Comparison of aerosol and dry deposition sampled at two sites in Southern China

Dry deposition and size-selected respirable particulate matter were simulta neously sampled on a daily basis at two locations, Shenzhen and Hong Kong, in April 1999. Ionic concentrations were generally similar at both location s, but with a greater abundance of crustal-derived ions at Shenzhen, and se asalt-derived ions at central Kowloon. Chloride depletion in the Hong Kong samples involved substitution by both nitrate and sulphate. The aerosol par ticle size distributions showed the presence of ammonium ion in the fine mo de, and crustal and seasalt-derived ions in the coarse mode. Formic and ace tic acids were roughly equally distributed between coarse and fine modes. D ry deposition fluxes in April are compared with annual means from Hong Kong Environmental Protection Department data, and dry deposition velocities ar e calculated. (C) 2001 Elsevier Science Ltd. All rights reserved.