Ecological and Human Health Risks of Metal–PAH Combined Pollution in Riverine and Coastal Soils of Southern Russia

Abstract

The floodplains and seacoasts of southern Russia are characterized by urbanization, developed agriculture, and rapidly developing industries. Anthropogenic activity leads to the long-term release of pollutants into the environment, which threatens the stability of ecosystems and public health. The study aimed to assess the ecological and human health risks posed by potentially toxic elements (PTEs) and polycyclic aromatic hydrocarbons (PAHs) in the topsoils of the Taganrog Bay coast and the Lower Don floodplain. Concentrations of PTEs and PAHs were measured using X-ray fluorescence and high-performance liquid chromatography, respectively. Except for the comparatively most toxic Cd, which ranged from low to moderate, ecological risk factors indicated a low risk for PTEs. The cumulative ecological risk of PTEs was low. Zn, As, Cd, and benzo[a]pyrene (BaP) were the most dangerous pollutants, with concentrations 1–2 orders of magnitude higher than the maximum permissible concentrations (MPCs). Mostly sandy soils were characterized by high and very high individual pollution since they have more stringent quality standards due to their lower resistance to contamination. Significant concern is caused by the total contamination of soils with PAHs. A comparison of the toxic equivalent quotient of PAHs with the MPC of BaP showed high or very high contamination in two-thirds of the samples. The non-carcinogenic risk for adults in the region was negligible, whereas the risk for children was low. Dermal contact with PTEs and PAHs contributed to a significant non-carcinogenic risk. Only the combined intake of pollutants poses a substantial risk for children. Over most of the research area, total carcinogenic risk surpasses the threshold, indicating a low risk, with As being the most important contributor. The results of the study showed that PAHs pose a greater potential ecological risk than PTEs, and the opposite trend was observed in relation to the risk of negative impacts on human health. In this regard, taking into account the combined influence of different types of components allows for a more comprehensive risk assessments.