Water Quality Evaluation and Correlation Analysis With Sediment in Freshwater Intensive Culture Ponds
The seasonal changes in contents of total nitrogen(TN),total phosphorus(TP),ammonia nitrogen(NH4+-N),nitrite nitrogen(NO2--N),nitrate nitrogen(NO3--N),total organic carbon(TOC),and permanganate index(CODMn)and pH value were monitored during the culture period,and the degree of water pollution was evaluated in water and sediments in a typical intensive freshwater pond with area of 6 600 m2,average water depth of 1.2 m,many years of uncleared sediment bottom with polyculture of common carp(Cyprinus carpio),catfish(Silurus asotus),grass carp(Ctenopharyngodon idella)and silver carp(Hypophthalmichthys molitrix)in Harbin in spring(April-May),summer(June-August)and autumn(September)by using the single pollution index method and the comprehensive pollution index method.The main drivers of water pollution were analyzed by principal component analysis,and the network relationship diagram was drawn based on substrate indices.The results showed that the pond water quality was found to be at a severe pollution level,with better in spring than in summer and autumn.In the evaluation,the pond water quality was classified as Class Ⅳ,Class Ⅴ and poor Class Ⅴ.The levels of exceeding water quality standard were increased with the extension of breeding time,and TN exceeded the warning level in the whole culture period.The contents of TN,TP,NH4+-N and CODMn were the main pollutants in the pond water.The results of factor analysis revealed that the water quality in the pond was mainly affected by the growth and metabolism of fish,dissolved oxygen level and feeding rate,with the primarily pollutants of N and P nutrients.There was a significant positive correlation between TP,TN,NH4+-N and sediment NO2--N(P＜0.01),and there was a significant positive correlation between TP,TN,NH4+-N and sediment TOC(P＜0.05).There was a co-occurrence of organic pollution in pond water and sediment,and there was a very significant positive correlation between water TOC and sediment TOC(P＜0.01).
万方数据
维普
