Content of potentially toxic chemical elements in plants of mountain river basins of the Caspian region

Abstract

This article analyzes the content of potentially toxic chemical elements in plants from the Caspian mountain River basins. The relevance of this study lies in identifying indicators of elevated levels of potentially toxic chemical elements in the landscapes of the Caspian River basins based on plant analysis. The aim of this study is to analyze the accumulation of potentially toxic chemical elements by plants in the Caspian River ba- sins. Methods. In the field seasons of 2024 and 2025, plant samples were collected at 193 sites in the basins of the Sunzha, Sulak, Ulluchay, Shura-Ozen, Samur, Karachay, and Atachay rivers. The content of 15 chemical elements was determined in the plants of the river basins: Mn, Fe, Co, Ni, Cu, Zn, As, Li, Be, Mg, Al, Ca, Sc, V, and Cr. The gross content of heavy metals and trace elements in the selected plant samples was determined us- ing a PlasmaQuant MS Elite S-NR:11-6000ST043 inductively coupled plasma mass spectrometer. Results. The dominant elements in the plants of the river basins of the Caspian region are biogenic macronutrients – Ca and Mg. Conditionally essential and potentially toxic elements such as Be, As, Sc, Li, and V are characterized by low concentrations (10-10-1 μg/g). Most plants accumulate a single toxic element. Five species exhibit a tendency to accumulate two elements: tamarisk (Tamarix sp.) – Be and V; narrow leaved oleaster (Elaeagnus angustifolia) – Fe and Be; Litvinov’s birch (Betula litwinowii) – Fe and As; domestic apple (Malus domestica) – Be and Sc; black-berry (Rubus sp.) – Fe and V. Analysis of the average values of chemical element content by life forms showed that toxic elements accumulate more intensively in herbaceous plants. In plants from the Sulak and Sunzha river basins, potentially toxic Ni and Sc accumulate more intensively; in the Ulluchay River basin, Al accumulates; in the Karachay and Atachay rivers, biogenic Ca accumulates. The data obtained on the content of potentially toxic chemical elements in plants can be used to reduce the environmental risk to the health of the population living in the basins of mountain rivers in the Caspian region.