Snow Samples Research Articles

Synthesis of Natural-Like Snow by Ultrasonic Nebulization of Water: Morphology and Raman Characterization.

The current devices used to produce massive amounts of snow (i.e., snow machines) can be improved with concern to both the energy efficiency and the quality of snow. Here we investigate an alternative snow production method based on the ultrasonic nebulization of water and its subsequent condensation on the cold surfaces of a refrigerator. Inspection of the snow samples with a stereo optical microscope shows both dendritic and granular snow morphologies. The characterization of the samples by Raman spectroscopy shows a behavior consistent with that of a natural, low-density snow. Our results indicate that ultrasonic nebulization of water is an effective strategy for producing natural-like snow at the laboratory scale.

A Complete Isotope (δ15N, δ18O, Δ17O) Investigation of Atmospherically Deposited Nitrate in Glacial‐Hydrologic Systems Across the Third Pole Region

AbstractThe Himalayas and Tibetan Plateau, identified as the Third Pole (TP), is a unique region because of its insertion into global environmental and climatic changes. Deposition of atmospheric nitrate in this region is one of the most important sources of reactive nitrogen to glacial‐hydrologic system and ecosystems. The isotopic composition of atmospherically deposited nitrate preserved in ice bodies plays a central role in delineating environmental and climatic changes, present, and past. Here, we provide an overview of the complete isotopic compositions (δ15N, δ18O, and Δ17O) of nitrate in aerosol, snow, ice, and water samples (n = 46) collected across the Southern, Southeastern, Central, and Northern TP to constrain complex nitrogen cycles of the atmosphere, cryosphere, hydrosphere, and, potentially, the biosphere. A large variability of snow nitrate isotopic compositions is observed across the TP at different spatial scales (from a single glacier to the entire plateau), likely due to the complex landscape and relevant physical and chemical processes across the TP. Large nitrate Δ17O values are observed in water samples collected from the Mt. Everest region, highlighting the considerable fraction (up to 45%) of atmospheric nitrate to the nitrate load in this Himalayan hydrologic system. Our work reveals the complex chemical, depositional, and postdepositional processes over the TP that are greater than previously thought and identifies further comprehensive investigations, which entail using nitrate isotopic compositions as an identifier for nitrate source apportionment in various ecosystems and understanding past atmospheric and climatic conditions in this region.

Tracking Dissolved Trace and Heavy Metals in the Ganga River From Source to Sink: A Baseline to Judge Future Changes

AbstractUnderstanding how dissolved trace elements chemically evolve in the Ganga River from source to sink is important to understand subcatchment contributions and chemical variability across space and time but remains poorly constrained. What exists is site‐specific data sets that are focused on capturing contamination “hotspots.” Here, we present riverine trace element concentrations of 38 targeted locations in the Ganga Basin. Samples in the headwater and the upstream segments of the river were collected during the premonsoon, monsoon, and postmonsoon seasons of 2014, 2015, and 2016, and the downstream samples were collected in 2016. In addition, monthly time‐series samples were collected at a downstream site to capture the geochemical variability at a higher temporal‐resolution. To evaluate the geogenic contributions, groundwater, rainwater, snow, glacier‐ice, and sediment samples were also analyzed. We find that the river chemistry displays a wide spatio‐temporal variability. Headwater samples are characterized by high concentrations of trace elements that are primarily controlled by ice meltwater, intense weathering, and interactions with glacial flour and are therefore geogenic in nature. Moreover, high concentrations of trace metals were also observed in a few localized downstream sites. However, such enriched signals are not persistent further downstream as they get diluted by the joining of large tributaries. We show that the dissolved trace element concentrations in the Ganga River are low compared to existing datasets and are comparable to the global average river water composition. We additionally quantified the present‐day “baseline” concentration ranges to facilitate future water quality assessment in the Ganga Basin.

Air pollution could drive global dissemination of antibiotic resistance genes.

Antibiotic-resistant pathogens pose a significant threat to human health. Several dispersal mechanisms have been described, but transport of both microbes and antibiotic resistance genes (ARGs) via atmospheric particles has received little attention as a pathway for global dissemination. These atmospheric particles can return to the Earth's surface via rain or snowfall, and thus promote long-distance spread of ARGs. However, the diversity and abundance of ARGs in fresh snow has not been studied and their potential correlation with particulate air pollution is not well explored. Here, we characterized ARGs in 44 samples of fresh snow from major cities in China, three in North America, and one in Europe, spanning a gradient from pristine to heavily anthropogenically influenced ecosystems. High-throughput qPCR analysis of ARGs and mobile genetic elements (MGEs) provided strong indications that dissemination of ARGs in fresh snow could be exacerbated by air pollution, severely increasing the health risks of both air pollution and ARGs. We showed that snowfall did effectively spread ARGs from point sources over the Earth surface. Together our findings urge for better pollution control to reduce the risk of global dissemination of antibiotic resistance genes.

Isotopic composition and hydrogeochemistry of a periglacial Andean catchment and its relevance in the knowledge of water resources in mountainous areas

ABSTRACT Glacial and periglacial basins contain the largest reserves of fresh water in the world. These areas are extremely sensitive to global warming and climate change. The dry Andes of South America are characterized by large periglacial areas. This study focuses on the water isotopic composition and hydrochemistry of a typical periglacial environment of the Andes, in the Vallecitos catchment (2400–5500 m a.s.l.), Cordillera Frontal, Argentina. Detailed fieldwork was conducted between 2013 and 2017 with 240 samples collected for major ions and physicochemical parameters, and 67 samples analysed for 2H and 18O. The chemical composition of precipitation is typical Ca-HCO3, while streams and groundwaters are Ca-MgSO4 type. The isotope content of precipitation shows a wide dispersion. The snow samples are in general more depleted than the rainfall. Some springs vary their composition seasonally, associated to the melting of perennial snow patches. In general, all samples from the upper basin present depleted isotope contents related to recharge at higher altitudes, whereas samples from the lower basin show more enriched values. Intermediate compositions reflect the melting of snow and degrading ice-rich permafrost. These results will give a better understanding of the dynamics of water to manage water resources.

Alpine snowpit profiles of polar organic compounds from Mt. Tateyama central Japan: Atmospheric transport of organic pollutants with Asian dust

Snowpit samples (n = 10) were collected (19 April 2008) from the snowpit sequences (depth 6.60 m) at the Murodo-Daira site (36.58°N, 137.60°E, elevation of 2450 m a.s.l.) of Mt. Tateyama (3015 m a.s.l.), central Japan. The first time, low molecular weight diacids, ω-oxoacids, pyruvic acid, and α-dicarbonyls were measured for this snowpit sequence. Higher concentrations of short-chain diacids (C2–C5) are observed in dusty snow than non-dusty snow samples. Longer chain diacids (C7–C12) are significant in granular and dusty snow samples. Aromatic and aliphatic unsaturated diacids showed higher concentrations in the slightly dusty layer deposited in winter. Except for a clean layer, molecular distributions of diacids are characterized by the predominance of oxalic acid (C2, ave, 20 ± 22 ng/g-snow) followed by succinic (C4, 7.2 ± 5.9 ng/g -snow), and malonic acids (C3, 3.3 ± 2.9 ng/g -snow) for all the snow layers. Lower C3/C4 ratios (0.46) suggest that organic aerosols are rather fresh without serious photochemical aging during the long-range transport over central Japan. The higher concentrations of the secondary species in dusty snow than non-dusty samples were mainly attributed to the heterogeneous reaction. The strong correlations of incloud oxidation products of isoprene, aromatic acids, and fatty acids suggest that condensation, oxidation, and photolysis are important reaction mechanisms for the formation of diacids. Chinese Loess (Kosa particles) and Mongolian Gobi desert's dust provided the surface area for polar organic compounds, traveled to several thousand kilometers in the lower troposphere, and snow metamorphism altered the chemical composition of diacids and related compounds.

Biofuel Burning Influences Refractory Black Carbon Concentrations in Seasonal Snow at Lower Elevations of the Dudh Koshi River Basin of Nepal

When deposited on snow and ice, light absorbing impurities (LAIs) such as dust and black carbon (BC) reduce surface albedo and enhance melt. BC comes from incomplete combustion of fossil fuels and biomass. Local and regional sources of BC exist in High Mountain Asia, such as dry-dung burning for heat and fuel, which occurs in close proximity to snow and glaciers. Local dust or dust transported from the Indo-Gangetic Plain is also present. In the Ganges River Basin, meltwater is dominated by seasonal snow, yet relatively few observations of impurities in seasonal snow exist. To understand sources of impurities and their concentrations for seasonal snow on land, we evaluated multiple lines of evidence to scale up from ground-based measurements in the Dudh Koshi River Basin, a remote headwater basin within the Khumbu Region of Nepal. We obtained ground-based in-situ observations of refractory black carbon (rBC) measured by Single Particle Soot Photometer (SP2), including size distributions in snow on land. We interpreted these results in the context of concurrent Moderate Imaging Spectroradiometer (MODIS) satellite observations and speciated aerosol optical depth derived from reanalysis products modeled with the Navy Aerosol Analysis Prediction System (NAAPS) global aerosol model. We collected snow samples, mostly in the Gokyo Valley, at varying distances from local tea houses along a 2000 meters above sea level (m.a.s.l) elevation transect from 3250 to 5299 m.a.s.l . rBC concentrations ranged from 3.9 to 76.8 µg-rBC/L-H2O. Although previous data do not exist at these lower elevations, our findings are higher than previous surface snow results at higher elevations in the nearby Khumbu Valley. In general, rBC concentrations were lower in fresh snow than aged snow; concurrent MODIS satellite observations of snow albedo also show smaller impacts from LAIs in visible wavelengths in fresh snow. rBC decreased with elevation in aged snow samples, as did concurrent MODIS albedo observations. rBC-particle size distributions also shifted to a larger mode for aged snow samples. Results from NAAPS indicate anthropogenic and biogenic fine aerosols from biofuel (dry-dung burning) are primary aerosol species for the study period, at ~thrice the concentration of dust and smoke.

The atmospheric iron variations during 1950–2016 recorded in snow at Dome Argus, East Antarctica

174 snow samples were collected from a 4.5 m snow pit at Dome Argus (Dome A), East Antarctica, during the 2015–2016 austral summer. They covered a period between 1950 and 2016. These samples were measured for iron (Fe) concentrations by the inductively coupled plasma mass spectrometry (ICP-MS). Both the total dissolvable Fe (TDFe) and dissolved Fe (DFe) were measured in order to evaluate the fractional Fe solubility (FFS), an important variable to determine the Fe availability for biological activities. The results show an average TDFe flux of 0.019 mg m−2 a−1 and DFe flux of 2.254 × 10−3 mg m−2 a−1 at Dome A. The mean FFS of 7.27% is consistent with previous studies on the Antarctic ice sheet. Based on the mean value of the TDFe fluxes from both the current and previous studies, the atmospheric TDFe flux in Antarctic modern snow was estimated at 19–140 × 10−3 mg m−2 a−1, potentially supporting 10.5–76.5 Tg C a−1 of primary production. This accounts about 1.21–8.80% of the annual primary production in the seasonal sea ice zone of Southern Ocean (SO), suggesting that atmospheric DFe is a minor component of Fe supply.

Warmer–wetter climate drives shift in δD–δ18O composition of precipitation across the Queen Elizabeth Islands, Arctic Canada

We examine how recent increases in air temperature and precipitation, together with reductions in sea ice extent, may have affected the regional δD–δ18O composition of precipitation. In spring 2014, 80 snow samples were collected from six glaciers and ice caps across the Queen Elizabeth Islands, and in 2009 and 2014, two shallow ice cores were collected from Agassiz Ice Cap and White Glacier, respectively. The snow samples showed average δ18O values from 2013 to 2014 to be approximately 2‰–3‰ higher than those recorded in 1973–1974 in nearby locations, with the ice cores showing similar trends in δ18O values. A zonal average water isotope model was used to help understand the causes of the increased δ18O values, using inputs calibrated for observed changes in temperature, vapour flux, and sea ice extent. Model results indicate that atmospheric temperature changes account for <1‰ of the observed change in δ18O values, and that changes in local water input and precipitation driven by changes in sea ice extent only have an effect in coastal regions. Enhanced meridional vapour flux to the Queen Elizabeth Islands is, therefore, also required to explain the observed increases in δ18O values, with fluxes ∼7% higher today than in the 1970s, consistent with the change in precipitation.

Chromato-mass spectrometric identification of asymmetric dimethylhydrazine and its derivatives in environmental objects and biological media in the population residing near the fall areas of separated rocket vehicles parts

Introduction. The issue of presence/absence of the consequences of technogenic space and rocket activity over the long period is on the agenda of the professional, social, and political communities, especially in regions were the certain territories have been appointed as the fall areas for the separated rocket vehicles parts, including the Republic of Altai.Aim of study. Identification of the chemical composition of snow samples, drinking water, and blood in the population residing in the fall areas of the separated rocket vehicle parts in the Republic of Altai.Material and methods. Identification of the chemical composition has been performed along with the quantitative determination of the content of N-nitrosamines in blood samples (n=50) in n the population who constantly live near to the fall areas of the separated rocket vehicles, as well snow samples (n=7), and drinking water (n=9). The samples were examined by a hybrid method using an Agilent gas chromatograph with a quadrupole mass spectrometric detector. In order to decrypt the results of the mass spectrometric analysis, we used the NIST Mass Spectrometry Data Library 08.L, WILEY275.L, PMW_TOX2.L., libraries of the United States Environmental Protection Agency, narcotic, herbal, toxic and contaminated substances. The quantitative determination of N-nitrosamines in the blood samples was performed by the method of chromatography-mass spectrometry.Results. During the library search, 94% of the studied blood samples in the population registered substances that can be identified as unsymmetric dimethylhydrazine and 6% of the samples contain its decomposition product N-nitrosodimethylamine. However, the probability of categorizing these impurities to the desired substances was of 4-26%. In the blood samples of residents in whom there were identified asymmetric dimethylhydrazine and N-NDMA by quantitative chromatography-mass spectrometric analysis, the tag (Alt+2) N-nitrosodimethylamine and N-nitrosodiethylamine was found in the concentration range of 0.00095-0.346 mg/dm3. In 100% of the studied drinking water samples, residual amounts of asymmetric dimethylhydrazine were identified with a low probability of matching the library mass spectrum of 12-33%.Conclusion. The conducted chromatography-mass spectrometry studies of snow samples, samples of the water, and blood of the population living near to the fall area of the separated rocket vehicle parts in the Republic of Altai allowed establishing the signs of residual quantities of dimethylhydrazine and N-nitrozodimethylamine.

Investigation of the spatio-temporal heterogeneity and optical property of water-soluble organic carbon in atmospheric aerosol and snow over the Yulong Snow Mountain, southeastern Tibetan Plateau

Atmospheric aerosols are a branch of active research in recent decades. The deposition of light-absorbing substances on high-altitude glaciers causes substantial adverse impacts on the cryospheric environment, cryosphere-hydrology, and climate system. Although, the concentrations of water-soluble organic carbon (WSOC) in snow/ice on glaciers of Tibetan Plateau (TP) have been reported, their transfer processes and optical properties in the context of summer precipitation-atmosphere-snow-river water continuum are seldom studied. In this study, we have systematically examined some scientific issues associated with WSOC concentrations and light absorption properties of WSOC in various forms of samples from the Mt. Yulong region. Statistical results demonstrate that the spatial distribution of WSOC in the snow of Baishui glacier was heterogeneous. The average WSOC concentrations of each snowpit were significantly decreased, and its light-absorbing properties were significantly elevated with the time extension. Aerosol WSOC concentrations and light absorption have distinct spatial disparity and seasonal variation. Pre-monsoon and monsoon have the highest and lowest WSOC content, respectively. Whereas the light-absorbing properties present contrasting seasonal trends. Rivers of which runoff was supplied by glacier meltwater have significantly lower WSOC concentrations (e.g., 0.42 ± 0.03 mg L−1) compared with other forms of water bodies. Mass absorption cross-section of WSOC (MAC-WSOC) in multiple snow and meltwater samples was significantly different and type-dependent. Atmospheric aerosol has the lowest MAC-WSOC value among the four types of samples, which was likely associated with exhaust emissions from private vehicles and tour buses. Statistical results indicated that the average AAE330-400 values of various snow/ice samples are subequal. Snow of glaciers supplies a desirable platform for the deposition of gaseous materials which experienced long-range transport in high altitude zones. Biomass-burning emissions made an immense contribution to the WSOC deposition over the study area, as demonstrated by the distribution of active fire points. However, this preliminary study represents the first systematic investigation of WSOC deposition in southeastern TP. Further robust in-situ field investigations and laboratory measurements are urgently necessary to improve our understanding of the transfer process and optical property of WSOC.

New insights into heavy metal elements deposition in the snowpacks of mountain glaciers in the eastern Tibetan Plateau

Atmospheric heavy metals have important environmental and health threats. To investigate atmospheric deposition and contamination of heavy metal elements in the glaciers of the eastern Tibetan Plateau (ETP), we collected the surface snow (cryoconites) samples in the Lenglongling Glacier (LG), the Gannan Snowpack (GS), the Dagu Glacier (DG), the Hailuogou Glacier (HG) and Yulong Snow-mountain Glacier (YG) in summer 2017. Samples were analyzed for concentrations and enrichment factors (EFs) of Al and trace elements (Pb, Co, Cd, Ba, Mn, Ga, Sc, V, Zn, Cr, Ni, Cu, Rb, Sb, Cs, As, Mo, Li) using inductively coupled plasma-mass spectrometry (ICP-MS). Results showed that the concentrations and EFs of heavy metals (e.g. Sb, Cu, Cr, Ni, As, Mo) were generally high value in YG, GS and LG, while were relatively low value in DG and HG, implying that ETP glaciers may have been affected by atmospheric anthropogenic pollutants deposition to varying degrees. Comparing the heavy metal concentrations in the glaciers with those in the precipitation of middle/eastern China cities and also the South Asian cities, we find that the glacial heavy metal concentrations were generally low level, though the anthropogenic pollutants were still significantly enriched. Taking the spatial distribution of As and Ni concentration/EFs in the glaciers and surrounding urban precipitation as an example, we find that the heavy metal pollutants were probably transported to the glaciers through three routes from the surrounding densely populated area of Asia. The MODIS AOD and NCEP/NCAR wind vector also demonstrated that the atmospheric pollutants originated from anthropogenic emissions of urban areas of both South Asia, and northwest and east China, mainly caused by the large scale atmospheric circulation (e.g. the South Asian Monsoon, westerlies and Eastern Asian Summer Monsoon). Therefore, control of these potential pollution emission sources of the surrounding densely populated areas in Asia could be important to ETP glaciers in future perspectives.

Snow Impurities in the Central Pyrenees: From Their Geochemical and Mineralogical Composition towards Their Impacts on Snow Albedo

The aim of this work is to understand aerosol transfers to the snowpack in the Spanish Pyrenees (Southern Europe) by determining their episodic mass-loading and composition, and to retrieve their regional impacts regarding optical properties and modification of snow melting. Regular aerosol monitoring has been performed during three consecutive years. Complementarily, short campaigns have been carried out to collect dust-rich snow samples. Atmospheric samples have been chemically characterized in terms of elemental composition and, in some cases, regarding their mineralogy. Snow albedo has been determined in different seasons along the campaign, and temporal variations of snow-depth from different observatories have been related to concentration of impurities in the snow surface. Our results noticed that aerosol flux in the Central Pyrenees during cold seasons (from November to May, up to 12–13 g m−2 of insoluble particles overall accumulated) is much higher than the observed during the warm period (from June to October, typically around 2.1–3.3 g m−2). Such high values observed during cold seasons were driven by the impact of severe African dust episodes. In absence of such extreme episodes, aerosol loadings in cold and warm season appeared comparable. Our study reveals that mineral dust particles from North Africa are a major driver of the aerosol loading in the snowpack in the southern side of the Central Pyrenees. Field data revealed that the heterogeneous spatial distribution of impurities on the snow surface led to differences close to 0.2 on the measured snow albedo within very short distances. Such impacts have clear implications for modelling distributed energy balance of snow and predicting snow melting from mountain headwaters.

Spatial distribution and potential sources of methanesulfonic acid in High Asia glaciers

As a receptor of atmospheric deposition, glaciers are considered an ideal archive in the study of climate change and geochemical cycles. The deposition of methanesulfonic acid (MSA) in the glaciers provides good opportunities to study the biogeochemical cycle of sulfur in the cryosphere. In the present work, snow samples were collected from six High Asia glaciers along a north-to-south transect to determine the spatial distribution of MSA and elucidate its potential sources. The median MSA concentration in the Urumqi Glacier No.1 of Tien Shan was 138.8 ng mL−1, which was distinctly higher than those observed in the Tibetan Plateau (TP) glaciers and polar regions. The levels of MSA in the interior TP glaciers were higher than those observed in the margins of northeastern and southeastern TP. Good correlations between MSA and K+ (r = 0.86, n = 30, α = 0.01), Mg2+ (r = 0.86), and NH4+ (r = 0.73) were observed in continental glaciers. Principal component analysis indicated that MSA may have terrigenous material inputs. At Yulong Snow Mountain, MSA was correlated with Na+ (r = 0.76, n = 8, α = 0.1), a sea-salt tracer ion, suggesting that MSA may be derived from marine environments. According to dimethyl sulfide (DMS) production and NH3 emissions in High Asia, we deduced that the high concentrations of MSA in continental glaciers are possibly related to the sources of hypersaline soil environments and animal husbandry in nomadic areas. This work is useful for further studies on regional sulfur cycling and the impacts of human activities on climate change.

A new method for microplastic sampling and isolation in mountain glaciers: A case study of one antisana glacier, Ecuadorian Andes

Microplastic contamination has become ubiquitous in terrestrial and marine environments. Recent studies have shown that the wind can transport and deposit microplastics in high mountain ecosystems, but microplastic contamination therein is unknown. Because mountain glaciers are the primary source of drinking water for large urban areas in the Andes, assessing recent and historical microplastic contamination is crucial. Surface snow can indicate recent microplastic deposition, whereas glacial ice cores can provide information on historical contamination. At mountain glaciers, the inhospitable conditions and the difficult accessibility are limiting factors for sampling. Therefore, sampling and laboratory analytical methods have to be integrated and planned ensuring replicability. Here, we present 1) a new methodology to identify sampling areas within the accumulation zone of a glacier to obtain samples of surface snow and ice cores; 2) a less-manipulative analytical technique for the preparation and isolation of microplastics derived from glaciers. In addition, we identified the minimum amount of sample necessary to obtain robust data on contamination by microplastics.

Sampling, Filtering, and Analysis Protocols to Detect Black Carbon, Organic Carbon, and Total Carbon in Seasonal Surface Snow in an Urban Background and Arctic Finland (>60° N)

Black carbon (BC), organic carbon (OC), and total carbon (TC) in snow are important for their climatic and cryospheric effects. They are also part of the global carbon cycle. Atmospheric black and organic carbon (including brown carbon) may deposit and darken snow surfaces. Currently, there are no standardized methods for sampling, filtering, and analysis protocols to detect carbon in snow. Here, we describe our current methods and protocols to detect carbon in seasonal snow using the OCEC thermal optical method, a European standard for atmospheric elemental carbon (EC). We analyzed snow collected within and around the urban background SMEARIII (Station for Measuring Ecosystem-Atmosphere Relations) at Kumpula (60° N) and the Arctic GAW (Global Atmospheric Watch) station at Sodankylä (67° N). The median BC, OC, and TC in snow samples (ntot = 30) in Kumpula were 1118, 5279, and 6396 ppb, and in Sodankylä, they were 19, 1751, and 629 ppb. Laboratory experiments showed that error due to carbon attached to a sampling bag (n = 11) was <0.01%. Sonication slightly increased the measured EC, while wetting the filter or filtering the wrong side up indicated a possible sample loss. Finally, we discuss the benefits and drawbacks of OCEC to detect carbon in snow.

Mass concentration and origin of black carbon in spring snow on glaciers in the Alaska Range

Black carbon (BC) is one of the light-absorbing particles that reduce the albedo of snow surfaces. Snow samples were taken from the surface of three glaciers in the Alaska Range in mid-April 2017. The BC size distribution and concentration were analyzed with a laser-induced incandescence (LII) method. The BC concentration of the snow samples was 1–6 μg L−1 and 0.5–3.1 μg L−1 at a depth of 0–2 cm (surface) and 2–10 cm (subsurface), respectively. These values are comparable to other Arctic areas and are considered to be the Alaskan background level. The BC concentrations are 0.5% of those of insoluble solid particles (ISPs) measured using an electrical sensing zone method. The surface albedo change due to BC and other ISPs concentrations was estimated to be 0.004–0.007 for the snow surface in April. The ablation at the observation sites on Gulkana Glacier would be 1.2% larger in the ablation season due to black carbon deposition. The chemical transport model revealed that 17%–34% of BC originates from biomass burning in Asia and Siberia, and 60% of BC originates from China in this study.

Spatial characteristics and geographical determinants of mercury and arsenic in snow in northeastern China

Mercury (Hg) and arsenic (As) have been the focus of extensive in environmental research due to their strong enrichment and high toxicity. Although their concentrations in snow are usually considered important indicators for assessing regional and global atmospheric environments, few studies have focused on the biogeochemical cycling behavior of Hg and As in snow, especially in northeastern China. Therefore, to evaluate their local atmospheric deposition and the influence of trace element pollution on the atmosphere, this study assessed the spatial distribution characteristics and sources of snow-borne Hg and As in northeastern China, based on 86 snow samples acquired from December 2017 to January 2018. The total mercury (THg) and total arsenic (TAs) in the samples were measured using atomic fluorescence spectroscopy, their spatial distribution was determined through spatial interpolation, and their sources were analyzed using a backward trajectory model. The results clearly demonstrated that variations in air-mass source and industrial outputs lead to complex spatial characteristics of Hg and As concentrations. This study provides a reference for regional cooperation and collaboration in environment regulation and pollution prevention.

In situ effective snow grain size mapping using a compact hyperspectral imager

AbstractEffective snow grain radius (re) is mapped at high resolution using near-infrared hyperspectral imaging (NIR-HSI). The NIR-HSI method can be used to quantify re spatial variability, change in re due to metamorphism, and visualize water percolation in the snowpack. Results are presented for three different laboratory-prepared snow samples (homogeneous, ice lens, fine grains over coarse grains), the sidewalls of which were imaged before and after melt induced by a solar lamp. The spectral reflectance in each ~3 mm pixel was inverted for re using the scaled band area of the ice absorption feature centered at 1030 nm, producing re maps consisting of 54 740 pixels. All snow samples exhibited grain coarsening post-melt as the result of wet snow metamorphism, which is quantified by the change in re distributions from pre- and post-melt images. The NIR-HSI method was compared to re retrievals from a field spectrometer and X-ray computed microtomography (micro-CT), resulting in the spectrometer having the same mean re and micro-CT having 23.9% higher mean re than the hyperspectral imager. As compact hyperspectral imagers become more widely available, this method may be a valuable tool for assessing re spatial variability and snow metamorphism in field and laboratory settings.

New insights into particle-bound trace elements in surface snow, Eastern Tien Shan, China

Trace elements (TEs) in the insoluble particles of surface snow are less affected by melting processes and can be used as environmental proxies to reveal natural and anthropogenic emissions. Here the first comprehensive study of the 16 TEs (Al, As, Ba, Bi, Cr, Cu, Fe, Mn, Ni, Pb, Sn, Sr, Ti, U, V, and Zn) in insoluble particles (>0.45 μm) from surface snow samples collected at Urumqi Glacier No. 1 (UG1), Eastern Tien Shan, China, from February 2008 to January 2010 were presented. Results show that concentrations of most insoluble particulate TEs (TEs insol) in the snow were higher in summer while lower in winter, due to the increasing particle inputs and melting processes. The abundances of As, Cr, Cu, Ni, Pb, and Zn in some samples were higher than those in surrounding urban soils, which might due to these TEs have further anthropogenic input beyond the already contaminated re-suspended urban soil particles and TEs were mainly enriched in particles with small grain size. Based on enrichment factor (EF) and principal component analysis (PCA), our results suggest that eight TEs (Al, Fe, Ti, Ba, Mn, Sr, U, and V) mainly came from mineral dust, while the remaining eight TEs (As, Bi, Cr, Cu, Ni, Pb, Sn, and Zn) were affected by coal combustion, mining and smelting of non-ferrous metals, traffic emissions, and the steel industry. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model suggests that pollutants might originate from Xinjiang province, Kazakhstan, and Kyrgyzstan. Moreover, UG1 received more significant inputs of particle-bound pollutants in summer than in winter due to the stronger convection and the prevailing valley wind that transports pollutants from the city of Urumqi.