronger complexes with DOM over time. Alternatively the DOM-complexed Hg may become more sterically protected from the ligand exchange reactions, as the binding environment changes within the DOM over time. These results have important implications to understanding Hg transformations in the natural environment, particularly in contaminated aquatic systems due to non-equilibrium interactions between Hg and DOM.

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“…Culture experiments with SRB and FeRB exposed to inorganic mercury in the presence of LMW thiols have shown increased rates of methylation compared to controls, which upsets the previously held hypothesis that passive diffusion of neutrally charged mercury species was the primary means of transport into the cell and that Hg complexation by organic ligands should lower its bioavailability (Mason et al, 1996;Schaefer and Morel, 2009;Schaefer et al, 2011). Mercury-organic ligand complexes are thought to be the dominant dissolved mercury species, but the identity and distribution of these compounds is not well known (Lamborg et al, 2003;Black et al, 2007). In the context of these recent discoveries, further examination of mercury speciation, particularly under conditions found in the upper ocean, may lead to a better mechanistic understanding of water column mercury methylation.…”

Section: The Role Of Thiols In Mercury Methylation and Bioavailabilitymentioning

confidence: 59%

Distribution of thiols in the northwest Atlantic Ocean

Kading¹

2013

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Thiol substances can form stable complexes with metals (especially copper and mercury) in the surface ocean that can impact cycling and bioavailability of those elements. In this study, I present seven concentration profiles of cysteine and glutathione, two low-molecular weight thiols, from the coastal northwest Atlantic Ocean and the Bermuda Atlantic Time Series (BATS) sampling site in the Sargasso Sea, a first for these regions. These two thiols were found in the upper 200 meters of the ocean at all sites, and the total thiol concentration varied from 0.2 to 3.2 nM. The highest concentration of both thiols was found at the deep chlorophyll maximum in most samples. Thiol concentrations were higher on the continental shelf than in the open ocean. The observed distribution of cysteine and glutathione and thermodynamic stability of copper complexes suggests that Cu(I)-dithiol complexes may be the dominant surface ocean copper and thiol species. Mercury-thiol complexes were also present in thermodynamically modeled seawater, which may provide a vector for mercury uptake in the surface ocean. 6 7

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Competing ligand exchange-solid phase extraction method for the determination of the complexation of dissolved inorganic mercury (II) in natural waters

Cited by 47 publications

References 47 publications

Chemical Speciation of Mercury in Soil and Sediment

Chemical Speciation of Mercury in Soil and Sediment

Competitive ligand exchange reveals time dependant changes in the reactivity of Hg–dissolved organic matter complexes

Distribution of thiols in the northwest Atlantic Ocean

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