Influence of Methanol on the Dynamics of the Retention and Release of Cyprodinil by an Agricultural Soil

Abstract

The influence of methanol on the adsorption of the fungicide cyprodinil by a crop soil was studied by equilibrium measurements and by determining the retention-release dynamics in a continuous stirred flow tank reactor (CSTR). Equilibrium measurements showed the effective coefficient of partition of cyprodinil between soil and solution, K(dc), decreases linearly as the concentration of methanol in the solution increases until a percentage of 20% is reached. In CSTR experiments, the retention of cyprodinil was found to be almost reversible; up to a 95% of the fungicide was desorbed. The retention-release dynamics showed biphasic behavior and was partially controlled by diffusion. This behavior was reproduced by a model of diffusion into micropores identifying the soil particles as spheres and taking into account both intraparticle nonlinear adsorption and nonlinear adsorption at external surfaces. In all cases, the sorption kinetics was not the limiting step. The main effect of methanol in the retention-release dynamics ended up being based on the changes produced in the adsorption equilibrium. Methanol also increased the effective diffusion coefficient and decreased the mass transfer coefficient. The optimized Freundlich's isotherm coefficients for <5% methanol were lower than those obtained from the batch experiments.

Determination of fungicides in sediments using a dispersive liquid–liquid microextraction procedure based on solidification of floating organic drop

“…The extraction time, defined as an interval from the injection of the mixture of extraction and dispersive solvents to the start of centrifugation in the DLLME procedure, was evaluated in a series of extraction times (5,7,9,11,13, and 25 min). The results show that the extraction equilibrium could be attained within 9 min and the long extraction time had no significant effect on EE ( Fig.…”

“…Especially for cyprodinil, difenoconazole, myclobutanil, and spiroxamine (Fig. ), the mechanism of action is based on the inhibition of methionine biosynthesis, the transport processes in the plasmatic membrane, fungal lanosterol‐14α‐demethylase activity, are four fungicides, which have a different mode of action compared to traditional fungicides . The occurrences of these fungicides in sediment related to crop production are very useful to evaluate the potential risks of freshwater fish and aquatic organisms under cropland use .…”

Behaviour of metalaxyl as copper oxychloride–metalaxyl commercial formulation vs. technical grade-metalaxyl in vineyards-devoted soils

“…Also, presence of organic co-solvents in the soil solution influences the partition and kinetics in laboratory [8]. However, influence of solid adjuvants on the soil-water partition experiments of metalaxyl is not published yet.…”

Review: Presence, distribution and current pesticides used in Spanish agricultural practices

“…A linear adsorption model involving non-equilibrium conditions and an irreversible adsorption term reproduces prior results concerning the impact of transport. In a study carried out in an agricultural field near Ourense, Spain, the influence of methanol on the dynamics of Cyprodinil retention and release was studied through an analysis of agricultural soil (López-Periago et al, 2006). The results of the influence of methanol on the adsorption of Cyprodinil concluded that the effective partition coefficient of Cyprodinil between the soil and the solution, Kdc, decreases linearly as the concentration of methanol in the solution increases until a percentage of 20 % is reached.…”