Effect of temperature on the accumulation kinetics of PAHs and PCBs in the zebra mussel, Dreissena polymorpha

The role of temperature on the accumulation and elimination kinetics of selected polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyl (PCB) congeners was examined for the zebra mussel, Dreissena polymorpha. Uptake and elimination rates were measured at intervals over a three year period in laboratory toxicokinetics studies in which zebra mussels were maintained at ambient field temperatures or acclimated to higher or lower temperatures. The uptake rate coefficients (k(u)) for benzo(a)pyrene (BaP) and 2,2',4,4'5,5'-hexachlorobiphenyl (HCBP) increased in proportion to temperature over a range from 4 to 20 degrees C when measured at the field-collected temperature. Both k(u) and the elimination coefficient (k(u)) also decreased with increasing organism size. However, no relationship with temperature was found for the k(u) of BaP in the following year nor was there a relationship between k(u) and temperature for pyrene and pentachlorophenol (PCP) when the kinetics were measured at field-collected temperatures. In laboratory acclimation studies, k(d) for three compounds (BaP, HCBP, and PCP) showed a significant positive relationship with temperature over the 4-20 degrees C range. Pyrene accumulation kinetics however, still exhibited no relationship with temperature. These results contradict the concept that uptake of contaminants changes over a season with temperature thereby, influencing contaminant toxicokinetics. Furthermore, the k(d) values observed for these compounds indicate that elimination was slow, and no relationship of k(d) was exhibited with water temperature, season, or year.