辽河干流水体中重金属时空分布特征及污染评价

为了研究辽河干流水体中重金属的污染情况,在辽河干流设置了8个采样点位。采用ICP-MS水质分析仪测定了待测水样中的13种重金属含量,分析水体中重金属含量和浊度、pH值之间是否具有线性关系,以探求重金属含量的变化规律。结果表明,pH值对辽河干流水体中重金属的含量没有显著的相关关系,而水体浊度对丰水期Ag和对枯水期Pb的含量及分布都有一定程度的影响。采用综合污染指数评价法对辽河干流水体中重金属的污染程度进行了评价,结果表明,辽河干流重金属含量在季节变化中表现出一定的规律:丰水期>枯水期。从空间角度上看,干流上游A1点位开始,污染程度呈大幅增加,到中游A3,A4和A5点位重金属含量达到了最高点,到入海口附近重金属含量从开始呈下降趋势。从整体上来看,辽河干流上中游重金属污染的情况要比下游更加严重。重金属Cr,Cu,Ni,Zn,Pb,Ag在不同时期都有不同程度的超标,特别是Cr的大量超标对辽河干流的整体水质带来巨大的影响。研究结果表明,辽河干流重金属的污染程度在逐年加剧,需要加强中上游沿河的治理。

In order to study water heavy metal pollution in the main stream of Liaohe River, eight sampling points were set up. It was determined by ICP-MS water quality analyzer to measure the content of 13 heavy metals of water samples. By analyzing whether there was a linear relationship between heavy metal content and turbidity, pH value, to explore the change rule of heavy metal content in water. The results showed that there was no significant correlation between pH value and the content of heavy metals in the main stream of the Liaohe River. The turbidity of the water had a certain degree of influence on the content and distribution of Ag in the high water period and Pb in the low water period. Comprehensive pollution index evaluation method was used to evaluate the pollution degree of heavy metals in the main stream of Liaohe River. The results indicated that the heavy metal content in the main stream of the Liaohe River displayed a certain regular pattern in the season change: high water period >low water period. From a spatial point of view, the A1 site in the upper reaches of the main stream started to increase the pollution level. The heavy metal content at the A3, A4, and A5 sites in the middle reaches reached the highest point, and then the heavy metal content near the estuary began to decrease. On the whole, the heavy metal pollution in the middle and upper reaches of the Liaohe River was more serious than in the downstream. Heavy metals(Cr, Cu, Ni, Zn, Pb, Ag)had different degrees of excessive levels at different periods. In particular, the excessive amount of Cr has a huge impact on the overall water quality of the Liaohe River. The research results revealed that the pollution degree of heavy metals in the main stream of the Liaohe River has been increasing year by year. It is necessary to strengthen the management of the rivers along the middle and upper reaches.