『Abstract
　Suspended solids (SS) in the first-flush runoff on highway was monitored in six continuous events from October to December 2000 in Winterthur, Switzerland, and some characteristics of particle-bound micropollutants such as polycyclic aromatic hydrocarbons, phthalate esters, and heavy metals were investigated. Among the three micropollutants, concentration of polycyclic aromatic hydrocarbon showed similar behavior to SS. Phthalate esters showed almost no correlation, whereas heavy metals showed increase in its concentration with lowers SS concentration. Three different characteristics of the micropollutants in the first flush indicated that the first-flush phenomenon is complex, and they may not be simply stated when considering suspended solids as an index for the runoff.

Keywords: Highway runoff; Suspended solids; Polycyclic aromatic hydrocarbons; Heavy metals; Phthalate esters』

1. Introduction
2. Materials and method
　2.1. Study area
　2.2. Sample collection
　2.3. Chemical analysis
　　2.3.1. Polycyclic aromatic hydrocarbons and phthalate esters
　　2.3.2. Heavy metal analysis
3. Results and discussion
　3.1. Flow rate vs SS in runoff events
　3.2. SS vs PAHs in runoff events
　3.3. SS vs phthalate esters in runoff events
　3.4. SS vs heavy metals in runoff events
4. Conclusion
References