A study of air quality and atmospheric deposition on a small urban catchment (Pin Sec catchment) has been carried out in Nantes, France, in 2007 and 2008 in the frame of a federative project aimed at understanding the origin of pollution in urban environments. Carbon monoxide, nitrogen monoxide, nitrogen dioxide, ozone, sulphur dioxide and particles less than 10 µm (PM 10) were monitored for air quality, whereas heavy metals, Polycyclic aromatic hydrocarbons (PAHs) and pesticides were analyzed in atmospheric deposition. Our results show that micro pollutant concentrations are very low. Air concentrations of carbon monoxide, NOX, ozone, sulphur dioxide and PM10 are similar to those measured in residential urban areas with low traffic. The concentrations of these pollutants never exceed legal mean hourly or daily limits. PAHs are only detected during the winter, due to heating, which is the main source of PAHs in urban environments during cold periods. Most pesticides concentrations are lower than the quantification limits, however, glyphosate and AMPA are detected in the summer. Annual metal fluxes show the absence of metal pollution on the Pin Sec catchment. Due to the low traffic density and to the absence of industrial activities on the study site, anthropogenic particles were rarely identified during scanning electron microscopy observations. On the contrary, particles of biological and detritic origins are ubiquitous in our samples.
