۱٫ Introduction

۲٫ Material and methods

۳٫ Results and discussion

۴٫ Conclusions

Acknowledgments

Appendix A. Supplementary data

References

Abstract

Petrochemical industries are widely distributed in China. As a negative consequence, heavy metals in petrochemical area can result in soil contamination. However, the relevant research of heavy metals contamination in petrochemical area was few. In this study, a total of 103 topsoil samples (<20 cm) and 25 profile soil samples were collected and examined in a retired petrochemical industrial area, South China. The results showed the mean contents of Hg, Cd, As, Pb, Ni and Cu were 0.18, 0.69, 16.22, 47.24, 31.62 and 93.06 mg kg−۱, respectively. The spatial distribution of six metals in topsoil was largely attributed to the industrial activities during the petroleum refining and transshipment process. Ni was the main pollutant in the petroleum refining process. While, the contamination of other metals mainly were caused by the leakage of the oil during transshipment. The migration of six metals to subsoil layers was also observable. In accordance, Hg, Cd, As, Pb, Cu, and Ni dropped by 95.02, 71.91, 89.45, 90.88, 99.22, and 65.07%, respectively, compared to their contents in topsoil. The contamination of the heavy metals was mainly caused during the process of petroleum refining and transshipment. The distribution of heavy metals in the factory was mainly affected by the industrial activities or the lateral infiltration of Lianhuashan River. Soil ingestion was the primary pathway for children and adults exposure to heavy metals. The total non-cancer human health risk induced by heavy metals was within the limit of USEPA (10−۶ a−۱). While the cancer risks alone induced by As through soil ingestion to children was 1.14 × ۱۰−۶ a−۱, which exceeded the limit of USEPA. This study indicated that not only petroleum hydrocarbon but also heavy metals can cause soil contamination in a retired petrochemical industrial area, which provides a novel cognition. Altogether, measures should be taken in practice to substantially improve the soil quality in petrochemical industrial area.

Introduction

Heavy metals’ pollution has become one of the main environmental soil problems worldwide (Asgari and Cornelis et al., 2015; Hossein et al., 2019). Anthropogenic activities such as agriculture, urbanization and industrialization are the main driving forces of soil heavy metal contamination rather than occurring from soils naturally (e.g., due to the erosion of parent rocks, atmospheric deposition, and volcanic activities) in recent years (Wu et al., 2013; Latare et al., 2014; Özkul et al., 2016; Wang et al., 2019 ). Industrialization has been noted as the primary source of heavy metal contamination (Martín et al., 2014; Meisam et al., 2017; Hossein et al., 2019). This pollution not only affects the quality of soil, but also poses serious health risks to individuals (Chabukdhara et al., 2013; Asgari and Cornelis, 2015). Human exposure to heavy metals takes place through soil ingestion, dermal contact, and inhalation (Mungai et al., 2016). Upon exposure, heavy metals can damage the body’s immune, reproductive and nervous systems (USEPA 2004).