Contamination, Sources and Health Risks of Toxic Elements in Soils of Karstic Urban Parks Based on Monte Carlo Simulation Combined with a Receptor Model

Understanding the health risks of toxic elements (TEs) in urban park soils and determining their priority control factors are crucial to public health and pollution management. In this work, soil samples from 33 urban parks in Guiyang, a typical karstic city, were collected. Results showed that Hg, Cd, As, Cu, and Pb were at relatively high pollution levels over most of the parks. Based on the positive matrix factorization (PMF) model, four sources governing TE pollution (including coal combustion, natural sources, traffic emissions, and industrial activities) were identified, with the contribution rates of 32.3%, 31.0%, 19.6%, and 17.1%, respectively. The probabilistic health risk assessment showed acceptable non-carcinogenic risks and high levels of carcinogenic risks in all populations. Based on the source-specific health risk assessment, coal combustion and arsenic were determined as the major contributors to the human health risks. Although several efforts have been taken by the local government to eliminate the coal-borne arsenicosis, our results revealed that the accumulation of arsenic in soil due to coal combustion still posed a potential threat to human health