Effects of anoxia and sulfide on concentrations of total and methyl mercury in sediment and water in two Hg-polluted lakes
Research output: Contribution to journal › Article
Between May and December 1996, monthly samples of surface sediment (0-1 cm), settling matter, and water were taken at a shallow site and a deep site in each of two consecutive Hg-polluted riverine lakes. In the upper lake, the sediment was polluted also with cellulose fiber. Both hypolimnia turned anoxic, but sulfide was detected only in the upper lake. When sulfide appeared, hypolimnetic methyl mercury (MeHg) increased and reached 47 pM (9.4 ng.L-1), whereas MeHg in the sediment below decreased. The increase in hypolimnetic inorganic Hg (IHg = total Hg - MeHg), which reached a peak of 40 pM (8.0 ng.L-1), was slower, possibly because mobilized IHg was methylated. In the lower lake, hypolimnetic MeHg and IHg increased less dramatically during summer stratification, reaching only 5 and 24 pM (1.0 and 4.8 ng.L-1), respectively. There was no detectable concomitant decrease in sediment MeHg. In both lakes, MeHg appeared to increase simultaneously with total Fe and Mn in the hypolimnion, as did IHg in the lower lake. Our observations suggest that the presence of hydrous ferric and manganese oxides decreased the mobility of Hg in both lakes but increased MeHg production in the upper lake.
|Research areas and keywords||
Subject classification (UKÄ) – MANDATORY
|Journal||Canadian Journal of Fisheries and Aquatic Sciences|
|Publication status||Published - 2001|
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