MELIMEX, AN EXPERIMENTAL HEAVY-METAL POLLUTION STUDY - CHEMICAL SPECIATION AND BIOLOGICAL AVAILABILITY OF COPPER IN LAKE WATER

The chemical speciation of dissolved copper was investigated in waters from the limno-corrals of the MELIMEX project and compared with speciation data from other Swiss lakes. Copper is complexed primarily by organic ligands having molecular sizes between 104 and 103 daltons. The mean concentration of the ligands is approximately 5×10-7 mole/mg DOC. The conditional stability constants (pH=8.8) are about 1011. An increased metal load did not induce an increase of binding ligands. A comparison of calculated Cu2+ concentration with corresponding copper contents in the biomass leads to the conclusion that organic ligands and pH are the most important factors in deciding the biological availability of copper. However the sorption capacity of the biomass depends as well on the variety of plankton species. © 1979 Birkhäuser Verlag.