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

Abstract

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 μg kg−1, with an average value of 5816.6 μg kg−1. The highest benzene content was 10900 μg kg−1, with an average value of 462.5 μg 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 distribution, 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, determination of pollution responsibility and effective management of soil pollution.