PERCH MERCURY CONTENT IS RELATED TO ACIDITY AND COLOR OF 26 RUSSIAN LAKES

We determined mercury in fish (perch Perca fluviatilis) from 26 Russia n lakes in three regions over four years. The lakes ranged in size fro m 2 to 395,000 ha, in pH from 4.5 to 10.4 and In color from 3 to 190 h azen. Sixteen lakes were drainage lakes, with permanent outlets, and 1 0 were seepage lakes, with no permanent inlet; or outlet. The lakes we re generally located in forested regions with little or no human habit ation in the watershed. The three regions were geologically distinct: Precambrian Shield granitic bedrock covered with thin soil; Triassic b edrock covered with thick glacial tills; and Triassic bedrock covered with thin sediments. At each lake water samples were collected and ana lyzed for pq acid neutralizing capacity (ANC), major cations, and anio ns. Dissolved mercury species were estimated with (I thermodynamic equ ilibrium model (MINTEQA2). Mercury content of dorsal muscle varied fro m 0.04 to 1.0 mu g/g wet weight, and was linearly related to calculate d HgCH3Cl(r(2)=0.68, p<0.001). Lake HgCH3Cl, in turn, was related to l ake pH (r(2)=0.86, p<0.001). Stepwise multiple regression selected lak e HgCH3 and color as the factors most highly related to fish mercury c ontent, with the model accounting for 75% of the variation.