Characterization of Suspended Solids and Heavy Metal Distributions during First Flush in Highway Runoff

Nonpoint source pollution has gradually received attention during stormater flush in highway runoff. The understanding the pollutant characteristics ill be critical issue to treat these types of pollution. In the present study, two monitoring stations were selected to measure hydrology and to take sampling during first flushing events at the Zhong-Shan freeway and East-West expressway in the Miaoli County. Taiwan. The results of monitoring stations in 2007 storm events found that normally the peak concentrations of total suspended solids (TSS) and heavy metals occurred at the initial stormwater and then the concentrations decreased when the measured time elapsed. The highest and lowest heavy metal concentrations were Fe and Ni, respectively, during the stormwater. Particle size distribution (PSD) mostly ranged from 12 μm and 96 μm at two measured sites. The event mean concentrations (EMCs) and loadings of TSS and heavy metals were also correlated with total runoff and total rainfall.