Cu污染条件下封闭循环水养虾系统的效能

Performance of shrimp recirculating aquaculture system with copper polluted water

为获得Cu2+污染对封闭循环水养虾系统的影响,选用0.3 mg/L Cu2+浓度,研究其对系统中水质、对虾生长、存活及生物滤器水处理效能的影响。结果表明,经过84 d的试验,养殖水体中Cu2+质量浓度在系统水处理单元作用下降为(0.089±0.012)mg/L,对虾能正常生长和存活,0.3 mg/L Cu2+处理质量浓度对生物滤器的化学需要量(COD)、NH4-N和NO2-N去除率及滤器中异养细菌、氨氧化菌和亚硝酸盐氧化菌的数量不造成显著影响。处理系统对虾体内Cu质量分数为(42.91±6.10)mg/kg,与对照中质量分数(29.36±4.06)mg/kg相比,具有显著差异,但均在国家无公害食品水产品中有毒有害物质限量标准(Cu≤50 mg/kg)范围内。在0.3 mg/L Cu2+质量浓度污染下,封闭循环水养虾系统仍能提供较好的水质条件,获得较高的产量和较低的饵料转化率,所养对虾符合无公害水产品要求。

The disease outbreaks,environmental degradation and poor management practice are the major problems to the shrimp aquaculture industry in recent years.With the developing of engineering,aeration and the high quality of artificial feeds,shrimp culture in a recirculating aquaculture system（RAS） becomes an environmentally and economically sustainable method to solve those problems.But the copper pollution has been a big problem in the coasts of China as a result of the developing of industry,and the shrimp cultures also use copper sulfate frequently to eradicate algae during Litopenaeus vannamei culturing.An experiment was conducted for intensive culture of shrimp（L.vannamei） in RAS for a period of three months to concentrate on the performance of the biofilter and the food safety under the copper polluted water（0.3 mg/L）.The results indicated that there was no significant difference in the removal rate on COD,NH4-N and NO2-N and the number of heterotrophic bacteria,ammonium-oxidizing bacteria and nitrite-oxidizing bacteria in the biofilm as the Cu^2＋ concentration decreased to（0.089±0.012） mg/L at the harvest.No significant difference was found between treatments concerning the feed conversion ratio（FCR）,the mortality rate and the yield.The accumulated concentration of Cu^2＋ in the shrimp at last was（29.36±4.06） mg/kg and（42.91±6.10） mg/kg in the control and treated RAS respectively,but it was in the range of national security standards of the green food and pollution-free agriculture products.The study suggests that the RAS can work well and supply safety food shrimp under 0.3 mg/L copper pollution in three month culturing period.