Elemental variations in glacier cryoconites of Indian Himalaya and Spitsbergen,Arctic

Cryoconite samples were collected from two different climatic domains i.e.,the Sutri Dhaka glacier,western Himalaya India and Svalbard glaciers,the Spitsbergen,Arctic,to understand the elemental source and elemental deposition patterns.The data of geochemical analysis suggest that the Himalayan cryoconite samples accumulate higher concentrations as compared to the cryoconite samples of the Arctic glaciers.The concentration of lithophile elements(Cs,Li,Rb and U)was recorded higher in the cryoconite holes of the Himalayas,especially,in the lower to the higher parts of the glacier,whereas,lower concentrations were recorded in the Arctic samples.Chalcophile elements in the Himalayan cryoconites are enriched in As and Bi while the Arctic cryoconite samples show a higher concentration of Bi,Pb and As.The higher concentrations are responsible for influencing the ecosystem and in human health related issues.Siderophile elements(Co,Fe,Mn and Ni)show high concentrations in the Himalayan samples,whereas,the Arctic samples show minor variations and low elemental concentration in these elements,respectively.In addition,a few elements,such as Ag,Mg,and Ca show higher concentration in the Himalayan glacier samples.Ca also occurs in high concentrations in Arctic glacier samples.R-mode factor analysis of the Himalayas(Arctic)samples indicate that the elements are distributed in four(three)factors,explaining 89%(90%)of the variance in their elemental distribution.The Factor 1 suggests statistically significant positive loadings for most of the lithophile,chalcophile and siderophile elements of the "Himalayan" and the Arctic cryoconite samples.The sample-wise factor score distribution shows a considerable variation in the sampling locations along the glaciers of both the regions.Factors 2 and 3,demonstrate insignificant loading for most of the elements,except statistically significant positive loading in some of the elements of the both,Himalayan and Arctic "cryoconites".The higher elemental concentration in the cryoconites of the Himalayan region may be an indicator of the natural processes and/or attributed to the rapid industrialization in the Asian countries.

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.

Potential transformation of organic matter by microbes in cryoconite,Tibetan Plateau

Microorganisms play an essential role in the glacier carbon cycle;how they transform organic matter in mountain glacial cryoconite remains to be studied.Here,we applied ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS)and deep sequencing of 16S rRNA gene,to investigate the temporal microbial transformation of dissolved organic matter(DOM)of the Tibetan Plateau cryoconite.During the 60-day incubation,we found that DOM in cryoconite underwent a three-stage transformation,with decreasing bioavailability over time.The microbial community did not change much in the first week while degrading DOM molecules that were associated with higher H/C_(wa)and lower O/C_(wa).During days 15-30,DOM composition remained stable while microbial diversity increased.By day 60,the DOM was microbially converted into a higher state of recalcitrance,with higher values of aromatic index,O/C_(wa),and lower H/C_(wa),which contained molecules containing more heteroatoms.Cooperation among various microbial taxa,like Cyanobacteria,Bacteroidota,Gammaproteobacteria,Firmicutes,and Actinobacteriota,drove the DOM transformation in cryoconite.This study sheds light on the in-situ transformation of DOM composition meditated by microbial populations in cryoconite at a temporal scale,providing new insights into understanding the microbial roles in the glacier organic carbon transformation.

Migration of organic carbon and trace elements in the system glacier-soil in the Central Caucasus alpine environment

Rapid deglaciation is one of the most important challenges in the Earth science today.One reason of this is specific supraglacial sediments–cryoconites,which represent carbon-containing dust with organomineral matter and living organisms.Investigation of physical and chemical characteristics of cryoconites in the Central Caucasus is necessary in order to understand their influence on alpine territories biogeochemical cycles,pollution and development in conditions of intensive glacial melting and active anthropogenic influence.For this research cryoconites as well as moraines,soil-like bodies and soils have been sampled from the alpine Bezengi Glacier and adjacent Khulamo-Bezengi Gorge.Key physicochemical features(pH values,total organic carbon content,microbial respiration,particle-size distribution)as well as content of trace elements have been defined in sampled materials and several pollution indices(Geoaccumulation index,Contamination factor and Degree of pollution)have been calculated.Results obtained show low values of total organic carbon in cryoconites(max.0.23%)but high values(max.7.54%)in top horizon of soils located in floodplain,indicating its active fluvioglacial transfer which may further accelerate the development of soils.Microbiological activity in the studied soils was mostly influenced by additional input of labile organic carbon from cryoconites with water flows.Particle-size distribution was similar among the studied cryoconites,indicating dominance of sand fraction(up to 85.28%)while studied soils showed higher variability due to influence of weathering.Among the trace elements,cryoconites were mostly polluted by Zn(max.85.70 mg·kg^(-1))which corresponds to high pollution according to pollution indices;Pb(max.24.90 mg·kg^(-1))and Cu(max.17.40 mg·kg^(-1)),up to moderate pollution level.Redistribution of polluted cryoconite material as well as local anthropogenic activities increased pollution of periglacial soils by Zn(max.89.20 mg·kg^(-1)),Pb(max.15.00 mg·kg^(-1))and Cu(max.12.80 mg·kg^(-1)),which was also proven by the pollution indices with up to high level of pollution.