太湖大气氮、磷营养元素干湿沉降率研究

分析了2002年7月—2003年6月太湖周边地区太湖站、拖山岛、东山站、无锡、苏州、湖州、常州、金坛等8个站、点大气TN、TP沉降通量和降水化学组成观测资料,测定和计算了水气界面TN、TP的表观总沉降率(RT)、湿沉降率(RW)和干沉降率(RD)。太湖大气TN的年平均RT为4226kg/(km2.a),TP的年平均RT为306kg/(km2.a)。大气TN、TP的年沉降负荷分别占由环湖河道等点污染源输入的N、P总负荷的48.8%和46.2%。指出形成太湖大气TN污染的主要途径是湿沉降,而大气TP污染则主要来自气溶胶等固体物质的干沉降;小雨携带入湖的大气TN、TP污染物通量高于中雨和大雨。TN总沉降率曲线在春季3—5月出现高峰值的现象对太湖水体的富营养化具有潜在的促进影响。

THE ATMOSPHERIC DEPOSITION OF NITROGEN AND PHOSPHORUS NUTRIENTS IN TAIHU LAKE

Taihu Lake is the third largest freshwater lake of China in southern part of Jiangsu Province, nurturing the most economically developed region including Shanghai, Suzhou, Wuxi, Changzhou cities and so on with high-density population and well-developed industry near Changjiang (Yangtze) River delta. However, this region suffered from environmental pollution and eutrophication by excessive atmospheric nitrogen and phosphorus deposits. To better understand the negative impact for remediation, wet and dry atmospheric deposition of nitrogen and phosphorus and chemical composition of rainwater were sampled and measured from 2002 to 2003 in the lake and the surrounding areas. Results show that the annual average R, (total apparent deposition rate) was 4226 for TN and 306 for TP in kg/km²*a. The annual atmospheric load of TN and TP accounted for 48.8% and 46.2% respectively of total point pollution sources from tributary rivers. Atmospheric rainfall was recognized as a major source of TN into Taihu Lake, whereas atmospheric TP is mainly resulted from dry deposition of solid material in aerosol. The amounts of atmospheric nitrogen and phosphorus pollutants deposited into Taihu Lake by light rain were higher than by heavier rain, and the value of RT peaked in spring (May to March). The current situation may aggravate the eutrophication in the lake area and damage relating aquatic ecosystem in Yangtze River delta.