Examination of interactions between heavy metals and benzotriazoles in rainwater runoff and snowmelt in an urban catchment in Poland

Heavy metals (HMs) are toxic pollutants that can accumulate and harm human health and the environment. Monitoring their concentration in water is an essential tool for evaluating the quality and safety of this vital resource. The aims of this study were (i) to characterize HMs contamination in rainwater runoff and snowmelt, identify likely sources and compliance with regulations and guidelines, and (ii) to conduct a preliminary assessment regarding the potential link between the occurrence of HMs and benzotriazoles based on a previous experiment. This study investigates the concentration of six HMs (cadmium, lead, nickel, chromium, copper, and zinc) in rainwater runoff and snowmelt samples collected in twelve Białystok locations in northeastern Poland. The highest concentration of Cu (517.5 μg/L) was identified in snowmelt from the city's ring road, with heavy vehicle traffic, and near an industrial area. A 4-lane asphalt street near the city center exhibited the highest concentrations of Pb (91.1 μg/L) and Ni (64.6 μg/L) for snowmelt and also for Cd (1.37 μg/L) and Ni (27.3 μg/L) in rainwater runoff. A snowmelt sample from a pedestrian-only area in the city center presented the highest Zn concentration (3672.2 μg/L). Considerable contents of Cr (353.2 μg/L) were found in snowmelt near an industrial and warehousing area. Snowmelt presented higher HMs concentrations than rainwater runoff. Our results indicate that most benzotriazoles and heavy metals occur independently. The analysis of the winds and the tendency of HMs to travel with dust particles suggest that specific contaminants might have originated in Belarus, a neighboring territory of Białystok.