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Bruno Merz - One of the best experts on this subject based on the ideXlab platform.
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1 2 and 3 dimensional modeling of water movement in the unsaturated Soil Matrix using a fuzzy approach
Advances in Water Resources, 1995Co-Authors: Andras Bardossy, Axel Bronstert, Bruno MerzAbstract:Modeling water movement in the unsaturated Soil Matrix is usually based on the numerical solution of the Richards equation. This approach requires much computational effort, therefore practical 2- or 3-dimensional applications are extremely rare. The purpose of this paper is to describe a computationally efficient and simple method. It is based on a transformation of the unsaturated Darcy law to a fuzzy rule system. The rule system is combined with the continuity equation yielding a fuzzy rule-based model for simulating the unsaturated flow. Basic definitions of fuzzy logic are given and the concept of the unsaturated flow model is outlined. The presented model performs well compared with a semi-analytical model and a 2-dimensional, numerical model. Furthermore the model has been incorporated into a physically-based and distributed, hydrological model. Model simulations for different types of hydrological situations show that the fuzzy rule-based approach is especially suitable for real-life applications.
Bjørn Kløve - One of the best experts on this subject based on the ideXlab platform.
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Mechanisms of Soil Matrix water replenishment in a sub-arctic till Soil based on an isotope tracer experiment
2020Co-Authors: Filip Muhic, Pertti Ala-aho, Matthias Sprenger, Hannu Marttila, Bjørn KløveAbstract:<p>Due to changes in the snowmelt timing and the potential shift towards less snowfall and more rainfall, infiltration patterns into the Soil will increasingly be altered in a warming climate. Mixing and transport processes of water in the unsaturated topSoil layer regulate the subsurface transport and retention of solutes and contaminants, as well as the distribution of plant available water. Recent advances in Soil isotope ecohydrology indicate that in some ecosystems, water in macropores largely bypasses Soil Matrix and rapidly percolates into the groundwater. Here we combine tracer experiments and geophysical surveys to explore Soil water mixing in non-stratified till Soil in the Pallas catchment located in sub-arctic conditions in Finnish Lapland. A 5x20 m plot at the Kentt&#228;rova hilltop was sprinkled with deuterated water (d<sup>2</sup>H 88&#8240;) for two days (totally 200 mm at average intensity of 6.7 mm/h), until surface water ponding was observed on substantial share of the plot. Soil moisture dynamic were monitored by a network of Soil moisture sensors and manual Soil probe measurements. Soil water was sampled hourly with suction cup lysimeters at three (5 cm, 30 cm, 60 cm) depths and pan lysimeter at 35 cm depth in two Soil profiles on the irrigation plot. Groundwater was sampled hourly, while xylem samples from spruce and birch trees in the plot were collected on each day of the experiment and on a weekly basis during the following month. Ground penetrating radar (GPR) survey and Soil coring with window sampler down to 1 m depth were completed four times over the course of the experiment, and additional set of Soil cores were taken two weeks after the experiment to inspect how natural precipitation events have infiltrated into the deuterium enriched zone. We investigate the mechanisms of Soil Matrix water replenishment by answering the following questions: i) Can all Soil Matrix water be displaced during high volume events and when does newly introduced Soil Matrix water become available to the plants?; ii) What is the extent of Soil water mixing at different depths?; and iii) What is the effect of increased moisture content and groundwater table rise on Soil water mixing? Due to paucity of field data sets and inability of most hydrological models to accurately simulate Soil freezing and thawing effects, ecohydrologic partitioning has been barely studied in Northern regions with seasonal snow cover. We present a novel field data set that focuses on Soil Matrix water replenishment in glaciated till Soil at sub-arctic conditions. Results support our understanding of ecohydrological processes in northern environments where hydrological cycle is dominated by intense infiltration events as it occurs during snowmelt.</p>
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Phosphorus forms and related Soil chemistry in preferential flowpaths and the Soil Matrix of a forested podzolic till Soil profile
Geoderma, 2012Co-Authors: Soile Backnäs, Hanne Laine-kaulio, Bjørn KløveAbstract:Abstract Preferential flow affects subsurface flow and solute transport processes in forested glacial till Soils. Preferential flowpaths (PFPs) have been detected in forest Soils, with higher microbial biomass, organic carbon content and increased nitrogen cycling compared with the Soil Matrix. However, the role of preferential flow in phosphorus (P) cycling in forest Soils is still unknown. This study characterised the P forms of a forested podzolic till Soil profile in Southern Finnish Lapland using P extraction and ignition procedures, fractionation and solution 31 P nuclear magnetic resonance (NMR) spectroscopy. PFPs were identified by introducing the dye tracer Acid Blue 9 at the surface of a 1.25 m 2 study plot. The Soil profile was vertically sliced and samples were collected from the unstained Soil Matrix and the dye-stained PFPs of each horizon of the podzol. Amorphous metal sesquioxides, naturally bound P (P ox ), total P (P t ), inorganic P (P in ), organic P (P o ), different inorganic P fractions (soluble P, Al–P, Fe–P, Ca–P, occluded P) and organic and inorganic P forms ( 31 P-NMR spectroscopy) were analysed in the samples. The concentrations of different forms of P and amorphous metal sesquioxides varied between the different PFPs and the Soil Matrix within the podzol Soil horizons. The PFPs in Soils on stone surfaces contained less amorphous metal sesquioxides, P ox and P t than the other flow regions. The PFPs related to coarse grains and roots contained equivalent or higher P ox and P t concentrations than the Soil Matrix. Inorganic P was present as orthophosphates and pyrophosphates, and was mainly bound with Al and Ca oxides in PFPs, but also with Fe oxides in the Soil Matrix. PFPs contained more occluded P than the Soil Matrix, especially on stone surfaces. The results indicate increased mobilisation and P losses in PFPs on stone surfaces due to enhanced mineral weathering, root uptake and leaching of P adsorbed by the sesquioxides. The results of the 31 P NMR study also showed higher proportions of pyrophosphate, orthophosphate diesters and monoesters other than phytic acid in the PFPs on stone surfaces than in the other flow regions, indicating higher amounts of labile forms of inorganic and organic P on stone surfaces than in other flow regions. To conclude, PFPs seem to have a twofold role in P dynamics: P can leach through PFPs on stone surfaces and accumulate on PFPs related to coarse grains and roots.
Dipak Roy - One of the best experts on this subject based on the ideXlab platform.
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Enhanced transport of bacteria through a Soil Matrix using colloidal gas aphron suspensions
Journal of Environmental Science and Health Part A, 1998Co-Authors: Andrew Jackson, Dipak Roy, Raghava R. Kommalapati, John H. PardueAbstract:Abstract The influence of an anionic surfactant sodium dodecylbenzene sulfonate (DDBS) in the form of either an aqueous solution or microgas dispersion known as colloidal gas aphron (CGA) on the transport of a Psendomonas psendoalcaligenes, strain through a saturated Soil Matrix was examined. The experiments were conducted in 30‐cm‐long and 6.35 cm internal diameter stainless steel columns packed with a sandy clay loam. A 10‐ml pulse (0.033 pore volumes) of a bacterial suspension containing 1010 colony forming units (cfu) per ml was injected, and the column was eluted with either deionized water, a solution of DDBS, or a CGA suspension at a surface loading rate of 0.16 cm/min. The bacterial distributions within the column were similar after the passage of the water and surfactant solutions; however, the distribution of bacteria in the columns and effluent after the passage of the CGA suspension was markedly enhanced. The bacterial concentration in the lower half of the column after the passage of the CGA ...
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Application of surfactant solutions and colloidal gas aphron suspensions in flushing naphthalene from a contaminated Soil Matrix
Journal of Hazardous Materials, 1995Co-Authors: Dipak Roy, S. Kongara, Kalliat T. ValsarajAbstract:Abstract The applicability of conventional surfactant solutions and colloidal gas aphron (CGA) suspensions to remove naphthalene from a contaminated Soil Matrix was investigated. Laboratory studies were conducted to evaluate the relative suitability of nonionic, cationic and anionic surfactants in removing naphthalene from the Soil. Nonionic surfactant was found to be more efficient than the ionic surfactants in removing napthalene from contaminated Soil Matrix in batch experiments and was selected for further flushing studies. The presence of surfactant reduced the volatilization of naphthalene. Micellar solubilization appears to be the primary mechanism of removal using both surfactant solutions and CGA suspensions. Increasing the concentration of the surfactant solution enhanced the percent removal of naphthalene. Using a CGA suspension as a flushing medium may result in channeling and pore clogging in the Soil Matrix, thereby affecting the overall efficiency of the process.
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Transport of a bacterial suspension through a Soil Matrix using water and an anionic surfactant
Water Research, 1994Co-Authors: Andrew Jackson, Dipak Roy, G. BreitenbeckAbstract:Abstract Down-flow column studies were used in this research to investigate the ability of an anionic surfactant, sodium dodecylbenzene sulfonate (DDBS), to facilitate transport of an isolate of Pseudomonas pseudoalcaligenes through a processed Soil Matrix under pressurized flow. The influences of bacterial density and the volume of bacterial suspension pumped were examined to determine their influence on bacterial transport in Soil. Experiments were conducted using 6.35 cm diameter by 30 cm long stainless steel columns packed with a sandy clay loam. Bacterial suspensions were prepared using either water or surfactant solutions. The surfactant solution enhanced the transport of bacteria through Soil columns at both bacterial densities of the pumping solution (10 10 and 10 8 cfu/ml) tested. Pumping a higher density of bacteria increased the number of bacteria recovered at all depths when either water or surfactant solutions were used. Increasing the volume of bacterial suspension pumped appears to cause significant pore blockage when water is used as the pumping suspension. However, use of DDBS facilitated the transport of bacteria by apparently reducing the extent of pore blockage.
G. Breitenbeck - One of the best experts on this subject based on the ideXlab platform.
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Transport of a bacterial suspension through a Soil Matrix using water and an anionic surfactant
Water Research, 1994Co-Authors: Andrew Jackson, Dipak Roy, G. BreitenbeckAbstract:Abstract Down-flow column studies were used in this research to investigate the ability of an anionic surfactant, sodium dodecylbenzene sulfonate (DDBS), to facilitate transport of an isolate of Pseudomonas pseudoalcaligenes through a processed Soil Matrix under pressurized flow. The influences of bacterial density and the volume of bacterial suspension pumped were examined to determine their influence on bacterial transport in Soil. Experiments were conducted using 6.35 cm diameter by 30 cm long stainless steel columns packed with a sandy clay loam. Bacterial suspensions were prepared using either water or surfactant solutions. The surfactant solution enhanced the transport of bacteria through Soil columns at both bacterial densities of the pumping solution (10 10 and 10 8 cfu/ml) tested. Pumping a higher density of bacteria increased the number of bacteria recovered at all depths when either water or surfactant solutions were used. Increasing the volume of bacterial suspension pumped appears to cause significant pore blockage when water is used as the pumping suspension. However, use of DDBS facilitated the transport of bacteria by apparently reducing the extent of pore blockage.
Andras Bardossy - One of the best experts on this subject based on the ideXlab platform.
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1 2 and 3 dimensional modeling of water movement in the unsaturated Soil Matrix using a fuzzy approach
Advances in Water Resources, 1995Co-Authors: Andras Bardossy, Axel Bronstert, Bruno MerzAbstract:Modeling water movement in the unsaturated Soil Matrix is usually based on the numerical solution of the Richards equation. This approach requires much computational effort, therefore practical 2- or 3-dimensional applications are extremely rare. The purpose of this paper is to describe a computationally efficient and simple method. It is based on a transformation of the unsaturated Darcy law to a fuzzy rule system. The rule system is combined with the continuity equation yielding a fuzzy rule-based model for simulating the unsaturated flow. Basic definitions of fuzzy logic are given and the concept of the unsaturated flow model is outlined. The presented model performs well compared with a semi-analytical model and a 2-dimensional, numerical model. Furthermore the model has been incorporated into a physically-based and distributed, hydrological model. Model simulations for different types of hydrological situations show that the fuzzy rule-based approach is especially suitable for real-life applications.
