上海市郊中小河流夏季水污染特征研究

WATER POLLUTION IN SMALL AND MEDIUM-SIZED RIVERS FROM SUBURBS OF SHANGHAI IN SUMMER

在夏季对上海郊区一典型的中、小河流河网水质进行监测 ,结果表明 :(1)河流水体普遍有很高的氮磷和有机负荷 ,其CODcr、总磷、总氮等指标均数倍于《地面水环境质量标准》中规定的V类水最大允许值 ,水体正处于严重的富营养化状态。位于集镇居民区和养殖场附近河流的污染更为严重。 (2 )受富营养化和河流底泥污染物释放的影响 ,河流水质还存在分层现象 ,尤其是水流滞缓、水深不足两米的小河流更为明显。主要表现为 :底层水氨氮 ,TRP(总反应态磷 )和SRP(溶解反应态磷 )的含量明显高于表层水 ;而表层水的 pH和DO高于底层水 ;同时 ,由于底层水处于厌氧的环境下 ,NO- 3-N、NO- 2 -N含量低于表层水。 (3)由于长期受纳污水、污物 ,中、小河流底泥有很高的氮磷累积 ,凯氏氮平均达 3.5 2 6 (N ,mg) / g ;总磷平均达 2 0 5 2 .2 5 0 (P ,mg) /kg。集镇居民区河流底泥总磷含量高达 5 813.838(P ,mg) /kg ;养殖场附近河流底泥凯氏氮高达 5 .96 4 (N ,mg) / g。底泥孔隙水中的NO- 3-N、NO- 2 -N含量很低 ;NH+4的含量是河流底层水的 3～ 2 4倍 ;SRP的含量约是河流底层水的 2～ 16倍。由于底泥有机污染重 ,耗氧量大 ,处于厌氧的环境 ,其交换态Fe2

The water quality in small and medium sized rivers from a typical network of waterways, suburbs of Shanghai, was monitored in the summer of 2000.The water from the rivers was under heavy eutropic conditions, with high loadings of nitrogen, phosphorus and organic contaminants. The COD\-\{cr\}, TN and TP were several times higher than the critical values of Type Ⅴ water, in 'Environmental Quality Standard for Surface water'. The waters from the rivers nearby residential areas and livestock farms were more seriously polluted. The eutrophication, as well as contaminant from the sediments, made the water quality of the rivers stratified. Such phenomenon was even more significant for slow flowing small rivers with depth less than 2 metres depth. The ammonium nitrogen, total reactive phosphorus (TRP) and soluble reactive phosphorus (SRP) in the bottom water were greater than those in the surface; while pH and DO in the surface water was larger than those in the bottom.Due to under anaerobic condition, the bottom water contained less NO\+-\-3 and NO\+-\-2 than the surface water. As a result of long-term accepting wastewater and other anthropogenic pollutants, large amounts of nitrogen and phosphorus were accumulated in the sediments of the rivers. K-nitrogen and total phosphorus of the sediments ranged from 1.243～5.964 (N, mg)/g and 858.453～5 813.838 (P, mg)/kg,respectively. Total phosphorus from the sediment of the river nearby the township residential areas reached as high as 5 813.838 (P, mg)/kg, K-nitrogen nearby the livestock farm, 5.964(N, mg)/g. Nitrate and nitrite concentrations in the pore-water of the sediments were too low to determine.However, ammonium nitrogen in the pore-water was 3～24 times higher than that in the bottom water and soluble phosphorus 2～16 times higher. Owing to the under anoxic condition, the sediments contained high amounts of exchangeable ferrous.