Heavy metal concentrations in dry and wet atmospheric deposits in Paris district: comparison with urban runoff

In urban areas, dry and wet atmospheric deposits are more rarely sampled th an atmospheric particles. Nevertheless, fallout data are needed in order to compare concentrations and fluxes with street deposits and with samples co llected during rain periods at roof outlets, gullies or within the sewer sy stem. Such comparisons represent key issues in the understanding of micropo llutant transport and evolution in urban areas. Within the Paris conurbatio n, four sites have been studied for dry, wet and total atmospheric deposits : Chatou, a suburb west of the Paris conurbation, Creteil, suburb, south-ea st, Fontainebleau at 48 km south-east from the centre of Paris, and 'Le Mar ais' within the centre of Paris. On each site, samples were continuously co llected from 2 to 13 months. Comparison of median values of metal concentra tions in various components of atmospheric fallout illustrates the influenc e of urban emissions: rainwater contamination with trace metals is only sli ghtly larger in the centre of Paris than at Fontainebleau which illustrates the occurrence of medium range transport of atmospheric contamination. Foc using on an experimental urban catchment equipped with combined sewers, sit uated inside the 'Le Marais' district, within Paris, this paper compares me tal concentrations of atmospheric deposits to dissolved and particulate one s in runoff from four roofs, three yards, six gullies, and at the catchment outlet. This comparison allows a better understanding of metal transport i n urban areas and of the evolution of metal distribution between dissolved and particulate fractions. (C) 1999 Elsevier Science B.V. All rights reserv ed.