scholarly journals Retrieval of volcanic ash and ice cloud physical properties together with gas concentration from IASI measurements using the AVL model

2013 ◽  
Author(s):  
S. Kochenova ◽  
M. De Mazière ◽  
N. Kumps ◽  
S. Vandenbussche ◽  
T. Kerzenmacher
Keyword(s):  
Physical Properties ◽  
Volcanic Ash ◽  
Gas Concentration ◽  
Ice Cloud

Physical Properties of Volcanic Ash Based Geopolymer Concrete

2016 ◽  
Vol 841 ◽  
pp. 1-6 ◽  
Author(s):  
Puput Risdanareni ◽  
Adjib Karjanto ◽  
Febriano Khakim
Keyword(s):  
Tensile Strength ◽  
Fly Ash ◽  
Physical Properties ◽  
Volcanic Ash ◽  
Setting Time ◽  
Physical And Mechanical Properties ◽  
Ash Content ◽  
Geopolymer Concrete ◽  
Split Tensile Strength ◽  
Time Test

This paper describes the result of investigating volcanic ash of Mount Kelud as fly ash substitute material to produce geopolymer concrete. The test was held on geopolymer concrete blended with 0%, 25%, 50% and 100% fly ash replacement with volcanic ash. Natrium Hidroxide (NaOH) with concentration of 12 molar and Natrium Silicate (Na2SiO3) were used as alkaline activator. While alkali-activator ratio of 2 was used in this research. The physical properties was tested by porosity and setting time test, while split tensile strength presented to measure brittle caracteristic of geopolymer concrete. The result shown that increasing volcanic ash content in the mixture will increase setting time of geopolymer paste. On the other hand increasing volcanic ash content will reduce split tensile strength and porosity of geopolymer concrete. After all replacing fly ash with volcanic ash was suitable from 25% to 50% due to its optimum physical and mechanical properties.

Spatial variation in soil physical properties and effects on soil NO3– production on forest hillslopes

2020 ◽  
Author(s):  
Tomoki Oda ◽  
Megumi Kuroiwa ◽  
Naoya Fujime ◽  
Kazuo Isobe ◽  
Naoya Masaoka ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Soil Moisture ◽  
Physical Properties ◽  
Spatial Variation ◽  
Volcanic Ash ◽  
Surface Soil ◽  
Soil Physical Properties ◽  
Slope Position ◽  
Surface Soil Moisture ◽  
Slope Bottom

<p>Ammonium (NH<sub>4</sub><sup>+</sup>) and nitrate (NO<sub>3</sub><sup>–</sup>) concentrations and production rates in forest soil vary by hillslope position due to variation in ammonia-oxidizing microorganism concentrations, soil chemistry, and surface soil moisture. These spatial distributions have a significant effect on nutrient cycles and streamwater chemistry. Soil moisture conditions significantly restrict microbial activity, influencing the spatial distribution of NO<sub>3</sub><sup>–</sup> concentrations on forest hillslopes. However, studies linking forest hydrological processes to nitrogen cycling are limited. Therefore, we investigated the determinants of spatial variation in soil moisture and evaluated the effects of soil moisture fluctuations on spatial variation in NO<sub>3</sub><sup>–</sup> concentration and production rate.</p><p>The study sites were the Fukuroyamasawa Experimental Watershed (FEW) and Oyasan Experimental Watershed (OEW) in Japan. The two have similar topographies, climates, and tree species. In each watershed, a 100 m transect was set up from the ridge to the base of the slope, and soil moisture sensors were installed at soil depths of 10 cm and 30 cm at both the top and bottom of the slope. We collected surface soil samples at a depth of 10 cm at the top, middle, and bottom of the slopes using 100 cm<sup>3</sup> cores, and measured soil physical properties, particle size distribution, volcanic ash content, chemical properties (pH, NO<sub>3</sub><sup>–</sup>, NH<sub>4</sub><sup>+</sup>, nitrification rate, and mineralization rate), and microbial content (archaeal content). Spatial and temporal changes in soil moisture on the hillslope were calculated using HYDRUS-2D to examine contributing factors of soil moisture.</p><p>At FEW, high NO<sub>3</sub><sup>–</sup> concentrations and nitrification rates were observed only at the slope bottom and middle, and no NO<sub>3</sub><sup>–</sup> concentrations were detected at up slope. By contrast, at OEW, high NO<sub>3</sub><sup>–</sup> concentrations and nitrification rates were observed at all points. NH<sub>4</sub><sup>+</sup> concentrations were similar at all points in both watersheds. At FEW, 10 cm surface soil moisture fluctuated within 25–40% at the slope top but was within 40–50% at the slope bottom. At OEW, surface soil moisture was 30–40% at both the slope top and bottom, with no significant differences according to slope position. It was confirmed that soil moisture was significantly involved in NO<sub>3</sub><sup>– </sup>concentration and nitrification rates. Model simulations showed that the difference in soil moisture fluctuations between FEW and OEW was mainly explained by the spatial variation in soil physical properties. In particular, volcanic ash influenced soil moisture along the entire slope at OEW, resulting in high water retention, but only influenced soil moisture at the slope bottom at FEW. These findings indicate that spatial variability in soil physical properties has a significant effect on soil moisture fluctuation and leads to a spatial distribution of NO<sub>3</sub><sup>–</sup> production.</p>

Effect of pasture improvement managements on physical properties and water content dynamics of a volcanic ash soil in southern Chile

2018 ◽  
Vol 178 ◽  
pp. 55-64 ◽  
Author(s):  
Iván Ordóñez ◽  
Ignacio F. López ◽  
Peter D. Kemp ◽  
Constanza A. Descalzi ◽  
Rainer Horn ◽  
...  
Keyword(s):  
Physical Properties ◽  
Water Content ◽  
Volcanic Ash ◽  
Southern Chile ◽  
Volcanic Ash Soil

scholarly journals Ice nucleation properties of volcanic ash from Eyjafjallajökull

2011 ◽  
Vol 11 (6) ◽  
pp. 17201-17243 ◽  
Author(s):  
C. R. Hoyle ◽  
V. Pinti ◽  
A. Welti ◽  
B. Zobrist ◽  
C. Marcolli ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Freezing Point ◽  
Ice Nucleation ◽  
Cloud Formation ◽  
Atmospheric Conditions ◽  
Model Calculations ◽  
Airborne Measurements ◽  
Ice Cloud ◽  
Ice Nuclei ◽  
Homogeneous Freezing

Abstract. The ice nucleation ability of volcanic ash particles collected close to the Icelandic volcano Eyjafjallajökull during its eruptions in April and May 2010 is investigated experimentally, in the immersion and deposition modes, and applied to atmospheric conditions by comparison with airborne measurements and microphysical model calculations. The number of ash particles which are active as ice nuclei (IN) is strongly temperature dependent, with a very small minority being active in the immersion mode at temperatures of 250–263 K. Average ash particles show only a moderate effect on ice nucleation, by inducing freezing at temperatures between 236 K and 240 K (i.e. approximately 3–4 K higher than temperatures required for homogeneous ice nucleation, measured with the same instrument). By scaling the results to aircraft and lidar measurements of the conditions in the ash plume days down wind of the eruption and by applying a simple microphysical model, it was found that the IN active in the immersion mode in the range 250–263 K generally occurred in atmospheric number densities at the lower end of those required to have an impact on ice cloud formation. However, 3–4 K above the homogeneous freezing point, immersion mode IN number densities a few days down wind of the eruption were sufficiently high to have a moderate influence on ice cloud formation. The efficiency of IN in the deposition mode was found to be poor except at very cold conditions (< 238 K), when they reach an efficiency similar to that of mineral dust with the onset of freezing at 10 % supersaturation with respect to ice, and with the frozen fraction nearing its maximum value at a supersaturation 20 %. In summary, these investigations suggest volcanic ash particles to have only moderate effects on atmospheric ice formation.

scholarly journals Ice nucleation properties of volcanic ash from Eyjafjallajökull

2011 ◽  
Vol 11 (18) ◽  
pp. 9911-9926 ◽  
Author(s):  
C. R. Hoyle ◽  
V. Pinti ◽  
A. Welti ◽  
B. Zobrist ◽  
C. Marcolli ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Freezing Point ◽  
Ice Nucleation ◽  
Cloud Formation ◽  
Atmospheric Conditions ◽  
Model Calculations ◽  
Airborne Measurements ◽  
Ice Cloud ◽  
Ice Nuclei ◽  
Homogeneous Freezing

Abstract. The ice nucleation ability of volcanic ash particles collected close to the Icelandic volcano Eyjafjallajökull during its eruptions in April and May 2010 is investigated experimentally, in the immersion and deposition modes, and applied to atmospheric conditions by comparison with airborne measurements and microphysical model calculations. The number of ash particles which are active as ice nuclei (IN) is strongly temperature dependent, with a very small minority being active in the immersion mode at temperatures of 250–263 K. Average ash particles show only a moderate effect on ice nucleation, by inducing freezing at temperatures between 236 K and 240 K (i.e. approximately 3–4 K higher than temperatures required for homogeneous ice nucleation, measured with the same instrument). By scaling the results to aircraft and lidar measurements of the conditions in the ash plume days down wind of the eruption, and by applying a simple microphysical model, it was found that the IN active in the immersion mode in the range 250–263 K generally occurred in atmospheric number densities at the lower end of those required to have an impact on ice cloud formation. However, 3–4 K above the homogeneous freezing point, immersion mode IN number densities a few days down wind of the eruption were sufficiently high to have a moderate influence on ice cloud formation. The efficiency of IN in the deposition mode was found to be poor except at very cold conditions (<238 K), when they reach an efficiency similar to that of mineral dust with the onset of freezing at 10 % supersaturation with respect to ice, and with the frozen fraction nearing its maximum value at a supersaturation 20 %. In summary, these investigations suggest volcanic ash particles to have only moderate effects on atmospheric ice formation.

Using wavelet analyses to identify temporal coherence in soil physical properties in a volcanic ash-derived soil

2020 ◽  
Vol 285-286 ◽  
pp. 107909 ◽  
Author(s):  
Sebastián Bravo ◽  
Mauricio González-Chang ◽  
Dorota Dec ◽  
Susana Valle ◽  
Ole Wendroth ◽  
...  
Keyword(s):  
Physical Properties ◽  
Volcanic Ash ◽  
Temporal Coherence ◽  
Soil Physical Properties ◽  
Wavelet Analyses
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