Benthic fluxes of mercury during redox changes in pristine coastal marine sediments from the Gulf of Trieste (northern Adriatic Sea)

Koron, Neža (author), Faganeli, Jadran (author)

Abstract Purpose: The Gulf of Trieste (northern Adriatic Sea) is an example of a coastal environment contaminated with mercury (Hg). Contamination is a consequence of nearly 500 years of activity at the Idrija Mine (western Slovenia), which is the second largest Hg mine in the world. Oxygen depletion can be common in the Gulf of Trieste due to late summer stratification of the water column and accumulation of labile organic matter. Since changing redox conditions can have an impact on Hg transformations, we studied the effect of oxzgen depletion, in parallel with sulphide, iron (Fe), manganese (Mn), fluorescent dissolved organic matter (FDOM) and nitrogen (N) and phosphorus (P) availability, on total Hg and methylmercury (MeHg) fluxes from sediments. Materials and methodsČ Pore water concentrations and benthic fluxes of total dissolved Hg and MeHg were studied in situ and in microcosm laboratory experiments using flux chambers encompassing three different stagesČ oxic, anoxic and reoxidation. Results and discussion: Our experiments showed that inthe oxic stage there were small effluxes of MeHg to the water column, which increased in the anoxic stage and dropped rapidly in a subsequent reoxic stage, showing influx. Our results support the hzpothesis that MeHg desorptionfrom reduced metal hzdroxides under anoxic conditions, and co-precipitation with Fe-oxides and MeHg demethylation in the reoxidation stage, may play a major role in determining MeHg benthic fluxes. For Hg and MeHg, it appears that there is little relationship between their pore water distribution and flux and that of FDOM, i.e. humics. Conclusions: The results indicate that there was no significant difference in Hg and MeHg pore water levels and their benthic fluxes between the contaminated northern and central parts of the Gulf of Trieste and the pristine southern part. This suggests that shallow and stratified coastal marine environments, in general, representareas with a risk of high benthic release of toxic MeHg.

• Language: English
• Keywords: morje, Tržaški zaliv, Jadransko morje, Živo srebro, kontaminacija, onesnaževanje, okoljske vede, sediment, bentoški pretok, biogeokemijsko kroženje, morske lagune, lagune, recenzirani zborniki
• Work type: Not categorized
• Typology: 1.08 - Published Scientific Conference Contribution
• Organization: BF - Biotechnical Faculty
• Year: 2012
• Number of pages: Str. 1604-1614
• Numbering: vol. 12, št. 10
• PID: 20.500.12556/RUL-37633
• UDC: 502
• ISSN on article: 1439-0108
• COBISS.SI-ID: 2644303
• Publication date in RUL: 10.07.2015

Record is a part of a proceedings

• Title: Proceedings of the IASWS 11, 12th International Symposium on the Interactions between Sediments and Water, June, 19-23, 2011, Darlington, England
• COBISS.SI-ID: 26272551

Record is a part of a journal

• Title: Journal of soils and sediments
• Publisher: Springer Nature
• ISSN: 1439-0108
• COBISS.SI-ID: 15925543