Paste, saturated

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 ...

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)...

Table 6.6. Comparisons of the redistribution of metals in two Israeli soils at 3T treatment. Soils were incubated for one year under the saturated paste (SP), field capacity (FC) and wetting-drying cycle (Cycle) moisture regimes (% of the sum of fractions, as means of two replicates) (from Han et al., 2001a, with permission from Lippincott Williams Wilkins)...

Figure 6.17. Relationships between the initial (the first day) fluxes of metals in the soluble plus exchangeable fraction and metal loading levels in Israeli soils. Soils received metal nitrates and were incubated in the saturated-paste (SP) and field capacity (FC) moisture regimes...

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. 

In both soils (pe + pH) decreased to a value of about four after 7-9 days of the saturated-paste incubation, and remained stable thereafter. Most of the change resulted from pe changes Eh decreased from 290 mV and 332 mV after one hour of incubation to -200 mV and -190 mV after 7-9 days of incubation in the sandy and loessial soil, respectively, and changed very little thereafter. During the same period, pH in the sandy soil was slightly increased from 7.2 to 7.5-7.7, and in the loessial soil it was decreased slightly from 8.0 to 7.0-7.4. With the decrease of Eh and (pe + pH) of the soils as a result of incubation in the saturated paste condition, Mn was chemically reduced and transformed between soil fractions. The changes in the (pe + pH) of the two soils in the field capacity condition are not available. 

Figure 6.21. Initial and annual distribution and transformations of Mn in the major solid-phase fractions in two Israeli soils. Soils were incubated at the saturated-paste regime (after Han and Banin, 1996. Reprinted from Soil Sci Soc Am J, 60, Han F.X., Banin A., Solid-phase manganese fractionation changes in saturated arid-zone soils Pathways and kinetics, p 1076, Copyright (1996), with permission from Soil Sci Soc Am)...

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)...

During incubation, anaerobic activity predominated as discussed previously, and Mn was reduced. Cobalt transformation closely followed the pathways of Mn transformation in the two soils throughout the whole period of the saturated paste incubation. The transformation of Co by itself may... 

Figure 6.29. Relationships between the Co and Mn contents in the CARB and ERO fractions in Israeli soils during the saturated paste incubation...

Figure 7.4. Comparisons of decreases in NH4N03-extractable Zn, Ni and Cu in an Israeli loessial soil receiving metal nitrates and incubated under saturated paste, field capacity, and wetting/drying cycle moisture regimes (Han and Banin, 1997,1999, and Han et al., 2001a)...

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