Comparative characteristics of aluminum and arsenic content in the surface waters of the Elbrus and Kazbek volcanic centers

Abstract

Relevance. Large year-round tourist clusters are located and developing in the regions of the Central and Western Caucasus. The main sources of water supply there are the basins of the sources of the Terek and Kuban rivers. This is an area of Quaternary volcanism, due to the activity of which surface waters can be enriched with a number of toxic elements. Aim of this work is a comparative study of the arsenic and aluminum content in the surface waters of the Elbrus and Kazbek volcanic centers and the identification of possible sources of their intake. Materials and methods. There are 105 sampling points in the area of the Elbrus Volcanic Center (EVC). 62 sampling points are located in the area of the Kazbek volcanic center. Water samples were taken in July and August during the period of intense melting of glaciers. The dissolved form of the elements was determined. That is why the samples were filtered through membrane filters with a pore size of 0.45 microns. The determination of aluminum and arsenic content was carried out using atomic absorption spectroscopy. The hydrogen index was determined using a portable pH meter. Results. Acid volcanism took place in the EVC area in the early stages of development and acid volcanites predominate. The surface waters are neutral, the pH does not exceed 8. The volcanites of the Kazbek center are derivatives of the main mantle magmas and pH values≥8.0 are typical for 30 watercourses (48.4%). The surface waters of the Kazbek volcanic center are depleted of aluminum compared to the EVC. Most likely, this is due to a range of factors, in particular, with differences in the features of volcanism – upper crust matter entered the lavas in the EVC, and deep mantle magmas in the Kazbek. In the area of the Kazbek volcanic center, aluminum appears to be immobilized at the geochemical barrier due to more widespread carbonate sedimentary rocks. Arsenic concentrations in the EVC (especially in the Southern Elbrus region) are significantly higher than in Kazbek. This is due to the presence of geochemical anomalies.