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1L - Exposure Modelling (WEP/91) Polychlorinated biphenyls in stormwater and consequences for the environment in urban areas. Rossi, Luca1, De Alencastro, Luiz2, Kupper, Thomas2, Tarradellas, Joseph2, 1 Swiss Federal Institute for Environmental Science and Technology, Duebendorf, ZH, Switzerland2 Swiss Federal Institute of Technology, Lausanne, VD, Switzerland ABSTRACT- Polychlorinated biphenyls (PCBs) are still present in the environment despite their almost worldwide prohibition. A study was conducted over a year in Switzerland to analyze PCBs in urban stormwater, considered as a potential source of contamination for the environment in urban areas. The concentration of PCBs in 89 rain events from five different strictly separated drainage systems (three in Lausanne and two in Geneva) were determined. The mean concentrations of PCBs in stormwater ranged from values below the detection limit (0.11-0.24 ng/l according to the congener) to 403 ng/l. A mass balance estimates a total input load of 110-125 kg/y PCBs in the Swiss urban water systems. The contribution of stormwater is 75-94 kg/y in combined sewer systems and 23-34 kg in separated sewer systems. This mass balance illustrates that a major part of the PCB load in the environment or in WWTP sludges originates from urban stormwater. This result was confirmed by a fingerprint of PCB congeners in stormwater, which showed a pattern identical to that found in sewage sludge in combined sewer systems. In fact, WWTP sludges are a good indicator of urban water pollution as they accumulate and concentrate organic compounds. In the near future, the prohibition of the use of wastewater sludges in agriculture will contribute to limit the dispersion of PCBs in the environment. However, if the problem of stormwater contamination is not taken into account for separated sewer systems, it will remain a main source of PCBs contamination to the environment. Key words: urban stormwater, polychlorinated biphenyls (PCBs), fingerprint, mass balance |
