Distribution, sources, and health risk assessment of VOCs/SVOCs in soils obtained from petrochemical-contaminated sites in Guangzhou, a subtropical coastal megacity in southern China

Investigation and analysis of the soil contamination characteristics of legacy petrochemical sites is the basis for safe land reuse. Volatile/semivolatile organic compounds (VOCs/SVOCs) are a group of mutagenic, carcinogenic, and teratogenic substances that can induce leukemia, brain tumors, asthma, and a variety of other cancers through oral ingestion, dermal exposure, and/or inhalation. This study was designed to explore the horizontal and vertical distribution characteristics, sources, and health risks of VOCs/SVOCs in different operational areas of an abandoned petrochemical enterprise site in Guangzhou City. The survey assessed the presence and amounts of 12 VOCs/SVOCs across 522 soil samples. Measurements were conducted using a combination of purge and trap-gas chromatography and mass spectrometry (P&T-GC-MS). The investigation revealed that the total content of the 12 compounds was 69798.7 mu g kg-1, with an average value of 5816.6 mu g kg-1. The highest benzene content was 10900 mu g kg -1, with an average value of 462.5 mu g kg -1, and the maximum value exceeded this average by 2.7-fold. According to the horizontal distribution, VOCs/SVOCs were mainly concentrated in the oil delivery console, storage tank area, oil refining area, and fire pumping stations. Depending on the vertical dis-tribution, pollutants were generally distributed in the plain fill layer, with a downward trend in the muddy silt and silt layers. The source apportionment of VOCs/SVOCs was analyzed and discussed with correlation analysis and a positive matrix factorization (PMF) model in this study. The source analysis results showed that a mixture of petroleum, solvent, and coal sources, solvent sources, and traffic sources were the main sources of VOCs/ SVOCs, and their contribution rates to VOCs/SVOCs were 17.7%, 70.0% and 12.3%, respectively. The health risk assessment showed that 8 carcinogenic VOCs/SVOCs carry potential carcinogenic risks for children and adults. This study can provide data support and a judgment basis for the redevelopment of contaminated sites, deter-mination of pollution responsibility and effective management of soil pollution.