MERCURY DEPOSITION AND REDISTRIBUTION PATTERNS (SOUTHERN LAKE-MAGGIORE, ITALY)

Lake Maggiore, Italy, has been exposed to mercury contamination from m ining and industrial activities for many years. Following to the reduc tion of the major industrial mercury source, a significative decrease of mercury concentrations in the recent sediment was to be expected. T he present study attempts to evaluate mercury contamination in the sou thern part of the lake, as well as to describe the average chemical co mposition of the sediments from this area. Metal contents in sediment contact water and sediment pore water have also been measured as an in dication of possible mercury exchange between sediments and water colu mn. The most recent sediment layers show mercury concentrations of 2.6 7 mg.kg(-1), contact water varies between 1 and 5 ng.1(-1) and pore wa ter between 9 and 26 ng.1(-1) of dissolved mercury. A comparison betwe en different sediment strata shows a general tendency towards levellin g at lower values, although the still high mercury concentrations are of continuing concern.