Sampling in the Middle Adriatic Sea – Relations Between Mercury and Microbial Species
Sampling in the Middle Adriatic Sea – Relations Between Mercury and Microbial Species
Abstract:
Chemical and biological processes can transform mercury species. These (bio)chemical reactions are of great importance because they facilitate mercury’s entrance into the marine food web where it readily bioaccumulates in the form of methylmercury (MeHg). Microorganisms might represent a critical Hg bioaccumulation step in the entire marine food web. In order to establish relationship between mercury and microbial species, we performed series of samplings. Samplings were conducted during oceanographic cruises aboard the Croatian research vessel Bios Dva from March 2014 to June 2015 in the Middle Adriatic Sea. Our research is constrained in transect from the Bay of Kaštela to the island of Vis. Water profiles of total mercury (THg), dissolved gaseous mercury (DGM), methylmercury (MeHg)1,2 and picoeukaryotes3 in non-filtered seawater samples were created for both coastal and open waters. THg concentrations range from 0.14-1.10 ng/L near the island of Vis, which represents pristine marine environment. The highest values for THg (0.92-5.58 ng/L) are found in the Bay of Kaštela that had been affected by previous contamination from chlor-alkali industrial waste waters. DGM always shows lower values in the pristine environment (22.1-245 pg/L) than in the contaminated area (31.8-351 pg/L). At the Split Channel stations, which is located between pristine and contaminated environment, values for DGM concentrations are in between 23.0-374 pg/L. MeHg concentrations vary, but range from 1.07-34.3 pg/L for all stations, with the highest values found in the Bay of Kaštela. Number of picoeukaryotes is the highest in the central part of the Bay of Kaštela (0.44×103-31.8×103/mL) while the lowest number (0.63×103-19.9×103/mL) is found at the island of Vis. All our results will be presented herein.
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