Extractable soils transformation

Bowman, R.A. and Cole, C.V. (1 978)Transformations of organic phosphorus substrates in soils as evaluated by NaHCOj extraction. Soil Science 125, 49-54. 

This was previously used as a herbicide, and attention has been directed to its degradation in storage areas or where it has been spilled. A strain of Clostridium bifermentans KMR-1 (that is protected by a U.S. patent) was unable to use dinoseb as carbon or energy source. In the presence of a starch extract, however, a low level of transformation was observed, and the products could subsequently be mineralized by aerobic bacteria (Hammill and Crawford 1996). These observations have been extended to the remediation of soil slurries from a contaminated site by adding phosphate and starch waste that achieved anaerobic conditions, and inoculation with a culture from a pilot-scale... 

Figure 5.6. Relationship between Co and Mn contents extracted from solid-phase of six Israeli arid-zone soils with sequential dissolution procedures (after Han et al., 2002b. Reprinted from J Environ Sci Health, Part A, 137, Han F.X., Banin A., Kingery W.L., Li Z.P., Pathways and kinetics of transformation of cobalt among solid-phase components in arid-zone soils, p 184, Copyright (2002), with permission from Taylor Francis)...

Heavy metals in the environment, especially their accumulation in soils, is a serious environmental problem which the whole world faces (Du et al. 2005). The farmland soils are an important media of the ecological cycle of Cadmium, and its harm to human health can t be neglected (Wu et al. 2004). Heavy metal migration, transformation and toxicity to plants in soil are directly influenced by the quantity proportions of various forms (Zhu et al. 2002). The toxicity of water-extractable and adsorbed and exchangeable metals are the greatest, and residual metals is the lowest (Liu etal. 2002). Different forms have different bioavailability thus their influences on the environment and human health are different. It is critical to have a good understanding of Cadmium forms in soil. This paper describes the Cadmium forms in the acid soils of eastern China. 

The enzymatic activity in soil is mainly of microbial origin, being derived from intracellular, cell-associated or free enzymes. Only enzymatic activity of ecto-enzymes and free enzymes is used for determination of the diversity of enzyme patterns in soil extracts. Enzymes are the direct mediators for biological catabolism of soil organic and mineral components. Thus, these catalysts provide a meaningful assessment of reaction rates for important soil processes. Enzyme activities can be measured as in situ substrate transformation rates or as potential rates if the focus is more qualitative. Enzyme activities are usually determined by a dye reaction followed by a spectrophotometric measurement. 

Precautions should be taken to avoid disulfoton loss from stored water, soil, sediment, crop, and vegetable samples (Belisle and Swineford 1988 Miller etal. 1981 Munch and Frebis 1992 Szeto and Brown 1982). Disulfoton, disulfoton sulfone, and disulfoton sulfoxide were not recovered from spiked well water stored 14 days however, sample extracts were stable for 14 days (84-92% recovery) (Munch and Frebis 1992). In most environmental samples, disulfoton will be present along with its environmental transformation products, disulfoton sulfone, disulfoton sulfoxide, disulfoton oxon, disulfoton oxon sulfone, and disulfoton oxon sulfoxide (Szeto and Brown 1982). Disulfoton and its oxon are very unstable, and they oxidize rapidly to the corresponding sulfoxides. The sulfoxides are relatively stable, but they oxidize slowly to their sulfones, which are most stable (Szeto and Brown 1982). Several methods for determining the metabolites of disulfoton in environmental samples are included in Table 6-2. 

Biological. In activated sludge, 31.5% of the applied chlorobenzene mineralized to carbon dioxide after 5 d (Freitag et al., 1985). A mixed culture of soil bacteria or a Pseudomonas sp. transformed chlorobenzene to chlorophenol (Ballschiter and Scholz, 1980). Pure microbial cultures isolated from soil hydroxylated chlorobenzene to 2- and 4-chlorophenol (Smith and Rosazza, 1974). Chlorobenzene was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum. At a concentration of 5 mg/L, biodegradation yields at the end of 1 and 2 wk were 89 and 100%, respectively. At a concentration of 10 mg/L, significant... 

Biological. 1-Naphthylamine added to three different soils was incubated in the dark at 23 °C under a carbon dioxide-free atmosphere. After 308 d, 16.6 to 30.7% of the 1-naphthylamine added to soil biodegraded to carbon dioxide (Graved et al., 1986). Li and Lee (1999) investigated the reaction of 10 mL of 7 mM 1-naphthylamine with 4 g of a Chalmers soil (pH 6.5, 11.1% sand, 72.8% silt, 16.0% clay). After 120 h, the soil was washed with acetonitrile and the extractant analyzed using GC/MS. The primary transformation product was a dimer tentatively identified as TV-(4-aminonaphthyl)-1-naphthylamine. The investigators hypothesized that the formation of this compound and two other unidentified dimers was catalyzed by minerals present in the soil. 

The degree of transformation can be quantified analytically through the ratio of Fe in the oxides (commonly extracted with the strong reductant sodium dithionite (Fed)) to the total amount of Fe (Fct) and also by the ratio of Fe"/Fe ", because the iron located in the primary minerals of the parent rock is predominantly Fe". With age, the ratio Fea/Fct gradually approaches unity and the total Fe"/Fe " approaches zero (Leigh, 1996). Therefore, both can serve as an indicator of the maturity of a soil as a function of time (chronosequence) (e.g. Italy Arduino et al., 1984 Nepal Baum-ler et al. 1991, Spain Simon et al. 2000 USA Barret, 2001 Egli et al. 2001). The... 

Lorenz, M. G. Wackernagel, W. (1991). High frequency of natural genetic transformation of Pseudomonas stutzeri in soil extract supplemented with a carbon/energy and phosphorus source. Applied and Environmental Microbiology, 57, 1246-51. 

Lorenz, M. G., Reipschlager, K. Wackernagel, W. (1992). Plasmid transformation of naturally competent Acinetobacter calcoaceticus in non-sterile soil extract and groundwater. Archives of Microbiology, 157, 355-60. 

Other applications of subcritical water extraction-solid-phase microextraction are the determination of terbuthylazine and its metabolites [123], polycyclic aromatic hydrocarbons [124,125] and polychlorobiphenyls [63]. Yang and Her [193] collected 1-chloronaphthylene, nitrobenzene and 2-chloro-toluene in soil on a hydrophobic polyisobutylene disc prior to analysis by attenuated total reflectance Fourier transform infrared spectroscopy. 

Hayes et al. (2008) described the uses of 0.1 M sodium pyrophosphate (Pyro) solutions for exhaustive extractions of soil organic matter at pH 7, pH 10.6, and at pH 12.6 (Pyro + 0.1 M NaOH). They showed that the fractions were compositionally different, with the most transformed (oxidized) fractions isolated at the lower pH value. However, only about 26% of the organic matter was isolated in the sequential process. 

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