Degradation of soils

Singh N, N Sethunathan (1992) Degradation of soil-sorbed carbofuran by an enrichment culture from carbo-furan-retreated Azo/Za plot. J Agric Eood Chem 40 1062-1065. 

In many mountain-industrial areas there are 3 1 landscape-functional zones with different extents of the anthropogenic transformation of natural environments. As a rule, the first zone is the spatial complex joining mines, pits and tails site area with almost whole degradation of soil and vegetation cover and high metal concentrations in dust, technogenic depositions, waters and plants. 

Gramss, G., Ziegenhagen, C., and Sorge, S. (1999). Degradation of soil humic extract by wood-and soil-associated fungi, bacteria and commercial enzymes. Microbial Ecol. 37,140-151. 

The complex nature of soil and soil processes means that many factors besides the type of reaction kinetics can aifect the course of the disappearance of a pesticide. An example would be a case of a volatile pesticide for which a significant part of the loss was caused by vaporization from the soil. A complete mathematical analysis would take into account chemical degradation, vaporization, and diffusion. It would yield a mathematical relation different from and more complicated than one expressing the chemical kinetics alone. An example is simultaneous diffusion and degradation of soil fumigants as described by Hemwall (3,4). 

Barratt, S. R., Ennos, A. R., Greenhalgh, M., Robson, G. D. Handley, P. S. (2003). Fungi are the predominant micro-organisms responsible for degradation of soil-buried polyester polyurethane over a range of soil water holding capacities. Journal of Applied Microbiology, 95, 78-85. 

Reductive degradations of soil and coal-derived humic acids with sodium amalgam have been reported to produce a variety of phenolic compounds (12, 13, 14) however, this procedure has been questioned by... 

Natural chelates include fulvic and humic acids formed by the degradation of soil organic matter. 

O Brien, P. 1972. The sweet potato its origin and dispersal. American Anthropologist 74 342-365. Oades, J.M. 1993. The role of biology in the formation, stabilization and degradation of soil... 

Adaptation of soil microorganisms for rapid degradation of soil-applied pesticides can occur as a result of the complex interactions between the soil, the pesticide, the microbes, and environmental conditions. The current research addresses the role of breakdown products from the pesticide in the development of the condition. 

Land use changes in Asia, particularly those related to agricultural expansion and yield growth on a massive scale were associated with considerable degradation of soil resources in terms of erosion, nutrient depletion and pollution (Table 5). 

The profiles of Ti, Al, Fe, K, Rb and also, to a limited extent. Mg are obvionsly determined by an input of terrestrial substance which is conseqnential to erosion. The enrves which are very similar to each other represent the intensity and the type of erosion on the continent, formation and degradation of soil, as controlled by climate changes. 

Resorcinol (CsH Oa) can be produced by the sodium-amalgam reductive degradation of soil hmnic acid. It became a fixms of research when it was discovered to be one of the strongest precursors of trihalomethane (THM) in water. This is its ability to become carcinogenic and mutagenic m the presence of chlorine in water (25,28,41). 

Three different films obtained by a hot pressing procedure of powder mixtures containing plasticized PVA, PVAc with and without bactmal PHB were submitted to the biological degradation of soil microorganisms in a respirometric test aimed at simulating soil burial conditions. The compositions of the blend films are summarized in Table 1. 

Soil Degradation Studies. Soil burial studies with starch-PE blends were conducted by mixing about 100 mg of blend with 100 g of moist soil in a 250 mL flask equipped with a C02 trap (14, 15). Since PE is not biodegradable, evolution of C02 was a measure of starch degradation when corrected for CXlj produced from degradation of soil organic components. Flasks were incubated at 25° C. 

As the boundary conditions are extremely important in the results observed, the container where the models were prepared need to be carefully chosen. Thus, the models were prepared and tested within an Equivalent Shear Beam (ESB) container, described by Schofield and Zeng (1992), having flexible walls intended to replicate the soil dynamic behavior and minimize boundary effects. However, due to the large degradation of soil properties during liquefaction caused by pore pressure build-up and subsequent effective stress reduction, the container cannot exactly match the soil behavior at all times during the test. 

Although the CPTu, SCPT, and geophysical methods are standard and necessary for characterizing hydraulic fills, they are not the only applicable tests. In some circumstances the self-bored pressure meter can provide data on the degradation of soil modulus with strain (useful for evaluation of lateral pile capacity in fills, especially under earthquake loading). The cone pressure meter , a combination of CPT and full-displacement pressure meter may also be useful for the same purpose. 

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