池塘河蟹生态养殖对水体环境的影响

为了评判河蟹生态养殖对周围水环境的影响,2004年4-11月对河蟹生态养殖池塘的水环境进行了现状调查与监测.水源区的水质主要超标项目为总氮、总磷、氨氮和高锰酸盐指数,表明水源区水质主要是富营养化和轻微的有机污染.在池塘生态养殖区中,水质主要超标项目为pH值和总磷.生态养殖区水质虽有超标,但超标幅度明显低于水源区.调查同时发现,河蟹生态养殖区因栽有大量的水草,对氮磷的吸收比较充分,故生态养殖区的氮磷在养殖周期中的变化较水源区要小得多,叶绿素A的动态变化也证明了水草的生态意义.总体而言,生态养殖区的水质要明显优于水源区,基本上达到地表水环境质量标准中的3级标准和渔业水质标准的要求.河蟹生态养殖不会对外界水环境产生不良影响.

Effect of river crab eco-culture in ponds on water environment

This paper aims at evaluating the effect on the water quality by the river crab Eriocheir sinesis pond eco-culture.Based on the spot survey and research analysis of the crab eco-culture done from April to November of 2004,the following results gained prove that in the water source area the main factors that fail to come up to the standard crab eco-culture quality are total nitrogen(TN),total phosphorus(TP),ammonium-nitrogen(NH~+_4-N) and chemical oxygen required by permanganate method(COD_(Mn)),which means eutrophication and slight organic pollution.However,in eco-culture pond area the main factors that fail to come up to the standard of fish-farming water quality are just pH and total phosphorus(TP).Though the water quality is not still up to the standard,the gap to the standard is evidently much narrower in eco-culture area than in the source area,for there exist many sorts of aquatic weeds in the eco-culture area,which contribute to the absorption of nitrogen and phosphorus.And,in turn,the nitrogen and phosphorus changing rate during the culture period proves much lower in crab culture area than that in water source area,and the dynamic change of chlorophyll-A also proves the ecological significance of the aquatic weeds.Thus,it can be concluded that the water quality in eco-culture area is better than that in water source area according to the eco-environment standard of the third grade of surface water and that of the crab-culture water quality.And so,the culture of river crab Eriocheir sinesis proves no harm on the outside water environment.