Multi-Level Approach of the Ecotoxicological Impact of a Combined Sewer Overflow on a Peri-Urban Stream

Céline Becouze-Lareure,Pascal Breil,Yves Perrodin,Christine Bazin,Philippe Namour

doi:10.4236/jwarp.2012.411114

Céline Becouze-Lareure, Pascal Breil + Show 3 more

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https://doi.org/10.4236/jwarp.2012.411114

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Abstract

In periurban zones, urban wet weather discharges have been recognized as the most significant vector of pollution in aquatic environments. The discharge of this water without treatment into the aquatic environment could present an ecotoxicological risk for biocenosis. The aim of the INVASION project is to assess the potential ecotoxicological impact of a combined sewer overflow (CSO) on a peri-urban stream. A comparative study between upstream and downstream areas of the CSO allowed observing significant effects of this overflow on the river. We studied three layers of stream: surface water, benthic layer and hyporheic layer. To characterize the potential ecotoxicological risk of water and sediments, we used a battery of 4 bioassays: Daphnia magna, Vibrio fischeri, Brachionus calyciflorus and Heterocypris incongruens. In parallel, we measured the physico-chemical parameters: ammonium (NH4+), chromium (Cr), copper (Cu) and lead (Pb). An ecological risk is greatest for the hyporheic zone in downstream river, particularly for the solid phase. These results corroborated with the physico-chemical data obtained.

Highlights

The general development of urban areas is generating increasing flows of pollutants in aquatic environments from urban drainage networks and stormwater management systems [1]
The aquatic organisms used come from breeding in laboratory or sporocysts bough in the shop.After validation of bioassays, we evaluate three layers of stream, surface water, benthic and hyporheic layers, through a comparative study of sampling sites both upstream and downstream of the combined sewer overflow (CSO) and to more accurately identify the zones that pose the greatest risks to aquatic organisms
At the time of sampling, the flow rate of the Chaudanne was approximately 400 L·s–1. This peak can be attributed to the storm event due to the quantity of stormwater (Imax = 19 mm·h–1), the surface runoff and the inflow from the CSO

Summary

Introduction

The general development of urban areas is generating increasing flows of pollutants in aquatic environments from urban drainage networks and stormwater management systems [1]. This water that flows into aquatic environments during wet weather conditions is defined as urban wet-weather discharges (UWWD). Concentrations and loads of main constituents and priority substances of European Water Framework Directive [4] have been well documented. These last years, several research projects like ESPRIT [5], ScorePP [6]

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