浙江省环太湖河流入湖污染物通量研究

Pollutant flux variations of all the rivers surrounding Taihu Lake in Zhejiang Province

根据2005-2007年浙江省环太湖河道水量巡测资料及水质监测资料,分析2005-2007年浙江省环太湖河流进出水量、水质及污染负荷的时空变化。结果表明,近儿年浙江环太湖河道水质总休上保持稳定,净入湖水量保持负值,其中苕溪是浙江入湖和出湖水量的最大贡献者。环太沏河流的入湖、出湖COD_(Mn)和总磷污染负荷通量呈增加趋势,而氨氮入湖与出湖通量下降。从净入湖量分析,COD_(Mn)和总磷污染负荷以外流为主,而氨氮以入流为主,存在一定程度的滞留。

This article is to give a statistic report on the pollutant influx variations of all the rivers surrounding Taihu Lake in Zhejiang Province. Knowing the pollutant flux variations of the nearby rivers can help to provide a sound background for making effective policies and decisions for pollution control in Taihu Lake Basin. Based on the statistics data on the water quality and quantity of the rivers surrounding Taihu Lake in Zhejiang from 2005 to 2007, we have made a thorough analysis over the temporal and spatial variation of water quantity, quality and pollutant influx of the above said rivers. The results of statistics and analysis show that the water quality of the rivers can be generally said regular and steady. The indexes, such as CODMn, TP of the most measured sections of the rivers can be categorized into National Grade Ⅲ . But, as an exception, most sections measured of Changxing can only be up to National Grad Ⅳ. From the point of view of physical and chemical compositions, the index of TN in some sections is over the state standard. The net water inlet volume from the rivers proves negative in recent years. For example, Tiaoxi River, being the main contributor of water volume inlet and outlet of Taihu Lake in all rivers, whose inlet water quantity accounts for over 60 % water quantity of the total region water inlet. On the contrary, the water quantity of inlet was more than that of outlet in the region of Changxing. Based on the water quality and quantity of inlet and outlet of the rivers, the influx and out-flux of CODMn and total phosphorus has been growing, though that of NH3 - N is declining in the past 3 years. The results have shown that the CODMn and total phosphorus out-flux were more than that of influx. There were about 6 000 t/a CODMn net influx and 76 - 78 t/a total phosphorus net out-flux out of the Lake. Comparatively speaking, the ammonia nitrogen out-flux turns to be less than that of influx. There were about 60 - 200 t/a net ammonia nitrogen influx into Taihu Lake, which has created the nitrogen backups in the lake. Compared with the historical data, the negative pollutant fluxes of the rivers are likely to be caused by the hydrological change because of the implementation of the Project Yangzt River Water transfer into Taihu Lake.