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At least 217 records · Page 12Linked to original sources
PubMed2005

Variation of POP concentrations in fresh-fallen snow and air on an Alpine glacier (Monte Rosa).

To understand better the mechanisms ruling the fate of POPs (persistent organic pollutants) in cold environments, a field campaign sampling fresh-fallen snow and air on an Alpine glacier was carried out during Summer 2003. The concentrations of all analyzed chemicals in fresh-fallen snow show a sharp decrease over time, particularly for the more volatile POPs, confirming the rather limited literature evidence of a rapid decline of such substances from the snowpack and/or ice. Even if the results presented here are preliminary and should be confirmed by further studies, some evidence of the influence of a night/day cycle of temperature on POP deposition and revolatilization mechanisms has been highlighted. Finally, the role of cold condensation and long-range atmospheric transport in the contamination of higher altitudes in this Alpine system has been substantiated, particularly for OC pesticides.

Air Pollutants↗
PubMed2005

Organochlorine compounds in ice melt water from Italian Alpine rivers.

Organochlorine chemicals (OCs) (dichlorodiphenyltrichloroethanes, hexachlorocyclohexanes, and hexachlorobenzene) were measured in ice melt water from five glaciers in the Italian Alps. Even though the data collected may not be sufficient for a precise description of persistent organic pollutant release patterns from glacier melting, they have, however, highlighted the potential for surface water contamination. Concentrations were of the same order of magnitude in all glacial streams, indicating comparable contamination levels in different glaciers of the alpine region. OC levels in nonglacial springs sampled in the same areas are usually lower. Even if differences during the melting season (from spring to autumn) have been identified, a regular seasonal pattern in OC concentrations was not observed. Risk for the aquatic environment is excluded through direct water exposure, but it is likely to occur through biomagnification and secondary poisoning exposure.

Environmental Monitoring↗
PubMed2005

An antarctic psychrotrophic bacterium Halomonas sp. ANT-3b, growing on n-hexadecane, produces a new emulsyfying glycolipid.

A bacterial strain ANT-3b was isolated at the sea-ice seawater interface from Terra Nova Bay station, Ross Sea, Antarctica. It was isolated on mineral medium supplemented with 2% diesel fuel as a sole carbon and energy source and grown routinely on 2% n-hexadecane. Analysis of 16S rRNA gene sequence indicates that the strain has 99.8% sequence similarity with Halomonas neptunia. The strain ANT-3b was grown in mineral medium supplemented with n-hexadecane between 4 and 20 degrees C, but not at 30 degrees C. The maximum degradation rate of the n-alkane was measured at 15 degrees C, with 5.6+/-1.7 mg O2 microg(-1) protein d(-1). The strain ANT-3b produced emulsifying compounds when grown on n-hexadecane, but not on mineral medium supplemented with D-fructose. A preliminary characterisation of the emulsifier was carried out. The lipid moiety contained a mixture of fatty acids with a following composition in molar ratio: caprylic acid 18.85, myristic acid 1.0, palmitic acid 9.68, palmitoleic acid 5.69 and oleic acid 1.26. The polysaccharide moiety also contained a mixture of sugars with the following molar ratio: mannose 1.71, galactose 1.00 and glucose 2.96. The molecular weight of the glycolipid component determined by gel permeation chromatography was in the 18 kDa range and contained smaller fragments, possibly oligomeric contaminants. Transmission electron microscopy showed contact between the glycolipid secreted by the strain and n-hexadecane broken down to nanodroplets at the water interface, to form a material with mesophase (liquid crystal) organisation.

Alkanes↗
PubMed2004

Extremotrophs, extremophiles and broadband pigmentation strategies in a high arctic ice shelf ecosystem.

Remnant ice shelves along the northern coast of Ellesmere Island, Nunavut, Canada ( approximately 83 degrees N) provide a habitat for cryo-tolerant microbial mat communities. Bioassays of bacterial and primary production were undertaken to quantify the short-term physiological response of the mats to changes in key variables that characterize this cryo-ecosystem (salinity, irradiance and temperature). The heterotrophic versus autotrophic community responses to these stressors differed markedly. The heterotrophic bacteria were extremophilic and specifically adapted to ambient conditions on the ice shelf, whereas the autotrophic community had broader tolerance ranges and optima outside the ambient range. This latter, extremotrophic response may be partly due to a diverse suite of pigments including oligosaccharide mycosporine-like amino acids, scytonemins, carotenoids, phycobiliproteins and chlorophylls that absorb from the near UV-B to red wavelengths. These pigments provide a comprehensive broadband strategy for coping with the multiple stressors of high irradiance, variable salinity and low temperatures in this extreme cryo-environment.

Adaptation, Biological↗
PubMed2005

Impacts of land use conversion on bankfull discharge and mass wasting.

Mass wasting and channel incision are widespread in the Nemadji River watershed of eastern Minnesota and northwestern Wisconsin. While much of this is a natural response to glacial rebound, sediment coring and tree ring data suggest that land use has also influenced these erosional processes. We characterized land use, inventoried mass wasting, surveyed stream channels and collected discharge data along segments of five streams in the Nemadji River watershed. Due to natural relief in this region, wetlands and agricultural lands are concentrated in the flatter terrain of the uplands of the Nemadji watershed, while forestland (coniferous or deciduous) is concentrated in the deeply incised (50-200% slope) stream valleys. Bankfull discharge was higher where forests had been converted from coniferous to deciduous forests and where there were fewer wetlands. Mass wasting increased exponentially with bankfull flows. While mass wasting was not correlated with forest type conversion and agricultural land use, it was negatively dependent upon wetland extent in headwater areas. Interactions between the spatial distribution of land use and terrain obfuscate any clear cause-and-effect relationships between land use, hydrology and fluvial processes.

Agriculture↗
PubMed2006

The derivation of radionuclide transfer parameters for and dose-rates to an adult ringed seal (Phoca hispida) in an Arctic environment.

Radionuclide transfer parameters and dose-rates for an adult ringed seal from Svalbard have been determined based on empirical and estimated tissue activity concentrations and detailed dietary and habitat information. Whole-body equivalent concentration factors determined for anthropogenic radionuclides ranged from 10(1) ((90)Sr) to 10(2) ((137)Cs, (238)Pu and (239,240)Pu), while natural radionuclides ranged from 10(2) ((210)Pb) to 10(4) ((210)Po). Employing a dietary composition of 40% fish, 40% zooplankton and 20% benthic invertebrates, a whole-body biological half-life of 29 days was derived for (137)Cs. A total dose-rate of approximately 0.19microGyh(-1) (1.7mGya(-1)) was derived for an adult ringed seal; this dose-rate is virtually entirely attributable to the internal components of (210)Po and (40)K. The dose-rates associated with the presence of anthropogenically derived radionuclides in the present assessment fall many orders of magnitude below the dose-rates at which any biological effects would be expected.

Animals↗
PubMed2004

Recycling of pathogenic microbes through survival in ice.

Viable microorganisms (e.g. fungi, bacteria, Archaea and viruses) are distributed by wind over great distances, including globally. Microbes may settle out of the atmosphere or may be incorporated into fog, rain, sleet, hail, or snow. These organisms fall into lakes, streams, oceans, or onto the land or glaciers. When they become incorporated into environmental ice (e.g. glaciers, ice sheets, and snow), those that survive freezing and thawing may persist for years, centuries, millennia, or longer. Once they melt from the ice, they may enter contemporary populations. This mixing of ancient and modern genotypes (i.e. temporal gene flow, or what we term "genome recycling") may lead to a change of allele proportions in the population, which may have effects on mutation rates, fitness, survival, pathogenicity and other characteristics of the organisms. Pathogenic microbes that survive freezing and thawing (e.g. influenza viruses, polioviruses, caliciviruses and tobamoviruses) can remain in these icy reservoirs long enough to avoid resistance mechanisms of the hosts, thereby conveying a selective advantage to these pathogens over those that cannot survive in ice. Ice is an abiotic reservoir of microbes that has been ignored in surveillance activities for human diseases.

Bacteria↗
PubMed2005

Anaerobic ammonium oxidation (anammox) in the marine environment.

Anammox, anaerobic ammonium oxidation with nitrite, is now recognized as an important process in the marine nitrogen cycle. The bacteria conducting anammox are highly specialized and appear to belong to the Planctomycetales. The process has now been found in a range of environments including marine sediments, sea ice and anoxic water columns, and it may be responsible for up to 50% of the global removal of fixed nitrogen from the oceans.

Bacteria, Anaerobic↗
PubMed2006

Historical population dynamics and demography of the Eastern Atlantic pomacentrid Chromis limbata (Valenciennes, 1833).

Recent studies have focused on the relationship between the marine fauna of the Eastern Atlantic and the Mediterranean Sea, but within the Atlantic, little is known about genetic relationships between populations of the Macaronesian islands. In this study, we tested whether the paleo-climatology and paleo-oceanography of the region could predict the genetic relationships among three Eastern Atlantic populations (Azores, Madeira, and Canaries) of a damselfish, Chromis limbata, and compared our results with its Mediterranean and adjacent Atlantic sister species, Chromis chromis. We combined phylogeographic and coalescent approaches using the fast evolving mitochondrial control region gene. No population structure was found for the three archipelagos. The coalescence time estimated for C. limbata (0.857-1.17 Mya) was much greater than that estimated for C. chromis. We propose that this difference reflects differences in glaciating extents in the Northeastern Atlantic and the Mediterranean. Diversity indexes (Hd and genetic distances) together with historical demographic parameters of C. limbata (Theta and g) revealed a more stable population history when compared to C. chromis. Our results suggest that the Macaronesian populations of C. limbata have probably been less affected by the last glaciation than the Mediterranean populations of C. chromis. Migration across the three archipelagos was estimated and a prevailing northwest trend was detected. This result supports the idea of a colonization of the Azores by warm water fish from Madeira or the westernmost Canary islands which acted as major glacial refugia for the tropical and subtropical marine fauna during the glaciations.

Animals↗
PubMed2002

Comparison of small intestinal submucosa-covered and noncovered nitinol stents in sheep iliac arteries: a pilot study.

PURPOSE: To compare the biocompatibility and performance of nitinol endografts covered externally or internally with small intestinal submucosa (SIS) with bare nitinol stents in medium-sized arteries. MATERIALS AND METHODS: Eighteen nitinol Zilver stents were used: six externally SIS-covered endografts (ECEs), six internally SIS-covered endografts (ICEs), and six bare stents (BSs). Devices were implanted in the balloon-injured external iliac arteries (EIAs) of nine female sheep via carotid approach. Arteriograms were obtained before and after implantation and before animal sacrifice at 1, 3, and 6 months. Histologic studies of explanted specimens were performed. RESULTS: Implantation of all BSs, ECEs, and ICEs was successful, but slight luminal narrowing of 19% +/- 5.3% (range, 12%-28%) was seen in ICEs on postimplantation angiograms. At sacrifice, all six BSs and ECEs were patent, with BSs showing a mean angiographic luminal narrowing of 8.4% +/- 7.2% (range, 0%-18%) and ECEs showing a mean angiographic luminal narrowing of 16% +/- 7.5% (range, 6.5%-26%) as a result of neointimal hyperplasia. Four ICEs showed luminal narrowing of 21% +/- 17% (range, 0%-35%) as a result of marked neointimal hyperplasia and two were occluded, one at 3 months and the other at 6 months. ECEs and BSs showed approximately 80% lumen endothelialization at 1 month, which increased to 100% at 3 and 6 months. ICEs did not show complete endothelialization. CONCLUSION: The BS had the least vessel wall reaction. ECEs exhibited early endothelialization with early mild to moderate wall reaction decreasing at the late study stages. ICEs showed extensive wall reaction, possibly as a result of technical problems with SIS attachment.

Alloys↗
PubMed2004

Assessment of sulfate sources in high-elevation Asian precipitation using stable sulfur isotopes.

Stable sulfur isotope measurements (delta34S) made on samples collected from a 2 m snowpit on the Inilchek Glacier, Tien Shan Mountains (42.16 degrees N, 80.25 degrees E, 5100 m) are used to estimate sources of sulfate (SO4(2-)) in high-elevation Central Asian precipitation. Comparison of snowpit oxygen isotope (delta18O) data with previous work constrains the age of the snowpit samples to the summer season during which they were retrieved (1999). Delta34S measurements were made at 10 cm resolution (20 samples total), with delta34S values ranging from 0.4/1000 during background ([SO4(2-)] < 1 microequiv L(-1)) periods to 19.4/1000 during a single high [SO4(2-)] event. On the basis of the significant correlation (r = 0.87) between [SO4(2-)] and delta34S values, coupled with major ion concentration time series and concentration ratios, we suggest a two-component mixing system consisting of evaporite dust and anthropogenic SO4(2-) to explain the observed delta34S values. Using a regression model, we estimate that during the 1999 summer season 60% of the deposited SO4(2-) was from an evaporite dust source, while 40% of the SO4(2-) was from anthropogenic sources. Due to the potentially large and unconstrained range of delta34S values for both evaporite and anthropogenic SO4(2-) sources in Asia, the error in our estimates is difficult to assess. However, the delta34S data from the 1999 Tien Shan snowpit provide the first unambiguous identification of evaporite and anthropogenic SO4(2-) in high-elevation Asian precipitation, and future ice core studies using improved analysis techniques and source delta34S values can provide detailed information on sulfur biogeochemistry and anthropogenic impacts in Asian alpine regions.

Air Pollutants↗
PubMed2005

Seasonal variation in the occurrence of pharmaceuticals in effluents from a sewage treatment plant and in the recipient water.

The occurrence of five pharmaceuticals (ibuprofen, naproxen, ketoprofen, diclofenac, and bezafibrate) in the influent and effluent water of a sewage treatment plant (STP) in the recipient river water and in a drinking water treatment plant (DWTP) located downstream from the STP was followed during three seasons: winter, spring, and summer. In the STP, the elimination of the pharmaceuticals decreased significantly (an average of 25% compared to spring and summer) in wintertime leading to increased concentrations of pharmaceuticals in the effluent water. The total concentration of all the studied pharmaceuticals in the effluent water was 3-5 times higher in wintertime (about 2500 ng L(-1)) than during the other seasons (about 500-900 ng L(-1)). Accordingly, the highest concentrations (up to 129 ng L(-1)) in the recipient river were measured in the wintertime. Pharmaceuticals were carried longer distances downstream from the STP when the river was covered by ice and snow. During a drastic increase in water flow rate (i.e., during snowmelting), a fast transportation of the pharmaceuticals was observed. The DWTP located downstream from the STP produced water that contained about 8 ng L(-1) of ibuprofen and ketoprofen in the winter sample, whereas in spring and summer the studied pharmaceuticals could not be detected in the drinking water. The results show that cold seasons in boreal areas can severely increase the environmental risk of pharmaceuticals and the risk for contamination of drinking water.

Chromatography, High Pressure Liquid↗
PubMed2006

Estimate of European 129I releases supported by 129I analysis in an Alpine ice core.

129I in the European environment originates predominantly from the industrial nuclear fuel reprocessing plants Sellafield (Great Britain), Marcoule, and La Hague (both France). While reliable data on 129I releases from La Hague exist for the whole period of operation, less is known about the contributions from Sellafield and Marcoule. For those periods where no data are available, i.e., for the first 16 years of the Sellafield operation and for the first 3 decades of the Marcoule operation, we estimated releases into the atmosphere of 118 GBq and 825 GBq, respectively. Hence, Marcoule was the major European source of airborne 129I, contributing about 45% to the total airborne 129I releases from all the European reprocessing facilities, until it was decommissioned in 1997. The estimated total emissions were compared with 129I deposition fluxes for the time period 1970-2002, obtained from the analysis of an ice core from Fiescherhorn glacier, Swiss Alps (46 degrees 33'N, 08 degrees 04'E; 3900 m asl). The temporal evolution of the 129I deposition agrees well with the total 129I releases into the atmosphere from the European reprocessing facilities and from atmospheric nuclear weapons tests, supporting our estimated release rates. However,the 129I concentrations and deposition fluxes at Fiescherhorn glacier were a factor of 6 lower than values obtained from the analysis of rainwater collected near Zurich (408 m asl) in Switzerland in the years 1994-97. This suggests a strong vertical concentration gradient of 129I, typical for water-soluble atmospheric trace species which are removed from the atmosphere in the course of days by precipitation scavenging, and must be taken into account if glaciers are used as an archive for a retrospective quantification of 129I deposition fluxes. In addition, the temporal evolution of the contribution of 129I re-emitted from the ocean's surface for the 129I inventory in the atmosphere was quantified for the first time. Although the annual amount of 129I released this way was very low until the early 1990s, it is similar to the airborne 129I releases from Sellafield and La Hague in the present time.

Environmental Monitoring↗
PubMed2004

Latitudinal variation in habitat specificity of ameronothrid mites (Oribatida).

Ameronothroid mites, including Ameronothridae, Fortuyniidae and Selenoribatidae, are unique among the Oribatida through having a global distribution from the tropics to the poles, and occupying a diversity of habitats including terrestrial, marine and freshwater. Their ecological diversification is of considerable interest from both the perspective of evolution over geological timescales, and the detail of the underlying processes. Given their widespread global distribution, it seems likely that historical global events (tectonic and climatic) have played a fundamental role in their ecological diversification. Previous studies of sub-Antarctic island arthropods have generated considerable circumstantial evidence in support of glaciation being a primary factor influencing ecological patterns: lower habitat specificity and weaker interspecific interactions are associated with more recent (postglacial) vegetated terrestrial biotopes, as compared to the older epilithic and littoral biotopes (which are assumed to have been present, albeit reduced in extent, during Neogene glacial maxima). Here, we use ameronothrid mites as a case study to examine the extent to which the above island scenario generalizes globally across latitudes affected by glaciation. We show that, unlike congeners or even conspecifics at lower latitudes in each hemisphere which are restricted to marine environments, the species found at higher latitudes (especially Alaskozetes antarcticus, Ameronothrus dubinini, Ameronothrus lineatus, and Halozetes belgicae) show greater affinity for terrestrial environments. They show a transition or expansion of habitat use (from marine-influenced to terrestrial habitats) implicit with a lower degree of habitat specificity, in relation to increasing latitude. We contend that the terrestrial environment at higher latitudes in both hemispheres has been colonized by these ameronothrid mite species following the various glaciation events, facilitated by a lack of competition experienced in their low diversity communities, in a manner which represents a larger scale demonstration of the processes described on sub-Antarctic islands.

Animals↗