MERCURY IN WATER AND SEDIMENTS OF THE SOUTHERN BALTIC-SEA

Total mercury concentrations [Hg,] were measured in samples of water a nd sediments collected from the southern Baltic Sea from the period 19 93-1995. Picomolar concentrations of HgT were found in offshore surfac e water. Higher levels were measured in samples from the plum of the V istula. An exceptionally high concentration of mercury (25 pM Hg-T, 5 pM methylmercury) was measured in the nearbottom, quasi-anoxic water o f the Gdansk Deep and explained by the release of mercury from fine gr ained sediments covering the bottom. In the sediments, the largest con tents of Hg-T were found in fine grained, organic rich deposits of the Baltic deeps. The increase in mercury contents in the upper layers of sediments deposited within the last 100-150 years was attributed to t he anthropogenic load of mercury and its increased scavenging to sedim ents with organic matter. (C) 1998 Elsevier Science B.V.