EMERGING CONTAMINANTS IN URBAN ENVIRONMENTS: FROM LEAKING SEWERS TO NANOPARTICLES IN CONCRETE

Groundwater and surface water contamination from emerging contaminants in urban environments may be related to infrastructure that is either very old or relatively new. It is important to understand the relationship between these contaminants, infrastructure, and water supplies in order to better protect public health. Sanitary sewers are an important component of the urban environment that protect the population from viruses and other pathogens found in human waste. However, as sewers age they can lose integrity and begin to leak into the subsurface. Several recent studies in Madison, Wisconsin detected human enteric viruses in both groundwater and public supply wells. These viruses are typically not monitored in groundwater and have been linked with aging, leaking urban sewers. The potential also exists for leaking sewers to impact surface water when the two are in close proximity. Current research in the Washington, D.C. area has the goal of determining if leaking sewers are a substantial source of microbiological contamination in urban streams. These studies have shed light on how deteriorating sewers may impact water quality in urban settings.

Compared with sanitary sewers, titanium dioxide concrete is a recent addition to the urban landscape. The addition of TiO₂ nanoparticles to concrete imparts photocatalytic properties that make it self-cleaning with the added benefit of improving air quality by reducing nitrous oxide concentrations. The growing use of these materials in buildings and roads is of concern because the release of TiO₂ nanoparticles due to weathering and their subsequent fate and transport are not well understood. Laboratory experiments determined the amount of TiO₂ nanoparticle release when these materials are subjected to ultraviolet light and acidic precipitation. The results of this research will guide the installation and management of TiO₂ concrete in urban environments in order to better protect water supplies.