Contamination levels, spatial distribution, and risk assessment of heavy metals and PCDD/Fs in fly ash from representative MSWIs in Zhejiang Province, China

Heavy metals and PCDD/Fs in fly ash from 32 MSWIs in Zhejiang were assessed. • Zn, Pb, and Cu dominated heavy metal profiles, PCDD/Fs were below thresholds. • Heavy metals and PCDD/Fs showed different spatial distribution patterns. • Heavy metals pose relatively high health and environmental risks. • PCDD/Fs pose high non-carcinogenic risk, especially for children. The occurrence of hazardous heavy metals and polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs) in fly ash from municipal solid waste incinerators (MSWIs) has raised increasing environmental concern. In this study, fly ash samples collected from 32 MSWIs across Zhejiang Province were analyzed to investigate the contamination levels, spatial heterogeneity, health, and environmental risks of heavy metals and PCDD/Fs. The results showed that several heavy metals exceeded their element-specific intervention thresholds, whereas the toxic equivalent concentrations of PCDD/Fs remained below the intervention thresholds of 3 μg TEQ/kg. Based on the sampled MSWIs, relatively higher heavy metal contamination levels were observed in several northern and southern sampling areas, particularly Huzhou and Wenzhou. Relatively higher PCDD/Fs levels were observed in some southeastern coastal sampling areas, including Taizhou and Wenzhou. Health risk assessment identified Cd, Cr, Pb, and Sb as the major contributors to potential human health risks, while ecological risk assessment indicated that Pb and Cu were the dominant ecological risk contributors. Although PCDD/Fs showed no significant ecological risk under the applied assessment framework, cumulative exposure to the 17 toxic congeners suggested a potential non-carcinogenic health risk, with the estimated risk for children being 3.64 times higher than that for adults. Overall, this study provides a province-wide characterization of the contamination levels, spatial distribution, health, and environmental risks of heavy metals and PCDD/Fs in representative MSWIs fly ash in Zhejiang Province, offering useful evidence for regional fly ash pollution control, risk prioritization, and environmental management. Download: Download high-res image (454KB) Download: Download full-size image