School of Earth and Environment, The University of Western Australia, M087, 35 Stirling Highway, Crawley 6009, Australia.
J Contam Hydrol. 2010 Apr 1;113(1-4):56-65. doi: 10.1016/j.jconhyd.2009.12.007. Epub 2010 Jan 6.
The timing and magnitude of rainfall events are known to be dominant controls on pesticide migration into streams and groundwater, by triggering rapid flow processes, such as preferential flow and surface runoff. A better understanding of how regional differences in rainfall impact rapid leaching risk is required in order to match the scale at which water regulation occurs. We estimated the potential amount of rapid leaching, and the frequencies of these events in a case study of the southwest of Western Australia, for one soil type and a range of linearly sorbing, first order degrading chemicals. At the regional scale, those chemicals with moderate sorption and long half lives were the most susceptible to rapid transport within a year of application. Within the region, this susceptibility varied depending upon application time and seasonality in storm patterns. Those chemicals and areas with a high potential for rapid transport on average, also experience the greatest inter-annual variability in rapid leaching, as measured by the coefficient of variation. The timing and frequencies of rapid leaching events appeared to strongly relate to an area's relative susceptibility to rapid leaching. In the study region the results also suggested that frontal rainfall dominates rapid leaching along the western and southern coasts while convective thunderstorms play a greater role in the arid east.
降雨事件的时间和规模是控制农药向溪流和地下水迁移的主要因素，因为它们会引发快速流动过程，如优先流和地表径流。为了匹配水调节发生的规模，需要更好地了解降雨的区域差异如何影响快速淋溶风险。我们针对西澳大利亚西南部的一种土壤类型和一系列线性吸附、一级降解的化学物质，估算了快速淋溶的潜在量和这些事件的频率。在区域尺度上，中等吸附和长半衰期的那些化学物质在施药一年内最容易快速迁移。在该区域内，这种易感性取决于施药时间和风暴模式的季节性。那些具有快速迁移高潜力的化学物质和区域，其快速淋溶的年际变异性也较大，如变异系数所示。快速淋溶事件的时间和频率似乎与一个地区对快速淋溶的相对敏感性密切相关。在研究区域，结果还表明，锋面降雨主导着西部和南部海岸的快速淋溶，而对流雷暴在干旱的东部则发挥更大的作用。
