汉江中下游水体重金属时空分布及污染评价

为探明汉江中下游水体中重金属的污染状况,分别于2019年6月(丰水期)和2020年1月(枯水期)在汉江中下游选取20个监测断面采集水样,监测水体中Cu、Zn、Pb、Fe、Mn、As、Se和Cd 8种重金属的含量,分析汉江中下游水体中重金属污染的时空分布特征,并对水体重金属污染状况进行评价。结果表明:汉江中下游水体重金属污染以Fe、Mn为主,其他6种重金属浓度均满足地表水Ⅱ类水标准。汉江中下游水体中Fe和Mn含量沿程波动较大,二者变化规律基本一致。Fe和Mn含量最大值在支流竹皮河,其中Fe浓度超标4.63倍,Mn超标13%;此外,位于汉川市的S17断面Fe元素含量超标3.89倍。结合历史数据分析,发现近年来汉江中下游水体重金属含量总体呈上升趋势。评价结果表明,汉江中下游大部分水体水质良好,钟祥市和汉川市是汉江中下游重金属污染相对较重的两个城市,支流竹皮河的水体重金属污染问题需引起重视。

Spatio-temporal Distribution and Pollution Assessment of Heavy Metals in the Middle and Lower Reaches of Hanjiang River

In the aim of investigating the pollution status of heavy metals in the middle and lower reaches of Hanjiang River, we collected water samples from 20 points in June 2019 (wet season) and January 2020 (dry season), respectively, and measured the concentrations of eight heavy metals (Cu, Zn, Pb, Fe, Mn, As, Se and Cd) in the waters. We further analyzed the spatio-temporal distribution characteristics of heavy metal pollution, and evaluated the pollution status of heavy metal. Our findings manifested that Fe and Mn were dominant heavy metals in the water body of the middle and lower reaches of Hanjiang River, while the concentrations of other six heavy metals met the surface water class-Ⅱ standard. The concentrations of Fe and Mn fluctuated greatly along the middle and lower reaches of the Hanjiang River, and their change rules were basically consistent. The maximum concentrations of Fe and Mn were detected at Zhupi River (a tributary), exceeding the limit of surface water environmental quality standard by 4.63 times and 0.13 times, respectively. In addition, the concentration of Fe in section S17 (Hanchuan City) exceeded the standard by 3.89 times. In association with historical data analysis, we found that heavy metal concentration of water body in the middle and lower reaches of Hanjiang River is on the rise in general in recent years. The evaluation results indicate that the water quality in the middle and lower reaches of Hanjiang River is generally good. Zhongxiang City and Hanchuan City are two cities with heavy metal pollution problems. The heavy metal pollution in the tributary Zhupi River should arouse more attention.