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.
<p>Cryoconites are a dark-colored granular sediments found in glacial landscapes. Cryoconites are known as a dark colored accumulation of various origin material in superficial holed of the glaciers which formed in polar and mountain regions of the Earth. They can significantly accelerate glacier retreating by reducing the albedo of the glacier and play a significant role in the colonization of the territory after its retreat, being an "oasis" for development of microorganisms on an uninhabited glacier surface. The understanding of key cryoconites properties is necessary to understand their impact on the mountain glaciers of the Central Caucasus, especially taking into account their recent rapid retreat.</p><p>The aim of this research is to study the physical and chemical characteristics of various cryoconites and cryoconite derived periglacial soils of the Central Caucasus. Eight cryoconite samples and eight soil samples from three soil sections were selected. The following characteristics of the samples were determined in laboratory conditions: total organic carbon (TOC), basal respiration level, pH H<sub>2</sub>O and exchangeable soil acidity, solid phase density and particle size distribution.</p><p>The results of the analyses showed both differences and some similarities in the physical and chemical characteristics of the cryoconites and soils of periglacial zone which were studied. Cryoconites, on average, are characterized by lower values of basal respiration than more developed soils from this region. The total organic carbon content in most samples was relatively low, but its values increase significantly soils investigated due to accumulation of carbon in fine earth under the influence of primary vegetation. The water extractable acidity values showed a significant similarity between the studied cryoconites and soils, they vary from slightly acidic to slightly alkaline in both groups. At the same time, the variation of exchangeable acidity values between cryoconite samples is significantly greater than in developed soils. Moreover, the density of the solid phase of the studied cryoconites varies in a larger range of values than that of the studied soils due to variety of sources of cryoconite materials. However, the analysis of particle size distribution showed a significant similarity of the studied objects: in almost all samples there is a significant dominance of the sand fraction (d=1-0.05 mm). The obtained data indicate both the difference in the physical and chemical properties of the studied cryoconites among themselves, and the probable influence of cryoconites on soil formation in this region.</p><p>This work was supported by Russian Foundation for Basic Research, project No <strong>19-05-50107</strong> &#160;&#8220;The role of microparticles of organic carbon in degradation of ice cover of polar regions of the Earths and in the process of soil-like bodies formation&#8221;.</p>
<p>Cryoconite is a dark-colored supraglacial dust which may be found in polar and mountain regions in the world. These sediments represent a combination of mineral particles, black carbon and organic matter. Cryoconite is considered as a microbial hotspot on an uninhabited surface of glaciers as well as material which influence the level of albedo. Due to relatively similar microbiological and physicochemical features of cryoconite it could take part in development of primary soils. This is important because of current rapid deglaciation in the Caucasus region which will intensify due to ongoing climate change.</p><p>The purpose of this research is to study physicochemical features of cryoconite, other types of sediments and cryoconite derived periglacial soils in Caucasus region, Kabardino-Balkarian republic as well as local Chernozems. Samples of cryoconite, moraines and mudflows were collected at Bezengi Glacier, the largest valley glacier at the Caucasus mountains. Cryoconite derived soils were collected in the adjacent Khulamo-Bezengi Gorge; Chernozems and fresh mudflow material were sampled at Baksan Gorge. Soil acidity (H<sub>2</sub>O, CaCl<sub>2</sub>), total organic carbon (TOC), basal respiration values and particle-size distribution were determined under laboratory conditions.</p><p>Almost all samples of materials from the Bezengi Glacier as well as Chernozems were characterized by a neutral reaction, while some samples of mountain soils of the Khulamo-Bezengi Gorge were characterized as slightly acidic and acidic, especially with regard to exchangeable acidity. Basal respiration values range from 2.20 mg of CO<sub>2</sub> per day in fresh mudflow to 35.09 mg of CO<sub>2</sub> per day in the upper horizon of mountain soils. In general, relatively high values of basal respiration were typical for mountain soils, which also has been observed in cryoconite from cracks and holes due to high amount of easily accessible organic matter. Most of cryoconite and moraines from the Bezengi Glacier were characterized by a low content of organic carbon (about 0.10%), while in the upper horizons of mountain soils these values were the highest (up to 7.54%) due to input of cryoconite material in soils through water streams in the warm period of the year.</p><p>Cryoconite and moraines were characterized by the predominance of coarse earth fraction while soils were characterized by the dominance of fine earth material. The study of particle-size of cryoconites and other materials from the Bezengi Glacier showed the dominance of the sand fraction (d=0.05-1mm). Fresh mudslides from the Baksan Gorge and mountain soils of the Khulamo-Bezengi Gorge were characterized in the same way. Chernozems of the Baksan Gorge were characterized by a high content of silt and clay fractions, which makes it possible to classify them as clay and clay loam.</p><p>This work was supported by Russian Foundation for Basic Research, project No 19-05-50107 &#8220;The role of microparticles of organic carbon in degradation of ice cover of polar regions of the Earth&#8221;.</p>
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.