昆山地区典型池塘虾蟹混养模式对水环境的影响

Impact of water environment by typical Chinese mitten crab-river prawn polyculture in Kunshan

虾蟹混养是昆山地区主要的池塘养殖模式。为深入研究虾蟹混养式养殖尾水对水环境的影响,对典型养殖区锦溪镇南前村的600×667 m^2虾蟹养殖基地的水源、池水和尾水在2012—2014年养殖期间的水质指标pH、亚硝酸盐、氨氮、总氮、总磷、COD监测。结果表明:在不同季节水源、池水和尾水的pH变化较大,变动范围在7.08~9.26之间;亚硝酸盐和氨氮浓度均处于很低的水平,优于地表水环境标准Ⅲ类水质标准,养殖尾水的氨氮浓度通常较水源和池水更低;除总氮和COD在2014春季高于水源外,其余年份各季节总氮、总磷和COD均接近或低于水源水指标值。除COD外,各项水质指标均符合太湖流域池塘养殖水排放一级标准,且呈现为低于或接近养殖用水源水的水质指标,可以认为池塘虾蟹混养模式对外部水环境影响很小。尾水排放前应加强对COD的控制。

Chinese mitten crab -river prawn polycuhure was the main aquaculture mode in Kunshan. A typ- ical aquaculture area in Nanqian village of Jinxi Town was chosen for water quality monitoring during 2012 and 2014 to study the impact of of water environment by this mode. Results showed that： values of pH changed be- tween 6.68 and 8.92, there were large different among water of source, water in pond and discharged water in dif- ferent season. Values of nitrites and ammonia nitrogen were at a low level, better than Ⅲ class water standards of the national groundwater environmental quality. Values of total nitrogen, total phosphorus and COD of disc water in each season were close to or below the value of source 2014. All of the water quality index except COD met with the harged water,except total nitrogen and COD in spring, first class standard for water discharge of pondaquaculture in Taihu river basin,and values of discharged water were close to or less than that of source water, which mean impact of water environment by typical Chinese mitten crab - river prawn polyculture was tiny. COD should be controlled before water discharge.