Soil degradation Table

Table 11.2 Indigenous knowledge of soil degradation in Asia (Ali 2003 Handayani et al. 2006)...

Efforts to decrease soil degradation and erosion have been demonstrated by the rapid adoption of conservation tillage and no-till by farmers within the United States as shown in Table 32.2. 

Note Data from Ghassemi et al. (1995) and Bridges and Oldeman (1999) are from tables titled with human-induced soil degradation . 

In this experiment, at a concentration of 10 Pg/ml of PCNB in the mixed bacterial culture, 99 of the actinomycetes propagules in the culture were eliminated without any effect on diphenamid degradation. On the other hand, the addition of the bactericide chloramphenicol to the bacterial cultures obtained from diphenamid -history soils strongly inhibited diphenamid degradation (Table I). 

After 56 days of incubation, degradation of 1000 ppm alachlor did not exceed 35% in any soil treatment (Table VI). About 33% of the applied alachlor was degraded in the inoculated, CS-amended soil after 28 days, but no further degradation was observed thereafter. In nearly every two-way comparison, alachlor degraded significantly faster in the 100 ppm treatments than in the 1000 ppm treatments. Coincidentally, soil dehydrogenase activity in all 1000 ppm treatments was severely depressed. 

Table 5. Changes in agricultural land use and soil degradation in Asia (Scherr, 1999).

With aldicarb, soil degradation can convert a leacher into a nonleacher . The herbicide, Dacthal provides an example of the reverse elfect, a nonleacher converted into a leacher . Because of its low solubility, high Kqc, and relatively short half-life this compound shows a low GUS value (Table 9.14) and would not be expected to leach. The methyl esters of this molecule hydrolyze to generate the diacid and the kinetics of this process have been smdied in the alkaline soils... 

Table 5.4 Toxicological and soil degradation data for benoxacor.

Once released into the environment, phthalates degrade rapidly the half-life of DEHP (the most widely used phthalate) in water is only 2-3 weeks. But in air, or when bound to soil, phthalates can be stable for longer periods of time. The reported levels of DEHP, the most common phthalate, in air, water, and soil (see Table 7.6) illustrate this. As with other EDCs, phthalates are also ubiquitous in the environment and are present in the human body, breast milk, blood, and urine. In one study, over 75% of the US population were found to have phthalate metabolites in the urine (Stahlhut et al., 2007). This is hardly a surprise as the available data suggests life-long human exposure to occur from in utero through death of individuals. 

Unlike other industrial sectors, mining activities particularly opencast mines, draw special attention from environmental degradation point of view. Besides air and water pollutions, it involves excavations of land, loss of soil, degradation/ disfiguring of surface area and deforestation. Valuable topsoil and usable land is lost forever, which cannot be fully recovered. Natural drainage system and groundwater table is disturbed which not only afiects the inhabitants in close proximity but also people living in faraway places. 

In the Table 16.3, it can be observed that the barren land in Indonesia was increased from 9.3 Mha in 1980 to 13.3 Mha in 2005. Surprisingly, it was found that these lands were from the forest areas of Sumatra and Kalimantan. The fact is that these lands were occupied by local farmers for their agriculture and later, they were abandoned due to soil infertility, as reported by the Global Assessment of Human-Induced Soil Degradation (Wicke et al., 2008). 

Table 5 Recoveries of tepraloxyim and degradates from soil dissipation studies conducted in the USA and Canada...

Dissolution of gasoline compounds to soil water is a function of each compound s solubility. A highly soluble gasoline substance often has a relatively low adsorption coefficient and also tends to be more readily degradable by microorganisms,19 as shown in Table 18.1. 

In all of the workshops, but especially in the FAT and Exposure Assessment workshops, the need for better understanding and model representation of soil systems, including both unsaturated and saturated zones, was evident. This included the entire range of processes shown in Table II, i.e., transport, chemical and biological transformations, and intermedia transfers by sorption/desorption and volatilization. In fact, the Exposure Assessment workshop (Level II) listed biological degradation processes as a major research priority for both soil and water systems, since current understanding in both systems must be improved for site-specific assessments. 

Table VIII shows a sensitivity analysis on the EXAMS model. Changing the input load dramatically changes the concentration of chemical in both water and sediment. Photolysis rates appear to effect the model less than input loads. Changing the soil type effects the purification time of the system and not so much the water concentrations of the chemical indicating the influence of chemical adsorption to degradation.

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