Soils biological factors affecting

Other factors affecting performance include the presence of toxic material, the redox potential, salinity of the groundwater, light intensity, hydraulic conductivity of the soil, and osmotic potential. The rate of biological treatment is higher for more permeable soils or aquifers. Bioremediation is not applicable to soils with very low permeability, because it would take a long time for the cleanup process unless many more wells were installed, thus raising the cost. 

Losi M.E., Amrhein C., Frankenberger W.T. Factors affecting chemical and biological reduction of Cr(VI) in soil. Environ. Toxicol Chem 1994 13 1727-1735. 

Degens, B.P. 1997. Macro-aggregation of soils by biological bonding and binding mechanisms and the factors affecting these a review. Australian Journal of Soil Research 35 431-459. 

Bushby, H.V.A. Marshall, K. C. (1977a). Some factors affecting the survival of root-nodule bacteria on desiccation. Soil Biology Biochemistry, 9, 143-7. 

The major factors affecting the fate and transport of TNT in soils are transformation, sorption, and irreversible soil binding and immobilization. TNT, RDX and HMX transformations are significantly enhanced under anaerobic conditions. The addition of Fe ions to soils is considered as the resource of transport and fate of NACs explosives where TNT transformation in soils can occur both biologically and abiotically. The transformation of TNT in soils is significantly dependent on pH in the presence of Fe ions. 

Detrital processing can be thought of as a continuum from fresh litter to stabilized SOM (Agren and Bosatta, 2002). At different stages in this continuum, the relative importance of each of these environmental and biological factors that have been identified as controlhng decomposition dynamics will likely vary. The initial stages of mass loss are characteristically most affected by climate, resource quality, and, when abundant, soil macrofauna. The physical soil environment also needs to be considered as an important control on the turnover of more humified SOM in the mineral horizons. It is also evident from this literature review that observed correlations between decay rates and decomposition factors are often attributable to both the direct effects of that factor on microbial metabolism and to the indirect interactions with other factors. 

The extractable nickel content of soil affects the uptake of nickel by plant roots. Extracta-bility of nickel from soil is influenced by physical factors (e.g., texture, temperature, and water content), chemical factors (e.g., pH, organic constituents, redox potential), and biological factors (e.g., plant species variability, microbial activity) (NAS 1975, Wallace et al. 1977, Heale and Ormond 1982, Hazlett et al. 1983). Extractable nickel concentrations in soils, measured by treating soil samples with solutions of potassium chloride, ammonium acetate, acetic acid, or EDTA, usually range from <0.01 to... 

Several important soil biological, chemical, and physical processes have major effects on the environment and are important for understanding the basis for several important environmental issues including air, soil, and water pollution, climate change, and the fate of pollutants and other materials added to soil. The magnitude and rate of many of these processes are affected by abiotic factors, such as temperature, aeration, soil water content, and soil moisture potential. 

Arif, M A S., Houwen, F, Verstraete, W. 1996. Agricultural factors affecting methane oxidation in arable soil. Biology and Fertility of Soils 21(1-2) 95-102. 

Biological and volcanic activities also have roles in the natural mobilization of elements. Plants can play multiple roles in this process. Root growth breaks down rocks mechanically to expose new surfaces to chenaical weathering, while chemical interactions between plants and the soil solution affect solution pFF and the concentration of salts, in turn affecting the solution-mineral interactions. Plants also aid in decreasing the rate of mechanical erosion by increasing land stability. These factors are discussed more fully in Chapters 6 and 7. 

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