Influence of mode of exposure and the presence of a tubiculous polychaete on the fate of benz[a]anthracene in the benthos

The distribution and metabolism of [14C-12]benz[a]-anthracene (BA) was followed in benthic microcosms in the presence and absence of the polychaete Nereis virens for periods of 4-25 days to simultaneously assess the effects of mode of introduction and the presence of large burrowing organisms on the fate of polycyclic aromatic hydrocarbons (PAH) and their metabolites in the benthos. Radiolabeled BA was added to the chambers in three ways: already sorbed to the entire sediment reservoir, directly into the water column, or incorporated into food for the worms. BA added to the water column was more available for uptake and metabolism by worms and microbial mineralization to CO2 than BA previously sorbed to the entire sediment reservoir. In experiments with the sediment reservoir uniformly labeled with BA, worms increased flux of BA from the sediment, and with time, their presence led to increased rates of microbial mineralization of BA to CO2. Dietary BA was most rapidly metabolized by Nereis