The objective here is to characterize atmospheric deposition in a small urban watershed. Our results show that micro pollutant concentrations are very low. Polycyclic aromatic hydrocarbons are only detected during the winter, while pesticides are detected in the summer. Due to the low traffic density and to the absence of industrial activities on the Pin Sec catchment, anthropogenic particles are rarely identified during scanning electron microscopy observations. On the contrary, particles of biological and detritic origins are ubiquitous. This characterization will be completed by a new approach aiming at a better knowledge of dry deposition
