Atmospheric bulk deposition of PAHs onto France : trends from urban to remoted sites

Fifty-eight weekly samples of atmospheric bulk deposition (dry and wet) were collected in France at six specific sites over a year. Urban, semi-rural, rural and forested sites were chosen on a transverse from West to East at the Paris latitude. Seasonal variations are described, with winter time concentrations 2–3 times higher than summer ones due to an increase in fossil fuel consumption in winter. When temperature did not exceed 12°C, mean PAH concentrations varied from 221 ng l^-1 in Paris to 25 ng l^-1 at a rural site. About 50 km far from Paris, PAH concentrations decreased by two-thirds. Urban emissions have a local impact on the fallout contamination. Fluxes at the Paris site (from 157–1294 ng m^-2 d^-1) were from 2.5–6 times higher than in the rural and forested sites. In the latter sites, mean daily fluxes (50 ng m^-2 d^-1) were close to those of high European mountains, considered as background levels. In rural sites, without treatment plant sludge spreading, atmospheric deposition is the major source of PAH inputs to soils.