Contamination characteristics in runoff fractions from a nuclear facility in São Paulo/Brazil

Abstract

Abstract The stormwater runoff may act as a nonpoint pollutant source and in urban environments contributes to aquatic ecosystem quality decay. Here, we examined the runoff characteristics on the export of total solids and total metals, as well as pH and conductivity responses during the rainfall evolution. In 2017 and 2018, 12 rain events in 4 sampling stations were monitored at a parking lot located at Nuclear and Energy Research Institute (IPEN/CNEN) in São Paulo/Brazil. A 4-chamber integrated collector allowed the sequential/temporal runoff evolution assessment. The runoff was composed of Ca > K > Mg > Si > Al > Fe > Na > Zn > Mn > Sr > Ti > Mo > V > Cu > B > Pb > Ni > Ce > Sb > Cr > La > U > Th > Cd. Total solids, Al and Fe exceed Brazilian water quality standards. Principal components analysis identified the elemental clusters linked to the facility activity, soil, traffic/atmospheric related deposition. Our results show that the runoff characteristics could be differentiated by pollutant source. Seasonal variation, rain event intensity, air mass from oceanic or continental origin, spatial distribution inside the monitoring area and the intensity of the first flush must be consider to disentangle the elemental clusters and pollution source contributions. In winter, continental air masses were associated with higher concentrations heavy metals in the surface runoff. Spatial changes with no seasonal variation were observed for U, Th, La and Ce.