Field and Laboratory Studies of the Toxicity to Phytoplankton of Polychlorinated Biphenyls (PCBs) Desorbed from Fine Clays and Natural Suspended Particulates

Abstract

Polychlorinated biphenyls (PCBs; Aroclor 1254) were adsorbed to natural (Hudson River and New York Bight) and commercial (illite) particles in the laboratory, then allowed to desorb for several hours into the surrounding aqueous medium in the presence of either of two laboratory strains of diatom species or a complete natural phytoplankton assemblage. Cell density, photosynthesis, and chlorophyll a concentration in the cultures were followed for 2 to 3 days. In two experiments, PCB-carrying natural particles were removed after desorption and prior to the introduction of algae. All incubations were carried out in the laboratory or in dialysis membrane bags suspended in the tidal channel of an estuarine marsh. Cultures containing 90 μg of illite-bound Aroclor 1254/L of water were severely damaged within 4 hours, by which time 72% of the PCBs had desorbed from particles and become available to the diatoms. Similarly, a natural phytoplankton community, incubated under natural conditions in the presence of 50 μg of Hudson River sediment-associated PCB/L of water, registered significant reductions of photosynthesis and chlorophyll a content for at least 3 days. When PCB-bearing New York Bight particles were removed from the medium prior to the introduction of algae, sufficient desorbed PCBs remained to reduce growth rates and chlorophyll a content of the culture. The latter experiment clearly demonstrates particle to water to cell transfer of desorbed PCBs.