Seasonal Deposition Fluxes of Polycyclic Aromatic Hydrocarbons (PAHs) in Lake Biwa, Japan

Abstract

Seasonal deposition fluxes of polycyclic aromatic hydrocarbons (PAHs) in the North Basin of Lake Biwa were investigated by monthly collecting sediment trap samples through a year from July 2003. Average deposition flux of total PAHs was 75 ng cm−2 year−1, similar to those for other rural area. Deposition fluxes of PAHs did varied seasonally. In the vertical mixing period of the lake, late autumn to early spring, the fluxes of less volatile PAHs were enhanced while those for volatile PAHs were not. The size difference of particles associated with volatile and less volatile PAHs caused the seasonal variation of the fluxes. Oil discharge from water delivery equipments may contribute the fluxes of volatile PAHs in summer to autumn.