上海松江泖港地区成蟹养殖对水质的影响

Effect of Eriocheir sinensis growing on the water quality in Maogang Town,Songjiang District,Shanghai

为了探究河蟹生态养殖对周围水环境的影响,于2013年3—10月对上海松江泖港地区成蟹池和水源水质进行了监测。结果表明,整个养殖区间水源和成蟹池总磷和总氮均超标,且成蟹池总磷总体上较水源高,水源和成蟹池总磷浓度最大超标幅度分别达213%和184.5%;水源总氮高于成蟹池,最大超标幅度分别达434.2%、211.7%。在养殖周期中,成蟹池CODMn持续升高,且总体上高于水源组,水源组CODMn则呈现先逐渐升高后逐渐下降的趋势,但二者基本上高于地表水环境质量标准中的Ⅲ级标准和渔业水质标准。参照地表水环境质量标准中的Ⅲ级标准和渔业水质标准,成蟹池中主要超标指数为总磷、总氮、p H值、CODMn;水源主要超标指数为总磷、总氮、硝酸盐、CODMn。从整个养殖周期来看,成蟹池中溶解氧、氨氮、亚硝酸氮、硝酸氮优于水源组,而p H值、CODMn、磷酸盐、总磷较水源略有超标,但超标幅度均较低。

This paper takes it as its focus to introduce our study results on the effects of the ecological culture of Eriocheir sinensis,a kind of crab,on the water quality in Songjiang,a suburban river in Shanghai.According to the culture cycle,culture season,and the favorable chance to market in the nearby towns and cities,this paper has done an investigation and monitoring of the water quality of the river crab eco-culture ponds and water source every 15 days during the period from March to October in 2013 to trace the effects of Eriocheir sinensis breeding patterns on the water environment quality as the culture goes on naturally.The investigation and monitoring results of this paper can be briefly stated as follows：The water source and the river crab eco-culture ponds in the said area have exceeded the third grade set by the state-regulated surface water quality standard for its following characteristic indexes：the maximum amplitude exceeding the standard of the total nitrogen（TN） is 434.2% and 211.7%,respectively,whereas the concentration of CODMnin the such crab eco-culture ponds has been keeping a growing trend in our experiments.At the same time,the changes of CODMnconcentration kept increasing in the water sources in the early period,and then the CODMnconcentration began to get declining gradually,and both of the groups have been proven higher than the third grade of the state-stipulated surface water quality standard.What is more,the nitrate（NO-3-N） and nitrite（NO-2-N） concentrations have also been proven substantially higher in the water source than in the river crab eco-culture ponds during the entire monitoring process.In the early stages of our experiment,ammonia nitrogen（NH＋4-N） concentration has been found lower in the water source than in the river crab eco-culture ponds.A period of the experiment later,the concentration of ammonia nitrogen（NH＋4-N）turned to be lower in the river crab eco-culture ponds than in the water source.However,on the whole,the phosphate（PO3-4-P）concentration remained higher in the river crab eco-culture ponds than in the water source for the entire monitoring period.Thus,all in all,the concentrations of nitrate（NO-3-N）,the nitrite（NO-2-N）,ammonia nitrogen（NH＋4-N）,the dissolved oxygen（DO）and the total nitrogen（TN） have turned better in the crab culture ponds than in the water sources.Nevertheless,the concentration of the total phosphorus（TP） and phosphate（PO3-4-P）,CODMn,and p H value,have all been found worse in the river crab ecoculture ponds than in the water sources.Thus,the results of our investigation show that more reasonable breeding density and feed formula are the most significant orientations for the future research trend in order to further reduce the impact of the crab culture on the ecological environment.