Soil incubations

Figure 5, Formation of H-nitrosoglyphosate in soils incubated at 25°C with 20 ppm of nitrite nitrogen as sodium nitrite and 740 ppm glyphosate (free acid equivalent) (6), Soil syrnbols , Fox A, Grandin Brookston and O, Granville,...

Soil incubation time (weeks) Yield of nitrosoatrazine ( )... 

Carboxylate Percent of carboxylate recovery after soil incubation ... 

J. N. Ladd, M. Amato, P. R. Grace, and J. A. Van Veen, Simulation of turnover through the microbial biomas.s in soils incubated with C-labelled residues. Soil Biol. Biochem. 27111 (1995). 

Table 3.3. Concentrations of trace elements in soil solutions extracted by saturated paste from two metal salt-spiked Israeli soils incubated at the saturated paste regime...

Table 6.2. The original metal concentration (HN03-extractable) in native soils and levels of addition to the two Israeli arid soils incubated under the saturated paste regime condition ...

Table 6.3. Treatment levels of trace metals in the two Israeli arid soils incubated under the field capacity and wetting-drying cycle moisture regimes...

The partition index (IR, which will be discussed in details below) of Cd, Cu, Cr, Ni and Zn in both soils rapidly increased from time zero (calculated value) to one day and further to one year. This was especially true for Cr, Cu and to some extent Ni and Cd (Table 6.5). This result indicates that added trace metals are initially and rapidly transferred from the labile EXC fraction into the more stable fractions. Furthermore, IR of trace metals in native arid soils incubated under the saturated paste regime decreased at the end of year. This indicates mobilization of trace elements in these soils as saturation (Table 6.5). Also, it can be seen that IR decreased, for any given time, with an increase of the loading level (Table 6.5, Fig. 6.5). This means that higher additions of soluble metals result in higher metal content in the labile fractions and lower metal binding intensity in soils. 

Table 6.5. Reduced partition index (IR) of trace metals in arid-zone soils incubated under saturated paste regime (after Han and Banin, 1997. Reprinted from Water Air Soil Pollut, 95, Han F.X., Banin A., Long-term transformations and redistribution of potentially toxic heavy metals in arid-zone soils. I Incubation under saturated conditions, p 411, Copyright (1997), with permission from Springer Science and Business Media)...

The transformation pathway(s) and kinetics of Mn in the solid-phase of two Israeli arid-zone soils incubated under saturated paste and field capacity conditions for a prolonged period of time is discussed below. 

Manganese transformations can be seen from changes in the equilibrium parameters of the various fractions (Utf,) and the whole soil (Ute) with time of incubation under saturation (Fig. 6.25). In both soils incubated under the saturation condition, the Utf parameters of the EXC and the CARB fractions increased and departed from the native state (Utf.Exc and... 

The section below will briefly address the distribution of Co, its transformation pathway(s), and kinetics among solid-phases in two selected Israeli arid-zone soils incubated under saturated paste conditions for prolonged periods of time (Han et al., 2002b). The parallel relationships of Co and Mn transformations among their solid-phases in soils are demonstrated. 

Figure 6.27. Distribution of Co in the solid-phase components in two Israeli arid soils incubated at the saturated paste regime (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 187, Copyright (2003), with permission from Taylor Francis)...

The major ion composition of dispersed soil solutions and saturation extracts from selected soils in California, U.S. Concentrations of trace elements in soil solutions of the California soils that received sludge applications. Concentrations of trace elements in soil solutions extracted by saturated paste from two metal salt-spiked Israeli soils incubated at saturated regime. 

However, rates of precipitation in soil systems may be quite different from those in solutions because precipitation is catalysed by adsorption of the reacting solutes onto soil surfaces the nature of the solid phases formed may be different and sorption may also alter the effects of inhibitors. There are very few data in the literature on these effects actually measured in soils. Figure 3.15 shows data of Huang (1990) for calcite precipitation in three soils incubated with urea. Precipitation was induced as the pH increased during urea hydrolysis ... 

The half-lives for malathion in soil incubated in the laboratory under aerobic conditions ranged from 0.2 to 2.1 d with an average of 0.8 d (Konrad et al, 1969 Walker and Stojanovic, 1973 Gibson and Burns, 1977). 

The average half-life for bromacil in soil incubated in the laboratory under aerobic conditions was 132 d (Zimdahl et al., 1970). In field soils, the average disappearance half-life was 349 d (Gardiner et al., 1969 Leistra et al., 1975). Under aerobic conditions, the mineralization half-lives for bromacil in soil ranged from 151 d to 4.5 yr (Gardiner et al., 1969 Wolf and Martin, 1974). 

CASRN 127-20-8 molecular formula C3H3Cl2Na02 FW 164.95 Soil. Undergoes dechlorination and the liberation of carbon dioxide in soil. The residual activity is limited to approximately 3-4 months (Hartley and Kidd, 1987). The average half-life for dalapon-sodium in soil incubated in the laboratory under aerobic conditions was 15 d (Namdeo, 1972). 

CASRN 944-22-9 molecular formula C10H15OPS2 C10H15OPS2 FW 246.32 Soil. The half-life for fonofos in soil incubated in the laboratory under aerobic conditions was 25 d (Lichtenstein et al., 1977). In field soils, the half-lives for fonofos ranged from 24 to 102 d (Kiigemgi and Terriere, 1971 Mathur et al., 1976 Schulz and Lichtenstein, 1971 Talekar et al, 1977). 

Phorate was moderately persistent in soil. Way and Scopes (1968) reported residues comprised 10% of applied dosage 540 d after application. The reported half-life in soil is 82 d (Jury et al., 1987) and 68 d in a sandy soil (Way and Scopes, 1968). The half-lives for phorate in soil incubated in the laboratory under aerobic conditions ranged from 7 to 82.5 d with an average half-life of 75 d (Getzin and Chapman, I960 Getzin and Shanks, 1970). Approximately 3 d after applying phorate to a sandy soil, 41% was lost to volatilization (Burns, 1971). 

Byast, T.H. and Hance, R.J. Degradation of 2.4.5-T by South Vietnamese soils incubated in the laboratory. Bull. Environ. Contam. Toxicol., 14(l) 71-76, 1975. 

Chapman, R.A. and Chapman, P.C. Persistence of granular and ec formulations of chlorpyrifos in a mineral and organic soil incubated in open and closed containers, J. Environ. Sci Health, B21(6) 447-456, 1986. 

In another study (Watwood, White Dahm, 1991), benzene mineralization occurred in soils incubated under an inert gas for 4 weeks. No attempt was made to remove residual oxygen from these soils and the possibility exists that benzene mineralization may have been linked to the consumption of oxygen. Alternately, it may have been that benzene was partially oxidized by microorganisms and the resulting product was amenable to anaerobic decay. An earlier study (Van Beelen Van Keulen, 1990) showed an extremely rapid rate of benzene mineralization 2% mineralized in 1 h and 5% in 7 days. No samples were taken between 1 and 7 days and further benzene mineralization was not observed. 

Zeddel, A., Majcherczyk, A. Huttermann, A. (1994). Degradation and mineralization of polychlorinated biphenyls by white-rot fungi in solid-phase and soil incubation experiments. In Bioremed tation of Chlorinated and Polycyclic Aromatic Hydrocarbon Compounds, ed. R. E. Hinchee, A. Leeson, L. Semprini S. K. Ong, pp. 436-40. New York Lewis Publishers. 

In other soil incubation studies Cheshire et al. (1974, 1979) found that some sugars in straw in labeled plant material decomposed rapidly, but others decomposed relatively slowly, and about 15% of these remained after five years. There was little indication that xylose or cellulose was synthesized by soil microorganisms. However, studies by Cheshire and Anderson (1975) showed that plant residues are essential to maintain the soil carbohydrate levels. Total carbohydrate contents of soils fallowed for 10 years fell by as much as 50%. Because there was no significant change in the compositions of the soil carbohydrate as the result of the fallow, it was concluded that the sugars were equally susceptible to metabolism regardless of the management system. 

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