scholarly journals Spatial-temporal dynamics of chemical composition of surface snow in East Antarctic along the transect Station Progress-Station Vostok

2013 ◽  
Vol 7 (3) ◽  
pp. 2007-2028
Author(s):  
T. V. Khodzher ◽  
L. P. Golobokova ◽  
Y. A. Shibaev ◽  
V. Y. Lipenkov ◽  
J. R. Petit
Keyword(s):  
Chemical Composition ◽  
Snow Cover ◽  
Temporal Dynamics ◽  
Temporal Variations ◽  
East Antarctica ◽  
Chemical Components ◽  
Antarctic Snow ◽  
Russian Antarctic Expedition ◽  
Continental Origin ◽  
Deep Distribution

Abstract. This paper presents data on chemical composition of the Antarctic snow sampled during the 53rd Russian Antarctic Expedition (RAE, 2008) along the first tractor traverse (TT) from Station Progress to Station Vostok (East Antarctica). Snow samples were obtained from the cores drilled at 55.3, 253, 337, 369, 403, 441, 480, 519, 560, 618, 819, and 1276 km from Station Progress. Data on horizontal and deep distribution of chemical components in the snow provide evidence of spatial and temporal variations of conditions for the snow cover formation along the transect under study. Sea salt was the main source for chemical composition of snow cover near the ice edge. Concentrations of marine-derived components decreased further inland. A hypothesis was put forward that some ions in the snow cover of the central part of East Antarctica were likely to be of continental origin. Elevated concentrations of sulphate ions of continental origin were recorded in some profiles of the transect at a depth of 130–150 cm which was attributed to buried signals of the Pinatubo volcano eruption (1991).

scholarly journals Physical properties of the seasonal snow cover in Dronning Maud Land, East Antarctica

2002 ◽  
Vol 34 ◽  
pp. 89-94 ◽  
Author(s):  
Eija Kärkäs ◽  
Hardy B. Granberg ◽  
Kimmo Kanto ◽  
Kai Rasmus ◽  
Chantale Lavoie ◽  
...  
Keyword(s):  
Snow Cover ◽  
Austral Summer ◽  
Research Programme ◽  
Temporal Variations ◽  
East Antarctica ◽  
Ice Shelf ◽  
Edge Zone ◽  
Snow Stratigraphy ◽  
Dronning Maud Land ◽  
Seaward Edge

AbstractSnow stratigraphy was analyzed in the Maudheimvidda area of western Dronning Maud Land, East Antarctica, during austral summer 1999/2000 as a part of the Finnish Antarctic Research Programme (FINNARP). Measurements were made in shallow (1–2m) snow pits along a 350 km transect from the coast to the polar plateau, covering at least one annual cycle and an elevation range from sea level to about 2500 m. The aim of the study is to document spatial and temporal variations in snow-cover properties, with the further aim of relating these variations to environmental factors and to patterns observable by remote sensing. The measurements suggest five principal snow zones: (i) sea ice, (ii) the seaward edge zone of the ice shelf, (iii) the inner parts of the ice shelf, (iv) the snow cover above the grounding line and (v) the local topographic highs. Local topographic highs such as ice domes and ice rises differ from other snow environments: the snow is less densely packed, possibly an indication of locally reduced speed of the katabatic outflow. Fewer and thinner crusts on the topographic highs are consistent with RADARSAT backscatter variations.

scholarly journals Chemical composition of aerosol in the atmospheric surface layer of the East Antarctica coastal zone

2016 ◽  
Vol 56 (2) ◽  
pp. 177-188 ◽  
Author(s):  
L. P. Golobokova ◽  
V. V. Polkin ◽  
N. A. Onischuk ◽  
O. I. Khuriganova ◽  
A. B. Tikhomirov ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Coastal Zone ◽  
Atmospheric Aerosols ◽  
Enrichment Factors ◽  
East Antarctica ◽  
Chemical Components ◽  
Aerosol Composition ◽  
Wide Range ◽  
Fresh Snow ◽  
The Antarctic

Chemical composition of aerosol in the ground layer of the coastal zone in East Antarctica is analyzed in the article. The aerosol samples were taken in 2006–2015 during seasonal works of the Russian Antarctic Expeditions (RAE), namely, these were 52nd–53rd, 55th, and 58th–60th expeditions. Samples were taken in the 200‑km band of the sea-shore zone along routes of the research vessels (REV) «Akademik Fedorov» and «Akademik Treshnikov» as well as on territories of the Russian stations Molodezhnaya and Mirny. Although the results obtained did show the wide range of the aerosol concentrations and a certain variability of their chemical composition, some common features of the variability were revealed. Thus, during the period from 2006 to 2014 a decrease of average values of the sums were noted. Spatially, a tendency of decreasing of the ion concentrations was found in the direction from the station Novolazarevskaya to the Molodezhnaya one, but the concentrations increased from the Molodezhnaya to the station Mirny. The sum of ions of the aerosol in the above mentioned coastal zone was, on the average, equal to 2.44 μg/m3, and it was larger than that on the territory of the Antarctic stations Molodezhnaya (0,29 μg/m3) and Mirny (0,50 ág / m3). The main part to the sum of the aerosol ions on the Antarctic stations was contributed by Na+, Ca2+, Cl−, SO4 2−. The main ions in aerosol composition in the coastal zone are ions Na+ and Cl−. The dominant contribution of the sea salt and SO4 2− can be traced in not only the composition of atmospheric aerosols, but also in the chemical composition of the fresh snow in the coastal areas of East Antarctica: at the Indian station Maitri, on the Larsemann Hills, and in a boring located in 55.3 km from the station Progress (K = 1.4÷6.1). It was noted that values of the coefficient of enrichment K of these ions decreases as someone moves from a shore to inland. Estimation of contributions of the continental and maritime factors to formation of the aerosol chemical composition revealed higher enrichment ratios for K+, Ca2+, SO4 2− (K = 3.6÷13.0). This reflects not only influence of the natural sources, but the intensity of human activities on the Antarctic continent as well. The elemental composition of solid aerosols was also analyzed. The largest concentrations were determined for Zn, Al and Fe. The ratio of concentration of the elements in both the soluble and insoluble phases of the aerosol showed that 84.1% of the total amount of the elements was contained in a water-insoluble state. Fractional relation between the element concentrations changed in different phases from 16 to 98%. High enrichment of the aerosol particles by Zn, Cu, Cr, Ba, Pb, Ni,Se, As, Cd (the enrichment factors = 27÷26 445) had been revealed. The content of dominant chemical components (Na+, Cl−, Zn, Fe), factors and coefficients of the element enrichment in the aerosols as well as in fresh snow of the coastal zone of East Antarctica are indicative of the identity of sources where their composition is formed.

scholarly journals The chemical composition of Lessonia berteroana (ex L. nigrescens) in kelp harvest management and open access areas near Coquimbo, Chile

2018 ◽  
Vol 46 (2) ◽  
pp. 258-267
Author(s):  
J.M. Alonso Vega ◽  
Pedro H. Toledo
Keyword(s):  
Resource Management ◽  
Chemical Composition ◽  
Open Access ◽  
Environmental Changes ◽  
Chemical Components ◽  
Optimal Harvesting ◽  
Harvest Management ◽  
Species Population ◽  
Pressure Indicators ◽  
Lessonia Berteroana

Lessonia berteroana (ex L. nigrescens) is kelp freely harvested from Open Access Areas (OAA), and to some extent controlled, from Management and Exploitation Areas for Benthic Resources (MEABR). Harvesting pressures can change population dynamics, mainly in OAAs. In particular, harvesting may alter the chemical components of plants. Therefore, the aim of this study was to determine the harvesting effects on the chemical composition of L. berteroana from MEABR and OAA sampled during different seasons (spring and fall) and at two sites (Talquilla and Lagunillas) near Coquimbo (30°S), Chile. The crude protein (13.5 ± 1.0%), total lipids (0.9 ± 0.2%), crude fiber (16.3 ± 1.6%), ash (30.1 ± 1.5%), and nitrogen-free extract (39.2 ± 2.0%) contents of L. berteroana were within reference values for Laminariales species. Population descriptors and chemical analyses showed that harvesting had local effects, rather than being affected by a resource management strategy (OAA vs MEABR). The seasonal anticipator nature of L. berteroana may explain the detected seasonality of it's chemical composition. Regarding functional morphological structures, chemical composition in the fronds was more variable than in the stipes and perennial holdfast, probably since leaves are ephemeral structures susceptible to environmental changes and that play a functional, rather than structural, role in kelp. In the context of Chilean kelp resource management, monitoring chemical composition is useful for determining optimal harvesting periods to local scale and for deciding when commercially valuable compounds, such as alginate, should be extracted. These data also complement harvesting pressure indicators based on L. berteroana demographic parameters.

scholarly journals Effects of rhizosphere fungi on the chemical composition of fruits of the medicinal plant Cinnamomum migao endemic to southwestern China

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Jingzhong Chen ◽  
Xiaolong Huang ◽  
Bingli Tong ◽  
Deng Wang ◽  
Jiming Liu ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Fungal Community ◽  
Small Population ◽  
Biologically Active ◽  
Fungal Communities ◽  
Chemical Components ◽  
Rhizosphere Fungi ◽  
Medicinal Value ◽  
Main Driver ◽  
Fungal Populations

Abstract Background This study examined how rhizosphere fungi influence the accumulation of chemical components in fruits of a small population species of Cinnamomum migao. Results Ascomycota and Basidiomycota were dominant in the rhizosphere fungal community of C. migao. Pestalotiopsis and Gibellulopsis were associated with α-Terpineol and sabinene content, and Gibellulopsis was associated with crude fat and carbohydrate content. There were significant differences in rhizosphere fungal populations between watersheds, and there was no obvious change between fruiting periods. Gibberella, Ilyonectria, Micropsalliota, and Geminibasidium promoted sabinene accumulation, and Clitocybula promoted α-Terpineol accumulation. Conclusion The climate-related differentiation of rhizosphere fungal communities in watershed areas is the main driver of the chemical composition of C. migao fruit. The control of the production of biologically active compounds by the rhizosphere fungal community provides new opportunities to increase the industrial and medicinal value of the fruit of C. migao.

scholarly journals In vitro study of human osteoblast proliferation and morphology on orthodontic mini-implants

2015 ◽  
Vol 85 (6) ◽  
pp. 920-926 ◽  
Author(s):  
Ricardo Carvalho Bueno ◽  
Roberta Tarkany Basting
Keyword(s):  
Chemical Composition ◽  
In Vitro Study ◽  
Chemical Components ◽  
Control Group ◽  
Osteoblast Proliferation ◽  
Mini Implants ◽  
Significant Difference ◽  
Implant Anchorage ◽  
Positive Effect

ABSTRACT Objective:  To evaluate the proliferation and morphology of human osteoblasts cultured on two brands of mini-implants after 24, 48, and 72 hours, in addition to the chemical composition found on their surface. Materials and Methods:  Two brands of mini-implant (Morelli and Neodent) were evaluated; polystyrene was used as a control group (n  =  3). Osteoblasts were cultured on the surface of sterilized mini-implants in a CO2 incubator at different time periods (24, 48, and 72 hours). Osteoblast proliferation was quantified by scanning electron microscopy using up to 5000× magnification, and cell morphology was analyzed by a single observer. For the chemical analysis, spectroscopy X-ray fluorescence was used to identify and quantify chemical components on the surface of the mini-implants. Results:  Two-way ANOVA showed no significant interaction between the factors studied (P  =  0.686). A Tukey test revealed no significant difference in osteoblast proliferation between the mini-implants at all studied periods; however, a difference in cell proliferation was detected between the Neodent and the control group (P  =  .025). For all groups, time had a direct and positive effect on osteoblast proliferation (P < .001). The significant elements present in both brands of mini-implants were titanium, aluminum, vanadium, and iron. Conclusions:  Osteoblast proliferation was present on the mini-implants studied, which increased over time; however, no significant difference between brands was observed. No difference was seen between the mini-implants evaluated in terms of chemical composition. Cell adhesion after 72 hours suggests that areas of bone remodeling can be achieved, thus initiating the process of mini-implant anchorage.

Reconstructing Antarctic snow accumulation using nitrogen isotopes of nitrate

2021 ◽  
Author(s):  
Pete D. Akers ◽  
Joël Savarino ◽  
Nicolas Caillon ◽  
Mark Curran ◽  
Tas Van Ommen
Keyword(s):  
Nitrogen Isotopes ◽  
Full Range ◽  
Ice Core ◽  
Ice Cores ◽  
Snow Accumulation ◽  
East Antarctica ◽  
Accumulation Rates ◽  
Sea Levels ◽  
Antarctic Snow ◽  
Parallel Reconstruction

<p>Precise Antarctic snow accumulation estimates are needed to understand past and future changes in global sea levels, but standard reconstructions using water isotopes suffer from competing isotopic effects external to accumulation. We present here an alternative accumulation proxy based on the post-depositional photolytic fractionation of nitrogen isotopes (d<sup>15</sup>N) in nitrate. On the high plateau of East Antarctica, sunlight penetrating the uppermost snow layers converts snow-borne nitrate into nitrogen oxide gas that can be lost to the atmosphere. This nitrate loss favors <sup>14</sup>NO<sub>3</sub><sup>-</sup> over <sup>15</sup>NO<sub>3</sub><sup>-</sup>, and thus the d<sup>15</sup>N of nitrate remaining in the snow will steadily increase until the nitrate is eventually buried beneath the reach of light. Because the duration of time until burial is dependent upon the rate of net snow accumulation, sites with lower accumulation rates have a longer burial wait and thus higher d<sup>15</sup>N values. A linear relationship (r<sup>2</sup> = 0.86) between d<sup>15</sup>N and net accumulation<sup>-1</sup> is calculated from over 120 samples representing 105 sites spanning East Antarctica. These sites largely encompass the full range of snow accumulation rates observed in East Antarctica, from 25 kg m-<sup>2</sup> yr<sup>-1</sup> at deep interior sites to >400 kg m-<sup>2</sup> yr<sup>-1</sup> at near coastal sites. We apply this relationship as a transfer function to an Aurora Basin ice core to produce a 700-year record of accumulation changes. Our nitrate-based estimate compares very well with a parallel reconstruction for Aurora Basin that uses volcanic horizons and ice-penetrating radar. Continued improvements to our database may enable precise independent estimates of millennial-scale accumulation changes using deep ice cores such as EPICA Dome C and Beyond EPICA-Oldest Ice.</p>

scholarly journals Frequency and distribution of winter melt events from passive microwave satellite data in the pan-Arctic, 1988–2013

2016 ◽  
Author(s):  
Libo Wang ◽  
Peter Toose ◽  
Ross Brown ◽  
Chris Derksen
Keyword(s):  
Snow Cover ◽  
Microwave Radiometer ◽  
Surface Air Temperature ◽  
Arctic Region ◽  
Temporal Variations ◽  
Passive Microwave ◽  
The Arctic ◽  
Winter Period ◽  
Strongly Correlated ◽  
Air Temperatures

Abstract. This study presents an algorithm for detecting winter melt events in seasonal snow cover based on temporal variations in the brightness temperature difference between 19 and 37 GHz from satellite passive microwave measurements. An advantage of the passive microwave approach is that it is based on the physical presence of liquid water in the snowpack, which may not be the case with melt events inferred from surface air temperature data. The algorithm is validated using in situ observations from weather stations, snowpit surveys, and a surface-based passive microwave radiometer. The results of running the algorithm over the pan-Arctic region (north of 50º N) for the 1988–2013 period show that winter melt days are relatively rare averaging less than 7 melt days per winter over most areas, with higher numbers of melt days (around two weeks per winter) occurring in more temperate regions of the Arctic (e.g. central Quebec and Labrador, southern Alaska, and Scandinavia). The observed spatial pattern was similar to winter melt events inferred with surface air temperatures from ERA-interim and MERRA reanalysis datasets. There was little evidence of trends in winter melt frequency except decreases over northern Europe attributed to a shortening of the duration of the winter period. The frequency of winter melt events is shown to be strongly correlated to the duration of winter period. This must be taken into account when analyzing trends to avoid generating false increasing trends from shifts in the timing of the snow cover season.

scholarly journals ECOGEOCHEMICAL DIAGNOSTICS CONDITION OF URBAN ENVIRONMENT ON POLLUTION SNOW COVER OF VORONEZH CITY

2015 ◽  
Vol 4 (4) ◽  
pp. 121-126
Author(s):  
Tatiana Ivanovna Prozhorina ◽  
Semyon Aleksandrovitch Kurolap ◽  
Nadezhda Ivanovna Yakunina
Keyword(s):  
Comparative Analysis ◽  
Chemical Composition ◽  
Snow Cover ◽  
Urban Environment ◽  
Chemical Elements ◽  
Rapid Assessment ◽  
High Sorption ◽  
Express Methods ◽  
Functional Areas ◽  
The City

Currently, the most popular are the express methods of quality control of the environment, which permit a relatively rapid assessment of ecological and geochemical situation. one such method is based on the use snow cover. snow has a high sorption capacity and is informative in identifying the object of man-made pollution of the urban environment. the paper presents the results of a study of the chemical composition of snow that had fallen in Voronezh during winter 2015. snow samples were taken in the period prior to snowmelt in various functional areas of the city. in order to identify the degree of technogenic impact on the various parts of the city of Voronezh, was made a comparative analysis of the results:аccording to the actual presence of pollutants in precipitation for the study of functional areas;сalculate the rate on the concentration of chemical elements for test samples of snow.according to the degree of mineralization and dust content in snow can be seen technogenic pressure on environment.therefore, a comparative analysis of the degree of contamination of snow in the various functional areas of the city were carried out for the two indicators of the chemical composition - the total mineralization and suspended particles(dust).the results of the analysis of the chemical composition of the melt water indicate an increased level of technogenic pollution of snow cover in all investigated functional areas of Voronezh.

scholarly journals Spatial and Temporal Variations of Nitrogen and Phosphorus in Surface Water and Groundwater of Mudong River Watershed in Huixian Karst Wetland, Southwest China

2021 ◽  
Vol 13 (19) ◽  
pp. 10740
Author(s):  
Linyan Pan ◽  
Junfeng Dai ◽  
Zhiqiang Wu ◽  
Liangliang Huang ◽  
Zupeng Wan ◽  
...  
Keyword(s):  
Surface Water ◽  
Temporal Dynamics ◽  
Flow Direction ◽  
Influencing Factor ◽  
Shallow Groundwater ◽  
Temporal Variations ◽  
Field Investigation ◽  
Spatial And Temporal Variation ◽  
Nitrogen And Phosphorus ◽  
River Watershed

When considering the factors affecting the spatial and temporal variation of nitrogen and phosphorus in karst watersheds, the unique karst hydrogeology as an internal influencing factor cannot be ignored, as well as natural factors such as meteorological hydrology and external factors such as human activities. A watershed-scale field investigation was completed to statistically analyze spatial and temporal dynamics of nitrogen and phosphorus through the regular monitoring and collection of surface water and shallow groundwater in the agricultural-dominated Mudong River watershed in the Huixian Karst Wetland over one year (May 2020 to April 2021). Our research found that non-point source pollution of nitrogen (84.5% of 239 samples TN > 1.0 mg/L) was more serious than phosphorus (7.5% of 239 samples TP > 0.2 mg/L) in the study area, and shallow groundwater nitrogen pollution (98.3% of 118 samples TN > 1.0 mg/L) was more serious than surface water (68.6% of 121 samples TN > 1.0 mg/L). In the three regions with different hydrodynamic features, the TN concentration was higher and dominated by NO3−-N in the river in the northern recharge area, while the concentrations of TN and TP were the highest in shallow groundwater wells in the central wetland core area and increased along the surface water flow direction in the western discharge area. This research will help improve the knowledge about the influence of karst hydrodynamic features on the spatial patterns of nitrogen and phosphorus in water, paying attention to the quality protection and security of water in karst areas with a fragile water ecological environment.

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