THE DESIGN AND APPLICATION OF A NOVEL AUTOMATED SAMPLER FOR WET AND DRY DEPOSITION TO WATER SURFACES

A novel automated wet and dry deposition collector utilising a wet-sur face surrogate for dry deposition sampling is described. This has been used at two sites in NW England to attempt to establish wet and dry d eposition fluxes of a range of polycyclic aromatic hydrocarbons (PAH) to natural water surfaces in the UK. The sample collection and analyti cal procedures are described. The wet flux of SIGMAPAH (n = 13) for th e winter period is more than double that for summer/autumn at both sit es. The pattern of PAH in the seasonally-averaged wet deposition data set stayed constant between seasons at the Castleshaw site, but not at Esthwaite Water. Both wet and dry deposition are found to be importan t to the overall atmospheric input at each site. The total (wet plus d ry) input rises from summer/autumn to winter: from 74 to 258 ng (SIGMA PAH) . m-2 . h-1 at Esthwaite; from 128 to 164 ng (SIGMAPAH) . m-2 . h -1 at Castleshaw. The proportion of the total flux of SIGMAPAH due to wet deposition doubles at Castleshaw from summer/autumn to winter but decreases at Esthwaite from 65 to 40%. Trends at the two sites may be explained by differences in the proximity of local point sources of PA H.