Ny-& Aring;lesund, located in Arctic Svalbard, is one of the most sensitive areas on Earth to global warming. In recent years, accelerated glacier ablation has become remarkable in Ny-& Aring;lesund. Glacial meltwaters discharge a substantial quantity of materials to the ocean, affecting downstream ecosystems and adjacent oceans. In August 2015, various water samples were taken near Ny-& Aring;lesund, including ice marginal meltwater, proglacial meltwater, supraglacial meltwater, englacial meltwater, and groundwater. Trace metals (Al, Cr, Mn, Fe, Co, Cu, Zn, Cd, and Pb), major ions, alkalinity, pH, dissolved oxygen, water temperature and electric conductivity were also measured. Major ions were mainly controlled by chemical weathering intensity and reaction types, while trace metals were influenced by both chemical weathering and physicochemical control upon their mobility. Indeed, we found that Br & oslash;ggerbreen was dominated by carbonate weathering via carbonation of carbonate, while Austre Lov & eacute;nbreen and Pedersenbreen were dominated by sulfide oxidation coupled with carbonate dissolution with a doubled silicate weathering. The higher enrichment of trace metals in supraglacial meltwater compared to ice marginal and proglacial meltwater suggested anthropogenic pollution from atmospheric deposition. In ice marginal and proglacial meltwater, principal component analysis indicated that trace metals like Cr, Al, Co, Mn and Cd were correlated to chemical weathering. This implies that under accelerated glacier retreat, glacier-derived chemical components are subjected to future changes in weathering types and intensity.

Progressive climate change may have unpredictable consequences for the Arctic environment. Permafrost catchments off the west coast of Svalbard, described as thin and warm, are particularly sensitive to climate change. The interdisciplinary research on the hydrochemical response of surface and underground water functioning within a small permafrost catchment area focused on the determination of the impact of meteorological conditions (temperature (T), precipitation (P)) on the mean daily discharge (Q), and the lowering of the groundwater table (H). We determined physical and chemical properties (pH and SEC) and concentrations of major elements (Ca, Mg, Na, K) and 23 trace elements (i.a. Cd, Cu, Hg, Pb, Zn) in 280 water samples. The results of the correlation matrix showed that an increase in the average air temperature in the summer of 2021 had a significant impact on the hydrochemistry of both types of waters operating in the catchment. In response to increase in T, the lowering of the H (0.52 < r < 0.66) and a decrease in Q (-0.66 < r < -0.68) were observed what in consequence also leads to changes in water chemistry. The principal component analysis (CA) indicates that chemical weathering and binding of elements to DOC are processes influencing water chemistry. Results of statistical analysis showed that the resultant of the hydrometeorological conditions that prevailed in that season and the type of geological formations on which they were located had a significant impact on the water chemistry at individual measurement points. Significant differences in the concentrations of elements between points on the same geological formations were also found.

Permafrost regions are under particular pressure from climate change resulting in wide-spread landscape changes, which impact also freshwater chemistry. We investigated a snapshot of hydrochemistry in various freshwater environments in the lower Kolyma river basin (North-East Siberia, continuous permafrost zone) to explore the mobility of metals, metalloids and non-metals resulting from permafrost thaw. Particular attention was focused on heavy metals as contaminants potentially released from the secondary source in the permafrozen Yedoma complex. Permafrost creeks represented the Mg-Ca-Na-HCO3-Cl-SO4 ionic water type (with mineralisation in the range 600-800 mg L-1), while permafrost ice and thermokarst lake waters were the HCO3-Ca-Mg type. Multiple heavy metals (As, Cu, Co, Mn and Ni) showed much higher dissolved phase concentrations in permafrost creeks and ice than in Kolyma and its tributaries, and only in the permafrost samples and one Kolyma tributary we have detected dissolved Ti. In thermokarst lakes, several metal and metalloid dissolved concentrations increased with water depth (Fe, Mn, Ni and Zn - in both lakes; Al, Cu, K, Sb, Sr and Pb in either lake), reaching 1370 mu g L-1 Cu, 4610 mu g L-1 Mn, and 687 mu g L-1 Zn in the bottom water layers. Permafrost-related waters were also enriched in dissolved phosphorus (up to 512 mu g L-1 in Yedoma-fed creeks). The impact of permafrost thaw on river and lake water chemistry is a complex problem which needs to be considered both in the context of legacy permafrost shrinkage and the interference of the deepening active layer with newly deposited anthropogenic contaminants.

Mineral organic carbon interactions (aggregation, organo-mineral associations and organo-metallic complexes) enhance the protection of organic carbon (OC) from microbial degradation in soils. The northern circumpolar permafrost region stores between 1,440 and 1,600 Pg OC of which a significant portion is already thawed or about to thaw in coming years. In the light of this tipping point for climate change, any mechanism that can promote OC stabilization and hence mitigate OC mineralization and greenhouse gas emissions is of crucial interest. Here, we study interactions between metals (Fe, Al, Mn and Ca) and OC in the moist acidic tundra ecosystem of Eight Mile Lake, near Healy, AK, USA. We collected thirteen cores (124 soil samples) in late summer 2019 with shallow and deep active layers (45 to 109 cm deep) and varying water table depths. We find that between 6% and 59% of total OC in Eight Mile Lake tundra soils is mineral-associated (mean 20%), in organomineral associations (association between poorly crystalline oxides and OC) and in organo-metallic complexes (associations between Fe, Mn, Al, Ca polyvalent cations and organic acids). We find that total Fe and Mn concentrations can be used as good proxies to assess the reactive pool of these metals able to form associations with OC, i.e., poorly crystalline oxides or metals complexed with OC. We observe that in the active layer, mineral OC interactions are mostly as organo-metallic complexes with Fe cations, with an accumulation at the water table level acting as a soil redox interface. In waterlogged soils with a water table level above surface, no such accumulation of OC-Fe complexes is found due to the absence of a redox interface below soil surface. In the permafrost layer, we find that a combination of complexed metals and poorly crystalline Fe oxides act as reactive phases towards OC. Knowing that upon permafrost thaw tundra soils will become wetter or drier, the assessment of mineral-bound OC in drier or wetter tundra soils is a needed step to better constrain the changes in the proportion of non-protected OC more likely to contribute to C emissions from tundra soils.

Acid mine drainage (AMD) is one of the leading causes of environmental pollution and is linked to public health and ecological consequences. Microbes-mineral interaction generates AMD, but microorganisms can also remedy AMD pollution. Exploring the microbial response to AMD effluents may reveal survival strategies in extreme ecosystems. Three distinct sites across a mine (inside the mine, the entrance of the mine, and outside) were selected to study their heavy metal concentrations due to significant variations in pH and physicochemical characteristics, and high-throughput sequencing was carried out to investigate the microbial diversity. The metal and ion concentrations followed the order SO42 , Fe, Cu, Zn, Mg, Pb, Co, Cr, and Ni from highest to lowest, respectively. Maximum sequences were allocated to Proteobacteria and Firmicutes. Among archaea, the abundance of Thaumarchaeota and Euryarchaeota was higher outside of mine. Most of the genera (23.12 %) were unclassified and unknown. The average OTUs (operational taxonomic units) were significantly higher outside the mine; however, diversity indices were not significantly different across the mine sites. Hierarchical clustering of selective genera and nMDS ordination of OTUs displayed greater segregation resolution inside and outside of mine, whereas the entrance samples clustered with greater similarity. Heterogeneous selection might be the main driver of community composition outside the mine, whereas stochastic processes became prominent inside the mine. However, the ANOSIM test shows a relatively even distribution of community composition within and between the groups. Microbial phyla showed both positive and negative correlations with physicochemical factors. A greater number of biomarkers were reported outside of the mine. Predictive functional investigation revealed the existence of putative degradative, metabolic, and biosynthetic pathways. This study presents a rare dataset in our understanding of microbial diversity and distribution as shaped by the ecological gradient and potential novelty in phylogenetic/taxonomic diversity in AMD, with potential biotechnological applications.

Glaciochemical records serve as one of the best archives and as good proxies to indicate regional and global anthropogenic influences. The Himalayas, with fragile ecosystems and pristine environments, hold the third largest reservoir of glacier ice and represent an ideal region to investigate trace metal pollution using glacier records. Limited studies on glacially recorded trace metals in the Himalayas usually collect samples from individual glaciers and report a few trace metals in different seasons. We provide a comprehensive and in-depth understanding of the glacially recorded trace metals in the central Himalayas regarding their spatial distribution, seasonal variability, and anthropogenic signals. We analyzed six representative metals (Cu, Zn, Cd, Cr, Pb, Co) and found that the trace metal concentration range largely varied between the studied metals and sampling sites. The Zn metal concentration is higher, attributed to the contribution of natural sources (e.g., forest fires, dust storms) and anthropogenic sources, including industrial and traffic-related emissions. The Pb concentration showed striking seasonality due to the relatively natural input of local material during the monsoon season and the regional and long-range transport of anthropogenic sources during the non-monsoon season. There was a clear spatial variation in certain trace metals, such as Cu, Zn, and Pb, showing decreasing trends with increasing elevation. The enrichment factor (EF) results showed that Zn metal was highly enriched, followed by Cu and Cd, indicating that Zn metal was relatively highly susceptible to intensified human activities. The seasonal paradox between the enrichment factor and metal concentration revealed that the EF of the monsoon season was usually higher than that of the non-monsoon season, and vice versa regarding metal concentrations primarily associated with metal deposition in regional climate regimes, particularly atmospheric circulation. We suggest that the analytical method can influence the trace metal concentration and EF calculation, resulting in a previously unrecognized bias in the seasonality of trace metals. Future research should prioritize stable isotopes of trace elements (e.g., Pb, Cu) in glaciers that would provide valuable information in identifying the potential source of anthropogenic inputs and the degree of extent affecting the glaciochemistry of the Himalayas.

Antibiotic resistance (AR) has been extensively studied in natural habitats and clinical applications. AR is mainly reported with the use and misuse of antibiotics; however, little is known about its presence in antibiotic-free remote supraglacial lake environments. This study evaluated bacterial strains isolated from supraglacial lake debris and meltwater in Dook Pal Glacier, northern Pakistan, for antibiotic-resistant genes (ARGs) and metaltolerant genes (MTGs) using conventional PCR. Several distinct ARGs were reported in the bacterial strains isolated from lake debris (92.5%) and meltwater (100%). In lake debris, 57.5% of isolates harbored the blaTEM gene, whereas 58.3% of isolates in meltwater possessed blaTEM and qnrA each. Among the ARGs, qnrA was dominant in debris isolates (19%), whereas in meltwater isolates, qnrA (15.2%) and blaTEM (15.2%) were dominant. ARGs were widely distributed among the bacterial isolates and different bacteria shared similar types of ARGs. Relatively greater number of ARGs were reported in Gram-negative bacterial strains. In addition, 92.5% of bacterial isolates from lake debris and 83.3% of isolates from meltwater harbored MTGs. Gene copA was dominant in meltwater isolates (50%), whereas czcA was greater in debris bacterial isolates (45%). Among the MTGs, czcA (18.75%) was dominant in debris strains, whereas copA (26.0%) was greater in meltwater isolates. This presents the co-occurrence and co-selection of MTGs and ARGs in a freshly appeared supraglacial lake. The same ARGs and MTGs were present in different bacteria, exhibiting horizontal gene transfer (HGT). Both positive and negative correlations were determined between ARGs and MTGs. The research provides insights into the existence of MTGs and ARGs in bacterial strains isolated from remote supraglacial lake environments, signifying the need for a more detailed study of bacteria harboring ARGs and MTGs in supraglacial lakes.

Studies of antibiotic-resistant bacteria (ARB) have mainly originated from anthropic-influenced environments, with limited information from pristine environments. Remote cold environments are major reservoirs of ARB and have been determined in polar regions; however, their abundance in non-polar cold habitats is underexplored. This study evaluated antibiotics and metals resistance profiles, prevalence of antibiotic resistance genes (ARGs) and metals tolerance genes (MTGs) in 38 ARB isolated from the glacier debris and meltwater from Baishui Glacier No 1, China. Molecular identification displayed Proteobacteria (39.3%) predominant in debris, while meltwater was dominated by Actinobacteria (30%) and Proteobacteria (30%). Bacterial isolates exhibited multiple antibiotic resistance index values > 0.2. Gram-negative bacteria displayed higher resistance to antibiotics and metals than Gram-positive. PCR amplification exhibited distinct ARGs in bacteria dominated by beta-lactam genes blaCTX-M (21.1-71.1%), blaACC (21.1-60.5%), tetracycline-resistant gene tetA (21.1-60.5%), and sulfonamide-resistant gene sulI (18.4-52.6%). Moreover, different MTGs were reported in bacterial isolates, including mercury-resistant merA (21.1-63.2%), copper-resistant copB (18.4-57.9%), chromium-resistant chrA (15.8-44.7%) and arsenic-resistant arsB (10.5-44.7%). This highlights the co-selection and co-occurrence of MTGs and ARGs in remote glacier environments. Different bacteria shared same ARGs, signifying horizontal gene transfer between species. Strong positive correlation among ARGs and MTGs was reported. Metals tolerance range exhibited that Gram-negative and Gram-positive bacteria clustered distinctly. Gram-negative bacteria were significantly tolerant to metals. Amino acid sequences of blaACC, blaCTX-M, blaSHV, blaampC, qnrA, sulI, tetA and blaTEM revealed variations. This study presents promising ARB, harboring ARGs with variations in amino acid sequences, highlighting the need to assess the transcriptome study of glacier bacteria conferring ARGs and MTGs.

High-latitude boreal and arctic surface/inland waters contain sizeable reservoirs of dissolved organic matter (DOM) and trace elements (TE), which are subject to seasonal freezing. Specifically, shallow ponds and lakes in the permafrost zone often freeze solid, which can lead to transformations in the colloidal and dissolved fractions of DOM and TE. Here, we present results from experimental freeze-thaw cycles using iron (Fe)- and DOM-rich water from thaw ponds situated in Stordalen and Storflaket palsa mires in northern Sweden. After ten cycles of freezing, 85% of Fe and 25% of dissolved organic carbon (DOC) were removed from solution in circumneutral fen water (pH 6.9) but a much smaller removal of Fe and DOC (< 7%) was found in acidic bog water (pH 3.6). This removal pattern was consistent with initial supersaturation of fen water with respect to Fe hydroxide and a lack of supersaturation with any secondary mineral phase in the bog water. There was a nearly two- to threefold increase in the low-molecular-weight (LMW) fraction of organic carbon (OC) and several TEs caused by the repeated freeze-thaw cycles. Future increases in the freeze-thaw frequency of surface waters with climate warming may remove up to 25% of DOC in circumneutral organic-rich waters. Furthermore, an increase of LMW OC may result in enhanced carbon dioxide losses from aquatic ecosystems since this fraction is potentially more susceptible to biodegradation.