Atmospheric Deposition of PAHs to a Small Urban Lake, Lake Luhu, Guangzhou

Abstract

Atmospheric concentrations and deposition fluxes of particle-associated polycyclic aromatic hydrocarbons (PAHs) were measured over a 1-year period (2001-2002) at a small urban lake, Lake Luhu, in Guangzhou, aiming to estimate their atmospheric loadings to the lake. The annual average PAH deposition fluxes was 0.47mg/(m2·a). It was estimated that within a whole year there was approximately 0.1kg of particle-associated PAHs depositing to the lake from atmosphere. Significant seasonal variations of the PAHs deposition fluxes were observed, suggesting that both highly variable atmospheric PAHs concentrations and complex scavenging processes controlled the result. In the whole year, the highest particle deposition fluxes of PAHs were observed in winter and spring and the lowest fluxes were in autumn. Compared the compositions of deposition fluxes of particle-associated PAHs to that of total suspended particle (TSP) in the air, wet deposition contributed the heavyweight PAHs to deposition fluxes, whilst dry deposition along with low temperature would favour the deposition of lightweight PAHs. With the increasing rainfall, the composition of particle-associated PAHs deposit to the urban lake became similar to that of the total suspended particulates (TSP).