Sediments from cryoconite holes and dirt cones on the surface of Svalbard glaciers:main chemical and physicochemical properties

The paper discussed the influence of the forms of sediment accumulation on the surface of glaciers on their chemical and physicochemical properties.The materials sampled from the surface of five glaciers of the Svalbard Archipelago was analyzed.We studied such forms of sediment accumulation as dirt cones-the ice core covered with sediments and cryoconite holes-hollows on the glacier surface containing cryoconite material.Parameters such as total organic carbon content,microbiological activity,pH,the content of mobile forms of potassium and phosphorus,and concentrations of heavy and trace metals were studied.Also,mesomorphological studies were carried out and the polydisperse composition of the sediments was determined.According to the results of this work,it was found that the content of organic carbon in the material selected from dirt cones and cryoconite holes can be up to 2.5%,but the content of clay particles in it is mainly at the 10–15%level.Potassium concentrations are up to 250 mg/kg,and phosphorus is up to 800 mg/kg.The content of metals is typical or lower than in the previously published data.The main influence on the chemical composition of materials has a geographical factor of the sampling site,rather than the form of material accumulation.

Geochemistry of cryoconite and soils in the Central Caucasus region and its environmental implications

Climate change and deglaciation are active processes in current changing environments.In the Central Caucasus region rapid degradation of glaciers is caused often by the formation of superficial blackcolored sediments-cryoconite.Cryoconite plays a crucial role in changing ecosystems and may contribute to the formation of primary soils after glacier retreat.Over the past 20 years,the frequency of mudflows and other dangerous mountain events have increased in the Central Caucasus,which is associated with the glacial retreats.Intensification of tourism results in increasing of traffic,recreational activity and environment contamination.Determination of the cryoconites geochemical properties in comparison with other types of sediments and local soils is crucial for investigation of geochemistry and contamination state of superficial glacial sediments.This environmental aspect is important in terms of the Central Caucasus settlements safety under conditions of deglaciation and anthropogenic influence.The sediments studied(cryoconite,mudflow,moraine)were sampled at Garabashi and Skhelda glaciers as well as some local soils at the Baksan gorge.Sampled materials were investigated in terms of physicochemical and agrochemical parameters.The concentrations of trace elements(Cu,Pb,Zn,Ni,Cd)were also determined and contamination indices(geoaccumulation index-Igeo,contamination factor-CF and degree of contamination-Cdegree)were used to evaluate the pollution status of studied material.Data obtained shows much higher content of organic carbon in soils(up to 7.82%)in comparison with cryoconite(max.1.63%)due to presence of vegetation,however,the basal respiration values in some cases were similar betweenсryoconite and soils,indicating high rates of microbial activity in a cryoconite holes.It was found that almost all materials studied have sandy structure.Cryoconite sediments on both of the glaciers are enriched with phosphorus,high values of K_(2)O(max.298 mg·kg^(-1))and N-NH4(max.247 mg·kg^(-1))are identified at Garabashi glacier which could be influenced by long-distant transfer but mostly a result of local anthropogenic activity.In case of trace elements,the highest content is identified for Zn(62 mg·kg^(-1) for cryoconite and 60.5 mg·kg^(-1) for soils)and the most contaminated materials are cryoconite from Garabashi glacier and Entisols,up to moderate level,which is mostly associated with local anthropogenic activity.