Sulfur speciation in mercury-contaminated sediments of a coastal lagoon: the role of elemental sulfur

Abstract

Chemical equilibrium studies have predicted that elemental sulfur (S0) could play a crucial role in mercury mobility in salt marsh sediments. This prompted us to consider the occurrence of S0 in conjunction with the degree of contamination in sediments of a coastal wetland (Pialassa Baiona, Italy) impacted by inputs of mercury derived from past industrial activity. The distribution of S0, total Hg, soluble sulfates and acid-soluble sulfides was studied in five sediment cores collected in two ponds of the lagoon. Sulfides, sulfates and S0 exhibited vertical profiles typical of salt marsh systems, with concentrations declining with depth. Mercury enrichment (2-23 mg kg-1) was detected at the surface strata where the highest concentrations of sulfides and S0 were found (up to 1.70 and 0.9 g kg-1, respectively). The effect of elevated levels of sulfides and elemental sulfur on the fate of mercury in the lagoon is discussed.

Recent evolution of sedimentary heavy metals in a coastal lagoon contaminated by industrial wastewaters (Pialassa Baiona, Ravenna, Italy)

“…Nevertheless, studies on mercury methylation have emphasized how redistribution processes seem capable of increasing the bioavailability of Hg. 8 Cattani et al (1999) focused their attention on biota: total Hg (THg) was found to range from 0.1 and 2.2 mg g -1 d.w. in samples of the green seaweed Ulva rigida collected across the lagoon, while in an active biomonitoring experiment carried out with transplanted mussels (Mytilus galloprovincialis), THg in soft tissues was found to be 4.4 times the initial background level after a 52-day exposure in the southernmost contaminated sub-basin (Fabbri et al, 2001b). During a campaign in 1997-1998, Trombini et al (2003 showed that the southern sub-basin still had values of total Hg and methyl Hg which pose an ecotoxicological risk.…”

“…In addition, high concentrations of polystyrene, PAHs, PCBs and PCDD/Fs were recently found in sediment samples in the southern area (Fabbri et al, 2001a;Matteucci et al, 2001). Lastly, recent studies on mercury methylation have highlighted the fact that redistribution processes can increase the bioavailability of Hg, with some risk to human health (Fabbri et al, 2001b;Trombini et al, 2003).…”

A sensitive resonance light scattering spectrometry of trace Hg2+ with sulfur ion modified gold nanoparticles

“…The aggregation of Au-NPs-S in the presence of Hg 2+ is attributed to the following reasons. Firstly, it has strong binding ability between Hg 2+ and S 2− at the surface of Au-NPs-S for very small solubility product constant of HgS (K sp = 4.0 × 10 −53 ) [48], which makes the formation of the much more insoluble HgS at the surface of AuNPs-S. Secondly, when Hg 2+ concentration is lower than that of S 2− , there exists strong binding between one Hg 2+ and two S 2− ions [49,50], that is to say, Hg 2+ can act as the linkage of adjacent Au-NPs-S through the bridging S-Hg-S bonds.…”

Anthropogenic disturbance and spatial heterogeneity of macrobenthic invertebrate assemblages in coastal lagoons: the study case of Pialassa Baiona (northern Adriatic Sea)

“…Total mercury in the sediment (Hg) was analysed by Cold Vapour Atomic Absorption Spectrometry (CVAAS) after digestion with nitric and sulphuric acid (as in Fabbri et al 2001a). Reagent blanks and certified reference materials, PACS-2, was analysed concurrently with sediment samples to validate the method used.…”