Impact of Shrubs on Winter Surface Albedo and Snow Specific Surface Area at a Low Arctic Site: In Situ Measurements and Simulations

AbstractErect shrubs in the Arctic reduce surface albedo when branches protrude above the snow and modify snow properties, in particular specific surface area (SSA). Important consequences are changes in the land surface–atmosphere energy exchange and the increase of snow melting in autumn, possibly inducing reduced soil thermal insulation and in turn permafrost cooling. Near Umiujaq (56.5°N, 76.5°W) in the Canadian low Arctic where dwarf birches (Betula glandulosa) are expanding, spectral albedo (400–1080 nm) under diffuse light and vertical profiles of SSA were measured in November and December 2015 at four sites: three with protruding branches and one with only snow. At the beginning of the snow season (8 November), shrub-induced albedo reductions were found to be wavelength dependent and as high as 55% at 500 nm and 18% at 1000 nm, which, integrated over the measurement range (400–1080 nm), corresponds to 70 W m−2 of additional absorbed energy. The impact of shrubs is not just snow darkening. They also affect snow SSA in multiple ways, by accumulating snow with high SSA during cold windy precipitation and favoring SSA decrease by inducing melting during warm spells. However, the impact on the radiation budget of direct darkening from shrubs likely dominates over the indirect change in SSA. Spectral albedo was simulated with a linear mixing equation (LME), which fitted well with observed spectra. The average root-mean-square error was 0.009. We conclude that LMEs are a suitable tool to parameterize mixed surface albedo in snow and climate models.

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Effect of Secondary Carbon Nanofillers on the Electrical, Thermal, and Mechanical Properties of Conductive Hybrid Composites Based on Epoxy Resin and Graphite

Materials ◽

10.3390/ma14154169 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4169

Author(s):

Marcel Zambrzycki ◽

Krystian Sokolowski ◽

Maciej Gubernat ◽

Aneta Fraczek-Szczypta

Keyword(s):

Mechanical Properties ◽

Specific Surface ◽

Epoxy Resin ◽

Surface Area ◽

Specific Surface Area ◽

Hybrid Composites ◽

Department Of Energy ◽

Carbon Nanofillers ◽

The Impact ◽

Secondary Carbon

In this work, we present a comparative study of the impact of secondary carbon nanofillers on the electrical and thermal conductivity, thermal stability, and mechanical properties of hybrid conductive polymer composites (CPC) based on high loadings of synthetic graphite and epoxy resin. Two different carbon nanofillers were chosen for the investigation—low-cost multi-layered graphene nanoplatelets (GN) and carbon black (CB), which were aimed at improving the overall performance of composites. The samples were obtained by a simple, inexpensive, and effective compression molding technique, and were investigated by the means of, i.a., scanning electron microscopy, Raman spectroscopy, electrical conductivity measurements, laser flash analysis, and thermogravimetry. The tests performed revealed that, due to the exceptional electronic transport properties of GN, its relatively low specific surface area, good aspect ratio, and nanometric sizes of particles, a notable improvement in the overall characteristics of the composites (best results for 4 wt % of GN; σ = 266.7 S cm−1; λ = 40.6 W mK−1; fl. strength = 40.1 MPa). In turn, the addition of CB resulted in a limited improvement in mechanical properties, and a deterioration in electrical and thermal properties, mainly due to the too high specific surface area of this nanofiller. The results obtained were compared with US Department of Energy recommendations regarding properties of materials for bipolar plates in fuel cells. As shown, the materials developed significantly exceed the recommended values of the majority of the most important parameters, indicating high potential application of the composites obtained.

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Chemical EOR in Low Permeability Sandstone Reservoirs: Impact of Clay Content on the Transport of Polymer and Surfactant

10.2118/200784-ms ◽

2021 ◽

Author(s):

Imane Guetni ◽

Claire Marlière ◽

David Rousseau

Keyword(s):

Porous Media ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Clay Content ◽

Low Permeability ◽

Depth Propagation ◽

The Impact ◽

Polymer Retention ◽

Injection Strategies

Abstract Application of chemical enhanced oil recovery (C-EOR) processes to low-permeability sandstone reservoirs (in the 10-100 mD range) can be very challenging as strong retention and difficult in-depth propagation of polymer and surfactant can occur. Transport properties of C-EOR chemicals are particularly related to porous media mineralogy (clay content). The present experimental study aimed at identifying base mechanisms and providing general recommendations to design economically viable C-EOR injection strategies in low permeability clayey reservoirs. Polymer and surfactant injection corefloods were conducted using granular packs (quartz and clay mixtures) with similar petrophysical characteristics (permeability 70-130 mD) but having various mineralogical compositions (pure quartz sand, sand with 8 wt-% kaolinite and sand with 8 wt-% smectite). The granular packs were carefully characterized in terms of structure (SEM) and specific surface area (BET). The main observables from the coreflood tests were the resistance and residual resistance factors generated during the chemical injections, the irreversible polymer retention and the surfactant retention in various injection scenarios (polymer alone, surfactant alone, polymer and surfactant). A first, the impact of the clay contents on the retention of polymer and surfactant considered independently was examined. Coreflood results have shown that retention per unit mass of rock strongly increased in presence of both kaolinite and smectite, but not in the same way for both chemicals. For polymer, retention was about twice higher with kaolinite than with smectite, despite the fact that the measured specific surface area of the kaolinite was about 5 times less than that of the smectite. Conversely, for surfactant, retention was much higher with smectite than with kaolinite. Secondly, the impact of the presence of surfactant on the polymer in-depth propagation and retention was investigated in pure quartz and kaolinite-bearing porous media. In both mineralogies, the resistance factor quickly stabilized when polymer was injected alone whereas injection of larger solution volumes was required to reach stabilization when surfactant was present. In pure quartz, polymer retention was shown, surprisingly, to be one order of magnitude higher in presence of surfactant whereas with kaolinite, surfactant did not impact polymer retention. The results can be interpreted by considering adsorption-governed retention. The mechanistic pictures being that (a) large polymer macromolecules are not able to penetrate the porosity of smectite aggregates, whereas surfactant molecules can, and (b) that surfactant and polymer mixed adsorbed layers can be formed on surfaces with limited affinity for polymer. Overall, this study shows that C-EOR can be applied in low permeability reservoirs but that successful injection strategies will strongly depend on mineralogy.

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Clouds damp the radiative impacts of polar sea ice loss

The Cryosphere ◽

10.5194/tc-14-2673-2020 ◽

2020 ◽

Vol 14 (8) ◽

pp. 2673-2686 ◽

Cited By ~ 1

Author(s):

Ramdane Alkama ◽

Patrick C. Taylor ◽

Lorea Garcia-San Martin ◽

Herve Douville ◽

Gregory Duveiller ◽

...

Keyword(s):

Sea Ice ◽

Climate Models ◽

Surface Radiation ◽

Radiation Budget ◽

The Arctic ◽

Cloud Properties ◽

Surface Radiation Budget ◽

Cloud Radiative Effect ◽

Radiative Impact ◽

The Impact

Abstract. Clouds play an important role in the climate system: (1) cooling Earth by reflecting incoming sunlight to space and (2) warming Earth by reducing thermal energy loss to space. Cloud radiative effects are especially important in polar regions and have the potential to significantly alter the impact of sea ice decline on the surface radiation budget. Using CERES (Clouds and the Earth's Radiant Energy System) data and 32 CMIP5 (Coupled Model Intercomparison Project) climate models, we quantify the influence of polar clouds on the radiative impact of polar sea ice variability. Our results show that the cloud short-wave cooling effect strongly influences the impact of sea ice variability on the surface radiation budget and does so in a counter-intuitive manner over the polar seas: years with less sea ice and a larger net surface radiative flux show a more negative cloud radiative effect. Our results indicate that 66±2% of this change in the net cloud radiative effect is due to the reduction in surface albedo and that the remaining 34±1 % is due to an increase in cloud cover and optical thickness. The overall cloud radiative damping effect is 56±2 % over the Antarctic and 47±3 % over the Arctic. Thus, present-day cloud properties significantly reduce the net radiative impact of sea ice loss on the Arctic and Antarctic surface radiation budgets. As a result, climate models must accurately represent present-day polar cloud properties in order to capture the surface radiation budget impact of polar sea ice loss and thus the surface albedo feedback.

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The Effects of Silica-Based Fillers on the Properties of Epoxy Molding Compounds

Materials ◽

10.3390/ma12111811 ◽

2019 ◽

Vol 12 (11) ◽

pp. 1811 ◽

Cited By ~ 6

Author(s):

Mitja Linec ◽

Branka Mušič

Keyword(s):

Mechanical Properties ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Fused Silica ◽

Spiral Flow ◽

Scanning Calorimetry ◽

Molding Compounds ◽

Material Development ◽

The Impact

Global design and manufacturing of the materials with superb properties remain one of the greatest challenges on the market. The future progress is orientated towards researches into the material development for the production of composites of better mechanical properties to the existing materials. In the field of advanced composites, epoxy molding compounds (EMCs) have attained dominance among the common materials due to their excellent properties that can be altered by adding different fillers. One of the main fillers is often based on silicon dioxide (SiO2). The concept of this study was to evaluate the effects of the selected silica-based fillers on the thermal, rheological, and mechanical properties of EMCs. Various types of fillers with SiO2, including crystalline silica and fused silica, were experimentally studied to clarify the impact of filler on final product. Fillers with different shape (scanning electron microscope, SEM), along with different specific surface area (specific surface area analyzer, BET method) and different chemical structure, were tested to explore their modifications on the EMCs. The influence of the fillers on the compound materials was determined with the spiral flow length (spiral flow test, EMMI), glass transition temperature (differential scanning calorimetry, DSC), and the viscosity (Torque Rheometer) of the composites.

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Retrieval of Snow Properties from the Sentinel-3 Ocean and Land Colour Instrument

Remote Sensing ◽

10.3390/rs11192280 ◽

2019 ◽

Vol 11 (19) ◽

pp. 2280 ◽

Cited By ~ 14

Author(s):

Alexander Kokhanovsky ◽

Maxim Lamare ◽

Olaf Danne ◽

Carsten Brockmann ◽

Marie Dumont ◽

...

Keyword(s):

Grain Size ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Environmental Changes ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

The Arctic ◽

Observation Data ◽

Snow Properties

The Sentinel Application Platform (SNAP) architecture facilitates Earth Observation data processing. In this work, we present results from a new Snow Processor for SNAP. We also describe physical principles behind the developed snow property retrieval technique based on the analysis of Ocean and Land Colour Instrument (OLCI) onboard Sentinel-3A/B measurements over clean and polluted snow fields. Using OLCI spectral reflectance measurements in the range 400–1020 nm, we derived important snow properties such as spectral and broadband albedo, snow specific surface area, snow extent and grain size on a spatial grid of 300 m. The algorithm also incorporated cloud screening and atmospheric correction procedures over snow surfaces. We present validation results using ground measurements from Antarctica, the Greenland ice sheet and the French Alps. We find the spectral albedo retrieved with accuracy of better than 3% on average, making our retrievals sufficient for a variety of applications. Broadband albedo is retrieved with the average accuracy of about 5% over snow. Therefore, the uncertainties of satellite retrievals are close to experimental errors of ground measurements. The retrieved surface grain size shows good agreement with ground observations. Snow specific surface area observations are also consistent with our OLCI retrievals. We present snow albedo and grain size mapping over the inland ice sheet of Greenland for areas including dry snow, melted/melting snow and impurity rich bare ice. The algorithm can be applied to OLCI Sentinel-3 measurements providing an opportunity for creation of long-term snow property records essential for climate monitoring and data assimilation studies—especially in the Arctic region, where we face rapid environmental changes including reduction of snow/ice extent and, therefore, planetary albedo.

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Retrieval of snow properties from the Sentinel-3 Ocean and Land Colour Instrument

10.20944/preprints201906.0162.v1 ◽

2019 ◽

Cited By ~ 1

Author(s):

Alexander Kokhanovsky ◽

Maxim Lamare ◽

Olaf Danne ◽

Marie Dumont ◽

Carsten Brockmann ◽

...

Keyword(s):

Grain Size ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Environmental Changes ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

The Arctic ◽

Observation Data ◽

Snow Properties

The Sentinel Application Platform (SNAP) architecture facilitates Earth Observation data processing (http://step.esa.int/main/toolboxes/snap/). In this work we present results from a new Snow Processor for SNAP. We also describe physical principles behind the developed snow property retrieval technique based on the analysis of Ocean and Land Colour Instrument (OLCI) onboard Sentinel-3A/B measurements over clean and polluted snow fields. Using OLCI spectral reflectance measurements in the range 400-1020nm, we derive important snow properties such as spectral and broadband albedo, snow specific surface area, snow extent and grain size on the spatial grid of 300m. The algorithm also incorporates cloud screening and atmospheric correction procedures over snow surfaces. We present validation results using ground measurements from Antarctica, the Greenland ice sheet and the French Alps. We find the spectral albedo retrieved with accuracy of better than 3% on average, making our retrievals sufficient for a variety of applications. Broadband albedo is retrieved with the average accuracy of about 5% over snow. Therefore, the uncertainties of satellite retrievals are close to experimental errors of ground measurements. The retrieved surface grain size shows good agreement with ground observations. Snow specific surface area observations are also consistent with our OLCI retrievals. We present snow albedo and grain size mapping over the inland ice sheet of Greenland for areas including dry snow, melted/melting snow and impurity rich bare ice. The algorithm can be applied to OLCI Sentinel-3 measurements providing an opportunity for creation of long – term snow property records essential for climate monitoring and data assimilation studies - especially in the Arctic region, where we face rapid environmental changes including reduction of snow/ice extent and, therefore, planetary albedo.

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New Production Route of Magnesium Hydroxide and Related Environmental Impact

Sustainability ◽

10.3390/su12218822 ◽

2020 ◽

Vol 12 (21) ◽

pp. 8822

Author(s):

Andrzej Jarosinski ◽

Piotr Radomski ◽

Lukasz Lelek ◽

Joanna Kulczycka

Keyword(s):

Environmental Impact ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Magnesium Hydroxide ◽

Flame Retardants ◽

Polymeric Materials ◽

New Production ◽

Constant Flow Rate ◽

The Impact

The paper presents research on a method of obtaining magnesium hydroxide from magnesium sulphate salts and NaOH. In order to acquire the desired and controlled properties, the method of precipitating in aqueous solutions by introducing a NaOH solution into a solution of MgSO4 has been applied. To get as stable a product as possible with graining, the introduction of NaOH takes place at a constant flow rate. In order to identify the environmental impact of the developed process, a life cycle assessment (LCA) has been made. The use of the proposed method for the synthesis of Mg(OH)2 incorporating washing with 25% ammonia solution and acetone enabled a product with a high specific surface area. The Mg(OH)2 obtained was characterised by a higher specific surface area than commercially available magnesium hydroxides that are used as additives for flame retardants in polymeric materials. This allows the material to be used as an anti-pyrogen for a wider group of polymeric materials. For the LCA analysis, two scenarios were assumed, from which the basic one included recovery of ammonia and acetone. The environmental analysis carried out confirmed the validity of this assumption, as it was stated that the main part of the impact was connected with the supply chain for the process examined.

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Influence of Pluronic® P123 Addition in the Synthesis of Bulk Ni Promoted MoS2 Catalyst. Application to the Selective Hydrodesulfurization of Sulfur Model Molecules Representative of FCC Gasoline

Catalysts ◽

10.3390/catal9100793 ◽

2019 ◽

Vol 9 (10) ◽

pp. 793 ◽

Cited By ~ 2

Author(s):

Valentin Hetier ◽

Diego Pena ◽

Alexandre Carvalho ◽

Laurence Courthéoux ◽

Valérie Flaud ◽

...

Keyword(s):

Catalytic Activity ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Intrinsic Activity ◽

Strong Increase ◽

Similar Amount ◽

X Ray ◽

Mos2 Catalysts ◽

The Impact

A way to improve hydrotreatment processes is to enhance the intrinsic activity of Ni or Co promoted MoS2 catalysts that are commonly used in such reactions. The aim of this work was to investigate the impact of the presence of Pluronic® P123 as a structuring agent during the synthesis of Ni promoted MoS2 catalysts (named NiMoS) in water at room temperature. A series of analyses, i.e., X-ray diffraction (XRD), chemical analysis, inductively coupled plasma mass spectrometry (ICP-MS), nitrogen adsorption-desorption isotherms, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), helped in characterizing the NiMoS-P123 and NiMoS catalysts, the latter being prepared in the absence of polymer. Both compounds contained MoS2 phase (~85 atomic% considering Mo atoms), a similar amount of mixed Ni-Mo-S phase (40–50% considering Ni) and some amount of NiS and Ni-oxidized impurity phases. The main differences between the two catalysts were a much larger specific surface area (126 m2·g−1 instead of 31 m²·g−1) and a better dispersion of the active phase as shown by the lower slab stacking (2.7 instead of 4.8) for NiMoS-P123, and the presence of C in NiMoS-P123 (9.4 wt.% instead of 0.6 wt.%), indicating an incomplete decomposition of the polymer during thermal treatment. Thanks to its larger specific surface area and lower slab stacking and therefore modification of active Mo site properties, the compound prepared in the presence of Pluronic® P123 exhibits a strong increase of the catalytic activity expressed per Mo atom for the transformation of 3-methylthiophene. Such improvement in catalytic activity was not observed for the transformation of benzothiophene likely due to poisonous residual carbon which results from the presence of Pluronic® P123 during the synthesis.

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INFLUENCE OF SYNTHESIS TECHNO-CHEMICAL PARAMETERS ON PHYSICOCHEMICAL CHARACTERISTICS OF BIOMIMETIC CALCIUM-PHOSPHATE NANOCOMPOSITE DOPED BY SILICATE AND CARBONATE ANIONS

Bulletin of Belgorod State Technological University named after V G Shukhov ◽

10.34031/2071-7318-2020-5-10-47-56 ◽

2020 ◽

Vol 5 (10) ◽

pp. 47-56

Author(s):

M. Troubitsin ◽

Viet Hung Hoang ◽

L. Furda

Keyword(s):

Calcium Phosphate ◽

Specific Surface ◽

Crystallite Size ◽

Surface Area ◽

Specific Surface Area ◽

Pore Volume ◽

Average Pore Size ◽

Average Crystallite Size ◽

Average Pore ◽

The Impact

The object of our investigation is a biomimetic calcium-phosphate nanocomposite doped by silicate and carbonate anions (BMHAP) synthesized by chemical deposition from aqueous solutions. The obtained samples are investigated using X-ray phase analysis (XRD), FTIR spectroscopy, and low-temperature nitrogen adsorption (BET method). The influence of the techno chemical synthesis parameters on the products characteristics (including phase composition, crystal lattice parameters, average crystallite size, specific surface area) is evaluated. The study on the effect of the synthesis temperature shows that with increasing in temperature from 22°C to 80°C, reveals a slight increase in the parameters of unit cells a and c, which leads to an increase in its volume. There is also a tendency towards a decrease in the average size of coherent scattering regions of crystallites (from 7,52 to 4,65 nm) and specific surface area (from 192,51 to 74,72 m2/g), but the pore volume and average pore diameter of the synthesized powders increases. The effect of the aging time of the sediment in the mother liquor is studied from 0,5 to 24 hours. It is found that with an increase in the maturation time of the sediment, the percent crystallinity of the powders improves by 1,7 times, an increase in the specific surface area from 163,43 to 192,51 m2/g and a slight decrease in the pore volume and average pore size of the samples are observed. The impact of the stirring rate of the reagents is investigated. An increase in speed from 300 to 1300 rpm has been shown to decrease the average crystallite size from 8,80 to 6,41 nm, and as a result, to increase the specific surface area of the synthesized samples from 178,58 to 192,51 m2/g, respectively.

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Meteorological, snow and soil data (2013–2019) from a herb tundra permafrost site at Bylot Island, Canadian high Arctic, for driving and testing snow and land surface models

10.5194/essd-2021-54 ◽

2021 ◽

Author(s):

Florent Domine ◽

Georg Lackner ◽

Denis Sarrazin ◽

Mathilde Poirier ◽

Maria Belke-Brea

Keyword(s):

Thermal Conductivity ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

High Arctic ◽

Specific Humidity ◽

The Arctic ◽

Canadian High Arctic ◽

Validation Data ◽

Bylot Island

Abstract. Seasonal snow covers Arctic lands 6 to 10 months of the year and is therefore an essential element of the Arctic geosphere and biosphere. Yet, even the most sophisticated snow physics models are not able to simulate fundamental physical properties of Arctic snowpacks such as density, thermal conductivity and specific surface area. The development of improved snow models is in progress but testing requires detailed driving and validation data for high Arctic herb tundra sites, which are presently not available. We present 6 years of such data for an ice-wedge polygonal site in the Canadian high Arctic, in Qarlikturvik valley on Bylot Island at 73.15 °N. The site is on herb tundra with no erect vegetation and thick permafrost. Detailed soil properties are provided. Driving data are comprised of air temperature, air relative and specific humidity, wind speed, short wave and long wave downwelling radiation, atmospheric pressure and precipitation. Validation data include time series of snow depth, shortwave upwelling radiation, surface temperature, snow temperature profiles, soil temperature and water content profiles at five depths, snow thermal conductivity at three heights and soil thermal conductivity at 10 cm depth. Field campaigns in mid-May for 5 of the 6 years of interest provided spatially-averaged snow depths and vertical profiles of snow density and specific surface area in the polygon of interest and at other spots in the valley. Data are available at https://doi.org/10.5885/45693CE-02685A5200DD4C38 (Domine et al., 2021). Data files will be updated as more years of data become available.

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