西安市城市主干道路面径流污染特征研究

Pollution characteristics of urban trunk road runoff in Xi'an City.

在西安市城市主干道南二环路建立路面径流原位采样站,利用自制流量等比例采样装置,全程收集2009年3月～2010年2月的32场降雨产生的路面径流,测试径流SS、COD、溶解性COD、NH3-N、Pb、溶解性Pb、Zn和溶解性Zn的事件平均浓度(EMC),研究路面径流污染强度、污染物赋存状态、相关关系、浓度影响因素以及季节变化规律.结果表明,城市主干道路面径流污染物EMC变异大且污染严重,SS、COD、溶解性COD、NH3-N、Pb、Zn、溶解性Zn的EMC中值分别为1543,574,129,1.86,0.042,0.219,0.111mg/L,变异系数0.41～0.8,其中SS、COD的EMC中值远大于《污水综合排放标准》三级标准,是主要污染物.路面径流中Pb主要以颗粒态存在,而47.4%的Zn、25.1%的COD呈溶解态.径流中颗粒物是许多其他污染物的载体,COD、Pb、Zn均与SS在显著性水平0.01时显著相关,相关系数分别为0.845,0.807和0.903.表征降雨特征的各因子中,降雨量、最大降雨强度与污染物浓度呈负相关,降雨历时与除NH3-N之外的其他污染物呈负相关,相关性依次为降雨量>最大降雨强度>降雨历时,前期晴天时间与溶解性Zn和溶解性COD浓度正相关,但与其它污染指标不相关.方差分析结果表明,SS、COD和NH3-N浓度随季节明显变化,而溶解态COD、重金属Pb、Zn和溶解态Zn的浓度季节差异不大.

Urban road runoff caused by 32 storm events were collected proportionally to the total volume and completely through the rainfall time at south second ring road in Xi＇an City using self-made volume proportional collecting device from March 2009 to February 2010.Event mean concentration（EMC） of SS,NH3-N,total and dissolved COD,Pb and Zn were tested.Pollution intensity,mode of occurrence,relationship,concentration influential factors,as well as seasonal variation of runoff pollutants were explored.The results showed that EMC of main runoff pollutants varied greatly and the median EMC of SS,COD,dissolved COD,NH3-N,Pb,Zn and dissolved Zn were 1543,574,129,1.86,0.042,0.219,0.111mg/L respectively.The coefficient of variation ranged from 0.41 to 0.8.The median EMC of SS and COD were far greater than the values of Integrated Wastewater Discharge Standard Grade III,so SS and COD were the main pollutants of road runoff.The occurrence of Pb was mainly granular state and 47.4% of Zn,25.1% of organic pollutants was dissolved.The correlation of COD,Pb and Zn with SS were significant at 0.01 level and the correlation coefficients were 0.845,0.807 and 0.903 respectively,which showed that particulate matters were carrier for many other pollutants.The descending order for influence weights of rainfall characteristics on concentration of pollutants was as follows： rainfall volume maximum rainfall intensity rainfall duration.Antecedent dry period（ADP） had no correlation with EMC of many pollutants except dissolved Zn and dissolved COD.Result of one factor analysis of variance showed that EMC of SS,COD and NH3-N varied with seasons significantly,while the variation tendency of other pollutants,such as dissolved COD,Pb and Zn was not obvious.