Potentially toxic elements in urban soils of the coastal city of the Sea of Azov: Levels, sources, pollution and risk assessment.

Coastal cities are major centers of economic activity, which at the same time has negative consequences for the environment. The present study aimed to determine the concentrations and sources of PTEs in the urban soils of Taganrog, as well as to assess the ecological and human health risks. A total of 47 urban and 5 background topsoils samples were analyzed by ICP-MS and ICP-AES. A significant excess of Cu, Zn, and Sb was noted in urban soils compared to the upper continental crust and average world-soil (1.7-2.9 times). Statistical analysis showed that the elements in soils were of geogenic, mixed and anthropogenic origin. According to the single pollution index (PI), the greatest danger of soil pollution was represented by anthropogenic elements, namely Cu, W, Pb, Zn, Cd, and Sn, the levels of which were increased in residential and industrial areas. The median contents of As, Mn, Cr, Sr, Mo, Sb, Cu, W, Pb, and Zn were 1.1-2.1 times higher, while Cd and Sn were 2.5 folds higher in the urban soils compared to the background ones. The total pollution index (ZC) showed that only 15% of the soils had high level of pollution, which is typical for the industrial areas. Overall ecological risks were negligible or low in 92% of soils, and were mainly due to elevated levels of Cu, Zn, As, and Pb. Non-carcinogenic risks to humans were mainly related to exposure to La and Pb. The hazard index (HI) values for all PTEs were less than ten, indicating that overall non-carcinogenic risk for adults and children was low-to-moderate and, moderate, respectively. The total carcinogenic risk (TCR) exceeded threshold and corresponded to low risk, with Pb, As, and Co being the most important contributors. Thus, the industrial activities of Taganrog is the main source of priority pollutants.

Anthropogenic factors affecting the Moskva River water quality: levels and sources of nutrients and potentially toxic elements in Moscow metropolitan area.

This study aims to identify the main patterns of distribution and sources of pollutants in the Moskva River and their influence on river water quality under different levels of anthropogenic stress caused by the largest megacity in Europe - Moscow. For this study, we determined concentrations of 18 trace elements, nutrient elements and major ions, chemical and biochemical oxygen demand, and physical parameters of water at 45 stations on the Moskva River and 20 stations on its tributaries during spring flood and low water of 2019 and 2020 to identify the extent and mechanisms of urban impact on its water chemistry. Chemical elements concentrations have been determined using ICP-MS and ICP-AES methods. Mn, Al, Cu, Sr, Zn, B, Mo, and inorganic nitrogen were outlined as key pollutants according to various drinking water and environmental guidelines. Using correlation and factor analysis, five groups of elements were identified, corresponding to different drivers controlling their unequal distribution within the watershed: mineral sources (Sr, Li, B, Mo, Ca), sewage and road runoff (TN, TP, Sb, Ni, N-NO2, BOD5, COD, V, Zn), impact of acidic wetlands (Al, COD, Zr, Bi), groundwater and landfills leachate (V, As, Pb, U, Sb), and industrial activities (Zn, Cu). Water quality in the Moskva Basin on the whole is good according to the CCME Water Quality Index. Local deterioration of water quality to marginal and even fair (depending on the reference water quality guideline) is confined to the Moskva River part downstream from the Kuryanovo aeration station to the Moskva mouth and to the mouths of several heavily contaminated tributaries.

Uptake of potentially toxic elements and polycyclic aromatic hydrocarbons from the hydromorphic soil and their cellular effects on the Phragmites australis.

The current study provides an information on the combined effect of pollution with potentially toxic elements (PTEs) and polycyclic aromatic hydrocarbons (PAHs) in hydromorphic soils on the accumulation, growth, functional and morphological-anatomical changes of macrophyte plant, i.e., Phragmites australis Cav., as well as information about their bioindication status on the example of small rivers of the Azov basin. The territory of the lower reaches of the Kagalnik River is one of the small rivers of the Eastern Azov region was examined with different levels of PTEs contamination in soils, where the excess of the lithosphere clarkes and maximum permissible concentrations (MPC) for Mn, Cr, Zn, Pb, Cu, and Cd were found. The features of the 16 priority PAHs quantitative and qualitative composition in hydromorphic soils and P. australis were revealed. The influence of soil pollution on accumulation in P. australis, as well as changes in the morphological parameters were shown. It has been observed that morphometric changes in P. australis at sites experiencing the сontamination and salinity are reflected with the changes in the ultrastructure of plastids, mitochondria, and EPR elements of plant cells. PTEs accumulated in inactive organs and damaged cell structures. At the same time, PAHs penetrated through the biomembranes and violated their integrity, increased permeability, resulted cell disorganization, meristem, and conductive tissues of roots. The nature and extent of the structural alterations found are dependent on the type and extent of pollution in the examined regions and can be utilized as bioindicators for evaluating the degree of soil phytotoxicity characterized by the accumulation of PTE and PAHs.