洪湖流域半封闭池塘河蟹养殖氮磷污染负荷研究

选取洪湖流域半封闭池塘河蟹养殖区域为调查样本,针对一个养殖周期内6个监测点位(1个背景点,3个养殖水体点,2个纳污水体点)TN、TP值进行监测分析。监测结果表明,养殖准备期(12月～1月),养殖水体TN、TP值与同期背景值没有明显差异;养殖中后期(3月～10月),养殖水体和纳污水体TN、TP均明显高于同期背景值,大部分为劣Ⅴ类水质。按5～10月份养殖水体TN、TP实测值进行化学分析法估算,一个养殖周期内养殖水体TN、TP污染负荷为27.61kg/hm2、7.33kg/hm2,则洪湖流域半封闭池塘河蟹养殖排放的TN、TP污染负荷约为269.11t/a、71.46t/a。另据对样本区域养殖生产过程的调查,按物料平衡法估算的TN、TP污染负荷为57.61kg/hm2、11.60kg/hm2,而洪湖流域半封闭池塘河蟹养殖TN、TP污染负荷约为561.51t/a、113.06t/a。

Investigation of Nitrogen and Phosphorus Pollution and Their Pollution Loads of Pond Crab Farming in Honghu Valley

Taking 266.67 hm2 semi-enclosed crab farming pond of Honghu valley as a sample, TN and TP of 6 inspected points(one spot of background, three spots of breeding water and two spots of disposal sewage) of this area were analyzed during one breeding cycle. The experimental results indicated that the total N and total P of breeding water had no evident difference from those of background spot during December to January, however TN, TP of breeding water and disposal sewage were obviously higher than those of background spot during Match to October, whose water quality mostly indicated below-Ⅴlevel. Calculation based on chemical analytical method and the testing data obtained from May to October showed that TN and TP pollution loads of pond crab farming during one breeding cycle reached 27.61kg/hm2 and 7.33kg/hm2 respectively, thus the pollution loads in the semi-enclosed crab breeding ponds of Honghu valley would be about 269.11t/a and 71.46t/a.