Organic Compounds In Snow Research Articles

Organic Compounds and Suspended Particulate Matter in Snow of High Latitude Areas (Arctic and Antarctic)

Long-term studies of suspended particulate matter (SPM) and organic compounds (OCs)—Corg, lipids, hydrocarbons (aliphatic—AHCs and polycyclic aromatic—PAHs), and chlorophyll a in the snow cover of the Arctic (Franz Victoria Trough, Mendeleev Rise, White Sea) and Antarctica (in the coastal waters on fast ice and on the mainland near Russian stations) were generalized. It was shown that in the Arctic, the influence of continental air masses leads to an increase in OCs in snow. Therefore, despite the fact that the Franz Victoria Trough and the Mendeleev Rise are at the same latitude (82° N), the OCs content in the snow in the region of the Mendeleev Rise was lower for aliphatic hydrocarbons 5 and 14–18 μg/L. In the White Sea, the AHC content in the snow and the upper layers of the ice in the mouth of the Severnaya Dvina River and in the Kandalaksha Bay was higher than that in the lower layers of the ice and sharply decreased with distance from the emission sources. As a result, the snow was supplied mainly by pyrogenic PAHs. In the Antarctica, the lowest OCs levels in atmosphere were found in areas where coastal hills are covered with snow. The maximum SPM and AHCs concentration was found in the sludge (SPM—to 4.37 mg/L, AHC—to 33 μg/L). An increase in the concentration of OCs and SPM in snow sampled on the continent took place in the areas of stations and oases (St. Novolazarevskaya) where the predominance of mineral particles in the SPM was registered. In the area of the operating stations, mainly low molecular weight PAHs with the dominance of petroleum PAHs were found in the SPM of snow and in mosses.

A new method for the determination of primary and secondary terrestrial and marine biomarkers in ice cores using liquid chromatography high-resolution mass spectrometry

The majority of atmospheric compounds measured in ice cores are inorganic, while analysis of their organic counterparts is a less well developed field. In recent years, understanding of formation, transport pathways and preservation of these compounds in ice and snow has improved, showing great potential for their use as biomarkers in ice cores. This study presents an optimised analytical technique for quantification of terrestrial and marine biosphere emissions of secondary organic aerosol (SOA) components and fatty acids in ice using HPLC-MS analysis. Concentrations of organic compounds in snow and ice are extremely low (typically ppb or ppt levels) and thus pre-concentration is required prior to analysis. Stir bar sorptive extraction (SBSE) showed potential for fatty acid compounds, but failed to recover SOA compounds. Solid phase extraction (SPE) recovered compounds across both organic groups but methods improving some recoveries came at the expense of others, and background contamination of fatty acids was high. Rotary evaporation was by far the best performing method across both SOA and fatty acid compounds, with average recoveries of 80%. The optimised preconcentration – HPLC-MS method achieved repeatability of 9% averaged for all compounds. In environmental samples, both concentrations and seasonal trends were observed to be reproducible when analysed in two different laboratories using the same method.

Spatial variability and possible sources of acetate and formate in the surface snow of East Antarctica

Spatial trends of acetate (Ac−) and formate (Fo−) were determined in surface snow samples along a coastal-inland transect (180km) in the ice cap region at Princess Elizabeth Land and along a coastal transect in the Amery Ice Shelf (130km), East Antarctica. Variations in both Ac− and Fo− seem to be unrelated to the acidity of snow. Ionic balance determined for the snow samples indicate the availability of HNO3 that could undergo photolysis to produce hydroxyl radical (OH), one of the major reactants involved in oxidation reactions with organic matter. The strong positive correlations between Ac− and NO3− in snow from both regions indicate that NO3− mediated OH-oxidation of organic compounds in snow could be an important source of Ac− within the snowpack. On the other hand, negative correlation between Fo− and NO3− might indicate that sources other than OH-oxidation of organic matter may be dominant in the case of Fo−. Higher Ac− concentrations in the ice cap compared to the ice shelf correspond with long-range transport of biomass burning emissions to the ice cap region. Interaction of Ac− and Fo− with alkaline minerals could lead to their stability in the snowpack and minimize their loss from the snow surface. Resident microbial communities could also influence the budget of the carboxylic acids in snow.

Measuring a 10,000-fold enhancement of singlet molecular oxygen (1O2*) concentration on illuminated ice relative to the corresponding liquid solution

Much attention has focused on the highly reactive hydroxyl radical in the oxidation of trace organic compounds on snow and ice (and subsequent release of volatile organics to the atmospheric boundary layer) but other oxidants are likely also important in this processing. Here we examine the ice chemistry of singlet molecular oxygen (1O2*), which can be significant in atmospheric water drops but has not been examined in ice or snow. To examine 1O2* on ice we illuminate laboratory ices containing Rose Bengal (RB) as the source of 1O2*, furfuryl alcohol (FFA) as the probe, and Na2SO4 to control the total solute concentration. We find that the 1O2*-mediated loss of FFA (and, thus, the 1O2* concentration) is up to 11,000 times greater on ice than in the equivalent liquid sample at the same photon flux. We attribute this large increase in the 1O2* steady-state concentration to the freeze-concentration of solutes into liquid-like regions (LLRs) in/on ice: compared to the initial solution, in the LLRs of ice the sources for 1O2* are highly concentrated, while the concentration of the dominant sink for 1O2* (i.e., water) remains largely unchanged. Similar to results expected in liquid solution, rates of FFA loss in ice depend on both the initial sensitizer concentration and temperature, providing evidence that these reactions occur in LLRs. However, we find that the enhancement in 1O2* concentrations on ice does not follow predictions from freezing-point depression, likely because experiments were conducted below the eutectic temperature for sodium sulfate, where all of the salt should have precipitated. We also explore a method for separating 1O2* and OH contributions to FFA oxidation in laboratory ices and show its application to two natural snow samples. We find that 1O2* concentrations in these snows are approximately 100 times higher than observed in polluted, mid-latitude fog waters, showing that the enhancement of 1O2* on ice is environmentally relevant and that 1O2* could be a significant sink for electron-rich organic compounds in snow.

Measurement of loss rates of organic compounds in snow using in situ experiments and isotopically labelled compounds

Organic molecular marker compounds are widely used to identify emissions from anthropogenic and biogenic air pollution sources in atmospheric samples and in deposition. Specific organic compounds have been detected in polar regions, but their fate after deposition to snow is poorly characterized. Within this context, a series of exposure experiments were carried out to observe the post-depositional processing of organic compounds under real-world conditions in snow on the surface of the Greenland Ice Sheet, at the Summit research station. Snow was prepared from water spiked with isotopically labelled organic compounds, representative of typical molecular marker compounds emitted from anthropogenic activities. Reaction rate constants and reaction order were determined based on a decrease in concentration to a stable, non-zero, threshold concentration. Fluoranthene- d 10 , docosane- d 46 , hexadecanoic acid- d 31 , docosanoic acid- d 43 and azelaic acid- d 14 were estimated to have first order loss rates within surface snow with reaction rate constants of 0.068, 0.040, 0.070, 0.067 and 0.047 h -1 , respectively. No loss of heptadecane- d 36 was observed. Overall, these results suggest that organic contaminants are archived in polar snow, although significant post-depositional losses of specific organic compounds occur. This has implications for the environmental fate of organic contaminants, as well as for ice-core studies that seek to use organic molecular markers to infer past atmospheric loadings, and source emissions. Keywords: Snow; photochemistry; air pollution; Greenland; Arctic To access the supplementary material to this article: 'Supplementary Figures & Table' and 'Supplementary File', please see Supplementary files in the column to the right (under Article Tools). (Published: 26 July 2012) Citation: Polar Research 2012, 31 , 11597, http://dx.doi.org/10.3402/polar.v31i0.11597

Snow - a photobiochemical exchange platform for volatile and semi-volatile organic compounds with the atmosphere

Environmental context Recent research has been directed towards the exchange of microorganisms and chemical compounds between snow and air. We investigate how microorganisms and chemical species in snow from the Arctic and temperate regions are transferred to the atmosphere and altered by the sun's energy. Results suggest that snow photo-biochemical reactions, in addition to physical‐chemical reactions, should be considered in describing organic matter in air–snow exchanges, and in investigations of climate change. AbstractField and laboratory studies of organic compounds in snow (12 species; concentrations ≤17 µg L–1) were conducted and microorganisms in snow and aerosols at urban and Arctic sites were investigated (snow: total bacteria count ≤40000 colony forming units per millilitre (CFU mL–1), fungi ≤400 CFU mL–1; air: bacteria ≤2.2 × 107 CFU m–3, fungi ≤84 CFU m–3). Bio-organic material is transferred between snow and air and influence on snow-air exchange processes is demonstrated. Volatile organic compounds in snow are released into the air upon melting. In vitro photochemistry indicated an increase of ≤60 µg L–1 for 1,3- and 1,4-dimethylbenzenes. Bacillus cereus was identified and observed in snow and air with ice-nucleating being P. syringae absent. As a result snow photobiochemical reactions should be considered in describing organic matter air–snow exchanges, and the investigation of climate change.

Volatile organic compounds in snow in the Quebec‐Windsor Corridor

Volatile organic compounds (VOC) were determined in snow to investigate the role of the snowpack as an exchange medium for atmospherically active compounds of anthropogenic and biogenic origin. The major question was which VOC species occur in snow and how the species identity and selected concentrations are related to the sampling area and environmental conditions. Samples were collected using a standardized sampling protocol in two distinct areas in six locations (near Mont‐Saint‐Hilaire, 45°33′06″N, 73°03′03″W (semirural) and Mont Tremblant, 46°20′11″N, 74°30′36″W (rural) in the heavily populated Quebec‐Windsor Corridor, Canada, with different characteristics regarding location and proximity to urban centers. A solid‐phase microextraction (SPME) procedure was employed for analysis, and VOC were identified using a gas chromatography method with mass spectrometric detection (GC/MS). Results revealed a broad spectrum of VOC in snow samples, including ethers, aldehydes, and aromatic and halogenated compounds, all of them active precursors for atmospheric reactions. Quantification was carried out for 11 aromatic and/or oxygenated compounds. Concentrations were found to be between 1.0 ± 0.2 ng/L (ethylbenzene) and 2.67 ± 0.06 μg/L (acetophenone), and limits of detection varied between 0.30 ng/L (benzene) and 78.2 ng/L (benzaldehyde). Principal component analysis was carried out to assess similarities between the sampling locations based on the types of species identified and concentration profiles. We discuss the implication of our results for atmosphere‐snowpack interactions of VOC including back trajectory calculations for the sampling dates.

A method for the analysis of ultra-trace levels of semi-volatile and non-volatile organic compounds in snow and application to a Greenland snow pit

A method was developed to quantify a suite of organic compounds from snow melt water samples present at trace level concentrations, using a dichloromethane liquid–liquid extraction and GC–MS. Samples from a 3-m snow pit sampled in 2005 from Summit, Greenland were analyzed using the method developed, and a profile of organics over the past ∼4 years was compiled. Supporting data including the concentrations of total organic carbon (TOC), low molecular weight acids, and trace elements were determined using well established methods. The results show that low molecular weight acids contribute a significant percentage, up to 20%, of the measured TOC. Hopanes were measured quantitatively for the first time in Greenland snow. Hopanes, as well as PAHs, are at very low concentrations and contribute 0.0002–0.004% to TOC. Alkanes and alkanoic acids were also quantified, and contribute less than 1% and up to 7%, respectively to TOC. No apparent seasonal pattern was found for specific classes of organic compounds in the snow pit. The lack of seasonal pattern may be due to post-depositional processing.

Determination of a wide range of volatile and semivolatile organic compounds in snow by use of solid-phase micro-extraction (SPME)

Quantification and transformation of organic compounds are pivotal in understanding atmospheric processes, because such compounds contribute to the oxidative capacity of the atmosphere and drive climate change. It has recently been recognized that chemical reactions in snow play a role in the production or destruction of photolabile volatile organic compounds (VOC). We present an environmentally friendly method for determination of VOC and semi-VOC in snow collected at three sites-remote, urban, and (sub-)arctic. A solid-phase micro-extraction (SPME) procedure was developed and (semi-)VOC were identified by gas chromatography with mass spectrometric detection (GC-MS). A broad spectrum of (semi-)VOC was found in snow samples, including aldehydes, and aromatic and halogenated compounds. Quantification was performed for 12 aromatic and/or oxygenated compounds frequently observed in snow by use of neat standard solutions. The concentrations detected were between 0.12 (styrene and ethylbenzene) and 316 microg L(-1) (toluene) and limits of detection varied between 0.11 (styrene) and 1.93 microg L(-1) (benzaldehyde). These results indicate that the SPME technique presented is a broad but selective, versatile, solvent-free, ecological, economical, and facile method of analysis for (semi-)VOC in natural snow samples.

Chemical interactions with snow: Understanding the behavior and fate of semi-volatile organic compounds in snow

Snow plays an important role in providing atmospherically derived semi-volatile organic compounds (SVOCs) to regions of high latitude and altitude. The accumulated winter snowpack serves as a reservoir for SVOCs, which may then be released to arctic/alpine catchments during seasonal snowmelt or entrained into deeper layers of snow and ice. This paper provides a review of the occurrence of SVOCs in snow, exploring sampling methodologies and field measurements. Furthermore, chemical fate following snowfall and the propensity of SVOCs to undergo revolatilization with snow metamorphosis are examined along with air–snow partitioning and the role of physical parameters such as snow density and snow surface area in controlling vapor-sorbed levels. Snowmelt and firnification processes are described, and the latter are related to SVOC measurements made in deeper snow layers and glacial ice cores. Evidence is provided that suggests that those SVOCs that possess relatively higher snow interfacial/air partitioning coefficients ( K ia snow ) or lower Henry's Law constants may be more efficiently retained in snow, with implications for the occurrence of currently used pesticides in the temperate mountain snowpack.

Climatic and environmental implications from organic matter in Dasuopu glacier in Xixiabangma in Qinghai-Tibetan Plateau

A series of organic compounds in snow and ice were identified from Dasuopu glacier in Xixiabangma in Qinghai-Tibetan Plateau. Organic compounds derived from natural organisms include n-alkanes ranging from C15 to C33, normal monocarboxylic acids of C 6 -C 18 , n-alkan-2-ones of C 24 -C 31 and esters. The unstable compounds widely present in lower troposphere disppear in the middle-upper troposphere. I^ots of other organic compounds from petroleum residues were also unexpectedly identified from the glacier, covering pristane, phytane, extended tricyclic terpanes of C 19 -C 29 , C 24 tetracyclic terpane, αβ hopane compounds of C 27 -C 35 , and cholestanes of C 27 -C 29 . The remote Xixiabangma region is unambiguously polluted from anthropology activities. The petroleum residues were proposed to be mainly from the Mideast and India, not from China. The organic pollutants from oil fires ignited during the well-known Gulf War which broke out in 1991 were also recorded in the glacier. Such organic indexes as n C 29 / n C1 7 , nC29/nC27 , n C29/ nC 24 , C 30 -ketone/C 30 -ester, C 24 -tetracyclic-/C 24 -tricyclic-terpane and CPIn ( n standing for n -alkanes) exhibit the same strong seasonal variation as δ 18 0, providing information on the atmospheric circulation of the plateau. These ratios decrease in summer half year when the monsoon dominated, and increase in winter half year when the westerly stream jet dominated.

Analysis of Organic Compounds in Antarctic Snow and Their Origin

Organic compounds extractable with n-hexane were identified and quantitatively determined in pack, surface and deep snow samples taken at different depths and collected at several altitudes above sea level from Antarctica during the 1993/94 Italian expedition. The comparison between the composition of organic compounds in snow and the ones in pack and sea-water samples pointed out that the three matrices substantially contain the same biogenic and anthropogenic organic compounds. The contribution of marine aerosol to organic content in the snow is confirmed by the enrichment ratios calculated for the more representative classes of identified compounds (n-alkanes, phthalates and low molecular weight alkylbenzenes). The changes in the composition of organic compounds in snow as the altitude increases seem to depend on the dimensional spectrum of the aerosol. Thus, smallest particles, richest in surfactant material, reach the highest altitudes.