Atmospheric deposition of PAHs to an urban site, Paris, France

Abstract

Atmospheric fallout were collected at Paris, France, in order to analyse polycyclic aromatic hydrocarbons (PAHs) classified by the Environmental Protection Agency as priority pollutants. Bulk (dry plus wet) atmospheric depositions were monthly analysed from November 1999 to October 2000. Fluoranthene and pyrene were the major components, each averaging about 19% of total. Total PAH concentrations in bulk precipitation ranged from 51 to 995 ng l −1 and were higher than those analysed in rivers crossing Paris area. Seasonal variations were described with the highest values measured in winter, and the same trend was observed for PAH concentrations in bulk (gaseous plus particulate) air measured by the Laboratoire d’Hygiène de la Ville de Paris. A relationship between PAH concentrations in bulk deposition and temperature was established. A bulk scavenging ratio, defined as PAH concentrations in bulk deposition versus bulk air, was discussed for fluoranthene and pyrene which are supposed to be present in air mainly in gaseous phase. Monthly fluxes ranged from 5.3 μg m −2 in August to 63 μg m −2 in December for total PAHs, with annual flux of 234 μg m −2, corresponding to 2.1 and 27.7 μg m −2 for the 6 PAHs of the WHO recommendations and 104 μg m −2 for a year. The winter loading was twice higher than the summer one, and heating contribution was estimated to be 41% of the annual loading.