Abstract
The globalisation and omnidirectional character of anthropogenic processes has challenged scientists around the world to estimate the harmful effects of these processes on ecosystems and human health. Polycyclic aromatic hydrocarbons (PAHs) is one the most infamous group of contaminants, originated both from natural and anthropogenic processes. They could transport to high latitudes and altitudes through atmospheric long-distance transfer and further enter ecosystems of these vulnerable regions by deposition on terrestrial surfaces. An interesting object for tracking transboundary contamination processes in high mountain ecosystems is called cryoconite. Cryoconite, a dark-coloured supraglacial sediment which is abundant in polar and mountain environments, is considered as a storage of various pollutants, including PAHs. Thus, it may pose a risk for local human health and ecosystem through short-distance transfer. Studied cryoconite sediments were collected at the surface of Skhelda and Garabashi glaciers, Central Caucasus high-mountain region, as well as mudflow, moraine material and local soils at the Baksan Gorge in order to examine levels of their contamination. We analysed the content of 15 priority polyaromatic compounds from the US EPA list and used the method of calculation of PAHs isomer ratios with the purpose of identifying their source. To estimate their potential toxicity, Benzo[a]pyrene (BaP) equivalents were calculated. Maximum concentration was defined for NAP (84 ng×g-1), PHE (40 ng×g-1) and PYR (47 ng×g-1), with the minimum concentration for ANT (about 1 ng×g-1). The most polluted material is a cryoconite from Garabashi glacier because of local anthropogenic activities and long-distance transfer. High-molecular weight PAHs are dominated in PAHs composition of almost all samples. The most common sources of PAHs in studied materials are combustion processes and mixed pyrolytic/petrogenic origin. Toxicity levels of separate PAHs did not exceed the maximum permissible threshold concentrations values in most cases. However, the sum of PAHs in BaP equivalents exceed the threshold values in all samples, in some of them more than twice.
Highlights
With the increase of anthropogenic activity on a global scale, the monitoring of various contaminants has become one of the priorities of the world community
The study focused on soil samples, soil-like bodies and cryoconite material sampled in the vicinity of Mount Elbrus and on the surface of the Skhelda and Garabashy glaciers (The Greater Caucasus)
The conducted study shows the contamination of cryoconite, soils and some other materials by 15 high-priority polycyclic aromatic hydrocarbons
Summary
With the increase of anthropogenic activity on a global scale, the monitoring of various contaminants has become one of the priorities of the world community. PAHs are very common organic pollutants in the environment, consisting of carbon and hydrogen atoms with two or more aromatic rings in their structure (Edwards 1983). US EPA 1982) and European Food Safety Authority 2008) published the priority pollutants lists with the most hazardous contaminants amongst PAHs which should be regulated, including benzo[k]fluoranthene (BkF), benzo[ghi]perylene (BPE), benzo[a]pyrene (BaP), chrysene (CHR) and dibenz[a,h]anthracene (DBA). BaP is one of the most toxic compounds which is associated with anthropogenic influence (Abakumov et al 2014, Sushkova et al 2017) and should be obligatorily controlled in the environment, including soils (Federal Service for Supervision of Consumer Rights Protection and Human Well-Being of the Russian Federation 2006). BaP can be estimated as a reference substance and, due to this, benzo[a]pyreneequivalent (BaP-EQ) is usually used in the determination of environmental object pollution by PAHs in current research (Callén et al 2007, Gao et al 2019, Yang et al 2021)
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