Polychlorobiphenyl flux in planktonic model ecosystems

Polychlorobiphenyl (PCB, Aroclor® 1242) loadings of 2.12, 21.5 and 212Μg.d−1 were added to three model planktonic ecosystems. Each loading consisted of a clay and water mixture in which 92% of the PCB was adsorbed to the clay particles. After addition, partitioning between soluble and particulate pools in the water and sedimentation of PCB was examined. Particulate PCB concentrations were positively related to changes in particulate organic carbon (POC) indicating a transfer of PCB from clay to the algal community. The percent of the total PCB concentration measured as soluble was inversely related to POC. The proportion of PCB added to each column that was sedimented, not recovered or remained in the water column was similar at all loading rates. Approximately one-half of the PCB added was not accounted for in sedimentation or the water and was assumed lost by volatilization. High algal biomass and sedimentation of organic matter reduced this loss.