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PubMed2000

[Psycrophilic organisms in snow and ice].

Psychrophilic and psycrotrophic organisms are important in global ecology as a large proportion of our planet is cold. Two-third of sea-water covering more than 70% of Earth is cold deep sea water with temperature around 2 degrees C, and more than 90% of freshwater is in polar ice-sheets and mountain glaciers. Though biological activity in snow and ice had been believed to be extremely limited, various specialized biotic communities were recently discovered at glaciers of various part of the world. The glacier is relatively simple and closed ecosystem with special biotic community containing various psychrophilic and psycrotrophic organisms. Since psychrophilic organisms was discovered in the deep ice-core recovered from the antarctic ice-sheet and a lake beneath it, snow and ice environments in Mars and Europa are attracting a great deal of scientific attention as possible extraterrestrial habitats of life. This paper briefly reviews the results of the studies on ecology of psychrophilic organisms living in snow and ice environments and their physiological and biochemical adaptation to low temperature.

Antarctic Regions↗
PubMed2001

[Chemical characteristics of fresh snow in Mount Everest Region].

The chemistry of fresh snow samples collected in August and September, 1998 from Mount Everest was studied and compared with other fresh snow samples collected in different seasons in this region. The results indicated that major species in precipitation were very low in late summer in Mount Everest region and may be representative of the background of precipitation chemistry of remote regions in the wold. Chemical Characteristics of fresh snow in different seasons had distinct differences and they may reflect different moist source and climatic status. The precipitation in August and September was mainly come from Indian summer monsoon and in April and May it was influenced deeply by the dust of semi-arid and arid regions in central Asia. This indicates the precipitation in this region is climatic sensitively.

Calcium↗
PubMed1981

Epidemic of fractures during period of snow and ice.

During four days of snow and ice in which more than 70% of pavements in the Cardiff area were covered by slippery hard snow and ice the number of patients who attended the accident and emergency department at this hospital with fractured bones increased 2.85 times as compared with those who attended during four control days with comparable hours of sunshine and four control calendar days a year later. Fractures of the arm were increased 3.7 times and of the forearm and wrist 7.3 times. For a town population of one million people who may walk on untreated slippery and icy pavements this means that on average in a single day 74 more people than usual sustain a fracture unnecessarily. This traumatic epidemic has all the characteristics of a "major accident" and should be treated as such, since mobilisation of additional facilities, staff, and reserves might be necessary. Snow and ice injuries, however, differ from injuries sustained in a major accident in one important point: they may be predicted and prevented. The mass media should warn the population about the oncoming hazards and give practical advice on safer walking on slippery surfaces. The most important aspect of prevention, however, is instant cleaning of pavements around buildings, shops, and houses, especially in town centres and other areas busy with pedestrians.

Accident Prevention↗
PubMed1982

[Alpha-spectroscopic determination of 210Pb and 210PO in snow samples].

The concentrations of 210Pb and 210PO in several snow samples were determined using alpha-spectrometry. After 5 l of snow-melt water was subjected to coprecipitation of both nuclides with AlPO4, the solvent extraction procedure with TBP (tri-butyl phosphate)-isopropyl ether was applied to purify the polonium fraction, followed by the spontaneous electro-deposition on a Ni-sheet. The alpha-spectrum was measured with a Si(Au)-semiconductor detector coupled with a multichannel pulse-height analyzer. After the first determination of 210PO, the concentration of 210Pb was estimated from second measurement of 210PO grown newly from the remaining Pb-fraction during the storage period of more than 3 months. In these analytical procedures, 212Pb and 208PO tracers were conveniently utilized for the determination of collection yield for 210Pb and of the final chemical yield of 210PO, respectively. The contents of 210PO and 210Pb in the fresh snow were 3--30 mBq/l(81--810 fCi/l) and 250--720 mBq/l (6.8--19.5 pCi/l), respectively, and the residence time of 210Pb was given to be 6--12 days from the decay-growth relationships of both nuclides.

Alpha Particles↗
PubMed1995

Electrical charging of skis gliding on snow.

Ski charging was measured using giant-slalom style skis as gliding capacitors. The voltage measured across the plates was proportional to the charge on the base. While resting on dry snow or suspended in the air, the voltage was slowly reduced by the data logger itself. On wet snow the decay was much faster. While stationary on powder snow the ski developed a slightly negative voltage, showed a small, transient positive peak when motion began, rapidly dropped to negative values, and then assumed a quasi-steady climb to positive voltages. A great deal of noise was superimposed on the general features of the signal when skiing on hard or bumpy surfaces. Thus, the accumulation of charge to high levels was only possible with long runs in deep powder. The rate of charging increased with speed but was not affected by use of one "antistatic" wax, and another such wax actually increased the measured voltage over that of an unwaxed base.

Air↗
PubMed1998

Hormones and territorial behavior during breeding in snow buntings (Plectrophenax nivalis): an Arctic-breeding songbird.

We examined hormonal profiles and behavior associated with maintaining a single-purpose territory in an Arctic-breeding songbird-the snow bunting (Plectrophenax nivalis). Snow buntings differ from many other Arctic-breeding passerines by using nest cavities, an uncommon and defended resource, but not relying upon the surrounding territory for forage. Circulating levels of testosterone in males were high when territories were established and then decreased over the breeding season. LH secretion was enhanced in females while laying eggs, followed by detectable levels of estradiol during incubation. Both sexes showed equivalent corticosterone responses to the stress of being captured and held. Male snow buntings vigorously defended territories in response to a simulated territorial intrusion both when initiating breeding and when feeding young. Exogenous testosterone implants surprisingly inhibited physical aggression but enhanced singing when birds were feeding young, thus suggesting that song and physical aggression are mediated by different hormonal mechanisms at this time of year. Together, these results contrast with hormonal profiles and behavior in other Arctic-breeding passerines.

Animals↗
PubMed2001

Changing images of John Snow in the history of epidemiology.

Ever since the end of the 19th century, the story of John Snow and his investigations into the contagiousness of cholera has fascinated epidemiologists. Several different lessons have been extracted from the interpretation and reinterpretation of Snow's work--according to prevailing insights. The story of John Snow continues to evolve, even into the 21st century.

Cholera↗
PubMed2000

Clean conditions for the determination of ultra-low levels of mercury in ice and snow samples.

Laboratory facilities and methods are presented for the determination of ultra-low levels of mercury (Hg) in ice and snow samples originating from polar ice caps or temperate regions. Special emphasis will be given to the presentation of the clean laboratory and the cleaning procedures. The laboratory is pressurized with air filtered through high efficiency particle filters. This first filtration is not enough to get rid of contamination by Hg in air. Experiments are conducted in a clean bench, especially built for Hg analysis, equipped with both particle filter and activated charcoal filter. It allows to obtain very low levels of atmospheric Hg contamination. Ultrapure water is produced for cleaning all the plastic containers that will be used for ice and snow samples and also for the dilution of the standards. Hg content in laboratory water is about 0.08+/-0.02 pg/g. A Teflon system has been developed for the determination of Hg in ice and snow samples based on Hg(II) reduction to Hg(0) with a SnCl2/HNO3 solution followed by the measurement of gaseous Hg(0) with a Hg analyzer GARDIS 1A+ based on the Cold Vapor Atomic Absorption Spectroscopy method. Blank determination is discussed.

Journal Article↗
PubMed1996

Thallium and cadmium in recent snow and firn layers in the Canadian Arctic by atomic fluorescence and absorption spectrometries.

Compared to the Antarctic and Greenland, the Canadian Arctic has seen extremely few trace metal studies on snow and ice. Surface, subsurface and depth samples of snow and firns were collected from the Agassiz Ice Cap, Ellesmere Island, Canada using clean room practices. Results for Tl (directly determined by LEAFS) and Cd (determined by GFAAS) are reported. To our knowledge, the thallium depth profile presented here is the first one so far reported for both polar systems, Greenland or other places. Tl concentrations peak in the winter-spring periods, when the Arctic atmosphere is loaded with foreign pollutants and suspended particulates which sometime severely reduce the visibility, creating a phenomenon commonly known as the Arctic haze. These results are in general accordance with the historical Arctic air pollution and acidity/conductivity data on ice cores. Surface concentrations of Tl range from 0.3 to 0.9 pg/g, which is a few times higher than those found in Antarctica. Cadmium shows seasonal characteristics similar to Tl although there is not a definite correlation between the two. However, there could be two predominant origins of metals which were deposited in the snow: Eurasian origin in January-April corresponding to high level metals (main deposition), and a less definite origin in May-December corresponding to low level metals.

Journal Article↗
PubMed1987

The effect of polluted and leached snow melt waters on the soil bacterial community-quantitative response.

The effect of polluted snow melt waters on the number of soil bacteria was determined using soil cores extracted from an upland catchment in the Cairngorm Mountains, Scotland. Total numbers of viable heterotrophic bacteria and bacterial denitrifiers were determined using plate and MPN counts. Separate soil cores were treated with simulated melt waters representative of either the composition of the first melt fraction from polluted or leached snowpacks. The number of bacteria in the Ah soil horizon (Hodgson, 1974) treated with polluted snow melt (PSM) water decreased significantly by 28-fold, but increased by 11-fold in the BC horizon. Denitrifier numbers decreased by 8-fold in the Ah horizon, but increased by over 2-fold lower down the profile. Overall the bacterial community exposed to simulated leached snow melt (LSM) waters showed little change in the Ah horizon. In the BC horizon (Hodgson, 1974), total viable bacterial numbers decreased by 20-fold, but denitrifiers numbers were unaffected.

Journal Article↗
PubMed2005

Observations of the PCB distribution within and in-between ice, snow, ice-rafted debris, ice-interstitial water, and seawater in the Barents Sea marginal ice zone and the North Pole area.

To evaluate the two hypotheses of locally elevated exposure of persistent organic pollutants (POPs) in ice-associated microenvironments and ice as a key carrier for long-range transport of POPs to the Arctic marginal ice zone (MIZ), dissolved and particulate polychlorinated biphenyls (PCBs) were analyzed in ice, snow, ice-interstitial water (IIW), seawater in the melt layer underlying the ice, and in ice-rafted sediment (IRS) from the Barents Sea MIZ to the high Arctic in the summer of 2001. Ultra-clean sampling equipment and protocols were specially developed for this expedition, including construction of a permanent clean room facility and a stainless steel seawater intake system on the I/B ODEN as well as two mobile 370 l ice-melting systems. Similar concentrations were found in several ice-associated compartments. For instance, the concentration of one of the most abundant congeners, PCB 52, was typically on the order of 0.1-0.3 pg l(-1) in the dissolved (melted) phase of the ice, snow, IIW, and underlying seawater while its particulate organic-carbon (POC) normalized concentrations were around 1-3 ng gPOC(-1) in the ice, snow, IIW, and IRS. The solid-water distribution of PCBs in ice was well correlated with and predictable from K(ow) (ice log K(oc)-log K(ow) regressions: p<0.05, r2=0.78-0.98, n=9), indicating near-equilibrium partitioning of PCBs within each local ice system. These results do generally not evidence the existence of physical microenvironments with locally elevated POP exposures. However, there were some indications that the ice-associated system had harbored local environments with higher exposure levels earlier/before the melting/vegetative season, as a few samples had PCB concentrations elevated by factors of 5-10 relative to the typical values, and the elevated levels were predominantly found at the station where melting had putatively progressed the least. The very low PCB concentrations and absence of any significant concentration gradients, both in-between different matrices and over the Eurasian Arctic basin scale, suggest that ice is not an important long-range transport purveyor of POPs to the Arctic MIZ ecosystem.

Journal Article↗
PubMed2002

Short-term variations in the occurrence of heavy metals in Antarctic snow from Coats Land since the 1920s.

Short-term variations in heavy metals concentrations in Antarctic snow have been investigated by analysing 13 metals (Al, V, Cr, Mn, Co, Cu, Zn, Ag, Cd, Ba, Pb, Bi and U) in a series of ultraclean samples collected from two snow pits in Coats Land in the Atlantic sector of Antarctica. The samples covered a approximately 70 years time period from the 1920s to 1990. They were analysed by inductively coupled plasma sector field mass spectrometry and graphite furnace atomic absorption spectrometry. The results conclusively show that there is a pronounced short-term (intra- and inter-annual) variability of heavy metal in Antarctic snow, with the highest concentrations being up to 100 times higher than the lowest ones for metal such as Cr, Mn, Pb and U. Contributions from the different possible natural and anthropogenic sources are found to be extremely variable. This is especially due to the large variability in the transport patterns of heavy metals from Southern America, Southern Africa and Australia to the Antarctic continent. Inputs from several volcanic events were identified in our samples from non-seasalt sulfate concentrations profiles. The only ones that gave clear signals for heavy metals were eruptions at Deception Island the proximity of which allowed for tropospheric transport to Coats Land.

Journal Article↗
PubMed1995

Deposition of motor vehicle emissions and winter maintenance along roadside assessed by snow analyses.

A vertical snow-sampling method, where a sample was taken throughout the snowpack, was used to estimate the pollutant load on a roadside where average daily traffic density was about 9100 motor vehicles. The snow samples were collected at two sites, forest and open field, at two distances of 10 and 30 m from the road. The concentrations of inorganic anions (Cl(-), NO(-)(3), SO(2-)(4)), total N, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated phenols (PCPhs) were analysed. The results suggest that on roadsides there is a deposition caused by road traffic emissions and winter maintenance which exceeds normal background deposition. Inorganic anions mainly in particle form, originating from winter maintenance, are deposited near the road. PAHs with low molecular weight (</=252) are mainly in gaseous form and are deposited further away from the road. Also, some PCPhs show similar behaviour. The dispersion is different at the forest site than at the open-field site. Our results also indicate that the vertical snow-sampling method can be used in studying pollutant load from traffic near the roads. However, studies should focus on individual PAH or PCPh compounds as markers of highway pollution. The deposition of mixtures of compounds does not bring sufficient information in the light of present knowledge.

Journal Article↗
PubMed1994

The incidence of meniscal tears associated with acute anterior cruciate ligament disruption secondary to snow skiing accidents.

In the acutely traumatized knee, meniscal tears are commonly encountered with an anterior cruciate ligament (ACL) injury. Because of the high incidence of ACL injuries related to snow skiing, a retrospective study was conducted to determine the incidence and location of concomitant meniscal injuries in a series of 328 acute ACL tears resulting from snow-skiing accidents. Seventy-five (23%) of the ACL injuries had coexistent meniscal injuries--43 (13%) lateral and 32 (10%) medial menisci. Thirty-two (43%) of the 75 meniscal tears were peripheral detachments from the capsule (red-red tears), which often heal without surgical intervention. Findings from this study indicate that the incidence of meniscal damage in acute knee injuries secondary to snow skiing accidents is substantially lower than in knee injuries sustained during other sports activities, which range from 53% to 65% in previous studies.

Anterior Cruciate Ligament↗
PubMed1994

Snow skiing combined anterior cruciate ligament/medial collateral ligament disruptions.

Recent reports indicate that combined anterior cruciate ligament/medial collateral ligament (ACL/MCL) knee injuries are usually associated with a lateral meniscus tear. In our center, snow skiing is the athletic activity most frequently associated with this double-ligament injury complex. A sports-specific analysis was undertaken to evaluate the hypothesis that the snow skiing ligament injury is different from similar injuries caused by other athletic activities. Of a total of 64 acute arthroscopically confirmed tears of both the MCL and ACL, 23 were caused by snow skiing and 41 by nonskiing activities. There were fewer lateral meniscus tears in skiers (43%) when compared with the nonskiers (88%). Skiers also had fewer medial meniscus tears (13%) than did nonskiers (37%). No medial meniscus tears occurred in the absence of a lateral meniscus tear. Although 78% of the skiers were women, only 12% of the nonskiers were women. Skiers were older (average age 35 years) than the nonskiers (average age 28 years). The right knee was injured almost twice as frequently as the left. These data suggest that the double (ACL/MCL) ligament injury in skiers might be distinctly different from that in nonskiers.

Adolescent↗
PubMed2000

Changes in Greenland ice sheet elevation attributed primarily to snow accumulation variability

The response of grounded ice sheets to a changing climate critically influences possible future changes in sea level. Recent satellite surveys over southern Greenland show little overall elevation change at higher elevations, but large spatial variability. Using satellite studies alone, it is not possible to determine the geophysical processes responsible for the observed elevation changes and to decide if recent rates of change exceed the natural variability. Here we derive changes in ice-sheet elevation in southern Greenland, for the years 1978-88, using a physically based model of firn densification and records of annual snow accumulation reconstructed from 12 ice cores at high elevation. Our patterns of accumulation-driven elevation change agree closely with contemporaneous satellite measurements of ice-sheet elevation change, and we therefore attribute the changes observed in 1978-88 to variability in snow accumulation. Similar analyses of longer ice-core records show that in this decade the Greenland ice sheet exhibited typical variability at high elevations, well within the long-term natural variability. Our results indicate that a better understanding of ice-sheet mass changes will require long-term measurements of both surface elevation and snow accumulation.

Journal Article↗
PubMed1982

Detection by immune electron microscopy of the Snow Mountain agent of acute viral gastroenteritis.

An extensive outbreak of acute gastroenteritis of unknown etiology occurred at Snow Mountain, Colorado, in December 1976. Virus-like particles, 27 nm in diameter, were observed by electron microscopy in two of five stool specimens from individuals in the outbreak. Oral administration of a filtrate from one of the specimens induced disease in nine of 12 normal volunteers. Experimentally induced illness was similar to that observed during the outbreak. Stool specimens examined by immune electron microscopy revealed 27-nm virus-like particles in three of nine ill volunteers at the onset of illness. When the particles were used as a source of antigen, increases in levels of serum antibody were demonstrated in persons with either experimentally induced or naturally occurring illness. Therefore, it is likely that this virus-like particle is the etiologic agent of the Snow Mountain outbreak. The Snow Mountain agent appears to be morphologically similar to, but antigenically distinct from, the Norwalk and Hawaii agents by immune electron microscopy and may represent an additional antigenic type among the agents that resemble the Norwalk particle.

Adolescent↗
PubMed2005

Phylogenetic analysis of snow sheep (Ovis nivicola) and closely related taxa.

Based on mitochondrial cytochrome b gene sequence analysis, the history of true sheep (Ovis) began approximately 3.12 million years ago (MYA). The evolution of Ovis resulted in three generally accepted genetic groups: Argaliforms, Moufloniforms, and Pachyceriforms. The Pachyceriforms of the subgenus Pachyceros comprise the thin-horn sheep Ovis nivicola (snow sheep), Ovis dalli (Dall and Stone sheep), and Ovis canadensis (Rocky Mountain and desert bighorn). North America wild sheep (O. canadensis and O. dalli) evolved separately from Eurasian wild sheep and diverged from each other about 1.41 MYA. Ancestral stock that gave rise to snow sheep, Moufloniforms, and Argaliforms occurred 2.3 MYA, which then gave rise to two different extant lines of snow sheep that diverged from each other about 1.96 MYA. The more recent nivicola line is genetically closer to the North American wild sheep and may represent a close association during the refugium when Alaska and Siberia were connected by the Bering land bridge. The earlier period of evolution of the Pachyceriforms suggests they may have first evolved in Eurasia, the oldest ancestor then giving rise to North American wild sheep, and that a canadensis-like ancestor most likely gave rise to nivicola. Cytogenetic analysis further validates that the standard diploid number for modern nivicola is 52.

Animals↗