长江口大气重金属污染特征及沉降通量

于2009年8月与2010年5月在长江口青草沙水库及长兴岛采集了大气颗粒物样品,测定了Zn、Pb、Cr、Cu等重金属元素的浓度,并初步估算了大气气溶胶中这些重金属在长江口的干沉降通量.结果表明:长江口PM10的平均浓度在109~197μg/m3,重金属元素浓度水平由高到低为Zn>Cr>Mn>Cu>Ti>Ni>Pb>V,其中Zn、Cr、Mn、Cu、Ni、Pb存在明显的元素富集,浓度分别达到297, 241, 186, 181, 52, 32ng/m3,而相应的日平均干沉降通量分别为0.14, 0.09, 0.08, 0.08, 0.02, 0.02mg/(m2·d).通过与长江口水库重金属浓度对比,大气干沉降的总Cu约占水体中总Cu浓度的25%左右,大气沉降可能是长江口水中重金属的重要来源之一.

Characteristics and depositional fluxes of heavy metals in aerosol of the Yangtze Estuary

Atmospheric aerosol at the Qingcaosha Reservoir and Changxing Island, in the Yangtze Estuary, were collected, and its heavy metals measured. Concentrations of PM10were from 109to 197μg/m3. The elemental concentrations followed the order Zn > Cr > Mn > Cu > Ti > Ni > Pb > V. Zn, Cr, Mn, Cu, Ni, and Pb were significantly enriched relative to crustal contributions. The average concentrations of Zn, Cr, Mn, Cu, Ni, and Pb were estimated to be 297, 241, 186, 181, 52, and 32ng/m3. Average daily dry-depositional fluxes to the Yangtze Estuary were estimated to be 0.14, 0.09, 0.08, 0.08, 0.02, and 0.02mg/(m2×d), respectively. Dry deposition accounted for about 25% of the Cu in the Qingcaosha Reservoir.