Aging determinant biodegradation

The age of diesel oil in the subsurface soil environment can be determined by utilizing the fact that the composition of the diesel oil (the ratio between -alkanes and isoprenoids) changes due to biodegradation. In one study, the ratio of C , to pristane was highly correlated with the residence time of diesel fuel at 12 test locations (Christensen et al 1993). 

The degree of bioavailability of organic compounds depends critically on their chemical structure which determines the kinds of interaction that may take place within the solid phase. For example, linear alkylbenzenesulfonates are readily desorbed from sediments, so that their biodegradability and potential toxicity is largely unaffected by the presence of sediments (Hand and Williams 1987). On the other hand, benzo[a]pyrene even though accessible to chemical extraction appears to be available to biota only to a limited extent (Varanasi et al. 1985). This is consistent with the view noted earlier that chemical extractability is not a useful measure of bioavailability for naturally aged samples as opposed to those which have been spiked with the contaminant (Kelsey et al. 1997). 

Concentrations of PS at any point in the rhizosphere are determined by a number of different factors. Inputs of PS will vary depending on the Fe (and possibly other metal) status of the plant (Shi et al, 1988), the plant species and genotype (Romheld, 1991), the time of day (Takagi et al., 1984), the type of root (Bernards et al., 2002) and the age of the plant (Cakmak et al., 1998). Plant uptake, biodegradation, diffusion and adsorption to the soil solid phase will affect removal of PS from the rhizosphere. While we will discuss effective concentrations within the rhizosphere, the concentration of PS at any point in the rhizosphere will vary and depend on a numher of factors (Fig. 2). Thus, the PS-defmed rhizosphere can he thought of as being composed of four parameters ... 

Major Applications Sensors, lithographic plates, optical recording media, photoreceptor, inks, indication system for product exceeding threshold temperature,lubricants, textiles, food stor-age,i3 determination of amiodarone, " astemizole, bromhexine,i6 clomipramine, deutiforin, domperidone, fluoroquinolone, roxithromycin, terfenadine, thiabendazole, antihistamines Safety/Toxicity Biodegradation and toxicity ... 

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