Sources and elemental composition of summer aerosols in the Larsemann Hills (Antarctica)

Atmospheric aerosols play a major role in the global climate change. A better physical characterization of the chemical composition of atmospheric aerosols, especially in remote atmosphere, is an important step to reduce the current uncertainty in their effect on the radiative forcing of the climate. In the present work, surface aerosols have been studied over the Southern Ocean and over Bharati, Indian Research Station at Larsemann Hills at the Antarctic coast during the summer season of 2009-2010. Aerosol samples were collected using optical particle counter (OPC) and high-volume air sampler. PM10 and PM2.5 aerosol samples were analyzed for various water-soluble and acid-soluble ionic constituents. The Hysplit model was used to compute the history of the air masses for their possible origin. Supplementary measurements of meteorological parameters were also used. The average mass concentration for PM10 over the Southern Ocean was found to be 13.4 μg m(3). Over coastal Antarctica, the mass of PM10 was 5.13 μg m(-3), whereas that of PM2.5 was 4.3 μg m(-3). Contribution of marine components, i.e., Na, Cl and Mg was dominant over the Southern Ocean (79 %) than over the coastal Antarctica where they were dominant in coarse mode (67 %) than in fine mode (53 %) aerosols. The NH4/nss-SO4 ratio of 1.12 in PM2.5 indicates that the NH4 and SO4 ions were in the form of NH4HSO4. Computation of enrichment factors indicate that elements of anthropogenic origin, e.g., Zn, Cu, Pb, etc., were highly enriched with respect to crustal composition.

Mercury in precipitation over the coastal zone of the southern Baltic Sea, Poland

An investigation of atmospheric mercury was conducted in the urban coastal zone of the Gulf of Gdansk (Baltic Sea, Poland) in 2008. Rainwater samples were collected in bulk samplers and Hg concentration was determined using AAS method. Total mercury concentration ranged from 1.9 to 14.8 ng l(-1) (the mean was 8.3 ng l(-1) with standard deviation ±3.7), out of which about 34 % were water-soluble Hg(II) forms. Distribution of Hg species in rainwater was related to both the emission source and the atmospheric processes. During the sampling period, two maxima of Hg concentration in precipitation were observed: the first in the cold season and the second one in the warm season. Elevated concentrations of Hg in wintertime precipitation were generally the result of local urban atmospheric emission connected with the following anthropogenic sources: intensive combustion of fossil fuels in domestic furnaces, individual power/heat generating plants, and motor vehicles. During summertime, Hg° re-emitted from contaminated land and sea surfaces was photochemically oxidized by active atmospheric substances (e.g., hydroxyl radicals, hydrogen peroxide, halogens) and could be an additional source of atmospherically deposited Hg. The results presented in this work indicate that rainwater Hg concentration and deposition values are not much higher in comparison with other urban locations along the Baltic Sea basin and other coastal cities. However, the elevated mercury concentration in rainwater and, consequently, higher deposition ratio could appear occasionally as an effect of intensive anthropogenic emissions (domestic heating) and/or photochemical reactions.

Chemical and morphological characteristics of solid metal-bearing phases deposited in snow and stream sediment as indicators of their origin

Detailed scanning electron microscopy/energy dispersive spectroscopy of metal-bearing particles in snow deposits and stream sediment from a steelworks area was performed. Identified metal-bearing phases were apportioned according to their chemical and morphological characteristics to anthropogenic phases and secondary weathering products. Anthropogenic metal-bearing phases are the most abundant in both media and are represented by various irregular ferrous oxides, ferrous alloys, spherical ferrous oxides, and ferrous silicates with variable contents of Cr, Mn, Ni, V, W, and Mo. Secondary weathering products are Al silicates, Fe oxy-hydroxides, and Fe oxy-hydroxy sulfates with minor contents of transition metals, resulting from weathering of anthropogenic phases and Pb-Zn ore minerals from a closed Pb-Zn mine located upstream from the study area. Comparison of anthropogenic metal-bearing phases in both media showed agreement in their compositions and morphologies and indicated their sources are high-temperature processes in steel production. It also showed that spherical metal-bearing phases were transported by the same transport medium, which is the atmosphere, while other phases were transported into stream sediment mostly by other pathways, such as precipitation runoff over contaminated surfaces.

[Spatial distribution characteristics of the physical and chemical properties of water in the Kunes River after the supply of snowmelt during spring]

Eight physical and chemical indicators related to water quality were monitored from nineteen sampling sites along the Kunes River at the end of snowmelt season in spring. To investigate the spatial distribution characteristics of water physical and chemical properties, cluster analysis (CA), discriminant analysis (DA) and principal component analysis (PCA) are employed. The result of cluster analysis showed that the Kunes River could be divided into three reaches according to the similarities of water physical and chemical properties among sampling sites, representing the upstream, midstream and downstream of the river, respectively; The result of discriminant analysis demonstrated that the reliability of such a classification was high, and DO, Cl- and BOD5 were the significant indexes leading to this classification; Three principal components were extracted on the basis of the principal component analysis, in which accumulative variance contribution could reach 86.90%. The result of principal component analysis also indicated that water physical and chemical properties were mostly affected by EC, ORP, NO3(-) -N, NH4(+) -N, Cl- and BOD5. The sorted results of principal component scores in each sampling sites showed that the water quality was mainly influenced by DO in upstream, by pH in midstream, and by the rest of indicators in downstream. The order of comprehensive scores for principal components revealed that the water quality degraded from the upstream to downstream, i.e., the upstream had the best water quality, followed by the midstream, while the water quality at downstream was the worst. This result corresponded exactly to the three reaches classified using cluster analysis. Anthropogenic activity and the accumulation of pollutants along the river were probably the main reasons leading to this spatial difference.

New insights into trace element wet deposition in the Himalayas: amounts, seasonal patterns, and implications

Our research provides the first complete year-long dataset of wet deposition of trace elements in the high Himalayas based on a total of 42 wet deposition events on the northern slope of Mt. Qomolangma (Everest). Except for typical crustal elements (Al, Fe, and Mn), the concentration level of most trace elements (Sc, V, Cr, Co, Ni, Cu, Zn, As, Mo, Cd, Sn, Cs, Pb, Bi, and U) are generally comparable to those preserved in snow pits and ice cores from the nearby East Rongbuk Glacier. Cadmium was the element most affected by anthropogenic emissions. No pronounced seasonal variations are observed for most trace elements despite different transport pathways. In our study, the composition of wet precipitation reflects a regional background condition and is not clearly related to specific source regions. For the trace element record from ice cores and snow pits in the Himalayas, it could be deduced that the pronounced seasonal patterns were caused by the dry deposition of trace elements (aerosols) during their long exposure to the atmosphere after precipitation events. Our findings are of value for the understanding of the trace element deposition mechanisms in the Himalayas.

Hydrochemistry dynamics in remote mountain lakes and its relation to catchment and atmospheric features: the case study of Sabocos Tarn, Pyrenees

Increasing the understanding of high mountain lake dynamics is essential to use these remote aquatic ecosystems as proxies of global environmental changes. With this aim, at Sabocos, a Pyrenean cirque glacial lake or tarn, this study shows the main results of a morphological and catchment characterization, along with statistical analyses of its hydrochemical trends and their concomitant driving factors from 2010 to 2013. Dissolved oxygen, water temperature stratification, and its snow and ice cover composition and dynamics have been also investigated. According to morphological analyses, Sabocos can be classified as a medium-large and deep lake, having a circular contour and a long water retention time as compared to Pyrenean glacial lake average values. Sabocos hydrochemistry is mainly determined by very high alkalinity, pH and conductivity levels, and high Ca(2+), Mg(2+), and SO4(2-) content, coming from the easily weatherable limestone-dolomite bedrock. Thus, lake water is well buffered, and therefore, Sabocos tarn is non-sensitive to acidification processes. On the other hand, the main source of K(+), Na(+), and Cl(-) (sea salts) and nutrients (NH4(+), NO3(-), and phosphorous) to lake water appears to be atmospheric deposition. Primary production is phosphorous limited, and due to the N-saturation stage of the poorly developed soils of Sabocos catchment, NO3(-) is the chief component in the total nitrogen pool. External temperature seems to be the major driver regulating lake productivity, since warm temperatures boot primary production. Although precipitation might also play an important role in lake dynamics, especially regarding to those parameters influenced by the weathering of the bedrock, its influence cannot be easily assessed due to the seasonal isolation produced by the ice cover. Also, as occurs in the whole Pyrenean lake district, chemical composition of bulk deposition is highly variable due to the contribution of air masses with different origin.

Spatial distribution and potential sources of trace metals in insoluble particles of snow from Urumqi, China

The purpose of this work is to characterize trace elements in snow in urban-suburb gradient over Urumqi city, China. The spatial distribution patterns of 11 trace metals in insoluble particulate matters of snow were revealed by using 102 snow samples collected in and around urban areas of Urumqi, a city suffering from severe wintertime air pollution in China. Similar spatial distribution for Mn, Cu, Zn, Ni, and Pb was found and their two significant high-value areas located in the west and east, respectively, and a high-value area in the south, which were correlated with factory emissions, traffic activities, and construction fugitive dust. The high-value areas of Cr, Ni, and V occurred in the northeast corner and along main traffic paths, which were linked to oil refinery and vehicular emissions. High value of Be presented in the west of the city. The high-value area of Co in the northeast could be related to local soil. Cd and U displayed relatively even spatial patterns in the urban area. In view of distance from the urban center, e.g., from the first circular belt to the fourth circular belt, except Be, V, Cd, and U, the contents of other metals generally decreased from the first circular belt to the forth circular belt, implying the effect of human activity clearly. Additionally, prevailing northwesterly winds and occasionally southeasterly winds in winter were associated with decreased, generally, concentrations of trace metal in snow from the urban center to the southern suburb along a northwest and southeast transect. The information on concentrations and spatial distributions of these metals in insoluble particles of snow in winter will be valuable for further environmental protection and planning.

Size distribution of airborne particle-bound polybrominated diphenyl ethers and its implications for dry and wet deposition

Size distribution of particles in part dictates the environmental behavior of particle-bound organic pollutants in the atmosphere. The present study was conducted to examine the potential mechanisms responsible for the distribution of organic pollutants in size fractionated particles and their environmental implications, using an e-waste recycling zone in South China as a case study. Size-fractionated atmospheric particles were collected at the heights of 1.5, 5, and 20 m near two residential apartments and analyzed for polybrominated diphenyl ethers (PBDEs). The concentrations of particle-bound ΣPBDE (sum of 18 PBDE congeners) were significantly greater at 5 and 20 m than those at 1.5 m. The size-fractionated distributions of airborne ΣPBDE displayed trimodal peaks in 0.10–0.18, 1.8–3.2, and 10–18 μm at 1.5 m but only an unimodal peak in 1.0–1.8 μm at 20 m height. Emission sources, resuspension of dust and soil, and volatility of PBDEs were important factors influencing the size distribution of particle-bound PBDEs. The dry deposition fluxes of particle-bound PBDE estimated from the measured data in the present study were approximately twice the estimated wet deposition fluxes, with a total deposition flux of 3000 ng m(–2) d(–1). The relative contributions of particles to dry and wet deposition fluxes were also size-dependent, e.g., coarse (aerodynamic diameters (Dp) > 1.8 μm) and fine (Dp < 1.8 μm) particles dominated the dry and wet deposition fluxes of PBDEs, respectively.

Urban snow indicates pollution originating from road traffic

Traffic is a major source of pollutants in cities. In this well-replicated study we analysed a broad array of contaminants in snowpacks along roads of different traffic intensities. The majority of pollutants showed a similar pattern with respect to traffic intensity: pH and conductivity as well as concentrations of PAHs, total suspended solids, phosphorus and most heavy metals were higher next to high intensity roads compared to low intensity roads. These pollutant levels also decreased considerably up to 5 m distance from the roads. Furthermore, apart from nitrogen, these variables increased in concentration from control sites in urban forest patches to road bank sites next to roads of low, intermediate and high traffic intensities. The deposition pattern of various traffic-derived pollutants--whether gaseous or particle-bound--was the same. Such information can be useful for the purposes of managing pollutants in urban areas.

Features of air masses associated with the deposition of Pseudomonas syringae and Botrytis cinerea by rain and snowfall

Clarifying the role of precipitation in microbial dissemination is essential for elucidating the processes involved in disease emergence and spread. The ecology of Pseudomonas syringae and its presence throughout the water cycle makes it an excellent model to address this issue. In this study, 90 samples of freshly fallen rain and snow collected from 2005-2011 in France were analyzed for microbiological composition. The conditions favorable for dissemination of P. syringae by this precipitation were investigated by (i) estimating the physical properties and backward trajectories of the air masses associated with each precipitation event and by (ii) characterizing precipitation chemistry, and genetic and phenotypic structures of populations. A parallel study with the fungus Botrytis cinerea was also performed for comparison. Results showed that (i) the relationship of P. syringae to precipitation as a dissemination vector is not the same for snowfall and rainfall, whereas it is the same for B. cinerea and (ii) the occurrence of P. syringae in precipitation can be linked to electrical conductivity and pH of water, the trajectory of the air mass associated with the precipitation and certain physical conditions of the air mass (i.e. temperature, solar radiation exposure, distance traveled), whereas these predictions are different for B. cinerea. These results are pertinent to understanding microbial survival, emission sources and atmospheric processes and how they influence microbial dissemination.

Volatile organic compounds in Arctic snow: concentrations and implications for atmospheric processes

The role of volatile organic compounds (VOC) in the snowpack for atmospheric oxidation, gas-particle transfer and aerosol formation remains poorly understood, partly due to a lack of methodology and unavailable data. We deployed solid phase micro-extraction (SPME) gas chromatography with flame ionization detection for measurement of halogenated, aromatic and oxygenated VOC in the snow pack in Alert, NU, Canada, a High Arctic site. Maximum concentrations in snow were 39 ± 6 μg L(-1) (styrene), indicating a potential VOC contribution to atmospheric oxidation and aerosol formation. Concurrently sampled air had concentrations of up to 1.0 ± 0.3 ng L(-1) (trichloroethene). Back trajectory data showed a change of air mass source region during a depletion event of several VOC in snow (e.g., trichloroethene and benzene). Snow profiles showed an enrichment of most compounds close to the surface. During a second study in Barrow, AK, USA VOC were quantified in snow and frost flowers in the Montreal lab. In Barrow work was carried out as part of the extensive OASIS (Ocean-Atmosphere-Sea Ice-Snowpack) field campaign. Maximum VOC concentrations were up to 1.3 ± 0.1 μg L(-1) (acetophenone). Bromoform in frost flowers averaged 0.19 ± 0.04 μg L(-1), indicating the potential to contribute to bromine generation through photolysis.

Persistent organic pollutant accumulation in seasonal snow along an altitudinal gradient in the Tyrolean Alps

The snow capacity for storage of a large number of pollutants such as polybromodiphenyl ethers (PBDE), including BDE-209, polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs), hexachlorocyclohexanes (HCHs; α- and γ-isomers), endosulfans (α- and β-isomers and the sulphate residue) and hexachlorobenzene (HCB), in a steep altitudinal gradient (1,101-2,500 m above sea level (asl); maximum planar distance 16 km) in a typical European mountain system, the Tyrolean Alps (Austria), was studied here for the first time. Snow samples representing the whole snowpack accumulated at the end of the cold season were collected in all cases. The snow specific surface area (SSA) of these samples, 140-260 cm(2) g(-1), was characteristic of aged snow with low retention capacity. PAHs were the pollutant group in highest concentrations (500-8,400 pg L(-1)). PCBs and PBDEs were found in concentrations of 460-900 and 8.5-290 pg L(-1), respectively. From the fourteen investigated BDE congeners, only BDE-47, BDE-99, BDE-100 and BDE-209 were found above the detection limit, which is consistent with the results found in the only previous study in the Tatra Mountains (Slovakia) which also involved a steep gradient (1,683-2,634 m asl; maximum planar distance 5 km; Arellano et al. 2011) and confirm the capacity of these low-volatile compounds for long-range transport from distant sources. HCB was found in a concentration range of 34-55 pg L(-1). Snow deposition fluxes of PCB-118, PCB-153, γ-HCH, α-endosulfan and BDE-47 showed statistically significant correlations with altitude, involving higher values at higher elevation. This trend may reflect cold trapping effects in view of the snow particle contents and SSA values. However, these gradients were only significant for this limited number of compounds within each pollutant group which may be explained by differences in physical-chemical properties of the compounds and the limited capacity of the aged snow for organic pollutant retention. In some other cases, for example benzo[a]pyrene, the observed vertical gradients may reflect higher preservations at lower temperatures.

Measuring solids concentrations in urban stormwater and snowmelt: a new operational procedure

A comparative study of five methods measuring suspended sediment or solid concentrations in water-sediment mixtures indicated that, depending on the method used, broadly varying results can be obtained. For water-sediment mixtures containing sand size particles, the standard TSS method produced negatively biased results, accounting for 0 to 90% of the present solids; the negative bias directly depended on the magnitude of the sand fraction in the water-sediment mixture. The main reason for the differences between the TSS and the rest of the methods laid in the handling of samples; in the former methods, whole samples were analysed, whereas the TSS analysis was performed on sub-samples withdrawn from the water sample, the withdrawal process tending to exclude large particles. The methods using whole water-solid samples, rather than aliquots withdrawn from such samples, produced accurate estimates of solid concentrations, with a fairly good precision. Two whole-sample methods were studied in detail, a slightly modified standard SSC-B method and the newly proposed operational procedure referred to as the Multiple Filter Procedure (MFP), using three filters arranged in a series with decreasing pore sizes (25, 1.6 and 0.45 µm). Both methods assessed accurately concentrations of solids in a broad range of concentrations (200-8000 mg L(-1)) and particle sizes (0.063-4.0 mm). The newly introduced MFP was in good agreement with the SSC procedure, the differences between the two procedures not exceeding the standard bias defined for the SSC-B method. The precision of both SSC and MFP was generally better than ±10%. Consequently, these methods should be used when the total mass of transported solids is of interest.

20th century atmospheric deposition and acidification trends in lakes of the Sierra Nevada, California, USA

We investigated multiple lines of evidence to determine if observed and paleo-reconstructed changes in acid neutralizing capacity (ANC) in Sierra Nevada lakes were the result of changes in 20th century atmospheric deposition. Spheroidal carbonaceous particles (SCPs) (indicator of anthropogenic atmospheric deposition) and biogenic silica and δ(13)C (productivity proxies) in lake sediments, nitrogen and sulfur emission inventories, climate variables, and long-term hydrochemistry records were compared to reconstructed ANC trends in Moat Lake. The initial decline in ANC at Moat Lake occurred between 1920 and 1930, when hydrogen ion deposition was approximately 74 eq ha(-1) yr(-1), and ANC recovered between 1970 and 2005. Reconstructed ANC in Moat Lake was negatively correlated with SCPs and sulfur dioxide emissions (p = 0.031 and p = 0.009). Reconstructed ANC patterns were not correlated with climate, productivity, or nitrogen oxide emissions. Late 20th century recovery of ANC at Moat Lake is supported by increasing ANC and decreasing sulfate in Emerald Lake between 1983 and 2011 (p < 0.0001). We conclude that ANC depletion at Moat and Emerald lakes was principally caused by acid deposition, and recovery in ANC after 1970 can be attributed to the United States Clean Air Act.

[Monitoring of the chemical composition of snow cover pollution in the Moscow region]

Monitoring of snow cover pollution as an indicator of ambient air pollution in 20 districts in the Moscow region during 2009-2013 was performed. The identification with a quantitative assessment of a wide array of organic compounds and the control of the main physical and chemical and inorganic indices of snow water pollution were carried out. More than 60 organic substances for most of which there are no the hygienic standards were established. The assessment of pollution levels of basic inorganic indices was given by means of the comparing them with the average values in the snow cover in the European territory of Russia and natural content in areas not been exposed to human impact.

The fate of per- and polyfluoroalkyl substances within a melting snowpack of a boreal forest

Per- and polyfluoroalkyl substances (PFAS) were measured systematically in a snowpack in northern Sweden to determine chemical behaviour during seasonal melt. Average PFAS concentrations were generally low, but displayed a wide range with median (range) concentrations of PFOA and PFOS of 66.5 pg L(-1) (ND-122) and 20.5 pg L(-1) (2.60-253) respectively. Average concentrations of the shorter chain, C4 and C5 perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs), were ∼10-fold higher. Differences in the PFAS concentrations and profile were observed between surface snow and deeper layers, with evidence of PFAS migration to deeper snow layers as melt progressed. Chemical loads (ng m(-2)) for C4-9 PFCAs decreased gradually as melt progressed, but increased for C4, C6-8 PFSAs and the longer chain C10-12 PFCAs. This enrichment in the diminishing snowpack is an unusual phenomenon that will affect PFAS elution with meltwater and subsequent entry to catchment surface waters.

Seasonal variations in the sources of natural and anthropogenic lead deposited at the East Rongbuk Glacier in the high-altitude Himalayas

Lead (Pb) isotopic compositions and concentrations, and barium (Ba) and indium (In) concentrations have been analysed at sub-annual resolution in three sections from a <110 m ice core dated to the 18th and 20th centuries, as well as snow pit samples dated to 2004/2005, recovered from the East Rongbuk Glacier in the high-altitude Himalayas. Ice core sections indicate that atmospheric chemistry prior to ~1,953 was controlled by mineral dust inputs, with no discernible volcanic or anthropogenic contributions. Eighteenth century monsoon ice core chemistry is indicative of dominant contributions from local Himalayan sources; non-monsoon ice core chemistry is linked to contributions from local (Himalayan), regional (Indian/Thar Desert) and long-range (North Africa, Central Asia) sources. Twentieth century monsoon and non-monsoon ice core data demonstrate similar seasonal sources of mineral dust, however with a transition to less-radiogenic isotopic signatures that suggests local and regional climate/environmental change. The snow pit record demonstrates natural and anthropogenic contributions during both seasons, with increased anthropogenic influence during non-monsoon times. Monsoon anthropogenic inputs are most likely sourced to South/South-East Asia and/or India, whereas non-monsoon anthropogenic inputs are most likely sourced to India and Central Asia.

Trace analysis of hydrophobic micropollutants in aqueous samples using capillary traps

Studying the fate of persistent organic pollutants (POPs) in glacier environments scientist face the challenge of snow and ice samples, in which concentrations of these pollutants are at the ultra-trace level and the amount of sample available is often very limited. We have improved an extraction method for hydrophobic organic pollutants such as polychlorinated biphenyls (PCBs) in aqueous media to meet the requirements of these challenging samples. It is based on partitioning of the analytes from the water into the polydimethylsiloxane (PDMS) coating of an open tubular-fused-silica capillary. By comparison with conventional liquid-liquid extraction, we validated the method for six indicator PCBs, covering a wide range of polarity. The new method has very low detection limits of 10-20pg/L for the investigated PCBs, a small uncertainty between 9% and 37%, depending on concentration, and requires a small sample volume of less than one liter. Further, it is characterized by easy handling and reduced organic solvents consumption. The method is comparatively insensitive to contamination, reproducible, and suitable for a wide range of applications.

Origin and sources of dissolved organic matter in snow on the East Antarctic ice sheet

Polar ice sheets hold a significant pool of the world's carbon reserve and are an integral component of the global carbon cycle. Yet, organic carbon composition and cycling in these systems is least understood. Here, we use ultrahigh resolution mass spectrometry to elucidate, at an unprecedented level, molecular details of dissolved organic matter (DOM) in Antarctic snow. Tens of thousands of distinct molecular species are identified, providing clues to the nature and sources of organic carbon in Antarctica. We show that many of the identified supraglacial organic matter formulas are consistent with material from microbial sources, and terrestrial inputs of vascular plant-derived materials are likely more important sources of organic carbon to Antarctica than previously thought. Black carbon-like material apparently originating from biomass burning in South America is also present, while a smaller fraction originated from soil humics and appears to be photochemically or microbially modified. In addition to remote continental sources, we document signals of oceanic emissions of primary aerosols and secondary organic aerosol precursors. The new insights on the diversity of organic species in Antarctic snowpack reinforce the importance of studying organic carbon associated with the Earth's polar regions in the face of changing climate.

Forensic source differentiation of petrogenic, pyrogenic, and biogenic hydrocarbons in Canadian oil sands environmental samples

To facilitate monitoring efforts, a forensic chemical fingerprinting methodology has been applied to characterize and differentiate pyrogenic (combustion derived) and biogenic (organism derived) hydrocarbons from petrogenic (petroleum derived) hydrocarbons in environmental samples from the Canadian oil sands region. Between 2009 and 2012, hundreds of oil sands environmental samples including water (snowmelt water, river water, and tailings pond water) and sediments (from river beds and tailings ponds) have been analyzed. These samples were taken from sites where assessments of wild fish health, invertebrate communities, toxicology and detailed chemistry are being conducted as part of the Canada-Alberta Joint Oil Sands Monitoring Plan (JOSMP). This study describes the distribution patterns and potential sources of PAHs from these integrated JOSMP study sites, and findings will be linked to responses in laboratory bioassays and in wild organisms collected from these same sites. It was determined that hydrocarbons in Athabasca River sediments and waters were most likely from four sources: (1) petrogenic heavy oil sands bitumen; (2) biogenic compounds; (3) petrogenic hydrocarbons of other lighter fuel oils; and (4) pyrogenic PAHs. PAHs and biomarkers detected in snowmelt water samples collected near mining operations imply that these materials are derived from oil sands particulates (from open pit mines, stacks and coke piles).

[Chemical characteristics and insoluble particulates' surface morphology of a snowfall process in the southeastern suburb of Urumqi]

In order to understand the composition and potential pollution of metal elements in precipitation in the southeastern suburb of Urumqi on February 21 to 23, 2012, soluble elements were determined by inductively coupled plasma mass spectrometry (ICP-MS); in addition, energy spectrum and morphological analysis were made for insoluble particulates. The results showed that the content of toxic heavy metals in snowfall was a little high; and the enrichment factors of Se, As and Cd were 124.65, 57.69 and 36.70, respectively, showing a typical coal pollution characteristic. The back trajectory cluster analysis suggested that the coal fly ash of snowfall mainly induced by air masses originated from the coal-fire power plant in the Southwestern sampling site. Morphology analyses conducted under an scan electron microscope demonstrated fly ash coming from coal burning process and irregular mineral are in the majority of insoluble particulates in snowfall, soot aggregates were compact, when the soot was wetted (the hygroscopic behaviour), and the morphology changed further. Insoluble particulates of the southeastern suburb of Urumqi were coal fly ash and insoluble soil minerals.

Degradation of organic pollutants in/on snow and ice by singlet molecular oxygen (¹O₂*) and an organic triplet excited state

Singlet molecular oxygen (¹O₂*) can be a significant sink for a variety of electron-rich pollutants in surface waters and atmospheric drops. We recently found that ¹O₂* concentrations are enhanced by up to a factor of 10(4) on illuminated ice compared to in the equivalent liquid solution, suggesting that ¹O₂* could be an important oxidant for pollutants in snow. To examine this, here we study the degradation of three model organic pollutants: furfuryl alcohol (to represent furans), tryptophan (for aromatic amino acids), and bisphenol A (for phenols). Each compound was studied in illuminated aqueous solution and ice containing Rose Bengal (RB, a sensitizer for ¹O₂*) and sodium chloride (to adjust the concentration of total solutes). The RB-mediated loss of each organic compound is enhanced on illuminated ice compared to in solution, by factors of 6400 for furfuryl alcohol, 8300 for tryptophan, and 50 for bisphenol A for ice containing 0.065 mM total solutes. Rates of loss of furfuryl alcohol and tryptophan decrease at a higher total solute concentration, in qualitative agreement with predictions from freezing-point depression. In contrast, the loss of bisphenol A on ice is independent of total solute concentration. Relative to liquid tests, the enhanced loss of tryptophan on ice during control experiments made with deoxygenated solutions and solutions in D₂O show that the triplet excited state of Rose Bengal may also contribute to loss of pollutants on ice.

Ionic composition of wet precipitation over the southern slope of central Himalayas, Nepal

Severe atmospheric pollution transported to Himalayas from South Asia may affect fragile ecosystem and can be harmful for human health in the region. In order to understand the atmospheric chemistry in the southern slope of central Himalayas, where the data is limited, precipitation has been sampled at four sites: Kathmandu (1,314 m), Dhunche (2, 065 m), Dimsa (3,078 m), and Gosainkunda (4,417 m) in Nepal for over a 1-year period characterized by an urban, rural, and remote sites, respectively. HCO3 − is the dominant anion, while the NH4 + is the dominant cation in precipitation at the four sites. Generally, most of ions (e.g., SO4 2−, NO3 −, NH4 +, HCO3 −, and Ca2+) have higher concentrations in urban site compared to the rural sites. Neutralization factor calculation showed that precipitation in the region is highly neutralized by NH4 + and Ca2+. Empirical orthogonal function and correlation analysis indicated that the precipitation chemistry was mostly influenced by crustal, anthropogenic, and marine sources in Nepal. Among different sites, urban area was mostly influenced by anthropogenic inputs and crustal dusts, whereas remote sites were mostly from marine and crustal sources. Seasonal variations show higher ionic concentrations during non-monsoon seasons mainly due to limited precipitation amount. On the other hand, lower ionic concentrations were observed during monsoon season when higher amount of precipitation washes out aerosols. Thus, precipitation chemistry from this work can provide a useful database to evaluate atmospheric environment and its impacts on ecosystem in the southern slope of central Himalayas, Nepal.

Total mercury in snow and ice samples from Canadian High Arctic ice caps and glaciers: a practical procedure and method for total Hg quantification at low pg g(-1) level

A newly developed procedure and method for studying total Hg (THg) in the High Arctic glaciers and ice caps, including container type selection, on-site sampling, sample protection and storage, and sample decontamination is reported in this study. Two analytical systems for THg quantification were also compared to confirm the accuracy and reproducibility. This study found that container types, storage time, sample protection from exposure to light and environment are all important for precise quantification of THg in snow and ice samples from the Canadian High Arctic glaciers and ice caps. With this newly developed procedure and method, we retrieved 28-year and 73-year archives for atmospheric THg deposition from Mt. Oxford and Agassiz Ice Cap respectively. Our results show that snow and ice samples contain THg concentrations varying from sub pg g(-1) to low pg g(-1). Comparison of THg concentration trends and fluxes from the two sites demonstrates that quantification of THg from the two locations with similar altitudes and latitudes can be reproducible, which suggests that historical THg information from atmospheric deposition can be preserved in snow and ice in the glaciers and ice caps. The high reproducibility of results achieved by this procedure and method, in return, confirmed its suitability for studies of THg in snow and ice samples from ice caps and glaciers.

A Chinese imprint in insoluble pollutants recently deposited in central Greenland as indicated by lead isotopes

A unique ∼ 10 year record of the lead isotopic composition of airborne insoluble particulate matter deposited in central Greenland was extracted from recent snow layers at NorthGRIP (75.1°N, 042.3°W; elevation 2,959 m), spanning the years 1989-2001. Comparison with lead isotopic signatures of both natural and anthropogenic northern hemisphere (NH) aerosol sources shows that human activities must have accounted for most of the insoluble lead deposited on Greenland during the late 1990 s, exceeding by far the natural contribution from large Asian mineral dust inputs. Lead isotopes imply predominance with time of European/Canadian sources over U.S.-derived lead, with an admixed signature typical of Chinese anthropogenic lead sources. The relative contribution of the latter shows a marked seasonal increase during spring. Our record also suggests that China's weight in the overall supply of insoluble pollutants deposited on Greenland was growing over the past decade of the 20th century.