Non-metal roofing materials as potential sources of pollutants- laboratory leaching studies on various roofing materials

Stormwater runoff from urban surfaces contains pollutants that harm the water quality of surface or groundwater bodies. While runoff quality from metal roofs has already been widely studied, the contribution of non-metal roofing materials to stormwater pollution is still unclear. A leaching test was conducted to determine the substance emission from non-metal roofing materials. Analyzing parameters in the leachate of eight leaching rounds at predefined time intervals allowed for determining area release rates and leaching mechanisms. The test was conducted with commonly used materials applied on inclined roofs: clay tiles, concrete tiles, fiber cement, bitumen shingles, wood shingles, and plastic roofing tiles. The scope of the analysis is based on substances repeatedly detected in stormwater: anions, cations, heavy metals, biocides, phthalates, PCBs, PFAS, PAHs, nonylphenols, and Bisphenol A. Several roofing materials released relevant amounts of hazardous substances impacting water quality. Clay tiles are a source of vanadium, manganese, and arsenic. Treated wood shingles release ammonium, boron, copper, and Bisphenol A. Fiber cement and concrete roofing tiles are a source of biocides. Bitumen shingles released Bisphenol A. Further research is recommended regarding leaching in long-term field experiments to evaluate the impact of real weather conditions and on developing treatment facilities.