绕城高速路面径流重金属初期效应研究

Research on Road Runoff of Heavy Metals First Flush Effect from City Beltway

以西安市绕城高速-高新段为路面径流采样点,采用降雨-产流-产污同步观测的试验方法,对2016年6-8月期间的6场降雨径流事件进行全程人工时间间隔监测,测试径流过程重金属Cu、Pb、Zn、Cr、Ni、Cd的浓度变化,分析路面径流重金属EMC值、污染水平及初期冲刷效应。结果表明,各场次降雨事件各重金属EMC值相差较大;Pb、Cr污染水平较高,大部分场次径流Pb、Cr的EMC值介于《地表水环境质量标准》Ⅲ与Ⅴ类标准限值间,Cu、Zn、Cd污染污染程度相对较轻;西安市绕城高速重金属Cu、Pb、Zn、Cr、Ni、Cd初期冲刷现象并非普遍存在,前峰型和平缓型降雨事件各重金属均显示中等程度初期效应,多峰型为中等或微弱,后峰型降雨事件各重金属均未出现初期冲刷效应;不同类型降雨事件初期冲刷强度顺序依次为:前峰型>平缓型>多峰型>后峰型,其重金属FF30均值分别是0.515、0.400、0.351、0.266;各重金属初期冲刷强度顺序依次为:Cu>Zn>Ni>Pb>Cr>Cd.其FF30均值分别为0.401、0.388、0.387、0.378、0.375、0.369。

Urban road runoff caused by 6 storm events were collected by labor using time-paced sampling method at Gaoxin beltway in Xi'an,Shaanxi province from Jun.to Aug.2016.Concentrations of Cu,Pb,Zn,Cr,Ni and Cd,were tested during the whole processes.Road runoff of heavy metals pollution levels and the first flush effect of the beltway were studied by the test methods of rainfall-produce runoff-produce pollution with simultaneous observations.The results show that heavy metals EMC values of each rainfall event differ greatly.The heavy metal of Pb,Cr have a high pollution level,which most of runoff events of EMC value ranged between Surface Water Environment Quality Standard Ⅲ to Ⅴ standard value,while pollution of Cu,Zn,Cd are relatively light.First flush phenomena of heavy metals such as Cu,Pb,Zn,Cr,Ni,Cd is not common in Xi'an beltway.In the former-peak and the flat type rainfall events,heavy metals have a moderate initial effects.As for multi-peak rainfall events,it has a medium or weak effects.Back-peak rainfall events have no first flush effects on heavy metals.The sequence of strength of the first flush of different rainfall events was former-peak> flat type> multi-peak>back-peak,which means of FF30Cu> Zn> Ni> Pb> Cr> Cd,which means of FF30 respectively were 0.401,0.388,0.387,0.378,0.375,0.369.