Comprehensive characterization of volatile organic compounds in Chinese chemical industry park soils: Spatial...

Ubiquitous contamination of the soil environment with volatile organic compounds (VOCs) has raised considerable concerns. However, there is still limited comprehensive surveying of soil VOCs on a national scale. Herein, 65 species of VOCs were simultaneously determined in surface soil samples collected from 63 chemical industrial parks (CIPs) across China. The results showed that the total VOC concentrations ranged from 7.15 to 1842 ng/g with a mean concentration of 326 ng/g (median: 179 ng/g). Benzene homologs and halogenated hydrocarbons were identified as the dominant contaminant groups. Positive correlations between many VOC species indicated that these compounds probably originated from similar sources. Spatially, the hotspots of VOC pollution were located in eastern and southern China. Soils with higher clay content and a higher fraction of total organic carbon (TOC) content were significantly associated with higher soil VOC concentrations. Precipitation reduces the levels of highly water-soluble substances in surface soils. Both positive matrix factorization (PMF) and principal component analysis-multiple linear regression (PCA-MLR) identified a high proportion of industrial sources (PMF: 59.2 % and PCA-MLR: 66.5 %) and traffic emission sources (PMF: 32.3 % and PCA-MLR: 33.5 %). PMF, which had a higher R² value (0.7892) than PCA-MLR (0.7683), was the preferred model for quantitative source analysis of soil VOCs. The health risk assessment indicated that the non-carcinogenic and carcinogenic risks of VOCs were at acceptable levels. Overall, this study provides valuable data on the occurrence of VOCs in soil from Chinese CIPs, which is essential for a comprehensive understanding of their environmental behavior.