太湖流域主要水系水环境特征分析与富营养化评价

对太湖流域苕溪、南溪、太湖、沿江和黄浦江5大水系水体环境特征进行2次全范围调查监测,在此基础上分析主要水系的水环境特征现状,并用模糊综合评价方法对主要水系的富营养化程度进行评价.结果表明,除苕溪和南溪水系外,太湖流域各水系水体透明度都较低,可能与部分水体泥沙含量较大有直接关系,但水体中藻类、有机物和水动力条件等可能也是影响透明度的因素；耗氧性有机污染物指标处于地表水Ⅳ类～Ⅴ类,且B/C(可生化性指标)比较高,分解利用引起水中溶解氧(DO)的快速下降.氮磷营养元素污染相对严重,基本处于地表Ⅴ类～劣Ⅴ类水平,且各水体中都以总磷(TP)污染最为突出.总氮(TN)和TP中分别主要以溶解无机氧( DIN)和PO43-的形式存在,其较高的浓度为藻类快速生长甚至爆发水华提供了必要条件.对污染指标主成分分析的结果表明,氮磷和有机物是流域水体污染的主要贡献指标.富营养化模糊综合评价结果表明,苕溪水系、南溪水系和太湖基本处于中度富营养化水平,而沿江水系和黄浦江水系基本处于重度富营养化水平.

Water quality analysis and eutrophication assessment on lakes in Taihu basin

Aimed at characterizing the water quality,identifying the key influencing environmental factors and evaluating the eutrophication in terms of fuzzy assessment model,we investigated water quality at 32 sites of the five water systems(Rivers Tiaoxi,Nanxi,Yanjiang,Huangpujiang and Taihu Lake) within Taihu Basin.The results showed that SD all were very low except rivers Tiaoxi and Nanxi,which may be related with the high levels of inorganic particles,but the content of algae,organic matter,hydrodynamic conditions etc may also be the important factors affecting SD.Oxygen-consuming organic pollutants in Taihu Lake Basin were at the surface water Ⅳ to Ⅴ class level,and the value of B/C was relatively high,which means organic pollutants were easy to be used by microorganisms,therefore causing the rapid decline of DO in water.Nutrients pollution was relatively serious.TN and TP were at the surface water Ⅴclass level,and TP was the most prominent factor in five river systems.DIN and PO3-4 were the main form of TN and TP,and the high concentration of them provided the conditions for algae growth.Principal component analysis showed that TN,TP and oxygen-consuming organic pollutants were the major contributors to water pollution in Taihu Basin.Fuzzy assessment results showed that the river systems of Tiaoxi,Nanxi and Taihu were in middle eutrophication state and the river system of Yanjiang and huangpujiang were in high eutrophication state.