Survey of PAH in low density residential stormwater ponds in coastal South Carolina: False dark mussels (Mytilopsis leucophaeata) as potential biomonitors

The distribution of PAHs was studied in sediment and false dark mussels, Mytilopsis leucophaeata, of three brackish stormwater retention ponds on Kiawah Island, a gated residential community and golf resort. Impervious surface in pond watersheds ranged from 5 to 30%. Sediment concentrations were lower than those found in other studies of suburban residential areas, and there were no significant differences among ponds or seasons. Mean ∑PAH16 values for sediments in Ponds 67, 100, and 37 were 184.7 ± 101.3 ng g−1, 67.5 ± 26.0 ng g−1, and 84.3 ± 75.5 ng g−1, respectively. Mussel ∑PAH16 concentrations from Pond 67 in August (mean 734.5 ± 148.1 ng g−1), and from Pond 37 in December (mean 1115.1 ± 87.7 ng g−1), were significantly higher than other ponds. Mean ∑PAH16 values for mussels in Ponds 67, 100, and, 37 were 555.9 ± 219.7 ng g−1, 312.5 ± 99.1 ng g−1 and 737.8 ± 419.8 ng g−1, respectively. The mean biota-to-sediment ratio was 7.6 ± 8.1. Isomer ratios generally suggested pyrogenic sources. False dark mussels are a promising indicator species for PAH contamination because they are abundant, easy to sample, bioaccumulate PAH profiles representative of the time-integrated sediment profiles, and their PAH levels are less variable than either stormwater or sediment samples.