Assessment of heavy metal pollution and health risks in urban park soil of Chengdu, China: implications for ecosystem management and public health.

Despite Chengdu's status as China's first 'park city', systematic assessment of heavy metal risks in its urban green spaces remains limited. This research investigates the concentrations and spatial distribution of heavy metals, including Mercury (Hg), Chromium (Cr), Arsenic (As), Cadmium (Cd), Lead (Pb), Copper (Cu), Nickel (Ni) and Zinc (Zn) in the surface soil of urban parks in Chengdu, China. The results indicate significant differences in metal concentrations, with higher median values for Hg, Cd, Ni, and Zn than that in suburban areas (p < 0.05). Spatial analysis highlights hotspots around urban centers, correlating with population density and traffic intensity (p < 0.05). Principal component analysis (PCA) help to identify potential sources of heavy metals, combined with the characteristics of heavy metal content in different regions, to understand the spatial distribution characteristics of heavy metals in the city. Multivariate analyses (PCA-HCA coupling) revealed three distinct pollution clusters: 80% experience no or light pollution, 8.6% moderate pollution, and 11.4% severe pollution, emphasizing the need for monitoring and remediation strategies. The health risk assessment, conducted using the United States Environmental Protection Agency model, suggests low non-carcinogenic risks for children and adults, with soil particle ingestion identified as the primary exposure pathway. Carcinogenic risks associated with Cd, Pb, Cr, and Ni are considered negligible, highlighting overall low health risks. However, caution is advised for children due to higher non-carcinogenic and carcinogenic risks value, particularly through hand-to-mouth contact. Overall, while heavy metal levels in Chengdu's urban parks soil generally comply with standards, targeted interventions are necessary to mitigate contamination hotspots and safeguard ecosystem health and public well-being.