长江口河段水环境现状分析

Analysis on the present situation of water environment in the Changjiang estuary

以2002年9月底长江口综合整治开发规划水文、水质原型观测资料为依据,运用W值法分析评价长江口河段水质污染现状及其空间分布特征。监测结果表明,长江口河段总体水质属Ⅲ类,个别断面达到了Ⅳ类和Ⅴ类,有多项水质指标出现超标。主要污染因子为TN、CODMn、总铅、氯离子和石油类等。长江口北支水质劣于南支、北港和南港;南支南岸水质劣于北岸;城市江段水质劣于非城市江段;低平潮期水质劣于高平潮期;浅水区水质劣于深泓区;下游水质劣于上游。影响长江口河段水质的污染物既有无机物又有有机物;污染源既有生活污染源又有工业污染源;既有固定源又有流动源;既有点源又有面源;既有随径流流入的又有随潮流带入的。

The present situation and distribution characteristics of water quality in the Changjiang estuary is analyzed using the W value method, according to the hydrological and water quality data measured during the comprehensive harnessment and development plan of the Changjiang estuary at the end of 2002. It shows that the water quality of the Changjiang estuary generally reaches the third water quality standard, while the water quality in some specific sections is in the fourth or fifth water quality standard. Quite a few water quality parameters are above the standard in various degrees. The main pollutants are TN, COD_(Mn), total lead, chlorine ion, oil, and so on. It also indicates that the water quality of the northern branch is worse than that of the southern branch, northern harbor and southern harbor, and the water quality of the southern bank of the southern branch is worse than that of the northern bank. The water quality of sections in urban areas is worse than that in rural areas. The water quality seems better in high-tide period than in low-tide period, in riffles than in pools, and upstream than downstream. The pollutants affecting the water quality include organic and inorganic matter. The pollution sources include domestic ones and industrial ones, static ones and mobile ones, and pointed ones and non-pointed ones. The pollutants can be taken into the estuary along with the runoff or tidal flows.