Field incubation

Barriuso, E., W. Koskinen, and B. Sorenson (1992c). Modification of atrazine desorption during field incubation experiments. Sci. Total Environ., 123/124 333-344. 

A study investigating the breakdown of clopytaUd [1702-17-6] reported half-Hves on different soils of approximately 2—7 weeks in a laboratory incubation (400) it was indicated that carryover was likely to occur in field soil. Picloram degrades and does not accumulate in field soil although low residue levels do persist for several years (401). The half-life for triclopyr [55335-06-3] is reported to be two weeks in two Canadian soils (402), and it has been shown to be rapidly degraded by aqueous photolysis (403). 

Figure 1.5 High-field (aliphatic) regions of 400 MHz H Hahn spin-echo NMR spectra of (a) E-199 culture medium (b) as (a) but following a 2 h incubation with neutrophils at 37°C (c) as (b) but incubated in the presence of 1.00 x 10 mol/dm phorbol 12-myrlstate 13-acetate (PMA). For abbreviations, see Fig. 1.2 with Met, methionine-S-Ctl3 group resonance MetSO, methionine sulphoxide-SO-CHs group resonance. The 2.245 p.p.m. singlet detectable in spectrum (c) arises from the -CH3 groups of acetone, the solvent in which PMA was...

The method was developed/validated using two typical rice field soils (alluvial soil and volcanic ash soil). In the extraction efficiency study, a soil sample that had been incubated for about 8 months under flooded conditions after addition of... 

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...

Soluble heavy metals initially added to arid soils were quickly transferred from the soluble and exchangeable form into the carbonate bound fraction. Within the first hour from the start of the saturation incubation, and/or during the first step of the SSD procedure, the metals in the freshly salt contaminated arid soils were predominately transferred from the EXC fraction into the CARB fraction (82% for Cd, > 50% for Ni and Cr, 40-85% for Zn, and 30% for Cu) (Han and Banin, 1997). Similarly, under the field... 

Figure 6.1. The fractional loading isotherms of Cu in a contaminated Israeli loessial soil at an initial (one hour) period and after 48 weeks. The soil was treated with increasing levels of metal nitrates and was incubated under the field capacity regime. Horizonal solid line represents the native content of Cu in the nonamended soil (Figure 6.1 - Figure 6.4, after Han and Banin, 2001. Reprinted from Commun Soil Sci Plant Anal, 32, Han F.X and Banin A.,The fractional loading isotherm of heavy metals in an arid-zone soil, pp 2700-2703, Copyright (2001), with permission from Taylor Francis)...

Following the initial fast retention, the slow redistribution of the added metals occurred over time. During one year of incubation under the field capacity regime, heavy metals were slowly transferred among solid-phase components as shown in Figs. 6.1-6.4. Added Cu and Ni were transferred from the EXC and CARB fractions into the ERO and OM fractions and Zn mainly into the ERO fraction. Chromium and Pb moved from the CARB fraction into the OM and ERO fractions, respectively. Cadmium redistributed from the EXC fraction into the CARB fraction. After one year of incubation under the field capacity regime, 65-100% of the added Cd was transferred to the CARB fraction. About 50% and 20% of the added Pb was redistributed to the CARB and ERO fractions, respectively. 

Figure 6.5. The initial reduced partition index, Ir, of six metals in two Israeli arid soils. Two soils were treated with metal nitrates at various loading levels. Soils were incubated under the field capacity moisture regime (modified after Han and Banin, 1999, with permission from Springer Science and Business Media)...

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