防控日益严重的水土重金属污染之我见

当前我国水土重金属污染严重。1996年颁布的GB8978—1996《污水综合排放标准》仍然是现行执法的依据,它明确规定排放的污染物按其性质分为两类,"汞、镉、铬、砷、铅、镍、铍、银"8种重金属为第一类污染物,要求不分行业和污水排放方式,也不分受纳水体的功能类别,一律在车间或车间处理设施排出口取样,必须满足最高允许排放浓度标准的规定。它完全不同于一般常规污染物可利用水环境容量,实行总量达标控制原则。这体现了对持久蓄积性污染物实行封闭零排放的原则精神。但目前从水质的监测、评价到污染物的削减控制过程中,存在着一系列背离和混淆两类污染物排放标准和控制要求的问题。防治重金属污染的任务十分艰巨,它涉及许多行业、部门和学科专业。为扭转当前我国水土重金属严重污染的局面,首先应从端正环保系统的技术路线开始;在重金属污染防治中,防要大于治、先于治;当前最紧迫的是从源头控制污染源的继续超量排放,而监控源头必先端正技术路线。

Viewpoints on prevention and control of more and more serious water and soil pollution by heavy metals

The water and soil pollution by heavy metals is currently very serious in China.The Integrated wastewater discharge standard(GB 8978—1996) enacted in 1996 has been still the law in execution.The discharged pollutants are definitely classified into two categories according to their nature,among which,8 heavy metals,Hg,Cd,Cr,As,Pb,Ni,Be and Ag,belong to the first type of pollutants and are requested to be sampled at the discharge ports of the plant workshop or the workshop treatment facilities and to meet the most strict discharge standards without considering the sectors,discharge behaviors or receiving water bodies.They are completely different from the general routine pollutants to use the environmental capacity and to implement the total load control,which reflects the principle of closed zero discharge for the persistent cumulative pollutants.However,at present,there exists a series of problems of violation and confusion of the discharge standards and control requirements of the above two categories of pollutants for the monitoring,evaluation and mitigation countermeasures of the water quality.The task of prevention and treatment of heavy metal pollution is very hard,and it relates to various sectors,departments and academic subjects.To change the present situation of serious water and soil pollution by heavy metals in China,some suggestions are proposed as follows:(1) the technical route of the environmental protection system should be first improved;(2) the prevention is more important and earlier than the treatment for the prevention and control of heavy metal pollution;(3) the most important is to control the excessive heavy discharge from the sources,and the source monitoring and control should have correct technical route.