Search results for "infiltration"
showing 10 items of 291 documents
Impact de l'hétérogénéité sédimentaire d'un dépôt fluvioglaciaire sur l'infiltration d'eaux pluviales en milieu urbain
2007
Gravity-Driven Infiltration and Subsidence Phenomena in Posidonia oceanica Residues
2019
A simplified infiltration model for highly permeable porous media was introduced, assuming the matric potential gradient as negligible compared to the gravitational gradient. This model enabled us to determine the delay time, i.e., the time that the water front takes (from the beginning of rainfall) to reach the bottom of the highly permeable layer. Posidonia oceanica (Linnaeus) Delile residues were used as a porous media, in order to study the infiltration process that provides salt leaching under natural rainfall when these residues are arranged in a storage area, before reusing. By using a laboratory rainfall simulator, delay times were measured to verify the applicability of the aforeme…
Importance of HLA-DR+ and CD1a+ Epidermal Cells for Cytokine Production in Psoriasis
1995
Psoriasis is an inflammatory skin disease characterised by marked hyperproliferation of keratinocytes in association with vascular expansion, leukocyte infiltration and lymphocyte activation1. Cytokines are thought to play a pivotal role in the pathogenesis. It is speculated that a dysregulation of the cytokine network involving tumor-necrosis-factor-a (TNF-α), interleukin-6 (IL-6) and interleukin-8 (IL-8) might be the basic mechanism of the psoriatic inflammatory response2. TNF-α is the prototype of a proinflammatory peptide exerting immunomodulatory effects. IL-6 is a multifunctional cytokine with a broad range of biological functions in both acute and chronic inflammatory reactions. IL-8…
The impact of the age of vines on soil hydraulic conductivity in vineyards in eastern Spain
2017
Soil infiltration processes manage runoff generation, which in turn affects soil erosion. There is limited information on infiltration rates. In this study, the impact of vine age on soil bulk density (BD) and hydraulic conductivity (Ks) was assessed on a loam soil tilled by chisel plough. Soil sampling was conducted in the inter row area of six vineyards, which differed by the age from planting: 0 (Age 0; just planted), 1, 3, 6, 13, and 25 years (Age 1, Age 3, Age 6, Age 13, and Age 25, respectively). The One Ponding Depth (OPD) approach was applied to ring infiltration data to estimate soil Ks with an α* parameter equal to 0.012 mm-1. Soil bulk density for Age 0 was about 1.5 times greate…
Variability of near-surface saturated hydraulic conductivity for the clay soils of a small Sicilian basin
2019
Abstract Proper characterization of saturated hydraulic conductivity, Ks, of clay soils in a hillslope or a basin is still a challenge for soil science. In this investigation, the clay soils of the Maganoce (Sicily, Italy) basin were sampled at 19 sampling sites by the BEST procedure of soil hydraulic characterization. More OM implied less compact conditions (decreasing dry soil bulk density; coefficient of determination, R2 = 0.67), more stability to water of the soil aggregates (increasing water stable aggregates; R2 = 0.83) and, consequently, higher Ks values (R2 = 0.54). Variability of Ks was lower in the steeper zones of the basin than in the flatter ones. A comparison with the Ks data…
Changes in soil redox potential in response to flood irrigation with waste water in central Mexico
2017
Irrigation with untreated sewage water adds fresh organic matter to the soil. When it is applied by flooding, as in the Mezquital Valley of Mexico, many of the pores in the soil become temporarily waterlogged and depleted of oxygen, and reduction generates nitrous oxide (N2O) and methane (CH4). We monitored the redox potential, Eh, in the soil at two sites in the Mezquital Valley to discover whether the short-term gaseous emissions matched the changes in Eh. One site is irrigated periodically by flooding with waste water and has alfalfa, rye grass and maize grown in succession; the other site grows maize with water from summer rain only. Each electrode buried in the soil for the purpose pro…
Absorption and desorption of liquid water by a superabsorbent polyelectrolyte: Role of polymer on the capacity for absorption of a ground
2001
To study the potentialities of a polyelectrolyte superabsorbent for the storage of water, we have studied a ground representative of the area of Haouz (area of Marrakesh, South of Morocco) in the presence of polymer. We sought the optimal proportions allowing the best retention of water by the mixture made up of the polymer and the ground and to prolong the storage period of water in the ground. We have also studied the effect of certain ions and the pH on the capacity for absorption of polymer. These ions can be naturally present in the ground or introduced by the means of manure and pesticides. The presence of polymer in the ground makes it possible to increase the capacity for absorption…
Spatial and short-term temporal variations in runoff, soil aggregation and other soil properties along a Mediterranean Climatological Gradient.
1998
Abstract Physical and chemical soil properties were measured along a mountainous climatological gradient in the province of Alicante (Spain). The objective was to evaluate how the climate affects certain soil properties at different temporal and spatial scales. These properties include infiltration, runoff and sediment concentrations resulting from rainfall simulation experiments performed in winter and in summer. Chemical soil properties like carbonate content, organic matter content and CEC were analysed in reference soil profiles along the gradient. Physical soil properties like soil moisture content, macroaggregation and waterstable microaggregation were measured at monthly intervals du…
The use of shallow dripwater as an isotopic marker of seepage in karst areas: A comparison between Western Sicily (Italy) and the Harz Mountains (Ger…
2013
Abstract The isotopic signature of slow-flowing dripwater collected in caves located in Western Sicily (Italy) was determined for evaluating its possible use as an isotopic tracer of the local groundwater recharge. These spot measures were compared with a longer series of local rain and spring compositions and with other samples taken, under different hydrogeological conditions, in caves of the Harz Mountains (Northern Germany). The slow flowing dripwater from Sicily showed δ 18 O/δD ratios similar to those of local rain and groundwater, demonstrating that these three are all parent waters. A parallel similarity was found in the vertical isotopic gradient (Δδ 18 O) of the three groups of wa…
The Coastal Sulfuric Acid Cave System of Santa Cesarea Terme (Southern Italy)
2017
Santa Cesarea Terme in Salento is the only area in which hypogenic caves have been recognized in the Apulia region. In this spa area, the rising of sulfidic thermal waters that mix with both recent fresh infiltration waters and coastal salt water has formed four active sulfuric acid speleogenesis (SAS) caves. These caves are characterized by the typical set of sulfuric acid meso- and micromorphologies, and also by the presence of both gypsum and native sulfur. In all caves, biofilms are visible in the sulfidic thermal waters and on the cave walls.