6.10 小 结
本章针对沘江流域进行野外实时监测暴雨—洪水过程及采集水和悬沙样品，主要探索在暴雨—洪水过程中，矿区重金属Pb和Zn污染物迁移至沘江河道的动态迁移过程及影响因素。结合悬沙量及流量等数据，计算一场暴雨过程中断面Pb和Zn污染物通量，从而评估金顶矿区对沘江主要介质（水体和悬沙）中Pb和Zn污染物的贡献。主要研究结论如下：
（1）相对基流，暴雨条件下河流水体中Pb和Zn含量增加，且水体中Zn含量显著高于Pb。矿区河段水体中Pb含量在暴雨过程中显著高于矿区上游河段，而Zn表现在暴雨结束后其含量显著高于矿区上游河段，滞后于暴雨过程，可能来自壤中流产流过程，受土壤的缓冲作用所致。
（2）暴雨对矿区河段悬沙中Pb和Zn含量影响显著且两种元素的变化趋势相同，即与降雨过程基本一致，呈阶段性、间歇性变化特点。与水体不同，矿区河段悬沙中Pb和Zn含量峰值与降雨量峰值发生时间比较接近，说明矿区河段悬沙中Pb和Zn含量的变化过程主要受地表径流产流过程的影响。
（3）河流上游至下游，矿区Pb和Zn污染物迁移主要以悬沙为载体，且存在一定的滞后性。
（4）暴雨是矿区Pb和Zn污染物进入沘江河道的一个重要动力因素。暴雨对矿区河段水体和悬沙中Pb和Zn含量的影响均是显著的，显著高于矿区上游和矿区下游河段。在暴雨—洪水过程中，金顶矿区对沘江水体中Zn含量贡献率达99.98%，对河流悬沙中Pb和Zn含量贡献率分别达88.93%和94.80%。
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