Polycyclic Aromatic Hydrocarbons Pollution Characteristics in Agricultural Soils of the Pearl River Delta Region, China

Abstract

In order to investigate the pollution status of polycyclic aromatic hydrocarbons (PAHs) in the agricultural soil, 240 agricultural soil topsoil samples were collected from nine Pearl River Delta cities from June to September 2019. In addition, 72 samples were collected for vertical soil profiles, which soil profiles were excavated to a depth of 80 cm. After sample preparation, GC-MS was used for the separation of compounds on a HP-5MS quartz capillary column. ArcGIS software was used to map the spatial distribution. Health risk assessment was conducted using USEPA standard. The results showed that the total concentration of 16 PAHs ranged from 43.4 to 5630 ng/g, with an average of 219 ng/g. The spatial distribution showed that most of the seriously polluted areas were in the coastal area, near the port, and there was point source pollution in the Gaoming of Foshan. Vertically distributed display Zhuhai, Jiangmen, Zhaoqing, Shenzhen and Dongguan increased and then decreased from bottom to bottom, showing a low-high-low pattern, the concentration of PAHs in Zhongshan and Foshan decreased with the soil depth, while the concentration of PAHs in Guangzhou and Huizhou was enriched with human activities. The PAHs components in soil samples were mainly medium and high rings (4–6 rings). The analysis of the origin of PAH in soil samples showed that the mixture of incomplete combustion sources of fossil fuels such as coal and biomass and traffic emission sources were the main sources of soil PAHs. A small amount can be attributed to oil sources such as oil spills. The human health risk assessment showed no cancer risk for children, while for adults, may cause a potential risk of cancer, which needs to be noticed. Spearman correlation analysis showed that PAH content was significantly correlated with SOC (p < 0.01) and pH (p < 0.05). Port transport, road emissions and industrial production make the area a pollution hot topic, and supervision should be strengthened to protect the environment and food safety.