一种兼顾目标总量和容量总量的水污染物排放限值确定方法

针对中国水污染物总量管理面临由目标总量管理向容量总量管理的转变趋势,提出了一种兼顾两种管理模式的水污染物排放限值计算方法.该方法建立在水体分类计算、汇水区与行政区相关联、自下而上、不同保护要求的水体予以差别化对待、污染物控制类型扩展的原则上,将水体按环境容量利用方式的不同划分为保护性利用、恢复性利用、控制性利用、开发性利用和限制性利用5种类型,分别采用目标总量、混合管理、容量总量、容量总量和混合管理等不同模式,并给出了分别按汇水区和行政区计算污染物排放限值的一般过程. 将上述方法应用于西南区域发展战略环评案例,结果表明云南省31.25%地市需调减COD总量,43.75%地市需调减氨氮总量,而贵州省55.56%地市可适当调增COD总量,44.44%地市可适当调增氨氮排放总量.该方法可将总量限值的确定与当地水环境质量改善紧密结合,强化水环境对现状质量不达标地区未来发展的约束,同时适当减弱水环境条件对达标地区的约束以换取其发展空间.以计算出的排放限值为依据对当前的减排目标进行调整可为云贵实现又好又快发展提供支撑.经案例验证,本文所建立的方法为中国水环境管理从目标总量模式向容量总量模式发展提供了技术手段.

A method for determining water pollutant discharge limit based on combination of administrative goal-oriented and environmental capacity-based total pollution load control patterns

Since China was facing the challenge to transit its control pattern on total pollution load from an administrative goal-oriented way to an environmental capacity-based way, an approach for determining water pollutant discharge limit which could combine advantages of two patterns was put forward. To establish the method, five principles were involved, i.e., calculations were dependent on water body classification; relations between catchment and administration boundaries were considered; bottom-up way was applied; protection levels for different water bodies were differentiated; and more kinds of pollutants were covered. Water bodies were grouped into five categories, according to different ways to utilize environmental capacities and corresponding total load management patterns. Five categories were named as protective utilization, restorative utilization, controlled utilization, developmental utilization, and restricted utilization, to which a goal-oriented pattern, mixed pattern, capacity-based pattern, capacity-based pattern, and mixed pattern was assigned, respectively. A general procedure instructing calculation of pollutant discharge limit for both catchment and administrative zone was given. The approach was applied to a project on strategic environmental assessment of social-economic development in Yunnan and Guizhou Province. The case study showed that 31.25% of cities in Yunnan should decrease the load of COD and 43.75% should decrease the load of ammonia nitrogen, while 55.56percent of cities in Guizhou could increase the load of COD properly and 44.44percent could increase the load of ammonia nitrogen properly. It was capable of linking pollution load reduction more closely to local water environmental improvement, tightening up environmental restrictions on regions with poor water quality by stricter discharge permit, and leaving more development room to regions with surplus environmental capacity by loosening existing pollutant reduction goals. For local governments, discharge limits given in the paper could be used to adjust existing pollution load control plans. The approach was a practical tool for China to transit its water pollution load management pattern.