求翻译：为了解上海市养殖池塘水环境状况及其对水环境的影响,于2011年10月至2012年4月对上海市部分养殖池塘作了调查。调查地区为青浦、奉贤、嘉定3个地区的养殖池塘，查指标主要包括总磷、总氮、亚硝态氮、氨氮、活性磷、高锰酸盐指数、叶绿素a等为主要水质指标，目的是了解并研究几种不同养殖品种池塘水质的监测与评估。调查结果显示，不同养殖种类池塘的水质差异并不明显，得出不同养殖种类池塘水质均为地面水环境质量标准﹙GB3838—2002)IV类水，主要污染源为氨磷污染。是什么意思？

In order to understand the Shanghai aquaculture pond water environment and its impact on the water environment, in October 2011 to April 2012, made a survey of the Shanghai part of the breeding ponds. The survey area for the three districts of Qingpu, Fengxian, Jiading pond, check the index as the m

For Shanghai, state of the Environment water pond aquaculture and its water environment, and the impact on October 2011 to April 2012 part of the city of Shanghai as a fish pond. Survey of the areas in the qingpu, fengxian, Jiading district 3 of the breeding pond, mainly comprised of the total phosp