| 1. |
- Björn, Erik, et al.
(författare)
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Recent Advances in Mercury Speciation Analysis with Focus on Spectrometric Methods and Enriched Stable Isotope Applications
- 2007
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Ingår i: Ambio. - 0044-7447 .- 1654-7209. ; 36:6, s. 443–51-
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Tidskriftsartikel (refereegranskat)abstract
- This paper discusses some recent advances in spectrometric methods and approaches for mercury speciation analysis of environmental samples with focus on isotope dilution techniques for determination of mercury species' concentrations in gaseous samples and reaction rates in soils and sediments. Such analytical data is important inter alia in fundamental research on mercury biogeochemistry and for risk assessments of mercury-contaminated soils and sediments and for designing effective remedial actions. The paper describes how the use of enriched stable isotope tracers in mercury speciation analysis can improve the traceability and accuracy of results, facilitate rational method developments, and be useful for studying biogeochemical processes, i.e. rate of reactions and fluxes, of mercury species. In particular the possibilities to study and correct for unwanted species transformation reactions during sample treatment and to study “natural” transformations of species in environmental samples, or micro- and mesocosm ecosystems, during incubations are highlighted. Important considerations to generate relevant data in isotope tracer experiments as well as reliability and quality assurance of mercury speciation analysis in general are also discussed.
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| 2. |
- Drott, Andreas, et al.
(författare)
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Do Potential Methylation Rates Reflect Accumulated Methyl Mercury in Contaminated Sediments?
- 2008
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 42:1, s. 153-158
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Tidskriftsartikel (refereegranskat)abstract
- Relationships between the short-term mono-methyl mercury (MeHg) production, determined as the specific, potential methylation rate constant Km (day−1) after 48 h of incubation with isotope-enriched 201Hg(II) at 23 °C, and the long-term accumulation of ambient MeHg, were investigated in contaminated sediments. The sediments covered a range of environments from small freshwater lakes to large brackish water estuaries and differed with respect to source and concentration of Hg, salinity, primary productivity, quantity and quality of organic matter, and temperature climate. Significant (p < 0.001), positive relationships were observed between Km (day−1) and the concentration of MeHg normalized to total Hg (%MeHg) for surface sediments (0–10, 0–15, and in one case 0–20 cm) across all environments, and across subsets of organic and minerogenic freshwaters. This suggests that the methylation process (MeHg production) overruled demethylation and net transport processes in the surface sediments. The lack of a relationship between Km and %MeHg in two brackish water sediment depth profiles (0–100 cm) indicates that demethylation and the net effect of input−output are relatively more important at greater depths. Differences in the primary production and subsequent availability of easily degradable organic matter (serving as electron donor for methylating bacteria) was indicated to be the most important factor behind observed differences in %MeHg and Km among sites. In contrast, concentrations of sulfate were not correlated to Km, %MeHg, or absolute concentrations of MeHg. We conclude that total concentrations of Hg are of importance for the long-term accumulation of MeHg, and that %MeHg in surface sediments can be used as a proxy for the rate of methylation, across a range of sites from different environments.
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| 3. |
- Drott, Andreas, et al.
(författare)
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Effects of oxic and anoxic filtration on determined methyl mercury concentrations in sediment pore waters
- 2007
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 103, s. 76-83
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Tidskriftsartikel (refereegranskat)abstract
- Accurate determination of methyl mercury (MeHg) concentrations in sediment pore waters is crucial for an improved understanding of mercury (Hg) biogeochemistry, and for improved risk assessment of Hg contaminated sites. In the present study, effects of oxic (air) and anoxic (N2) filtration (after centrifugation) on determined pore water MeHg concentrations were investigated in severely Hg contaminated pulp fibre sediments from two estuaries of the Bothnian Sea, Sweden. MeHg was determined in the filtrate using species-specific isotope dilution gas chromatography inductively coupled plasma mass spectrometry (SSID–GC–ICPMS), after ethylation with sodium tetraethylborate. Determined concentrations of MeHg were greater after anoxic filtration than after oxic filtration for all samples investigated, with MeHg(N2)/MeHg(air) ratios ranging between 3.4 and 343. Adsorption to newly formed Fe(III)/Mn(III/IV)-oxy/hydroxide surfaces is proposed as the main mechanism responsible for MeHg removal during oxic filtration. This is supported by decreases in dissolved Fe and Mn concentrations during oxic filtration, and by decreases in dissolved sulphur concentrations during oxic filtration in the samples with largest effect on MeHg concentrations. The latter is explained by adsorption of SO42− to newly formed Fe(III)/Mn(III/IV)-oxy/hydroxide surfaces. The effect of oxidation during filtration on pore water MeHg concentrations was largest in samples in which FeS(s) was not present, but with calculated pe-values below − 3. Thus, our results indicate that the largest errors with respect to pore water MeHg concentrations when filtering in air can be expected in samples with an intermediate redox potential, possibly buffered by a mixture of oxidation sensitive Fe(II/III) minerals.
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| 4. |
- Drott, Andreas, et al.
(författare)
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Importance of Dissolved Neutral Mercury Sulfides for Methyl Mercury Production in Contaminated Sediments
- 2007
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 41:7, s. 2270-6
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Tidskriftsartikel (refereegranskat)abstract
- Biotic transformation of inorganic mercury, Hg(II), to mono methyl mercury (MeHg) is proposed to be largely controlled by passive uptake of neutral Hg complexes by sulfate reducing bacteria (SRB). In this study, the chemical speciation of Hg(II) in seven locally contaminated sediments covering environments such as (i) brackish water, (ii) low-productivity freshwater, and, (iii) high-productivity freshwater was related to potential Hg methylation rates, determined by incubation at 23 C for 48 h under N2(g), and to total MeHg concentrations in sediments. Pore water speciation was modeled considering Hg complexes with halides, organic thiols [Hg(SR)2(aq), associated to dissolved organic matter], monosulfides, and bisulfides. The sum of neutral mercury sulfides [Hg(SH)20(aq)] and [HgS0(aq)] was significantly, positively (p < 0.001, n = 20) correlated to the specific methylation rate constant (Km, day-1) at depths of 5-100 cm in two brackish water sediments. Total Hg, total mercury sulfides or Hg(SR)2(aq) in pore water gave no significant relationships with Km. In two sub-sets of freshwater sediments, neutral mercury sulfides were positively correlated to total Hg in pore water, and therefore, total Hg also gave significant relationships with Km. The sum of [Hg(SH)20(aq)] and [HgS0(aq)] was significantly, positively correlated to total sediment MeHg (g kg-1) in brackish waters (p < 0.001, n = 23), in southern, high-productivity freshwaters (p < 0.001, n = 20), as well as in northern, low-productivity freshwater (p = 0.048, n = 6). The slopes (b, b') of the relationships Km (day-1) = a + b([Hg(SH)20(aq)] + [HgS0(aq)]) and MeHg (g kg-1) = a' + b'([Hg(SH)20(aq)] + [HgS0(aq)]) showed an inverse relationship with the C/N ratio, supposedly reflecting differences in primary production and energy-rich organic matter availability among sites. We conclude that concentrations of neutral inorganic mercury sulfide species, together with the availability of energy-rich organic matter, largely control Hg methylation rates in contaminated sediments. Furthermore, Hg(SH)20(aq) is suggested to be the dominant species taken up by MeHg producing bacteria in organic-rich sediments without formation of HgS(s).
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| 5. |
- Drott, Andreas, et al.
(författare)
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Potential demethylation rate determinations in relation to concentrations of MeHg, Hg and pore water speciation of MeHg in contaminated sediments
- 2008
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Ingår i: Marine Chemistry. - : Elsevier. - 0304-4203 .- 1872-7581. ; 112:1-2, s. 93-101
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Tidskriftsartikel (refereegranskat)abstract
- Specific, potential demethylation rate constants (kd, day− 1) were determined in fresh and brackish water sediments from seven different sites in Sweden originally contaminated with either Hg0(l) or phenyl-Hg. Variations in kd among and within sites were related to ambient concentrations of Hg (1–1143 nmol g− 1) and MeHg (4.4–575pmol g− 1), and to pore water speciation of MeHg. Chemical speciation modeling revealed that MeHgSH(aq), MeHgS−(aq) and MeHg–thiol complexes [MeHgSR(aq)] associated to dissolved organic matter were the dominant MeHg species in the sediment pore water at all sites. Potential rates of MeHg demethylation were determined as the decomposition of isotopically enriched Me204HgCl during 48 h of incubation in darkness under N2(g) at 23 °C. There was a significant (p < 0.001) positive relationship between ambient MeHg concentrations in sediments and kd across all sites, but no significant relationship between ambient Hg and kd. At the three sites with the highest ambient Hg concentrations in sediments (average ± SD, 185 ± 249 nmol g− 1), kd was not significantly correlated with pore water MeHg speciation. At sites with lower concentrations of ambient Hg in sediments (average ± SD, 11 ± 8.4 nmol g− 1), there was a significant (p = 0.02) positive relationship between calculated concentrations of MeHgSH(aq), MeHgS−(aq), or the sum of these two species, and kd. If it is assumed that an oxidative demethylation process dominated at sites with lower concentrations of ambient Hg in sediments, the results suggest that it may be dependent on a passive uptake of inorganic MeHgSH molecules. It was shown that additions of different amounts of MeHg and Hg tracers, in relation to the ambient concentrations of MeHg and Hg, could result in dramatically different kd values within and between sites. At one brackish water site, both absolute demethylation rates and kds were significantly, inversely related to ambient concentrations of MeHg (and Hg). In contrast, at another brackish water site with generally less kds, samples with low ambient MeHg experienced toxic effects and demethylation was not detected. This implies that added (and possibly ambient) MeHg/Hg, depending on the environmental conditions, may have either stimulating or inhibitory effects on demethylation processes.
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| 6. |
- Havarinasab, Said, et al.
(författare)
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Dose-response study of thimerosal-induced murine systemic autoimmunity
- 2004
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Ingår i: Toxicology and Applied Pharmacology. - : Elsevier BV. - 0041-008X. ; 194:2, s. 169-179
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Tidskriftsartikel (refereegranskat)abstract
- The organic compound ethylmercurithiosalicylate (thimerosal), which is primarily present in the tissues as ethylmercury, has caused illness and several deaths due to erroneous handling when used as a disinfectant or as a preservative in medical preparations. Lately, possible health effects of thimerosal in childhood vaccines have been much discussed. Thimerosal is a well-known sensitizing agent, although usually of no clinical relevance. In rare cases, thimerosal has caused systemic immune reactions including acrodynia. We have studied if thimerosal might induce the systemic autoimmune condition observed in genetically susceptible mice after exposure to inorganic mercury. A.SW mice were exposed to 1.25–40 mg thimerosal/l drinking water for 70 days. Antinucleolar antibodies, targeting the 34-kDa protein fibrillarin, developed in a dose-related pattern and first appeared after 10 days in the two highest dose groups. The lowest observed adverse effect level (LOAEL) for antifibrillarin antibodies was 2.5 mg thimerosal/l, corresponding to an absorbed dose of 147 μg Hg/kg bw and a concentration of 21 and 1.9 μg Hg/g in the kidney and lymph nodes, respectively. The same LOAEL was found for tissue immune-complex deposits. The total serum concentration of IgE, IgG1, and IgG2a showed a significant dose-related increase in thimerosal-treated mice, with a LOAEL of 5 mg thimerosal/l for IgG1 and IgE, and 20 mg thimerosal/l for IgG2a. The polyclonal B-cell activation showed a significant dose–response relationship with a LOAEL of 10 mg thimerosal/l. Therefore, thimerosal induces in genetically susceptible mice a systemic autoimmune syndrome very similar to that seen after treatment with inorganic mercury, although a higher absorbed dose of Hg is needed using thimerosal. The autoimmune syndrome induced by thimerosal is different from the weaker and more restricted autoimmune reaction observed after treatment with an equipotent dose of methylmercury.
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| 7. |
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| 8. |
- Lambertsson, Lars, 1971-
(författare)
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Mercury species transformations in marine and biological systems studied by isotope dilution mass spectrometry and stable isotope tracers
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis focuses on the implementation of species-specific isotope dilution (SSID) methodology and stable isotope tracers to determine mercury species occurrence and transformation processes in-situ and during sample treatment. Isotope enriched tracers of methyl-, ethyl- and inorganic mercury were synthesised and applied in different combinations to marine and biological samples. Experimental results were obtained using gas chromatography-inductively coupled plasma-mass spectrometry (GC-ICP-MS). Mercury methylation and methylmercury demethylation processes in surface sediments were studied in the brackish Öre River estuary, Bothnian Bay. Uni- and multivariate data evaluation identified the organic material content and mercury methylation potential in the sediments as important factors controlling incipient methylmercury levels. Mercury species distribution in mice treated with the pharmaceutical preservative Thimerosal (ethylmercurithiosalicylate) was studied. The ethylmercury moiety of Thimerosal was observed to rapidly convert to inorganic mercury in the mice during the treatment period as well as during sample treatment, hence necessitating SSID methodology for accurate ethylmercury determinations in biological samples. To facilitate the introduction of SSID as a routine quantitative method in mercury speciation, a methylmercury isotopic certified reference material (ICRM) was produced. Prior to certification, the stability of the material was examined in conventional and isochronous stability studies spanning 12 months, which permitted uncertainty estimation of the methylmercury amount content for two years of shelf-life. Finally, a field-adapted SSID method for methylmercury determinations in natural water samples was developed. The proposed analytical protocol significantly simplified sample storage- and treatment procedures without sacrifices in analytical accuracy.
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| 9. |
- Lambertsson, Lars, et al.
(författare)
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Organic Material: The Primary Control on Mercury Methylation and Ambient Methyl Mercury Concentrations in Estuarine Sediments
- 2006
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Ingår i: Environmental Science & Technology. - : ACS Publications. - 0013-936X .- 1520-5851. ; 40:6, s. 1822-9
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Tidskriftsartikel (refereegranskat)abstract
- Estuarine environments that have no direct sources of mercury (Hg) pollution may have sediment concentrations of methylmercury (MeHg) as high as those of polluted marine environments. In this study we examined the biogeochemical factors affecting net methylation and sediment MeHg concentrations in an unpolluted estuarine environment, the Öre River estuary, which discharges into the Bothnian Bay (20-120 ng total Hg g-1 dry sediment, salinity 3-5‰). We analyzed the spatial and temporal differences in surface sediment profiles of MeHg concentration, Hg methylation, MeHg demethylation, and concentrations of sulfide and oxygen between accumulation and erosion type bottoms. The main difference between the bottoms studied was in the proportion of organic material (OM) in the sediment, ranging between 0.8% and 10.8%. The pore water sulfide concentration profiles also differed considerably between sites and seasons, from 0 to 20 μM, with 100 μM as the extreme maximum. The sediment MeHg concentration profiles (0-10 cm) mostly varied between 0.1 and 7 ng g-1 dry weight (dw, as Hg). The MeHg demethylation rates were relatively low and the depth profiles of the rates were relatively constant over season, site, and depth. In contrast, both rates and depths of maximum Hg methylation differed between the bottoms. The results indicate that the amount of OM accumulated at the bottoms was the main factor affecting net MeHg production, while the total amount of Hg had little or no influence on the amount of MeHg in the sediment.
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| 10. |
- Lambertsson, Lars, et al.
(författare)
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Rapid dissolution of cinnabar in crude oils at reservoir temperatures facilitated by reduced Sulfur Ligands
- 2018
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Ingår i: ACS Earth and Space Chemistry. - : American Chemical Society (ACS). - 2472-3452. ; 2:10, s. 1022-1028
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Tidskriftsartikel (refereegranskat)abstract
- Mercury (Hg) is present in petrochemical samples, including crude oils, and the processing and use of petroleum products contribute to global Hg emissions. We present a refined theory on geochemical processes controlling Hg concentrations in crude oil by studying dissolution kinetics and solubility thermodynamics of cinnabar (α-HgS(s)) in different crude oils held at reservoir temperatures. In a black light crude oil, α-HgS(s) dissolved in an apparent zero-order reaction with a rate of 0.14−0.58 μmoles m−2 s −1 at 170−230 °C and an estimated activation energy of 43 kJ mol−1 . For crude oil samples with a total sulfur concentration spanning 0.15− 2.38% (w/w), the measured dissolution rate varied between 0.05 and 0.24 μmoles m−2 s−1 at 200 °C. Separate tests showed that thiols and, to a lesser extent, organic sulfides increased the solubility of α-HgS(s) in isooctane at room temperature compared to thiophenes, disulfides, and elemental sulfur. Long-term (14 days) α-HgS(s) solubility tests in a crude oil at 200 °C generated dissolved Hg concentrations in the 0.3% (w/w) range. The high α-HgS(s) dissolving capacity of the crude oils was more than 2 orders of magnitude greater than the highest reported Hg concentration in crude oils globally. On the basis of the kinetic and solubility data, it was further concluded that α-HgS(s) is not stable under typical petroleum reservoir conditions and would decompose to elemental mercury (Hg0 ). Our results suggest that source/reservoir temperature, abundance of reduced sulfur compounds in the crude oil, and dissolved Hg0 evasion processes are principal factors controlling the ultimate Hg concentration in a specific crude oil deposit.
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