湘江流域铊污染物水环境容量与总量控制

Water environment capacity and total amount control of thallium pollutants in the Xiangjiang River watershed

针对湖南湘江流域含铊工业废水大量排放,引起部分河段地表水铊含量超标的问题,通过对河流相应集水区各涉铊污染源进行调查分析,计算铊污染物入河量,选择模型,按水功能区划要求的水质目标,估算出目标河段铊污染物的水环境容量,并按容量总量管理模式,提出各地区、各污染源铊污染物排放与削减的分配方案.结果显示,湘江干流永州、郴州、衡阳和娄底段尚有一定的环境容量,而株洲、湘潭、长沙和岳阳段容量计算结果为负值,表明该河段铊污染物含量已超过水环境容量;除汨罗江外,湘江一级支流均有剩余的铊环境容量,容量较大的是耒水,其次是洣水和舂陵水;10条涉及铊排放的二级支流,都还有剩余环境容量,容量最多的是西河,其次是永乐江和攸水.铊排放超出环境容量的区域,须进行铊污染物削减,需要削减的地市有永州、衡阳、湘潭、长沙和岳阳,需要削减的行业涉及化工、有色、钢铁、锰业和玻璃行业,削减总量达到每年3.188 t.化工行业排放最大,为每年3.239 t,需要削减的量也最大,为每年2.862 t,占削减总量的89.8%.

In view of the situation that a lot of Tl（thallium） industrial wastewater is discharged into Xiangjiang River leading to Tl concentration beyond the environment quality standards in surface water,this paper estimated water environmental capacity of Tl pollutants by zero-dimensional calculation based on the provisions of water environmental functional demarcation for Hunan surface river and the survey results of the pollutant loads of the main thallium point sources. Furthermore,Tl water environment residual capacity and the demand for reducing the application were allocated to each pollution sources and each regions respectively. Results indicated that Tl water environmental capacities were still abundant in the reaches of Xiangjiang River in Yongzhou,Chenzhou,Hengyang and Loudi. On the other hand,Tl water environmental capacities were negative values in the reaches of Zhuzhou,Xiangtan,Changsha and Yueyang,which was meaning that Tl emission exceed the water environmental capacity in those regiones. The industries must reduce their application and emission of Tl in the corresponding catchment where Tl emission was exceeding the environmental capacity.The total reduction reaches 3.188 t·a^（-1）in the Xiangjiang Rive watershed. The chemical industry was demanded for the maximum reducing Tl emission,whose reduction rate was 89.8%.