Bioenergetics of iron snow fueling life on Europa.

The main sources of redox gradients supporting high-productivity life in the Europan and other icy ocean world oceans were proposed to be photolytically derived oxidants, such as reactive oxygen species (ROS) from the icy shell, and reductants (Fe(II), S(-II), CH4, H2) from bottom waters reacting with a (ultra)mafic seafloor. Important roadblocks to maintaining life, however, are that the degree of ocean mixing to combine redox species is unknown, and ROS damage biomolecules. Here, we envisage a unique solution using an acid mine drainage (AMD)-filled pit lakes analog system for the Europan ocean, which previous models predicted to be acidic. We hypothesize that surface-generated ROS oxidize dissolved Fe(II) resulting in Fe(III) (hydr)oxide precipitates, that settle to the seafloor as "iron snow." The iron snow provides a respiratory substrate for anaerobic microorganisms ("breathing iron"), and limits harmful ROS exposure since they are now neutralized at the ice-water interface. Based on this scenario, we calculated Gibbs energies and maximal biomass productivities of various anaerobic metabolisms for a range of pH, temperatures, and H2 fluxes. Productivity by iron reducers was greater for most environmental conditions considered, whereas sulfate reducers and methanogens were more favored at high pH. Participation of Fe in the metabolic redox processes is largely neglected in most models of Europan biogeochemistry. Our model overcomes important conceptual roadblocks to life in icy ocean worlds and broadens the potential metabolic diversity, thus increasing total primary productivity, the diversity and volume of habitable environmental niches and, ultimately, the probability of biosignature detection.

Genetic consequences of Last Glacial-Holocene changes in snowfall regime in Arnica mallotopus populations: A plant confined to heavy-snow areas of Japan.

PREMISE: Snow is an important environmental factor affecting plant distribution. Past changes in snowfall regimes may have controlled the demographies of snow-dependent plants. However, our knowledge of changes in the distribution and demographies of such plants is limited because of the lack of fossil records. METHODS: Population genetic and landscape genetic analyses were used to investigate the response of population dynamics of Arnica mallotopus (Asteraceae)-a plant confined to heavy-snow areas of Japan-to changes in snowfall regimes from the Last Glacial Period to the Holocene. RESULTS: The population genetic analysis suggested that the four geographic lineages diverged during the Last Glacial Period. The interaction between reduced snowfall and lower temperatures during this period likely triggered population isolation in separate refugia. Subpopulation differentiation in the northern group was lower than in the southern group. Our ecological niche model predicted that the current distribution was patchy in the southern region; that is, the populations were isolated by topologically flat and climatically unsuitable lowlands. The landscape genetic analysis suggested that areas with little snowfall acted as barriers to the Holocene expansion of species distribution and continued limiting gene flow between local populations. CONCLUSIONS: These findings indicate that postglacial population responses vary among regions and are controlled by environmental and geographic factors. Thus, changes in snowfall regime played a major role in shaping the distribution and genetic structure of the snow-dependent plant.

Black carbon: a general review of its sources, analytical methods, and environmental effects in snow and ice in the Tibetan Plateau.

Tibetan Plateau (TP) is known as the water tower of Asia, and glaciers are solid reservoirs that can regulate the amount of water. Black carbon (BC), as one of the important factors accelerating glacier melting, is causing evident environmental effects in snow and ice. However, a systematical summary of the potential sources, analytical methods, distributions, and environmental effects of BC in snow and ice on the TP's glaciers is scarce. Therefore, this study drew upon existing research on snow and ice BC on glaciers of the TP to describe the detection methods and uncertainties associated with them to clarify the concentrations of BC in snow and ice and their climatic effects. The primary detection methods are the optical method, the thermal-optical method, the thermochemical method, and the single-particle soot photometer method. However, few studies have systematically compared the results of BC and this study found that concentrations of BC in different types of snow and ice varied by 1-3 orders of magnitude, which drastically affected the regional hydrologic process by potentially accelerating the ablation of glaciers by approximately 15% and reducing the duration of snow accumulation by 3-4 days. In general, results obtained from the various testing methods differ drastically, which limited the systematical discussion. Accordingly, a universal standard for the sampling and measurement should be considered in the future work, which will be beneficial to facilitate the comparison of the spatiotemporal features and to provide scientific data for the model-simulated climatic effects of BC.

Adaptive traits of cysts of the snow alga Sanguina nivaloides unveiled by 3D subcellular imaging.

Sanguina nivaloides is the main alga forming red snowfields in high mountains and Polar Regions. It is non-cultivable. Analysis of environmental samples by X-ray tomography, focused-ion-beam scanning-electron-microscopy, physicochemical and physiological characterization reveal adaptive traits accounting for algal capacity to reside in snow. Cysts populate liquid water at the periphery of ice, are photosynthetically active, can survive for months, and are sensitive to freezing. They harbor a wrinkled plasma membrane expanding the interface with environment. Ionomic analysis supports a cell efflux of K+, and assimilation of phosphorus. Glycerolipidomic analysis confirms a phosphate limitation. The chloroplast contains thylakoids oriented in all directions, fixes carbon in a central pyrenoid and produces starch in peripheral protuberances. Analysis of cells kept in the dark shows that starch is a short-term carbon storage. The biogenesis of cytosolic droplets shows that they are loaded with triacylglycerol and carotenoids for long-term carbon storage and protection against oxidative stress.

FROST 2.0: Factors Predicting Orthopaedic Trauma Volumes - A Validation Study.

The anecdotal relationship between weather, season, and orthopaedic trauma volumes is understood by patients and healthcare providers: when the winter ground is icy, people fall. Previous research established that winter and summer months as well as ice and snow were significant predictors of orthopaedic trauma and surges in volumes. The current study validates the previously established predictive model in one Canadian city; the original methods were repeated using a new, yet geographically similar dataset. The effect of month and ice were consistent, which suggests the proposed model has sufficient external validity to guide resource allocation and primary prevention strategies.

A first assessment of microplastic contamination in the snow of Ankara, Turkey.

Microplastics (MPs), affecting aquatic and terrestrial ecosystems, have spread globally. The atmosphere is known as a pollutant acceptor and carrier among other ecosystems. However, the fate and amount of microplastics in the atmosphere have been the subject of less research. Therefore, it is quite important to study the amount and properties of microplastics in atmospheric fallout. The main purpose of this article is to discover microplastics in fresh snow samples collected in three different regions of Ankara and to identify potential sources of supply. The morphologies and compositions of microplastics were analyzed and characterized using scanning electron microscopy (SEM/EDS). µ-Raman spectroscopy was used to reveal the various polymer types of the selected samples. As a result, microplastics were found in all snow samples. Among the nine snow samples examined, 537 particles were recognized as MPs. The average abundance of MPs in snow samples was 59.66 items L-1. Fibers, fragments, films, and circular forms were found in all snow samples. Fragments predominated for all samples (50.08%), followed by films (28.54%), fibers (16.86%), and circulars (4.50%). The proportion of small plastics was quite high when compared to the large plastics captured by snow. Smaller MP particles found in the snow had more variety, suggesting that the microplastics in the snow samples have been broken down by long-range transport and deposition. Six different polymer types were discovered in the snow samples in this study. The most frequently identified polymer was polyethylene (31%), succedded by polystyrene (28%), and polypropylene (21%). Polyethylene terephthalate (12%), polyvinyl chloride (5%), and nylon were present in smaller proportions.

[Expression of Cyclooxygenase-2 in Patients With Snow-White Sign of Advanced Colorectal Adenomas].

Objective To analyze the expression of cyclooxygenase-2 (COX-2) in the patients with snow-white sign of advanced colorectal adenoma (ACA) and explore its clinical significance.Method Western blotting was employed to determine the expression of COX-2 in the adenoma tissue and the normal tissue adjacent to the adenoma tissue (>5 cm away from the distal end of the adenoma tissue) of 40 ACA patients with snow-white sign and 40 ACA patients without snow-white sign.Results The appearance of snow-white sign in ACA patients was associated with patient age (P=0.001) and not associated with sex,smoking history,drinking history,ethnic groups,family history of colorectal cancer,abdominal pain,diarrhea,constipation,fecal occult blood,or tumor markers (all P>0.05).Snow-white sign mainly appeared in the ACA patients with multiple adenomas (P=0.004),large adenomas (P=0.006),adenomas in distal colon (P=0.015),protruding polyps (P=0.044),and late-stage pathology (P=0.010).The occurrence of snow-white sign showed no difference in the ACA patients with different results of Japan NBI Expert Team classification (P=0.502).The expression of COX-2 in the adenoma tissue was higher than that in the adjacent normal tissue in the patients with and without snow-white sign (P<0.001,P=0.004).The patients with snow-white sign had higher expression of COX-2 protein in the adenoma tissue than the patients without snow-white sign (P=0.001).The expression of COX-2 protein in the adjacent healthy tissue had no significant difference between the patients with and without snow-white sign (P=0.603).Conclusions Snow-white sign is more like to appear in the ACA patients with young age,multiple and large adenomas,adenomas in distal colon,protruding polyps,and late-stage pathology.Moreover,the expression of COX-2 in the ACA patients with snow-white sign is significantly higher than that in the ACA patients without snow-white sign.The adults with snow-white sign are prone to cancerization than those without snow-white sign.

Uptake of Hydrogen Peroxide from the Gas Phase to Grain Boundaries: A Source in Snow and Ice.

Hydrogen peroxide is a primary atmospheric oxidant significant in terminating gas-phase chemistry and sulfate formation in the condensed phase. Laboratory experiments have shown an unexpected oxidation acceleration by hydrogen peroxide in grain boundaries. While grain boundaries are frequent in natural snow and ice and are known to host impurities, it remains unclear how and to which extent hydrogen peroxide enters this reservoir. We present the first experimental evidence for the diffusive uptake of hydrogen peroxide into grain boundaries directly from the gas phase. We have machined a novel flow reactor system featuring a drilled ice flow tube that allows us to discern the effect of the ice grain boundary content on the uptake. Further, adsorption to the ice surface for temperatures from 235 to 258 K was quantified. Disentangling the contribution of these two uptake processes shows that the transfer of hydrogen peroxide from the atmosphere to snow at temperatures relevant to polar environments is considerably more pronounced than previously thought. Further, diffusive uptake to grain boundaries appears to be a novel mechanism for non-acidic trace gases to fill the highly reactive impurity reservoirs in snow's grain boundaries.

Reflection of Solar Light from Surface Snow Loaded with Light-Absorbing Impurities: A Case Study of Black Carbon, Mineral Dust, and Ash.

Using a hemispherical directional reflectance factor instrument, spectral data of dirty snow containing black carbon (BC), mineral dust (MD), and ash was collected from multiple locations to investigate the impact of these light-absorbing impurities (LAIs) on snow reflectance characteristics. The findings revealed that the perturbation of snow reflectance caused by LAIs is characterized by nonlinear deceleration, indicating that the reduction in snow reflectance per unit ppm of LAIs declines as snow contamination increases. The reduction in snow reflectance caused by BC may reach saturation at elevated particle concentrations (thousands of ppm) on snow. Snowpacks loaded with MD or ash initially exhibit a significant reduction in spectral slope around 600 and 700 nm. The deposition of numerous MD or ash particles can increase snow reflectance beyond the wavelength of 1400 nm, with an increase of 0.1 for MD and 0.2 for ash. BC can darken the entire measurement range (350-2500 nm), while MD and ash can only affect up to 1200 nm (350-1200 nm). This study enhances our understanding of the multi-angle reflection characteristics of various dirty snow, which can guide future snow albedo simulations and improve the accuracy of LAIs' remote sensing retrieval algorithms.

GERD surgery in non-neurologic patients: Modified Laparoscopic Hill-Snow Repair is a valid alternative to Nissen fundoplication. Results of a 20 years of follow-up.

Nowadays laparoscopic Nissen fundoplication represents the gold standard in surgical treatment of complicated Gastro-Esophageal-Reflux Disease (GERD), above all in cerebral palsy patients. In non-neurological patients without gastrostomy Nissen fundoplication can create some problems (gas bloat syndrome, dysphagia). Laparoscopic Hill-Snow repair is an established surgical alternative, but it is reported only in adult population. We describe our modification of Hill-Snow technique and our experience in a large series of non-neurological children in order to report its effectiveness and applicability in pediatric patients affected by complicated GERD. Between 2000 and 2022, 319 children underwent surgical correction of gastro-esophageal reflux at our Department. All were affected by complicated gastro-esophageal reflux unresponsive to PPI (Proton Pump Inhibitors). 251 underwent laparoscopic Nissen fundoplication; 68 non-neurological patients underwent laparoscopic Hill-Snow repair. Of these 68 children 48 were males (71%) and 20 females (29%); median age was 5years (3 months-11 years). Weight range was 4-37kg. 52 patients (76.5%) presented the following symptoms: retrosternal pain, dysphagia, regurgitation, coughing, failure to thrive, persisting reflux esophagitis. 16 (23.5%) had chronic respiratory problems (aspiration, apneic-spells, dysphagia, coughing, choking, gagging). For 8 (11.8%) symptoms were expression of chronic recurrent gastric volvulus. All underwent modified-laparoscopic-Hill-Snow repair. Contrast study showed sliding hiatal hernia in 55 patients (81%), while endoscopy demonstrated 16 cases of histologically severe esophagitis (23.5%) and 52 of mild esophagitis (76.5%). No intraoperative/postoperative complications were recorded. 60patients had a complete follow-up (range 1-20 years). 60/68 patients were evaluated with barium-swallow-study at 6-12 months; 40/68 patients with upper-gastrointestinal-endoscopy at 12months. No relapse was reported. 50 patients (73.7%) were symptom-free. 18 (26.3%) referred occasional epigastric pain, associated with vomit in 2 cases. 64 (94.1%) referred ability to vomit; 4 temporary difficulty to swallow (average 30 days). All patients reported being able to burp. 3(4.5%) presented episodes of gas-air-bloat during the first 2 months with spontaneous resolution. No case of dumping syndrome was recorded. This technique's modification yields excellent results in term of relapse and side effects at long-term follow-up. We reported the first and largest pediatric series in non-neurological children with encouraging results.

Dust dominates the summer melting of glacier ablation zones on the northeastern Tibetan Plateau.

Dust and black carbon (BC) can darken snow and ice surface and play pivotal roles in glacier mass loss. Thus, a quantitative assessment of their contributions to glacier summer melting is critical. During the summer of 2018, surface snow and ice were sampled, and the albedo and mass balance were continuously measured in the ablation zone of Laohugou Glacier No. 12 in the western Qilian Mountains. The physical properties of dust and BC were measured in the laboratory, and their impacts on glacier surface albedo reduction and melting were simulated. The results indicate that the ice surface in the ablation zone was enriched with substantial amounts of particles, and the average particle concentrations of these samples were hundreds of times higher than those of fresh snow. The BC mass absorption cross-sections (MACs) ranged from 3.1 m2 g-1 at 550 nm for dirty ice to 4.6 m2 g-1 for fresh snow, largely owing to meltwater percolation and particle collapse. The spectral variations in dust MACs were significantly different in the visible light bands and near-infrared bands from those in the other areas. Moreover, the two-layer surface energy and mass balance model with the new albedo parameterization formula was validated and agreed well with the experimental measurements of spectral albedo, broadband albedo, and mass balance. BC and dust combined resulted in 26.7 % and 54.4 % of the total mass loss on the cleaner and dirtier (particle enriched) surfaces in the ablation zone, respectively, compared to particle-free surfaces, and although both impurities played vital roles, dust was the more prominent factor in accelerating glacier melting on the northeastern Tibetan Plateau. This study emphasizes the importance of dust in cryosphere changes where Tibetan glaciers are strongly affected by Asian dust deposition.

Black carbon and dust alter the response of mountain snow cover under climate change.

By darkening the snow surface, mineral dust and black carbon (BC) deposition enhances snowmelt and triggers numerous feedbacks. Assessments of their long-term impact at the regional scale are still largely missing despite the environmental and socio-economic implications of snow cover changes. Here we show, using numerical simulations, that dust and BC deposition advanced snowmelt by 17 ± 6 days on average in the French Alps and the Pyrenees over the 1979-2018 period. BC and dust also advanced by 10-15 days the peak melt water runoff, a substantial effect on the timing of water resources availability. We also demonstrate that the decrease in BC deposition since the 1980s moderates the impact of current warming on snow cover decline. Hence, accounting for changes in light-absorbing particles deposition is required to improve the accuracy of snow cover reanalyses and climate projections, that are crucial for better understanding the past and future evolution of mountain social-ecological systems.

Dyadobacter diqingensis sp. nov., isolated from Baima snow mountain of Diqing Tibetan Autonomous Prefecture in Yunnan province, south-west China.

A Gram-negative, aerobic, nonmotile, rod-shaped and yellow-pigment-producing bacteria was isolated from Baima snow mountain of Diqing Tibetan Autonomous Prefecture in Yunnan province, south-west China and characterized using a polyphasic approach. The results of 16S rRNA gene sequence similarity analysis showed that strain YIM B04101T was closely related to the type strain of Dyadobacter koreensis DSM 19938T (97.81%) and Dyadobacter frigoris AR-3-8T (97.95%). The predominant respiratory quinone was menaquinone-7 (MK-7). The major polar lipid was phosphatidylethanolamine. The major fatty acids were summed feature 3 (C16:1ω7c/C16:1ω6c), C18:1ω9c and C16:0. The DNA G + C content was 43.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain YIM B04101T belonged to a cluster comprising species of the genus Dyadobacter. However, it differed from its closest relative, Dyadobacter koreensis KCTC 12537T and Dyadobacter frigoris AR-3-8T, in many physiological properties. Based on these phenotypic characteristics and phylogenetic distinctiveness, strain YIM B04101T is considered to be a novel species of the genus Dyadobacter, for which the name Dyadobacter diqingensis sp. nov. is proposed. The type strain is YIM B04101T (= CGMCC 1.19249T = CCTCC AB 2021270).

Ultra-sensitive solid-phase Microextraction-Gas Chromatography-Mass spectrometry determination of polycyclic aromatic hydrocarbons in snow samples using a deep cavity BenzoQxCavitand.

A very sensitive and selective solid-phase microextraction-gas chromatography-mass spectrometry method based on the use of a deep cavity BenzoQxCavitand as innovative coating was developed and validated for the simultaneous determination of the 16 US-EPA priority pollutants polycyclic aromatic hydrocarbons (PAHs) in snow samples at ultra-trace levels. The presence of a 8.3 Å deep hydrophobic cavity allowed the engulfment of all the 16 PAHs, providing enhanced selectivity also in presence of interfering aromatic pollutants at high concentration levels. Validation proved the reliability of the method for the determination of the investigated compounds achieving detection limits in the 0.03-0.30 ng/L range, good precision, with relative standard deviations <18% and recovery rates in the 90.8(±2.1)%-109.6(±1.0)%. The detection of low-molecular weight PAHs in snow samples from Antarctica and Alps confirms the widespread occurrence of these compounds, thus assessing the impact of anthropogenic activities onto the environment.

Distribution and temporal variability of uranium and toxic metal(loid)s in snow and rainwater from an oil industry and urban area in Thessaloniki-Greece.

The concentrations of uranium and nine elements (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in snow and rainwater samples were determined. Samples were collected in Thessaloniki-northern Greece in three sites, one in the industrial area close to an oil production power plant and two in the centre of the city. Snow samples were collected during January-February 2019 and 2021 whereas in the case of rainwater, a two-year survey has been performed during 2019 and 2020. The activity concentrations of the uranium radioisotopes were measured by alpha spectrometry whereas the metal(loid)s concentrations were determined by inductively coupled plasma mass spectroscopy (ICP-MS). The elevated concentrations of uranium (U) and the deviation of the isotopic ratio of U-234/U-238 from the equilibrium value indicated intensive dissolution of uranium. The results were analyzed using statistical analysis (Shapiro-Wilk, Friedman and Kruskal-Wallis tests). The obtained data and the calculated enrichment factors (Efs) denote variation of the concentration values between industrial and urban area and different elemental distribution influenced from anthropogenic contributions, meteorological conditions and the COVID-19 pandemic.

Black carbon footprint of human presence in Antarctica.

Black carbon (BC) from fossil fuel and biomass combustion darkens the snow and makes it melt sooner. The BC footprint of research activities and tourism in Antarctica has likely increased as human presence in the continent has surged in recent decades. Here, we report on measurements of the BC concentration in snow samples from 28 sites across a transect of about 2,000 km from the northern tip of Antarctica (62°S) to the southern Ellsworth Mountains (79°S). Our surveys show that BC content in snow surrounding research facilities and popular shore tourist-landing sites is considerably above background levels measured elsewhere in the continent. The resulting radiative forcing is accelerating snow melting and shrinking the snowpack on BC-impacted areas on the Antarctic Peninsula and associated archipelagos by up to 23 mm water equivalent (w.e.) every summer.

A re-analysis and review of elemental and polycyclic aromatic compound deposition in snow and lake sediments from Canada's Oil Sands Region integrating industrial performance and climatic variables.

Much of the research from Canada's oil sands region (OSR) shows contaminants of concern (CoCs) throughout the ambient environment surrounding the industrial facilities. While there are some well-established sources of the CoCs, there is also spatial and temporal variability suggesting activity intensity, changes in technology, types and amounts of fuels combusted at the facilities, and climate may affect the results of deposition studies. This study re-analysed published data on the deposition of elements and polycyclic aromatic compounds (PACs) in snow and the sediments of some lakes by incorporating production data from facilities and climate. Using the Elastic Net (EN) regularized regression, variables describing potential associations between facility-specific activity and climate on the deposition of CoCs were identified. Among the selected variables, the combustion of delayed petroleum coke at the Suncor Basemine was associated with the deposition of CoCs, including elements in snow and in some lakes. Similarly, combustion of petroleum coke at Syncrude Mildred Lake was also identified in some models. In both cases, the effects of petroluem coke combustion are likely associated with the emission and deposition of fly ash. The mass of stored petroleum coke was not selected in snow CoC models, but the speed of the wind was a common driver for PACs. However, the mass of stockpiled petcoke was more closely associated with both elements and PACs in lake sediments. While the potential influence of other variables on the occurrence of CoCs in the OSR was also identified, including the production of crude bitumen and synthetic crude, the use of process and natural gases, temperature, and precipitation, these analyses support much of the earlier work and provides additional nuance. While more work is required, these results suggest facility-specific production and climatic data can be coupled with existing approaches to improve the identification of sources of CoCs in Canada's OSR and practices associated with their release.

A sensitive microextraction by packed sorbent-gas chromatography-mass spectrometry method for the assessment of polycyclic aromatic hydrocarbons contamination in Antarctic surface snow.

For the first time an eco-friendly method involving microextraction by packed sorbent (MEPS) coupled to gas chromatography-mass spectrometry (GC-MS) was developed for the determination of the 16 US-EPA priority pollutant polycyclic aromatic hydrocarbons (PAHs) as indicators of anthropogenic contamination in snow samples collected in polar regions. MEPS was carried out by using C8 sorbent material packed in a barrel insert and needle (BIN) and integrated in the eVol® semi-automatic device. For optimization purposes a Face Centred Design and the multicriteria method of the desirability functions were performed to investigate the effect of some parameters affecting the MEPS extraction efficiency, i.e. the number of loading cycles and the number of elution cycles. The developed MEPS-GC-MS method proved to be suitable for PAHs analysis at ultra-trace level by extracting small sample volumes achieving detection limits for 16 PAHs in the 0.3-5 ng L-1 range, repeatability and intermediate precision below 11% and 15%, respectively, and good recovery rates in the 77.6 (±0.1)-120.8 (±0.1)% range for spiked blank snow samples. Enrichment factors in the 64 (±7)-129 (±18) range were calculated. Finally, the proposed method was successfully applied to the determination of PAHs in surface snow samples collected in 2020-2021 from four locations of Northern Victoria Land, Antarctica. Local emission sources such as ships and research stations were found to influence PAHs concentrations in the surface snow.