|
|
Impacts of sampling size on estimation accuracy of road runoff event mean concentration-taking time-interval sampling method for example |
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 |
|
|
Abstract In order to investigate the impacts of sample size on estimation accuracy of road runoff event mean concentration (EMC), road runoff samples over the whole time range of 3 storm events occurred at Taibai Interchange of the south second-ring road in Xi'an, Shaanxi province were collected by the manual time-interval sampling method from August to November 2014, and concentrations of SS, COD, Pb, Zn, dissolved Pb and dissolved Zn of the samples were determined. Then, self-compiled VBA programing based on random sampling method was utilized for the estimation. The results indicated that, in different types of rainfall events, pollutant concentrations in the initial duration of runoff were relatively high, fluctuated sharply and were affected by the rainfall intensity significantly. However, pollutant concentrations in mid and late duration of runoff were decreased and tended to be stable. For improving the estimation accuracy of EMC, runoff samples should be collected in the whole duration of rainfall event, and in the initial duration of runoff, the runoff samples should be collected intensively. The estimation accuracy of EMC was significantly influenced by sampling size when using time-interval sampling method. The estimated EMC based on concentrations of samples and runoff volume of corresponding periods dispersed widely when sample size was small. However, the dispersion of the estimated EMC decreased with the increasing of sample size, the estimated EMC tended to be stable as well. The maximum relative error between the estimated EMC based on different pollutant indexes in different runoff events and the approximate true value of EMC was decreased with the increasing of sample size. However, the degrees of decrease which were related to the fluctuation of water quality and volume of runoff were quite different. If the sample size was less than 10, the maximum relative error between the estimated EMC and the approximate true value of EMC was close to 40%, and the error could be reduced to 30% and 20% when the sample size were increased to 13 and 19 respectively.
|
Received: 01 June 2016
|
|
|
|
|
[1] |
USEPA. Results of the nationwide urban runoff program[R]. Washington D C:US Environmental Protection Agency, 1983.
|
[2] |
Clark D L, Asplund R, Ferguson J, et al. Composite sampling of highway runoff[J]. Journal of the Environmental Engineering, 1981,107(5):1067-1081.
|
[3] |
Ma J A. Characteristics of pollutants in highway runoff. Regression, representativeness and first flush[D]. Dissertation submitted to the University of California for the Degree of Doctor of Philosophy, 2002.
|
[4] |
陈莹,赵剑强,胡博.西安市城市主干道路面径流污染特征研究[J]. 中国环境科学, 2011,31(5):781-788.
|
[5] |
Khan S, Lau S L, Kayhanian M, et al. Oil and grease measurement in highway runoff-sampling time and event mean concentration[J]. Journal of Environmental Engineering, 2006, 132(3):415-422.
|
[6] |
Harmel R D, King K W, Slade R M. Automated storm water sampling on small watersheds[J]. Applied Engineering in Agriculture, 2003,19(6):667-674.
|
[7] |
Ackerman D, Stein E D, Ritter K J. Evaluating performance of stormwater sampling approaches using a dynamic watershed model[J]. Environmental Monitoring and Assessment, 2011, 180(1-4):283-302.
|
[8] |
Harmel R D, Cooper R J, Slade R M, et al. Cumulative uncertainty in measured streamflow and water quality data for small watersheds[J]. Transactions of ASAE, 2006,49(3):89-701.
|
[9] |
Lee H J, Swamikannu X, Radulescu D, et al. Design of stormwater monitoring programs[J]. Water Research, 2007, 41(18):4186-4196.
|
[10] |
Ma J A, Kang J H, Kayhanian M, et al. Sampling issues in urban runoff monitoring programs:Composite versus grab[J]. Journal of Environmental Engineering, 2009,135(3):118-127.
|
[11] |
King K W, Harmel R D, Fausey L. Development and sensitivity of a method to select time and flow-paced storm event sampling intervals for headwater streams[J]. Journal of Soil and Water Conservation, 2005,60(6):323-331.
|
[12] |
Stone K C, Hunt P G, Novak J M, et al. Flow-proportional, time composited, and grab sample estimation of nitrogen export from an Eastern Coastal Plain watershed[J]. Transactions of ASAE, 2000,43(2):281-290.
|
[13] |
Leecaster M K, Kenneth S, Liesl L T. Assessment of efficient sampling designs for urban stormwater monitoring[J]. Water Research, 2002,36(6):1556-1564.
|
[14] |
任玉芬,王效科,欧阳志云,等.北京城市典型下垫面降雨径流污染初始冲刷效应分析[J]. 环境科学, 2013,34(1):373-378.
|
[15] |
李贺,张雪,高海鹰,等.高速公路路面雨水径流污染特征分析[J]. 中国环境科学, 2008,28(11):1037-1041.
|
[16] |
Chen M, Zheng Z H, Fu D F, et al. Characteristics of Hg pollution in urban stormwater runoff[J]. Journal of Southeast University (English Edition), 2014,30(2):158-163.
|
[17] |
王龙涛,段丙政,赵建伟,等.重庆市典型城镇区地表径流污染特征[J]. 环境科学, 2015,36(8):2809-2816.
|
[18] |
袁宏林,郑鹏,李星宇,等.西安市不同下垫面路面径流雨水中重金属的四季污染特征[J]. 生态环境学报, 2014,23(7):1170-1174.
|
[19] |
欧阳威,王玮,郝芳华,等.北京城区不同下垫面降雨径流产污特征分析[J]. 中国环境科学, 2010,30(9):1249-1256.
|
[20] |
韩景超,毕春娟,陈振楼,等.城市不同功能区径流中PCBs的污染特征及毒性评价[J]. 中国环境科学, 2013,33(3):546-552.
|
[21] |
王倩,张琼华,王晓昌.国内典型城市降雨径流初期累积特征分析[J]. 中国环境科学, 2015,35(6):1719-1725.
|
|
|
|