FREE CUPRIC ION CONCENTRATIONS AND CU COMPLEXATION IN SELECTED SWISS LAKES AND RIVERS

[Cu2+] and Cu complexation parameters in some selected freshwater syst ems in Switzerland were determined by the technique of ligand-exchange and DPCSV. Results from the water columns of some eutrophic and oligo trophic lakes are presented and compared to small acid lakes. Cu is st rongly complexed by organic ligands which with very high stability con stants at low concentrations are probably biologically produced, as in dicated by the seasonal variations in the eutrophic lakes and by the r elationship between Cu complexation and algal activity in the eutrophi c (pCu=15-16), oligotrophic (pCu=13-14) and acidic (pCu=9-10) lakes. T he extent of Cu complexation in river waters was generally lower than in the eutrophic lakes, at similar DOC levels. No obvious correlation between Cu complexation and DOC was observed, indicating that Cu compl exing ligands are specific organic compounds.