Rainwater quality in Special Economic Zone (SEZ) in Poland

In the face of climate change, rainwater harvesting has become a valuable solution providing an alternative water source and helping mitigate the sewage system overload. Using rainwater necessitates ensuring that its quality is appropriate for its intended purpose. In industrial areas, the nature of the activities conducted poses a substantial risk of rainwater quality deterioration, particularly due to heavy metals (HMs) contamination. Within the article scope, the rainwater quality analysis from the Special Economic Zone (SEZ) in Lower Silesia (Poland) was examined. The research included analysis of physicochemical parameters, as well as cations, anions, and HMs concentrations in rainwater samples. The measurements were made in the certified laboratory between April 2022 and June 2023. The samples were taken from 5 representative points of the SEZ area: drains into the ditch and storage tanks. From analyzed anions and cations, Cl^- (205 mg/L) and Ca²⁺ (69.6 mg/L) showed the highest concentration, respectively. Cu was the most abundant HMs (up to 0.049 mg/L). Cd and Cr were not detected at all. It has been shown that the most of the analyzed quality parameters complied with WHO guidelines. The detected contaminants mainly come from industrial activity (like incineration; vehicles, batteries, and electronic manufacturing or concrete production), as well as from materials coating buildings and pavements prone to release undesired components. Vehicle traffic, natural sources (e.g. weathering ions from soils) also was shown to contribute to rainwater quality. Tap water periodically used for washing the roads and pavements unintentionally transported to sampling points may contribute to Cl^- and Ca²⁺ presence.