Soil retention

Retaining Walls, Sea Walls, etc or carefully selected Planted Trees on slopes, shores and coasts for Soil Retention. 

Geotextile filter design parallels sand filter design with some modifications. The three elements of adequate flow, soil retention, and clogging prevention remain the same. 

An example of the kinds of data required for land disposal options would be Information on soll/pestlclde Interactions to determine the effect of the pesticide on the soil and soil on the pesticide. The physical composition of the soil and the physical properties of the pesticide and Its formulation will determine the adsorption, leaching, water dispersal, and volatilization of the pesticide which. In turn, determine the mobility of the pesticide In soil. Even pesticides of closely related structures may have very different soil retention properties. Much of this data will be available from that developed to meet other registration data requirements with the exception that disposal rates are often orders of magnitude higher than normal application rates and the difference must be considered. 

Filonow AB, Jacobs LW. Mortland MM. 1976. Fate of polybrominated biphenyls (PBBs) in soils. Retention of hexabromobiphenyl in four Michigan soils. J Agric Food Chem 24(6) 1201-1204. 

Piirainen, S., L. Finer, and M. Starr. 1998. Canopy and soil retention of nitrogen deposition in a mixed boreal forest in eastern Finland. Water, Air and Soil Pollution 105 165-174. 

Unlike the transformation processes that reduce the total amount of triazine present in soil, retention only decreases the amount available for weed control, microbial transformations, or transport. The amount retained or sorbed by soil can range from 0% to 100% of the amount applied, but sorption on silt loam, loam, or clay loam soils typically ranges from 50% to 80%. Triazine retention in soil is influenced primarily by organic carbon content, soil clay content and type, and soil pH. Other factors influencing retention include the amount of triazine applied, the amount of dissolved organic carbon (DOC) in soil solution, soil water content, and triazine to soil contact time (aging). 

Certain fibers are easier to wash than others. The hardness of the fiber surface, which varies not only with the basic fiber but also with the surface finish, affects both soilability and soil removal. Generally, soft finishes pick up and retain soil more readily than hard finishes, since soft surfaces permit greater soil-surface contact. The hydrophobicity of the fiber surface also influences soilability and soil removal, and the more hydrophobic fibers show greater soil retention especially for hydrophobic soils such as oils. These effects are explained by the high-energy interface existing between hydrophobic fibers and water (59, 60). Many soil components lower the interfacial energy and therefore locate at the fiber-water interface. 

The stable forms of Cu in the earth s crust are chiefly sulfides the most abundant Cu mineral is chalcopyrite, CuFeS2 (Krauskopf, 1972). Copper is strongly retained by soils (retention may be increased by the application of... 

Part II (1952). Soiling and soil retention in textile fibers. 

Unsaturated soil to root depth Evaporation Leaching Root Uptake 0 Surface- Subsurface application Washoff Transport Degradation (chemical/biological) Soil Retention Root uptake Transport. ... 

Unsaturated soil zone below root depth (vadose zone) Movement Upward A Lateral Downward Transport % Degradation (chemical/biological) Soil Retention Transport. 

One school of thought maintains that certain sites on soil surfaces can retain these cations strongly radiographs show the cations are both bunched and spread out on soil surfaces. Another school suggests that these adsorption sites are where the cations can mix as solid solutions with the other ions on the surfaces. The free energy of mixing on the surfaces (Appendix 3.2) is responsible for the strong retention rather than any uniquely favorable adsorption spots on soil particle surfaces. In any case, soil retention can reduce the aqueous solubility of these ions to well below that in equilibrium with their pure hydroxyoxides. 

Soil retention is less pH sensitive than for hard Lewis acids. 

Anions strongly retained by soils include PO -, AsO -, MoO -, CrO -, and F-. These anions are essential microelements for plants and animals and are present in trace concentrations in the solutions of native soils. Because the amounts and tenacity of soil retention of these ions is so much greater than Cl, NO3, and others, this retention has been misnamed as specific adsorption. These anions are simply... 

Cuddihy, E.F., "Theoretical Considerations of Soil Retention", Solar Energy Materials, Vol. 3, pp. 21-33,... 

Similar to the filtration function, the requirements for drainage are soil retention, adequate flow capacity, and long term soil-to-geotextile flow equilibrium, in respect of minimum clogging of the pore spaces. Apart from the flow capacity within the plane of the geosynthetic material, the other aspects have been dealt with above. We will therefore now consider the inplane flow characteristics. 

The soil retention function of the geotextile separator can be seen as similar to the geotextile filter, in that for a suitable separator the AOS of the geotextile must be related to the particle size distribution and, as stated under the filtration function, this aspect will be considered in more detail later when describing the relationship between structure, properties, and functionalities of geotextiles. 

High performance textiles for geotechnical engineering 309 Table 8.5 Summary of soil retention requirements for geotextile filters... 

The relationship of O95 with djs is used because the clogging resistance criterion is generally smaller (for silt/clay size particles) than the O95 value for soil retention. 

Reinforced earth walls are commonly used for some form of soil retention. For example, a vertical face constructed without reinforcement would fail in time, depending on the value of the soil parameters. If the soil in the region of the face is reinforced, however, it will form a stable mass, which can support the unreinforced soil behind it. The same principle applies to reinforced slopes constructed to an angle steeper than their angle of internal friction. 

Two sets of existing PTFs used in similar sandy soil Vereecken PTF et al. (1989,1990) andANN (Schaap et al., 2001) were applied to estimate soil retention parameters of Zhangwu County soils, and their performance in estimating the soil hydrauhe parameters were compared to the PTFs derived in this study. 0-20 cm and 20-40 cm soil depth intervals, LRP and ANN PTFs are accurate and precise for prediction of 9r, 9s and a with ME and MAE values were close to 0, while VER has a lower accurate and precise for prediction of a with ME and MAE values ranging from 0.63 (1/cm) to 0.74 (1/cm), which was far higher than that of LRP and ANN. In general, all models are more precise and accurate in 20 0 cm depth interval than 0-20 cm depth intervals MAE and ME values of the three PTFs prediction for n are less accurate and precise than the other three parameters. 

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