Snow Chemistry Research Articles

Surface snow bromide and nitrate at Eureka, Canada, in early spring and implications for polar boundary layer chemistry

Abstract. This study explores the role of snowpack in polar boundary layer chemistry, especially as a direct source of reactive bromine (BrOx = BrO + Br) and nitrogen (NOx = NO + NO2) in the Arctic springtime. Surface snow samples were collected daily from a Canadian high Arctic location at Eureka, Nunavut (80° N, 86° W) from the end of February to the end of March in 2018 and 2019. The snow was sampled at several sites representing distinct environments: sea ice, inland close to sea level, and a hilltop ∼ 600 m above sea level (a.s.l.). At the inland sites, surface snow salinity has a double-peak distribution with the first and lowest peak at 0.001–0.002 practical salinity unit (psu), which corresponds to the precipitation effect, and the second peak at 0.01–0.04 psu, which is likely related to the salt accumulation effect (due to loss of water vapour by sublimation). Snow salinity on sea ice has a triple-peak distribution; its first and second peaks overlap with the inland peaks, and the third peak at 0.2–0.4 psu is likely due to the sea water effect (a result of upward migration of brine). At all sites, snow sodium and chloride concentrations increase by almost 10-fold from the top 0.2 to ∼ 1.5 cm. Surface snow bromide at sea level is significantly enriched, indicating a net sink of atmospheric bromine. Moreover, surface snow bromide at sea level has an increasing trend over the measurement period, with mean slopes of 0.024 µM d−1 in the 0–0.2 cm layer and 0.016 µM d−1 in the 0.2–0.5 cm layer. Surface snow nitrate at sea level also shows a significant increasing trend, with mean slopes of 0.27, 0.20, and 0.07 µM d−1 in the top 0.2, 0.2–0.5, and 0.5–1.5 cm layers, respectively. Using these trends, an integrated net deposition flux of bromide of (1.01 ± 0.48) × 107 molec.cm-2s-1 and an integrated net deposition flux of nitrate of (2.6 ± 0.37) × 108 molec.cm-2s-1 were derived. In addition, the surface snow nitrate and bromide at inland sites were found to be significantly correlated (R = 0.48–0.76) with the [NO3-]/[Br-] ratio of 4–7 indicating a possible acceleration effect of reactive bromine in atmospheric NOx-to-nitrate conversion. This is the first time such an effect has been seen in snow chemistry data obtained with a sampling frequency as short as 1 d. BrO partial column (0–4 km) data measured by MAX-DOAS show a decreasing trend in early spring, which generally agrees with the derived surface snow bromide deposition flux indicating that bromine in Eureka atmosphere and surface snow did not reach a photochemical equilibrium state. Through mass balance analysis, we conclude that the average release flux of reactive bromine from snow over the campaign period must be smaller than the derived bromide deposition flux of ∼ 1 × 107 molec.cm-2s-1. Note that the net mean fluxes observed do not completely rule out larger bidirectional fluxes over shorter timescales.

A comprehensive assessment of ions in snow and ice cores based on global observational data

Snow and ice are important reservoirs of atmospheric ions, yet a comprehensive understanding of ions in snow/ice remains a challenge due to spatiotemporal limitations of field campaigns. To address this issue, mathematical statistics were employed to summarize global observational data from 49 published sources covering 546 snow and 19 ice core sampling sites. The findings show remarkable variability in ion concentrations and compositions in snow, with differences spanning 4 to 6 orders of magnitude. This variation changes with elevation, season and historical development, and differs regionally and within regions. These complex patterns of ion distribution in snow and ice are shaped by a range of factors, including local and remote emission sources, trans-regional transports, atmospheric circulations, natural climate variability, geographical features and environmental factors. This comprehensive global analysis would effectively enhance our understanding of snow and ice chemistry and its significant environmental implications, particularly in the context of a rapid changing global climate.

A Guided-Inquiry Activity for Introducing Students to Figures from Primary Scientific Literature

Reading and understanding scientific literature is an essential skill for any scientist to learn. While students’ scientific literacy can be improved by reading research articles, an article’s technical language and structure can hinder students’ understanding of the scientific material. Furthermore, many students struggle with interpreting graphs and other models of data commonly found in scientific literature. To introduce students to scientific literature and promote improved understanding of data and graphs, we developed a guided-inquiry activity adapted from a research article on snow chemistry and implemented it in a general chemistry laboratory course. Here, we describe how we adapted figures from the primary literature source and developed questions to scaffold the guided-inquiry activity. Results from semi-structured qualitative interviews suggest that students learn about snow chemistry processes and engage in scientific practices, including data analysis and interpretation, through this activity. This activity is applicable in other introductory science courses as educators can adapt most scientific articles into a guided-inquiry activity.

Urban air quality in Xinjiang and snow chemistry of Urumqi Glacier No. 1 during COVID-19's restrictions.

The unprecedented COVID-19 outbreak impacted the world in many aspects. Air pollutants were largely reduced in cities worldwide in 2020. Using samples from two snow pits dug separately in 2019 and 2020 in Urumqi Glacier No. 1 (UG1) in the Xinjiang Uygur Autonomous Region (Xinjiang), China, we measured water-stable isotopes, soluble ions, and black and organic carbon (BC and OC). Both carbon types show no significant variations in the snow-pit profiles dated from 2018 through 2020. The deposition of anthropogenically induced soluble ions (K+, Cl−, SO42−, and NO3−) in the snow decreased to 20–40% of their respective concentrations between 2019 and 2020; however, they increased 2- to fourfold from 2018 to 2019. We studied the daily concentrations of SO2 (2019–2020), NO2 (2015–2020), CO (2019–2020), and PM2.5 (2019–2020) measured in the sixteen major cities and towns across Xinjiang. The variabilities in these air pollutants were supposed to illustrate the air quality in the urban area and represent the change in the source area. The NO2 decreased in response to mobility restrictions imposed by local governments, while SO2, CO, and PM2.5 did not consistently correspond. This difference indicates that the restriction measures primarily affected traffic. The increases in chemical species in the snow from 2018 to 2019 and the subsequent decreases from 2019 to 2020 were consistent with the variations in SO2 and NO2 measured in urban air and estimated by MERRA-2 model. Therefore, the pandemic could possibly have an impact on snow chemistry of the Tien-Shan glaciers via reduced traffic and industrial intensity; more evidence would be obtained from ice cores, tree rings, and other archives in the future.

Intercomparison Experiment of Water-Insoluble Carbonaceous Particles in Snow in a High-Mountain Environment (1598 m a.s.l.)

The harmonization of sampling, sample preparation and laboratory analysis methods to detect carbon compounds in snow requires detailed documentation of those methods and their uncertainties. Moreover, intercomparison experiments are needed to reveal differences and quantify the uncertainties further. Here, we document our sampling, filtering, and analysis protocols used in the intercomparison experiment from three laboratories to detect water-insoluble carbon in seasonal surface snow in the high-mountain environment at Kolm Saigurn (47.067842° N, 12.98394° E, alt 1598 m a.s.l.), Austria. The participating laboratories were TU Wien (Austria), the University of Florence (Italy), and the Finnish Meteorological Institute (Finland). For the carbon analysis, the NIOSH5040 and EUSAAR2 protocols of the OCEC thermal-optical method were used. The median of the measured concentrations of total carbon (TC) was 323 ppb, organic carbon (OC) 308 ppb, and elemental carbon (EC) 16 ppb. The methods and protocols used in this experiment did not reveal large differences between the laboratories, and the TC, OC, and EC values of four inter-comparison locations, five meters apart, did not show meter-scale horizontal variability in surface snow. The results suggest that the presented methods are applicable for future research and monitoring of carbonaceous particles in snow. Moreover, a recommendation on the key parameters that an intercomparison experiment participant should be asked for is presented to help future investigations on carbonaceous particles in snow. The work contributes to the harmonization of the methods for measuring the snow chemistry of seasonal snow deposited on the ground.

Cultural Relevance in Chemistry Education: Snow Chemistry and the Iñupiaq Community

Cultural Relevance in Chemistry Education: Snow Chemistry and the Iñupiaq Community

A case study using 2019 pre-monsoon snow and stream chemistry in the Khumbu region, Nepal

This case study provides a framework for future monitoring and evidence for human source pollution in the Khumbu region, Nepal. We analyzed the chemical composition (major ions, major/trace elements, black carbon, and stable water isotopes) of pre-monsoon stream water (4300–5250 m) and snow (5200–6665 m) samples collected from Mt. Everest, Mt. Lobuche, and the Imja Valley during the 2019 pre-monsoon season, in addition to a shallow ice core recovered from the Khumbu Glacier (5300 m). In agreement with previous work, pre-monsoon aerosol deposition is dominated by dust originating from western sources and less frequently by transport from southerly air mass sources as demonstrated by evidence of one of the strongest recorded pre-monsoon events emanating from the Bay of Bengal, Cyclone Fani. Elevated concentrations of human-sourced metals (e.g., Pb, Bi, As) are found in surface snow and stream chemistry collected in the Khumbu region. As the most comprehensive case study of environmental chemistry in the Khumbu region, this research offers sufficient evidence for increased monitoring in this watershed and surrounding areas.

Measurement report: Spatial variations in ionic chemistry and water-stable isotopes in the snowpack on glaciers across Svalbard during the 2015–2016 snow accumulation season

Abstract. The Svalbard archipelago, located at the Arctic sea-ice edge between 74 and 81∘ N, is ∼60 % covered by glaciers. The region experiences rapid variations in atmospheric flow during the snow season (from late September to May) and can be affected by air advected from both lower and higher latitudes, which likely impact the chemical composition of snowfall. While long-term changes in Svalbard snow chemistry have been documented in ice cores drilled from two high-elevation glaciers, the spatial variability of the snowpack composition across Svalbard is comparatively poorly understood. Here, we report the results of the most comprehensive seasonal snow chemistry survey to date, carried out in April 2016 across 22 sites on seven glaciers across the archipelago. At each glacier, three snowpits were sampled along the altitudinal profiles and the collected samples were analysed for major ions (Ca2+, K+, Na+, Mg2+, NH4+, SO42-, Br−, Cl−, and NO3-) and stable water isotopes (δ18O, δ2H). The main aims were to investigate the natural and anthropogenic processes influencing the snowpack and to better understand the influence of atmospheric aerosol transport and deposition patterns on the snow chemical composition. The snow deposited in the southern region of Svalbard is characterized by the highest total ionic loads, mainly attributed to sea-salt particles. Both NO3- and NH4+ in the seasonal snowpack reflect secondary aerosol formation and post-depositional changes, resulting in very different spatial deposition patterns: NO3- has its highest loading in north-western Spitsbergen and NH4+ in the south-west. The Br− enrichment in snow is highest in north-eastern glacier sites closest to areas of extensive sea-ice coverage. Spatial correlation patterns between Na+ and δ18O suggest that the influence of long-range transport of aerosols on snow chemistry is proportionally greater above 600–700 m a.s.l.

Brief communication: Spatial and temporal variations in surface snow chemistry along a traverse from coastal East Antarctica to the ice sheet summit (Dome A)

Abstract. To better understand snow chemistry in different environments across the Antarctic ice sheet, we investigated snow ions on a traverse from the coast to Dome A. Results show that the non-sea-salt (nss) fractions of K+, Mg2+, and Ca2+ are mainly from terrestrial particle mass and nssCl− is associated with HCl. Spatially, the non-sea-salt fractions of ions to the totals are higher in the interior areas than on the coast, and seasonally, the proportions are higher in summer than in winter. Negative nssSO42- on the coast indicates sea salts from the sea ice, and marine biogenic emissions dominate snow SO42- in interior areas throughout the year.

Hydrological and meteorological data from research catchments at the Marcell Experimental Forest, Minnesota, USA

AbstractThe Marcell Experimental Forest (MEF) in northern Minnesota, USA, with hydrological research and monitoring of peatland catchments in a low‐topographic relief landscape, contrasts with the mountainous terrain that typifies most research catchments. Six research catchments were instrumented and hydrological and meteorological monitoring was initiated during 1960. Paired‐catchment studies, which started during 1969, have been used to assess land management and environmental change effects on forests, water availability, and biogeochemistry. Over the decades, the research and collaborations have proliferated to include new monitoring and ecosystem experiments. We provide an overview of available datasets and access information for hydrological and meteorological data. Data on streamflow, water table elevation, precipitation, snow, ground frost, air temperature, soil moisture, upland runoff, and water chemistry are discoverable with associated metadata and are archived through several Web‐based, community repositories. The research programme is ongoing and we anticipate updates on an annual or more frequent basis. Additionally, we aim to release other physical, chemical, and isotopic measurements associated with long‐term catchment monitoring and studies at the MEF.

Variation in recent annual snow deposition and seasonality of snow chemistry at the east Greenland ice core project (EGRIP) camp, Greenland

We collected snow samples from two pits with depths of 4.02 and 3.18 m at the East Greenland Ice Core Project camp (75°37′N, 35°59′W), Greenland in the summer of 2016 to estimate recent annual snow deposition and examine seasonal variation in major ion species, stable isotopes of water and microparticles (dust). Dating based on clear seasonal variation in chemical components indicated that the 4.02- and 3.18-m-deep pits included snow deposition corresponding to ten years from 2006 to 2016 and seven years from 2009 to 2016, respectively. The mean values for annual snow deposition for the 4.02-m-deep pit were 138 and 145 mm yr−1 in water equivalent (mm w.e. Yr−1) in 2006–2016 and 2009–2016, respectively. The average deposition for the 3.18-m-deep pit was 149 mm w.e. Yr−1 between 2009 and 2016. Seasonal variation in concentrations of major ion species and dust were similar to those previously reported for Greenland. The maximum Cl−/Na+ concentration ratios in the summer were much higher than the ratios at other sites in Greenland.

Estimating meltwater retention and associated nitrate redistribution during snowmelt in an Arctic tundra landscape**The data that support the findings of this study are available from the corresponding author upon reasonable request.

Nitrogen availability in Arctic ecosystems is a key driver for biological activity, including plant, growth and thereby directly linked to the greening of the Arctic. Here, we model the redistribution of meltwater following spring snowmelt as well as the accumulation of meltwater and dissolved nitrate at landscape scale. By combining snow mapping with unmanned aerial systems, snow chemistry, and hydrological modelling, we argue that the majority of nitrate in the snowpack is flushed out of the landscape due to the limited storage capacity of meltwater in the early growing season frozen soil. We illustrate how landscape micro-topography is a crucial parameter to quantify storage capacity of meltwater at landscape scale and thereby the associated pool of soluble compounds such as nitrate. This pool will be available for plants and may be important for plant diversity and growth rates in the wettest part of the landscape. This study illustrates that the evenly distributed nitrate input during the Arctic winter may be redistributed during the initial snowmelt and lead to marked differences in biologically available nitrate at the onset of the growing season, but also that the majority of deposited nitrate in snow is lost from the terrestrial to the aquatic environment during snowmelt.

Periodic Graphics: The chemistry of snow and ice

The chemistry of snow and ice To download a PDF of this article, visit: cenm.ag/snowice References used to create this graphic: Connor, Deanna. How snowflakes get their shapes. Accessed Jan. 21, 20...

Wet Deposition and Long-range Transport of Major Ions Related to Snow at Northwestern Himalayas (India)

ABSTRACT The present study was carried out to understand the snow chemistry with special emphasis on the estimation of wet deposition fluxes and transportation of ionic species to the Himalayan regions from December 2015 to March 2017. All the snow samples were collected from three different sites of two locations, Jammu & Kashmir and Himachal Pradesh. In Jammu and Kashmir we have selected two sites, (an urban area Leh and other one was semi-urban area Beerwah). In Himachal Pradesh, we selected a site at Nirmand village which was a rural area. At Leh and Nirmand village, samples were showing higher alkalinity than at Beerwah site. The pH values of snow at Leh and Nirmand were recorded above 5.6 except one sample of both the sites. However, at Beerwah site almost 60% of the samples were found acidic (below 5.6) in nature. All these three sites showed three different means of neutralization and pH control. The study revealed that the high pH value of snowfall at Leh site could be due to the presence very high value of Ca2+ whereas the moderate pH at Nirmand village may be due to moderate concentration of Ca2+ and high NH4+. In contrast at Beerwah site, low pH is probably due to very low concentrations of all the major cations. This study also suggested that non-sea salt sources contributed a significant fraction of SO42–, K+, Ca2+, and Mg2+. However, on average, a significant amount of HCO3– was measured at all the three sites, indicating a substantial role of crustal sources in the study sites. Results of this study showed that these ionic species are contributed by local as well as long-distance sources in the region. Backward airmass trajectory analysis revealed that the ionic species were contributed by the airmasses coming from North Atlantic Ocean, Africa, Europe, Middle East, and Mediterranean region to all these sites through long-range transport (LRT).

Chemistry of snow and ice cores along the ice flow lines at Lake Vostok (Antarctica)

The authors present the results of high resolution chemical studies of snow cover from pits and cores along the ice flow lines from Ridge B to Lake Vostok across its southern (profile VFL) and northern (profile NVFL) parts. The sampling was performed between 2006–2013 during the seasonal 52nd–57th Russian Antarctic expeditions (RAE). Chemical signals of non-sea-salt sulphates and an analysis of the morphology, size and composition of microparticles allowed for the identification of the products of large volcanic eruptions during the 19th and 20th centuries, including the eruptions of Tambora (1815), Krakatoa (1883), Agung (1963) and Pinatubo (1991). In the layers with high non-sea-salt sulphate concentrations, we found small aluminosilicate particles with K, Fe and Mg inclusions, which could be of volcanic origin. Using volcanic markers, we calculated snow accumulation rates for the past 200 years along the two ice flow lines. The maximal snow accumulation rates (33 mm in water equivalent yr−1) were found in the northern ice flow line, and the minimal rates (25 mm in water equivalent yr−1) were found in the southern ice flow line.

Electric Phenomena as a Possible Driver of Polar Snow-air Interactions: Does this Factor Act Synergistically with Photoinduced Effects?

Processes that occur inside polar snow cover significantly affect polar atmosphere but they are still poorly understood. Most studies consider photochemistry as the dominant mechanism of chemical transformations but recent field data cannot be interpreted only by such photochemical model. A concept is proposed to consider electric phenomena that are well known to physics but their role was never analyzed by snow chemistry specialists. But there is a question on how to differentiate influences of photo effects and electric phenomena. It can be supposed that these factors are not independent. On the contrary, they reinforce each other and act synergistically.

Should We Not Further Study the Impact of Microbial Activity on Snow and Polar Atmospheric Chemistry?

Since 1999, atmospheric and snow chemists have shown that snow is a very active photochemical reactor that releases reactive gaseous species to the atmosphere including nitrogen oxides, hydrocarbons, aldehydes, halocarbons, carboxylic acids and mercury. Snow photochemistry therefore affects the formation of ozone, a potent greenhouse gas, and of aerosols, which affect the radiative budget of the planet and, therefore, its climate. In parallel, microbiologists have investigated microbes in snow, identified and quantified species, and sometimes discussed their nutrient supplies and metabolism, implicitly acknowledging that microbes could modify snow chemical composition. However, it is only in the past 10 years that a small number of studies have revealed that microbial activity in cold snow (< 0 °C, in the absence of significant amounts of liquid water) could lead to the release of nitrogen oxides, halocarbons, and mercury into the atmosphere. I argue here that microbes may have a significant effect on snow and atmospheric composition, especially during the polar night when photochemistry is shut off. Collaborative studies between microbiologists and snow and atmospheric chemists are needed to investigate this little-explored field.

Hydrochemical assessment (major ions and Hg) of meltwater in high altitude glacierized Himalayan catchment.

Snowpack and glacial melt samples were collected to understand the hydrochemical, isotopic characteristics and the source of Hg contamination in high altitude glacierized Himalayan catchment. Both the snow and glacial melt were acidic in nature with calcium and magnesium as the dominant cations and bicarbonate and chloride as the dominant anions. The major ion concentrations for cations were found to be Ca2+ > Mg2+ > Na+ > K+ and HCO3- > Cl- > SO42- > NO3- for anions. The atmospheric processes like the precipitation source and aerosol scavenging control the snow chemistry and the weathering of the rocks modify the hydrochemistry of glacial melt. The samples of both the snow and glacial melt were classified as Ca-Mg-HCO3- type. The concentration of Hg in snow (154.95ngL-1) and glacial melt (112.04ngL-1) was highest (still lower compared to the maximum permissible limit (1000ngL-1) by WHO in drinking water) during summer season (August-September) and lowest (snow 2.2 and 40.01ngL-1 for glacial melt) during winter (November). The results reveal that mercury concentration in snowpacks is attributed to the combined mixing of long-range transport of pollutants via westerlies throughout the year and the industrial effluents coming from highly industrial belts of Panjab, Haryana, Rajasthan, Indo-Gangetic plains, and neighboring areas via southwest monsoons during August-September. However, in glacial melt, the Hg concentration was typically controlled by rate of melting, leaching, and percolation. Higher degree and rate of glacial melting decreases the Hg concentration in glacial melt. Stable isotopic analysis and backward air mass trajectory modeling also corroborate the source of precipitation from southwest monsoons during August-September, with its air mass trajectories passing through the highly industrialized belts of Indo-Gangetic plain and adjoining areas.

Contribution of Saharan Dust to Ion Deposition Loads of High Alpine Snow Packs in Austria (1987–2017)

We investigate the influence of Saharan dust (SD) on the chemical composition and deposition loads of a 31-year long snow chemistry data set (1987 to 2017) of high alpine snow packs situated close to the Sonnblick Observatory, a global GAW (Global Atmospheric Watch) station, in the National Park Hohe Tauern in the Austrian Alps. Based on the snow pack of the winter accumulation period 2015/2016, when two SD events were visible by a reddish color of the snow, we define a pH >5.6 together with a Ca2+ concentration >10µeq/l as thresholds to identify SD affected snow layers (= Saharan Dust Layers, SDLs). This criterion is checked with an intercomparison with trajectories and on-line aerosol data determined at the Sonnblick Observatory. This check was extended to the accumulation periods 2014/15 and 2016/2017 before the whole time series is investigated regarding the contribution of Saharan dust to ion deposition loads. Especially Mg2+, Ca2+ and H+ depositions are strongly affected by SD input causing as average values across the 30 years period increased Mg2+ (25%) and Ca2+ (35%) contributions of SDLs, while the contribution of SDLs to the snow water equivalent (SWE) was only 11%. For H+ SDLs show a much lower contribution (2%) while the contribution of other ions is well comparable to the deposition amount expected according to the SWE of SDLs. The pH range of SDLs covers 5.58 to 7.17, while the median value of all samples is 5.40. The long term trends of ion deposition are not affected by the deposition of Saharan dust.

Polar Plunge: Semester-Long Snow Chemistry Research in the General Chemistry Laboratory

An introductory general chemistry laboratory course was developed to provide an authentic research experience in environmental chemistry. First- and second-year students learned general chemistry concepts and laboratory skills in the context of snow chemistry while participating in the course-based undergraduate research experience. Students were guided through all steps of the research process, including research question development, data collection and processing, interpretation of results in the context of scientific literature, and both written and oral presentations. A key component of the course was an individual laboratory experiment in which snow samples from the Arctic were analyzed for pH and ion content. Assessment of the course via pre- and postcourse surveys indicated that students, the majority of whom were women, experienced greater gains in confidence of research skills and general attitudes toward chemistry as compared to the traditional general chemistry laboratory course. This course r...