Priority pollutants in urban stormwater: Part 1 – Case of separate storm sewers

Organic and mineral pollutants have become part of today's urban environment. During a rain event, stormwater quality as well as the corresponding contaminant loads is affected by both atmospheric deposition and the various types of impervious surfaces (roads, rooftops, parking lots etc.) on which runoff occurs. This study provides results on stormwater pollution in Paris and its suburbs from three separate storm sewers (n = 20 samples). These results show that the stormwater had been contaminated by 55 chemical substances out of the 88 investigated. A particular attention was given to stormwater particle contamination. Concentrations are provided for: metals, PAHs, PCBs, organotins, alkylphenols, phthalates, pesticides, and VOCs. Our findings are among the first available in the literature since the relevant analyses were all conducted on both the particulate (P) and dissolved (D) phases. For most substances, particles from the three storm sewers were more heavily contaminated than dredged sediments and settleable particles from the Seine River. As a consequence of this finding, the release of untreated stormwater discharges may impact the receiving waters and contribute to sediment contamination.

► Amongst the 88 monitored substances, 55 were observed at least once. ► 15 PAHs, Cu, Zn, diuron, TBT, DEHP, nonylphenols were present in all samples. ► Particulate stormwater concentrations were not different for the 3 watersheds. ► Stormwater particles were more polluted than dredged sediments of the Seine River. ► Metals and PAHs in stormwater particles constitute a risk to receiving waters.