engleski

Influence of sulfur cycle on mercury speciation in solid and dissolved phases on contaminated coastal sediments

In anoxic sediments solubility and thus toxicity of mercury is controlled by its interaction with sulfur and carbon cycles. The main objective of this work was to investigate speciation of mercury and sulfur in solid and dissolved phases of contaminated coastal sediments in order to elucidate interactions between theses cycles. The study was performed in the Kastela bay (located in the central part of the Eastern Adriatic coast) polluted by mercury originating from a chlor-alkali plant. The solid phase was analysed for total Hg, MeHg (methylmercury), AVS (Acid Volatile Sulfides), CRS (Chromium Reducible Sulfur), organic carbon and carbonate. The total Hg (20-60 mg/kg) and MeHg (20-50  g/kg) concentrations in a sediment core collected in October 2001 were about 100 and 10 times, respectively, higher than typically for uncontaminated marine sediments. The sediment was anoxic, rich in organic matter (50-60 g/kg) and characterised with high level of AVS already in the surface layer. Results obtained demonstrated good correlation along the core between MeHg, AVS and organic carbon in the solid phase, whereas total Hg was better correlated with the carbonate content (20-40 g/kg). In the sediment porewater total Hg, MeHg and dissolved sulfur species were measured. It was found that both total Hg and MeHg in porewater were correlated with dissolved sulfides, suggesting a significant role of sulfides in the distribution of dissolved mercury species and production of MeHg.

nije evidentirano

nije evidentirano