Research On Permit Limits Of Pollution Discharge Based On Water Quality In Zhangjiakou Section Of Upper Yongding River

With the rapid development of domestic economy,environmental problems are becoming more and more prominent.As the basic core system of environmental quality improvement,pollutant discharge permit restricts the discharge behavior of enterprises and plays a huge role in the improvement of water environmental quality.At the present stage,the formulation of technical standards for pollutant discharge permit in China mainly considers the industry characteristics of enterprises themselves,and sets the limit of pollutant discharge permit according to the technical level of industrial production at the present stage,without directly considering the standard of water environmental quality,and lacks of connection with the relevant environmental management system.This study establishes a set of perfect drainage license limit accounting system based on water quality,in order to realize the river water quality standards for the purpose,in a typical northern type water river Yongding river as an example,aiming at improving water quality stationary sources pollution load reduction plan is put forward,further perfecting the control unit water quality target management technology,through the contribution coefficient,identify the unfair factors,combined with GIS analysis the spatial difference of the unfair factors in the study area distribution,Environmental Gini coefficient method was used to analyze the influence of land,population,gross domestic product(GDP)and other factors on pollutant emissions(chemical oxygen demand,ammonia nitrogen)in each control unit,and Gini coefficient minimization model was used to work out the allocation scheme of allowable pollutant emissions.The results showed as follows: 1)the environmental Gini coefficients of COD emissions based on land area,population and GDP of each control unit were 0.5044,0.3068 and0.2341,respectively,and the environmental Gini coefficients of ammonia nitrogen emissions based on land area,population and GDP of each control unit were 0.5725,0.4091 and 0.3571,respectively.Among them,the environmental Gini coefficient of COD emission based on land area of each control unit exceeds the warning value,and the environmental Gini coefficient of ammonia nitrogen emission based on land area and population number of each control unit exceeds the warning value,which is an unfair phenomenon.2)Through the analysis of contribution coefficients of different indicators in this area,it can be found that the main unfair area in the study area is the central area of Zhangjiakou,with excessive pollutant emission.3)By analyzing the status quo of the study area,comparing the differences between two sets of accounting systems of pollutant discharge permit limits based on water quality and based on technology,and taking the concentration limit based on the mixed area as a reference,a more fair and reasonable technical method for the verification of pollutant discharge permit limits of fixed pollution sources is finally formulated.