Bioaccumulation of phenanthrene and benzo[a]pyrene in Calanus finmarchicus

With petroleum exploration and development expanding in the Arctic (AMAP, 2007) there is a need to obtain additional information on the ecotoxicology of Arctic organisms. Here we perform 192 h laboratory exposure experiments on the keystone Arctic zooplankton species, Calanus finmarchicus. We trace the accumulation and depuration of two polycyclic aromatic hydrocarbons (PAHs): phenanthrene and benzo[a]pyrene (B[a]P) using 14C labeled PAH compounds. Copepods were not fed during the experiment, limiting uptake to diffusion processes alone. The lighter PAH compound, phenanthrene, accumulated rapidly in C. finmarchicus, reaching steady state within 96 h. The heavier PAH compound, B[a]P, accumulated more slowly and steady state was not reached within the 192 h exposure period. As expected, the bioconcentration factor (BCF) for B[a]P was higher than for phenanthrene in accordance with a higher octanol/water partition coefficient for B[a]P (log Kow=6.04) compared to phenanthrene (log Kow=4.53). However, for both compounds, log BCF was lower than log Kow that may indicate active biotransformation and excretion of the selected PAH compounds. These findings on the bio-uptake kinetics for petroleum hydrocarbons are essential for evaluating the potential consequences of an oil spill in the Arctic.

► We examine the bioaccumulation of the PAHs phenanthrene and benzo[a]pyrene in the Sub-arctic copepod Calanus finmarchicus.
► Accumulation of the three ringed PAH phenanthrene is faster than accumulation of the five ringed PAH benzo[a]pyrene.
► Bioconcentration factor (BCF) of benzo[a]pyrene is higher than BCF of phenanthrene.
► The effect of petroleum exposure will depend on duration of exposure and composition of the oil.