The purpose of the present study was to elucidate the characteristic accumulation patterns of the Polycyclic Aromatic Hydrocarbons (PAHs) in various organisms inhabited in the typical eutrophic lake “Lake Suwa”. We also calculated the Biota Sediment Accumulation Factors (BSAF) of each organism to estimate the difference in the pattern of PAHs accumulation among their tropic levels or habitat.
We showed that the concentrations of Σ₁₁PAHs was highest in phytoplankton (mainly Aphanizomenon sp.) (36,900±2,800 ng/g-lipid), followed by chironomid (3, 130±380 ng/g-lipid), catfish (1,720±1,360 ng/g-lipid), zooplankton (mainly Bosmina sp.) (890±170 ng/g-lipid), cherry salmon (270±70 ng/g-lipid), freshwater prawn (240±70 ng/g-lipid), largemouth bass(130±20 ng/g-lipid), Japanese smelt (140±30 ng/g-lipid), crucian carp (120±4 ng/g-lipid), and common carp (50±16 ng/g-lipid). We also analyzed dioxins (DXNs) in largemouth bass.The concentration of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), non-ortho dioxin like-PCBs, and mono-ortho-substituted dioxin-like PCBs (dioxin-like PCBs) were 7±1, 3±1, 117±13 ,and 3,770±930 ng/g-lipid, respectively. Based on these data, we calculated the BSAF of each organism. Σ₁₁PAHs BSAF exceeded 1.0 only in phytoplankton (18.7 g-ignition loss/g-lipid) and chironomid (1.6 g-ignition loss/g-lipid), and other organisms, especially fish, were below 1.0. These results indicated that PAHs were the substances mainly accumulated in primary consumers but not in higher tropic level consumers. On the other hand, BSAF of PAHs and dioxin like-PCBs in largemouth bass had large difference. This may due to the high metabolic rate of PAHs compared to dioxin like-PCBs. These results indicated that ability to metabolize PAHs is important to estimate accumulation pattern of PAHs.
From our results, different accumulation pattern of PAHs in invertebrate and fish were observed. Invertebrates accumulate high Kow PAHs compared to fish. These results may also due to the difference in the ability to metabolize PAHs between fish and invertebrates.