样品数量对径流事件平均浓度估算结果的影响--以时间间隔采样法为例  

Impacts of sampling size on estimation accuracy of road runoff event mean concentration-taking time-interval sampling method for example

作　　者：陈莹[1] 王昭[1] 赵剑强[1] 杨文娟[1] CHEN Ying;WANG Zhao;ZHAO Jian-qiang;YANG Wen-juan(Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education, School of Environmental Science and Engineering, Chang’an University, Xi’an 710054, China)

机构地区：[1]长安大学环境科学与工程学院旱区地下水文与生态效应教育部重点实验室,陕西西安710054

出　　处：《中国环境科学》2017年第2期620-627,共8页China Environmental Science

基　　金：国家自然科学基金资助项目(51308050);中央高校基本科研业务费专项资金资助项目(CHD2011JC114)

摘　　要：在西安市城市主干道南二环路太白立交高架段设置路面径流采样点,采用人工时间间隔采样法对2014年8月~2014年11月的3场径流事件全程采样,测试径流过程SS、COD、Pb、Zn、溶解态Pb、溶解态Zn的浓度变化及出流规律,基于随机抽样法编程研究时间间隔采样法样品数量对场次径流事件平均浓度(EMC)估算准确性的影响.结果表明,无论何种类型的降雨事件,径流初期污染物浓度较高、波动剧烈且受雨强影响较大,径流中后段浓度下降且逐渐趋于平稳,为提高EMC估算的准确性应对径流全程采样并在初期加密样品采集.时间间隔采样法样品数量对EMC估算结果产生显著影响.场次径流样品数量较少时,根据样品浓度结合相应时段径流量计算的EMC呈较大离散性,随着样品数量增加估算EMC值离散性逐渐减小并趋于稳定.不同场次径流各污染指标估算EMC值与EMC近似真值的最大相对误差随样品增多而降低的趋势不尽相同,其与径流水质水量波动程度有关.若场次径流样品数量小于10,各污染指标估算EMC值与EMC近似真值的最大相对误差接近40%,当样品数量增至13个或19个,其最大相对误差分别小于30%和20%.In order to investigate the impacts of sample size on estimation accuracy of road runoff event meanconcentration(EMC),road runoff samples over the whole time range of3storm events occurred at Taibai Interchange ofthe south second-ring road in Xi’an,Shaanxi province were collected by the manual time-interval sampling method fromAugust to November2014,and concentrations of SS,COD,Pb,Zn,dissolved Pb and dissolved Zn of the samples weredetermined.Then,self-compiled VBA programing based on random sampling method was utilized for the estimation.Theresults indicated that,in different types of rainfall events,pollutant concentrations in the initial duration of runoff wererelatively high,fluctuated sharply and were affected by the rainfall intensity significantly.However,pollutantconcentrations in mid and late duration of runoff were decreased and tended to be stable.For improving the estimationaccuracy of EMC,runoff samples should be collected in the whole duration of rainfall event,and in the initial duration ofrunoff,the runoff samples should be collected intensively.The estimation accuracy of EMC was significantly influencedby sampling size when using time-interval sampling method.The estimated EMC based on concentrations of samples andrunoff volume of corresponding periods dispersed widely when sample size was small.However,the dispersion of theestimated EMC decreased with the increasing of sample size,the estimated EMC tended to be stable as well.Themaximum relative error between the estimated EMC based on different pollutant indexes in different runoff events and theapproximate true value of EMC was decreased with the increasing of sample size.However,the degrees of decreasewhich were related to the fluctuation of water quality and volume of runoff were quite different.If the sample size wasless than10,the maximum relative error between the estimated EMC and the approximate true value of EMC was close to40%,and the error could be reduced to30%and20%when the sample size were increased to13and19respectively.

关 键 词：路面径流 事件平均浓度 样品数量 时间间隔采样法 随机抽样 误差 

分 类 号：X522[环境科学与工程—环境工程]