Chemical, microbiological, and spatial characteristics and impacts of contaminants from urban catchments: CABRRES project

Abstract

Chemical and microbial contaminations of urban waters including stormwater runoff, wastewaters, and combined sewer overflow waters have been shown for a number of years. It is clearly demonstrated, for example, that metallic ions, polycyclic aromatic hydrocarbons (PAH), pesticides, and microbial pathogens can be conveyed by such waters, and they have been found strongly associated with suspended matters. The “Water Framework Directive” (WFD) led to the launching of several research initiatives toward the “Best Management Practices – BMP,” through novel or improved technologies aiming at reducing the ecotoxicological impacts and health risks associated with these waters. Some of these techniques consist at keeping these waters for a certain amount of time in a confined system in order to favor settling of their suspended particles and lead, in part, to the natural biological degradation of their contaminants. These systems are typically impervious basins that can receive stormwaters, e.g. detention basins, biofilters, artificial wetlands, or combined sewer overflows, e.g. stabilization ponds of wastewater treatment lagoons. Several key mechanisms occur in these systems (Fig. 1). The deposits formed constitute areas of high levels of contamination. These structures (basins) are ecosystems with an important biological diversity. They can represent a high risk of contamination of the connected surfaces, streams, or groundwater environments into which they are discharged. Investigations regarding their efficiency at retaining and transforming pollutants and killing undesirable microbes are thus required. When landscaped, these structures may lead to the development of urban public spaces. In this context, they are subjected to social practices generally associated with public gardens, practices which accidentally or regularly expose the public to their contaminants. In addition, these structures require maintenance and specific management, exposing workers to their contaminants. It is therefore essential that the chemical and microbiological contaminants present in these systems are accurately characterized and measured (i.e. which chemical forms and microbial species and genotypes, and how much?), and their health hazards and risks be inferred or estimated. In this context, several biofilters, detention basins, and stabilization ponds have been monitored and investigated around the world. The CABRRES project (Chemical, microbiological, spatial characteristics and impacts of contaminants from urban stormwater detention basins: Assessment and Management of Environmental and Human Health Risks, http://www.graie. org/cabrres), funded by the French National Research Agency (ANR), is one of these research initiatives. It is an interdisciplinary research project (Fig. 2) aiming at better defining the interactions between chemical pollutants (including toxic Responsible editor: Philippe Garrigues