Seasonal changes of PFOS and PFOA concentrations in Lake Biwa water.

A survey on seasonal concentration changes of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) was performed for surface water in Lake Biwa (14 sites) from February to November in 2009. The concentrations of PFOS and PFOA were 0.8-1.6 and 7.0-10 ng/L in northern basin of Lake Biwa (eight sites), 0.9-1.7 and 8.3-13 ng/L in southern basin of Lake Biwa except Akanoi Bay (four sites), 1.4-2.8 and 9.1-17 ng/L in Akanoi Bay (8C) and 2.4-5.3 and 12-26 ng/L in Akanoi Bay (168), respectively. Seasonal changes were recognized for both of PFOS and PFOA in the two sites of Akanoi Bay but not in the other sites of the southern and northern basins of Lake Biwa. Monthly detailed surveys in the surface water were performed on the changes of PFOS and PFOA concentrations from June in 2009 to May in 2010 and further on the changes of conductivity values. The changes of PFOS and PFOA concentrations were well consistent with those of conductivity values.