Model-unidentifiable

The occurrence of a persistent absorbance change (AA ) for the [M, Fe] hybrids is a slight complication that requires an extended kinetic model (Scheme II) in which (MP) is reduced not only by Fe P (regenerating the [MP, Fe P] state), but also by an as yet unidentified amino acid residue X and/or solution impurities (Eq. (3)) leading to [M, Fe " ] ... 

Soil. Lu et al. (1977) studied the degradation of benzo [a] pyrene in a model ecosystem containing Drummer silty clay loam. Samples were incubated at 27.6 °C for 1, 2, and 4 wk before extraction with acetone for TLC analysis. After 4 wk, only 8.05% of benzo [a] pyrene degraded forming one polar compound and two unidentified compounds. The reported half-lives for benzo [a] pyrene in a Kidman sandy loam and McLaurin sandy loam are 309 and 229 d, respectively (Park et al., 1990). 

In a model aquatic ecosystem, methoxychlor degraded to ethanol, dihydroxy ethane, dihy-droxyethylene, and unidentified polar metabolites (Metcalf et al, 1971). Kapoor et al. (1970) also studied the biodegradation of methoxychlor in a model ecosystem containing snails, plankton, mosquito larvae, Daphnia magna, and mosquito fish Gambusia affinis). The following metabolites were identified 2-(/5-methoxyphenyl)-2-(p-hydroxyphenyl)-l,l,l-trichloroethane, 2,2-bis (p-hydroxyphenyl) -1,1,1 -trichloroethane, 2,2-bis (p-hydroxyphenyl) -1,1,1 -trichloroethylene,... 

Nitrophenol, paraoxon, and three unidentified metabolites were identified in a model ecosystem containing algae, Daphnia magna, fish, mosquitoes, and snails (Yu and Sanborn, 1975). 

Fig. 17.9 Model of the mechanism of Fe " oxidation by Thioba-cillusferrooxidans. PL-Fe phospholipid bound Fe x enzyme (unidentified) Ru rusticyane, a Cu-containing protein cyt c c-type cytochrome cyt ox cytochrome oxidase complex ATP adenosine 5 -triphosphate (Ghiorse Ehrlich, 1992 with permission).

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