scholarly journals Atmosphere–snow interaction by a comparison between aerosol and uppermost snow-layers composition at Dome C, East Antarctica

2004 ◽  
Vol 39 ◽  
pp. 53-61 ◽  
Author(s):  
Roberto Udisti ◽  
Silvia Becagli ◽  
Silvia Benassai ◽  
Emiliano Castellano ◽  
Ilaria Fattori ◽  
...  
Keyword(s):  
Size Distribution ◽  
Fine Fraction ◽  
Ice Cores ◽  
Principal Component ◽  
East Antarctica ◽  
Chemical Components ◽  
Ionic Balance ◽  
Aerosol Composition ◽  
Depositional Processes ◽  
Distribution Ranges

AbstractThe study of aerosol composition and air–snow exchange processes is relevant to the reconstruction of past atmosphere composition from ice cores. For this purpose, aerosol samples, superficial snow layers and firn samples from snow pits were collected at Dome Concordia station, East Antarctica, during the 2000/01 summer field season. The aerosol was collected in a ‘coarse’ and a ‘fine’ fraction, roughly separated from each other by a stacked filter system (5.0 and 0.4 μm). Atomic Force Microscopy (AFM) direct measurements on the fine fraction showed that 72% of surface size distribution ranges from 1.0 x 105 to 1.2 x 106 nm2. Assuming a spherical model, the volume size distribution of particles smaller than 5.0 μm shows a mode in the radius range 0.2–0.6 μm. Ion chromatographic (IC) measurements of selected chemical components allowed calculation of the ionic balance of the two size fractions. The fine fraction is dominant, representing 86% of the total ionic budget, and it is characterized by high content of sulphate and acidity. Principal component analysis (PCA) identified sea-spray and biogenic aerosol sources and showed some particulars of the transport and depositional processes of some chemical components (Ca2+, MSA, nssSO42–). Comparative analysis of aerosol, surface hoar and superficial snow showed differences in chemical composition: nitrate and chloride exhibit very high concentrations in the uppermost snow layers and in the surface hoar, and low values in the aerosol. This evidence demonstrates that nitrate and chloride are mainly in gas phase at Dome C and they can be caught on the snow and hoar surface through dry deposition and adsorption processes.

scholarly journals Snow Stratigraphic Studies At Dome C, East Antarctica: An Investigation Of Depositional and Diagenetic Processes

1982 ◽  
Vol 3 ◽  
pp. 239-242 ◽  
Author(s):  
J. M. Palais ◽  
I. M. Whillans ◽  
C. Bull
Keyword(s):  
Ice Sheets ◽  
Ice Cores ◽  
Snow Accumulation ◽  
East Antarctica ◽  
Polar Ice ◽  
Depositional Processes ◽  
Diagenetic Processes ◽  
Snow Stratigraphy ◽  
Stratigraphic Record ◽  
Polar Ice Sheets

The increased interest in past climatic changes, as revealed by studies of long ice cores from polar ice sheets, has stressed the need for a better understanding of the development of the stratigraphic record preserved in these cores. This paper presents some results of surface investigations at Dome C (74°30'S, 123°10'E), East Antarctica, carried out in austral summers 1978-79 and 1979-80. An explanation is presented of the snow stratigraphy, in terms of depositional and post-depositional processes, that is supported by detailed accumulation measurements at stakes and by snow-pit studies. Temporal and areal variability of snow accumulation are investigated to determine how representative the results interpreted from a single core might be for the Dome C region. Finally, the reliability of several stratigraphic methods for defining annual layers is assessed.Snow-pit studies show that major depositional features are preserved with depth. Visible annual strata at Dome C are composed of thin, hard crusts overlying thicker layers of soft to medium-hard snow. Low density depth-hoar layers, when they occur, are usually found below the thin, hard crusts. Depth profiles of gross 8-radioactivity and of microparticles concentration exhibit annual cyclicity which, together with the detailed visible stratigraphy, can be used to assign dates to the layers.

scholarly journals Snow Stratigraphic Studies At Dome C, East Antarctica: An Investigation Of Depositional and Diagenetic Processes

1982 ◽  
Vol 3 ◽  
pp. 239-242 ◽  
Author(s):  
J. M. Palais ◽  
I. M. Whillans ◽  
C. Bull
Keyword(s):  
Ice Sheets ◽  
Ice Cores ◽  
Snow Accumulation ◽  
East Antarctica ◽  
Polar Ice ◽  
Depositional Processes ◽  
Diagenetic Processes ◽  
Snow Stratigraphy ◽  
Stratigraphic Record ◽  
Polar Ice Sheets

The increased interest in past climatic changes, as revealed by studies of long ice cores from polar ice sheets, has stressed the need for a better understanding of the development of the stratigraphic record preserved in these cores. This paper presents some results of surface investigations at Dome C (74°30'S, 123°10'E), East Antarctica, carried out in austral summers 1978-79 and 1979-80. An explanation is presented of the snow stratigraphy, in terms of depositional and post-depositional processes, that is supported by detailed accumulation measurements at stakes and by snow-pit studies. Temporal and areal variability of snow accumulation are investigated to determine how representative the results interpreted from a single core might be for the Dome C region. Finally, the reliability of several stratigraphic methods for defining annual layers is assessed. Snow-pit studies show that major depositional features are preserved with depth. Visible annual strata at Dome C are composed of thin, hard crusts overlying thicker layers of soft to medium-hard snow. Low density depth-hoar layers, when they occur, are usually found below the thin, hard crusts. Depth profiles of gross 8-radioactivity and of microparticles concentration exhibit annual cyclicity which, together with the detailed visible stratigraphy, can be used to assign dates to the layers.

scholarly journals Deep ice as a geochemical reactor: insights from iron speciation and mineralogy of dust in the Talos Dome ice core (East Antarctica)

2021 ◽  
Author(s):  
Giovanni Baccolo ◽  
Barbara Delmonte ◽  
Elena Di Stefano ◽  
Giannantonio Cibin ◽  
Ilaria Crotti ◽  
...  
Keyword(s):  
Ross Sea ◽  
Mineral Dust ◽  
Ice Core ◽  
Ice Cores ◽  
East Antarctica ◽  
Main Process ◽  
Polar Ice ◽  
Atmospheric Species ◽  
Depositional Processes ◽  
Fe Mineralogy

Abstract. Thanks to its insolubility, mineral dust is considered a stable proxy in polar ice cores. With this study we show that below an ice-depth of 1000 m, the Talos Dome ice core (Ross Sea sector of East Antarctica) presents evident and progressive signs of post-depositional processes affecting the mineral dust records. We applied a suite of established and cutting edge techniques to investigate the properties of dust present in the Talos Dome ice core, ranging from concentration and grain-size to elemental-composition and Fe-mineralogy. Results show that through acidic/oxidative weathering, the conditions of deep ice at Talos Dome promote the dissolution of specific minerals and the englacial formation of others, deeply affecting dust primitive features. The expulsion of acidic atmospheric species from ice-grains and their concentration in localized environments is likely the main process responsible for englacial reactions and is related with ice re-crystallization. Deep ice can be seen as a "geochemical reactor" capable of fostering complex reactions which involve both soluble and insoluble impurities. Fe-bearing minerals can efficiently be used to explore such transformations.

scholarly journals A Nine-year series of daily oxygen and hydrogen isotopic composition of precipitation at Concordia station, East Antarctica

2020 ◽  
Author(s):  
Barbara Stenni ◽  
Giuliano Dreossi ◽  
Mathieu Casado ◽  
Claudio Scarchilli ◽  
Amaelle Landais ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
General Circulation ◽  
Meteorological Data ◽  
Ice Cores ◽  
General Circulation Models ◽  
Southern Annular Mode ◽  
East Antarctica ◽  
Depositional Processes ◽  
Clean Area ◽  
Isotopic Records

<p>The atmospheric processes determining the isotopic composition of precipitation on the Antarctic plateau are yet to be fully understood, as well as the post-depositional processes altering the snow pristine isotopic signal. Improving the comprehension of these physical mechanisms is of crucial importance for interpreting the isotopic records from ice cores drilled in the low accumulation area of Antarctica, e.g., the upcoming Beyond EPICA drilling at Little Dome C.</p><p>Up to now, few records of the isotopic composition of precipitation in Antarctica are available, most of them limited in time or sampling frequency. Here we present a 9-year long δ<sup>18</sup>O and δD record (2008-2016) of precipitation at Concordia base, East Antarctica. The snow is collected daily on a raised platform (1 m), positioned in the clean area of the station; the precipitation collection is still being carried out each year by the winter over personnel.</p><p>A significant positive correlation between isotopes in precipitation and 2-m air temperature is observed at both seasonal and interannual scale; the lowest temperature and isotopic values are usually recorded during winters characterized by a strongly positive Southern Annular Mode index.</p><p>To improve the understanding of the mechanisms governing the isotopic composition of precipitation, we compare the isotopic data of Concordia samples with on-site observations, meteorological data from the Dome C AWS of the University of Wisconsin-Madison, as well as with high-resolution simulation results from the isotope-enabled atmospheric general circulation models ECHAM5-wiso and ECHAM6-wiso, nudged with the ERA-Interim and ERA5 reanalyses respectively.</p>

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 Deep ice as a geochemical reactor: insights from iron speciation and mineralogy of dust in the Talos Dome ice core (East Antarctica)

2021 ◽  
Vol 15 (10) ◽  
pp. 4807-4822
Author(s):  
Giovanni Baccolo ◽  
Barbara Delmonte ◽  
Elena Di Stefano ◽  
Giannantonio Cibin ◽  
Ilaria Crotti ◽  
...  
Keyword(s):  
Ross Sea ◽  
Mineral Dust ◽  
Ice Core ◽  
Ice Cores ◽  
East Antarctica ◽  
Main Process ◽  
Polar Ice ◽  
Atmospheric Species ◽  
Depositional Processes ◽  
Fe Mineralogy

Abstract. Thanks to its insolubility, mineral dust is considered a stable proxy in polar ice cores. With this study we show that the Talos Dome ice core (TALDICE, Ross Sea sector of East Antarctica) displays evident and progressive signs of post-depositional processes affecting the mineral dust record below 1000 m deep. We apply a suite of established and cutting-edge techniques to investigate the properties of dust in TALDICE, ranging from concentration and grain size to elemental composition and Fe mineralogy. Results show that through acidic/oxidative weathering, the conditions of deep ice at Talos Dome promote the dissolution of specific minerals and the englacial formation of others, affecting primitive dust features. The expulsion of acidic atmospheric species from ice grains and their concentration in localized environments is likely the main process responsible for englacial reactions. Deep ice can be seen as a “geochemical reactor” capable of fostering complex reactions which involve both soluble and insoluble impurities. Fe-bearing minerals can efficiently help in exploring such transformations.

scholarly journals Size-Segregated Atmospheric Humic-Like Substances (HULIS) in Shanghai: Abundance, Seasonal Variation, and Source Identification

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 526
Author(s):  
Tianming Sun ◽  
Rui Li ◽  
Ya Meng ◽  
Yu Han ◽  
Hanyun Cheng ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Size Distribution ◽  
Principal Component ◽  
Water Soluble ◽  
Atmospheric Particulate Matter ◽  
Biomass Combustion ◽  
Vehicle Exhaust ◽  
Total Suspended Particulates ◽  
Condensation Mode ◽  
Water Soluble Organic Carbon

Humic-like substances (HULIS) are of great interest due to their optical and chemical characteristics. In this study, a total of 180 samples of atmospheric particulate matter (PM) of different sizes were collected from summer 2018 to spring 2019, in order to analyze the size distribution, to investigate the seasonal variation and then to identify the key sources of HULIS. The annual mean concentration of HULIS in the total suspended particulates reached 5.12 ± 1.42 μg/m3. The HULIS concentration was extremely higher in winter (8.35 ± 2.06 μg/m3) than in autumn (4.88 ± 0.95 μg/m3), in summer (3.62 ± 1.68 μg/m3) and in spring (3.36 ± 0.99 μg/m3). The average annual ratio of water-soluble organic carbon (WSOC) to OC and the ratio of HULIS to WSOC reached 0.546 ± 0.092 and 0.56 ± 0.06, respectively. Throughout the whole year, the size distributions of WSOC and HULIS-C were relatively smooth. The peaks of WSOC appeared at 1.8~3.2 μm and 0.56~1.0 μm, while the peaks of HULIS-C were located at 3.2~5.6 μm, 1.0~1.8 μm and 0.18~0.32 μm. The distribution of the HULIS particle mode was similar in spring, summer and autumn, while there was a lower proportion of the coarse mode and a higher proportion of the condensation mode in winter. By using the comprehensive analysis of principal component analysis (PCA), air mass backward trajectories (AMBTs) and fire point maps, key sources of WSOC and HULIS in Shanghai were identified as biomass combustion (48.42%), coal combustion (17.49%), secondary formation (16.07%) and vehicle exhaust (5.37%). The remaining part might be contributed by crustal dust sources, marine sources and/or other possible sources. This study provides new insight into the characteristics and size distribution of HULIS in Shanghai, thereby providing a practical base for further modeling.

scholarly journals Characterization of the Volatile Profile of Cultivated and Wild-Type Italian Celery (Apium graveolens L.) Varieties by HS-SPME/GC-MS

2021 ◽  
Vol 11 (13) ◽  
pp. 5855
Author(s):  
Samantha Reale ◽  
Valter Di Cecco ◽  
Francesca Di Donato ◽  
Luciano Di Martino ◽  
Aurelio Manzi ◽  
...  
Keyword(s):  
Solid Phase ◽  
Principal Component ◽  
Apium Graveolens ◽  
Gas Chromatography Mass Spectrometry ◽  
Bioactive Metabolites ◽  
Chemical Components ◽  
Volatile Profile ◽  
Wild Type ◽  
Multivariate Statistical ◽  
Clear Differentiation

Celery (Apium graveolens L.) is a vegetable belonging to the Apiaceae family that is widely used for its distinct flavor and contains a variety of bioactive metabolites with healthy properties. Some celery ecotypes cultivated in specific territories of Italy have recently attracted the attention of consumers and scientists because of their peculiar sensorial and nutritional properties. In this work, the volatile profiles of white celery “Sedano Bianco di Sperlonga” Protected Geographical Indication (PGI) ecotype, black celery “Sedano Nero di Torricella Peligna” and wild-type celery were investigated using head-space solid-phase microextraction combined with gas-chromatography/mass spectrometry (HS-SPME/GC-MS) and compared to that of the common ribbed celery. Exploratory multivariate statistical analyses were conducted using principal component analysis (PCA) on HS-SPME/GC-MS patterns, separately collected from celery leaves and petioles, to assess similarity/dissimilarity in the flavor composition of the investigated varieties. PCA revealed a clear differentiation of wild-type celery from the cultivated varieties. Among the cultivated varieties, black celery “Sedano Nero di Torricella Peligna” exhibited a significantly different composition in volatile profile in both leaves and petioles compared to the white celery and the prevalent commercial variety. The chemical components of aroma, potentially useful for the classification of celery according to the variety/origin, were identified.

scholarly journals A fast and low-cost approach to quality control of alcohol-based hand sanitizer using portable near infrared spectrometer and chemometrics

2021 ◽  
pp. 096703352098731
Author(s):  
Adenilton C da Silva ◽  
Lívia PD Ribeiro ◽  
Ruth MB Vidal ◽  
Wladiana O Matos ◽  
Gisele S Lopes
Keyword(s):  
Quality Control ◽  
Discriminant Analysis ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Principal Component ◽  
Partial Least Square ◽  
Least Square ◽  
Chemical Components ◽  
Linear Discriminant ◽  
Hand Sanitizer

The use of alcohol-based hand sanitizers is recommended as one of several strategies to minimize contamination and spread of the COVID-19 disease. Current reports suggest that the virucidal potential of ethanol occurs at concentrations close to 70%. Traditional methods of verifying the ethanol concentration in such products invite potential errors due to the viscosity of chemical components or may be prohibitively expensive to undertake in large demand. Near infrared (NIR) spectroscopy and chemometrics have already been used for the determination of ethanol in other matrices and present an alternative fast and reliable approach to quality control of alcohol-based hand sanitizers. In this study, a portable NIR spectrometer combined with classification chemometric tools, i.e., partial least square discriminant analysis (PLS–DA) and linear discriminant analysis with successive algorithm projection (SPA–LDA) were used to construct models to identify conforming and non-conforming commercial and laboratory synthesized hand sanitizer samples. Principal component analysis (PCA) was applied in an exploratory data study. Three principal components accounted for 99% of data variance and demonstrate clustering of conforming and non-conforming samples. The PLS–DA and SPA–LDA classification models presented 77 and 100% of accuracy in cross/internal validation respectively and 100% of accuracy in the classification of test samples. A total of 43% commercial samples evaluated using the PLS–DA and SPA–LDA presented ethanol content non-conforming for hand sanitizer gel. These results indicate that use of NIR spectroscopy and chemometrics is a promising strategy, yielding a method that is fast, portable, and reliable for discrimination of alcohol-based hand sanitizers with respect to conforming and non-conforming ethanol concentrations.

scholarly journals Flow Characteristics and Grain Size Distribution of Granular Gangue Mineral by Compaction Treatment

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Ran Yuan ◽  
Dan Ma ◽  
Hongwei Zhang
Keyword(s):  
Weight Loss ◽  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Water Flow ◽  
Fine Particles ◽  
Flow Characteristics ◽  
Test System ◽  
Chemical Components ◽  
Gangue Mineral

A test system for water flow in granular gangue mineral was designed to study the flow characteristics by compaction treatment. With the increase of the compaction displacement, the porosity decreases and void in granular gangue becomes less. The main reason causing initial porosity decrease is that the void of larger size is filled with small particles. Permeability tends to decrease and non-Darcy flow factor increases under the compaction treatment. The change trend of flow characteristics shows twists and turns, which indicate that flow characteristics of granular gangue mineral are related to compaction level, grain size distribution, crushing, and fracture structure. During compaction, larger particles are crushed, which in turn causes the weight of smaller particles to increase, and water flow induces fine particles to migrate (weight loss); meanwhile, a sample with more weight of size (0–2.5 mm) has a higher amount of weight loss. Water seepage will cause the decrease of some chemical components, where SiO2 decreased the highest in these components; the components decreased are more likely locked at fragments rather than the defect of the minerals. The variation of the chemical components has an opposite trend when compared with permeability.

Sign in / Sign up

Export Citation Format

Share Document