苏州市农业面源污染源强解析与评价

采用清单分析、等标排放量、内梅罗综合水质指数评价等方法,对长三角典型区域苏州市的农业面源污染的来源、地区分布和污染风险进行了解析。研究结果发现,苏州市农业面源污染物排放量较大,年排放COD 171 268.2 t,氨氮6 510.5 t、总氮21 839.3t,总磷3 335.7 t,属于典型的生产与生活复合型污染。面源污染物来源多元化,发现畜禽养殖业是COD 和总磷排放的重要来源,而氨氮和总氮主要来自农村生活源。按照地区来说,太仓市COD和总磷排放量居首,而苏州市区是氨氮和总氮的最主要排放地区。苏州市农业面源污染造成的综合水质指数均值为2.6,在中等污染水平,其中苏州市区和昆山市为轻污染,张家港市为中等污染,而常熟市和太仓市均属于严重污染区域。农业面源污染强度与地方农林经济并未有显著的关系。

Estimation and Source Apportionment of Agricultural Non-point Source Pollution in Suzhou City, China

The primary source, influence factors and spatial distribution characteristics of agricultural non-point source pollution in Suzhou City (a typical area of the Yangtze River Delta) were analyzed by inventory analysis, equivalent standard load and Nemerow analysis methods of water quality. Results showed that the absolute real emissions of COD, ammonium nitrogen, TN and TP from agricultural non-point source pollution in Suzhou were still greater, which was 171 268.2, 6 510.5, 21 839.3 t·a^-1 and 3 335.7 t·a^-1, respectively. And the agricultural nonpoint source pollution in Suzhou was combined with production and life sources. In addition, livestock industry was an important source of the emission of COD and total phosphorus, while ammonium nitrogen and total nitrogen were mainly coming from rural life source. However, Taicang City was the most severe area of COD and TP emission, while ammonium nitrogen and TN were mainly discharged from the Suzhou urban area. The mean value of comprehensive water quality index (CWQI) of Suzhou City was 2.6, reaching the moderate pollution level. As for the different zones in Suzhou City, the comprehensive water quality index of Changshu and Taichang all reached serious pollution level; Suzhou urban area and Kunshan were light pollution and Zhangjiagang was moderate pollution, respectively. In contrast, there was no significant relationship between the agricultural non-point source pollution intensity and local agro-forestry economy.