巢湖流域水产养殖尾水水质分析与评价

Analysis and evaluation of water quality of aquaculture tail water of Chaohu Lake basin

为探明巢湖流域水产养殖尾水的污染状况,2019年4、7、9和11月对该地区几种主养淡水品种养殖尾水的水质状况进行监测,并分析水体理化因子的动态变化规律。采用单因子污染指数法对pH、溶解氧(DO)、总氮(TN)、总磷(TP)、氨氮(NH4+-N)和高锰酸盐指数(CODMn)进行单项评价,用内梅罗污染指数法对各监测位点尾水水质进行整体评价。结果表明:pH、TN和TP因子均符合《淡水池塘养殖水排放要求》的二级标准,DO、NH4+-N和CODMn因子存在超标。单因子污染指数分析结果显示:尾水未受到pH、TN和TP因子的污染;受DO、NH4+-N和CODMn因子污染的监测位点占比分别为12.5%、25.0%和87.5%。内梅罗污染指数计算结果表明,75%的监测位点处于轻度至中度污染等级。巢湖流域水产养殖尾水主要污染物为CODMn,污染较为严重。

In order to find out the status for pollution from aquaculture tail water in the Chaohu Lake Basin, the water quality of the aquaculture tail water of several major freshwater species in the basin was monitored in April, July, September and November 2019. The dynamic changes of physical and chemical factors of the water bodies were analyzed. The single-factor pollution index method was employed for individual evaluation of pH, dissolved oxygen(DO), total nitrogen(TN), total phosphorus(TP), ammonia nitrogen(NH+4-N), and permanganate index(CODMn), and the Nemerow pollution index method was applied for overall evaluation on the water quality of each monitoring site.The results showed that the contents of pH, TN and TP were in line with the Level II standard of stipulated in the Freshwater Pond Aquaculture Water Discharge Requirements, and the contents of DO, NH4+-N and CODMnexceeded the standards in some sites. The results of single-factor pollution index analysis showed that the tail water was not polluted by pH, TN and TP. The proportions of monitoring sites with pollution factor of DO, NH4+-N and CODMnwere 12.5%, 25.0% and 87.5% respectively. The results of Nemerow pollution index calculation showed that 75% monitoring sites were at the slightly or moderately polluted level.The main pollutants of aquaculture tail water in Chaohu Lake Basin was CODMn. The pollution status was serious.