Lee Haejin, Lau Sim-Lin, Kayhanian Masoud, Stenstrom Michael K
Department of Civil and Environmental Engineering, 5714 Boelter Hall, University of California, Los Angeles, CA 90095, USA.
Water Res. 2004 Nov;38(19):4153-63. doi: 10.1016/j.watres.2004.07.012.
California's climate, typified by winter and spring precipitation and summer drought, is often called a Mediterranean climate, and creates a long period for pollutant build-up. The initial storms of the winter season usually have higher pollutant concentrations, which is called a seasonal first flush. To investigate the existence of a seasonal first flush, we analyzed four major data sets, collected over the 1999-2000 to 2002-2003 wet seasons. Trends in seasonal loads were quantified by plotting pollutant concentrations or cumulative pollutant load versus cumulative rainfall or cumulative runoff volume. Pollutant concentrations in the first part of the wet season were ranged from 1.2 to 20 times higher than concentrations near the end of the season, and mass emission rates were similarly higher at the beginning of the season. A seasonal first flush existed for most cases and was strongest for organics, minerals and heavy metals except lead. This result suggests that applying treatment Best Management Practices (BMPs) early in the season could remove several times more pollutant mass than randomly timed or uniformly applied BMPs.
加利福尼亚的气候以冬春降水和夏季干旱为典型特征，常被称为地中海气候，这种气候会导致污染物长期累积。冬季的初雨通常污染物浓度较高，这被称为季节性首次冲刷。为了研究季节性首次冲刷的存在情况，我们分析了在1999 - 2000年至2002 - 2003年雨季期间收集的四个主要数据集。通过绘制污染物浓度或累积污染物负荷与累积降雨量或累积径流量的关系图来量化季节性负荷趋势。雨季初期的污染物浓度比季末附近的浓度高出1.2至20倍，且季节开始时的质量排放率同样较高。大多数情况下存在季节性首次冲刷，除铅外，有机物、矿物质和重金属的首次冲刷最为强烈。这一结果表明，在季节早期应用处理最佳管理措施（BMPs）比随机定时或均匀应用BMPs能去除多几倍的污染物质量。
