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Because organic sorption in soil may never reach equilibrium, a thin-disc flow nonequilibrium method may be helpful in understanding herbicide-soil interactions. This research was conducted to (i) determine the influence of incubation time on imazaquin [2-(4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl)-3-quinolinecarboxylic acid] desorption from soil, (ii) examine the influence of solution flow velocities on desorption, and (iii) elucidate the most appropriate kinetic model to describe imazaquin leaching. Soil at 7.5% moisture w/w was treated with imazaquin and incubated for 24, 72, and 168 h. Treated soil was sealed in an in-line filter apparatus and rinsed with 5.0 mM CaCl 2 at 0.33, 0.67, or 1.0 mL min -1 . Effluent was collected as 1.0-mL fractions for a total of 50 mL. Flow was stopped for 24 h. When flow resumed, fractions were collected for an additional 15 mL. After the initial desorption, 79% of the imazaquin incubated for 24 h was leached. Increasing incubation time beyond 24 h reduced imazaquin leaching. After both desorption events, 13% of the initially applied imazaquin remained in the soil incubated for 168 h, compared with 7% with soil incubated for 24 h. Elovich and Freundlich kinetics accounted for 98% of the variance observed in the imazaquin desorption curves. First-order and diffusion kinetics accounted for 91% of the variance. Incubating soil for 72 h before desorption reduced the rate of imazaquin desorption by approximately 12%, compared with the 24-h incubation treatment. Imazaquin desorption was not affected by wash solution flow rate. These data suggest that the kinetics of desorption in prolonged desorption events are limited by transport phenomena (i.e., particle and film diffusion).

The inositol isomer composition of phosphoinositides, polyphosphoinositols, phosphatidylinositol-linked glycans, and glycosyl phosphatidylinositol-anchored proteins of logarithmic phase Tetrahymena vorax was determined by GC-MS analysis of trimethylsilylimadazole derivatives. The most abundant inositol found was the myo-isomer; however, appreciable percentages of scylloinositol were present in the free inositol pool, phosphatidylinositol-linked glycan fraction, and glycosyl phosphatidylinositol-anchored protein fraction. Trace quantities of chiro- and neo-inositols also were present.

Only limited information exists concerning the fate of aged herbicide residues in subsurface soils. To assess the importance of degradation and leaching in the persistence of aged herbicide residues in subsoils, formulations of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine), metribuzin (4-amino-6-tert-butyl-4,5-dihydro-3-methylthio-1,2,4-triazin-5-one), metolachlor (2-chloro-6'-ethyl-N-(2-methoxy-1-methylethyl)acet-o-toluidide), pidoram (4-amino-3,5, 6-trichloropyridine-2-carboxylic acid), 2,4-D (2,4-dichlorophenoxyacetic acid), and alachlor (2-chloro-2',6'-diethyl-N-methoxyethylacetanilide) were applied separately to two moist Arkansas subsoils and buried for up to 3 yr. The treated subsoils were placed in one of two storage container types, buried in situ at 30, 90, or 150 cm within the soil profile, and retrieved at 6-mo intervals. Amounts of herbicide remaining in the subsoils at two study locations were determined chromatographically. Use of two different types of storage containers allowed for comparison of the relative degradation and leaching that occurred with time. Statistical evaluation of these data found that significant early (less than 6 mo after treatment) degradation occurred in 80% of 36 possible herbicide x soil depth x location combinations. Early leaching occurred between 30 and 50% of the time. Long-term degradation (greater than 6 mo after treatment) occurred in 23 of 28 cases, while long-term leaching occurred in 7 cases. Slow degradation and notable leaching of picloram occurred at 90 and 150 cm at the loamy fine sand location. In addition, prolonged persistence of alachlor relative to metoachlor was observed in subsoils at both study locations.