Polychlorinated biphenyl partitioning in the waters of a remote mountain lake

The dissolved-particulate phase distribution of polychlorobiphenyls (PCBs) in the waters of a high mountain lake (Redó Lake, Pyrenees) has been studied. The lake is oligotrophic and its water hydrology is dominated by atmospheric precipitation; inputs from catchment or other sources are not significant. Samples were collected in several periods encompassing the summer and winter seasons. The PCB congener concentrations were rather uniform both in terms of water depth and seasonality showing steady state conditions. Seventy percent of the variation of the PCB particulate-dissolved phase coefficient (Kd) was correlated with temperature and log octanol-water (Kow)). Lower temperatures and hydrophobicity involved a higher association with the particulate phase. This behavior is consistent with the predominance of plankton among suspended particles following a two compartment model. Thus, temperature dependence seems mainly related to a rapid phase transfer mechanism such as surface adsorption to the cell membranes and log Kow influence could reflect steric restrictions for the uptake of these compounds upon algal ingestion.