Predicting release and transport of pesticides from a granular formulation during unsaturated diffusion in porous media.

The release and transport of active ingredients (AIs) from controlled-release formulations (CRFs) have potential to reduce groundwater pesticide pollution. These formulations have a major effect on the release rate and subsequent transport to groundwater. Therefore the influence of CRFs should be included in modeling non-point source pollution by pesticides.

Influence of pore water velocity on the release of carbofuran and fenamiphos from commercial granulates embedded in a porous matrix.

Pore water flow velocity can influence the processes involved in the contaminant transport between relative stagnant zones of porous media and their adjacent mobile zones. A particular case of special interest is the occurrence of high flow rates around the controlled release granules containing pesticides buried in soil. The release of the pesticides carbofuran and fenamiphos from commercial controlled release formulations (CRFs) was studied, comparing release tests in a finite volume of water with water flow release tests in saturated packed sand at different seepage velocities.

Influence of soluble copper on the electrokinetic properties and transport of copper oxychloride-based fungicide particles.

This article describes the influence of dissolved copper on the electrokinetic properties and transport of a copper oxychloride-based fungicide (COF) in porous media. The Zeta potential (ζ) of COF particles increases (viz. becomes less negative) with increasing concentration of Cu(2+) in the bulk solution.

Effect of particle size on copper oxychloride transport through saturated sand columns.

Understanding the mechanisms behind the transport of particulate contaminants in porous media is crucial with a view to evaluating their potential impact on the environment. Much of the copper used in agriculture is sprayed as colloidal copper oxychloride, and despite its potential environmentally adverse consequences, colloidal transport of particulate formulations of copper remains poorly understood. In this work, transport of copper colloids from a commercial copper oxychloride based fungicide formulation was studied by measuring its breakthrough in saturated quartz sand columns.

Transport of copper oxychloride-based fungicide particles in saturated quartz sand.

Intensive use of copper-based fungicides in agriculture causes contamination of subsurface environment. While the transport of dissolved copper in porous media has been widely studied, transport mechanisms of particles of copper-based fungicides are poorly understood. This paper reports the results of tests involving the transport of colloid-size particles of a copper oxychloride-based fungicide (COF) in water-saturated quartz sand columns under varying electrochemical and hydrodynamic conditions.

Influence of soil characteristics on copper sorption from a copper oxychloride fungicide.

The objective of this work was to assess the sorption of copper (Cu) applied as a Cu-oxychloride metalaxyl formulation by soils characterized by anthropogenic accumulation of Cu due to agricultural activity. The methods involved batch incubation of soils with a Cu-oxychloride metalaxy-based fungicide suspended in 0.01 M CaCl(2), phase separation, and determination of the concentration of Cu (Cu) in solution.

Determination of metalaxyl and identification of adjuvants in wettable powder pesticide technical formulas.

Foliar runoff is one of the most important processes affecting off-target movement of fungicides. In this way, Ridomil Gold Plus and Ridomil Gold MZ are two types of wettable powder technical formulations which contain metalaxyl and they are used for such a purpose. A method for quantitative determination of metalaxyl in pesticide formulas has been developed, validated, and subsequently applied to Ridomil Gold Plus and Ridomil Gold MZ.

Simulating washoff of Cu-based fungicide sprays by using a rotating shear device.

Foliar washoff causes a loss of copper-based pesticides sprayed on crops, leading to an increase in the number of applications and contamination of the soil with Cu. In field studies, the variables that determine the amount of Cu loss are difficult to control. An experimental setup based on a rotating shear device (RSD) was used to estimate the influence of physical factors in the loss of Cu due to washoff of three copper-based fungicides: copper oxychlorhide (CO), Bordeaux mixture (BM), and a mixture of copper oxychlorhide and propylene glycol (CO-PG).

Occurrence and downslope mobilization of quaternary herbicide residues in vineyard-devoted soils.

The aim of this study was to examine the fate of quaternary herbicides in soil deposits derived from erosion of vineyard-devoted soils. Herbicide occurrence in the crop soils was due to the farmer application inputs. Special attention should be paid to the presence of paraquat (PQ) in the studied vineyard-devoted soils.

Treatment of an acid soil with bentonite used for wine fining: effects on soil properties and the growth of Lolium multiflorum.

When used to fine wines, bentonite acquires a protein load that makes it a potentially useful fertilizer. Other properties of bentonite are also potentially useful for soil amendment. In the work described in this paper, waste bentonite from a winery was applied to an acid soil, and its effects on soil properties and on the growth of Lolium multiflorum were evaluated.

Influence of copper on the adsorption and desorption of paraquat, diquat, and difenzoquat in vineyard acid soils.

Retention of the cationic herbicides paraquat (PQ), diquat (DQ), and difenzoquat (DFQ) in two vineyard soils with a different management history and retention capacity was examined. The influence of copper on the ability of the soils to retain the herbicides was determined by comparing the results of adsorption and desorption tests on untreated and Cu-enriched soil samples, and also on soils that were previously treated with EDTA to extract native copper. The three herbicides were strongly adsorbed by both soils.

Dynamics of pesticides in potato crops.

This study investigated the behavior of pesticides commonly used on potato in a part of northwestern Spain with a large area devoted to this crop. Experimental potato plots were treated with commercial formulations of two insecticides, a nematicide, a herbicide, and a combination of two fungicides, and the concentrations of the active ingredients were monitored throughout the growing season in the 0-1 and 1-15 cm soil layers, in water dripping off the potato plants, and in the potatoes themselves. The technique used for pesticide determination was gas chromatography with mass selective detection.

Transport of commercial endosulfan through a column of aggregated vineyard soil by a water flux simulating field conditions.

Endosulfan is a potentially harmful, degradation resistant pesticide that is found in soils where it has been used. Despite being hydrophobic and having high affinity for soil matrix components, it has also been found in groundwater. To investigate this behavior, we studied the passage of a commercial emulsified formulation through a column of aggregated vineyard soil under simulated light rain.

Variation in concentrations of the fungicides tebuconazole and dichlofluanid following successive applications to greenhouse-grown lettuces.

Residual levels and degradation rates of tebuconazole and dichlofluanid in lettuce plants grown in a greenhouse under agricultural conditions typical of northwestern Spain were studied. Lettuce plants were sprayed four times with a homogeneous 0.2% aqueous solution of Folicur Combi (wettable powder containing 40% dichlofluanid and 10% tebuconazole) at a rate of 2500 g/ha.

Procedure for the measurement of soil inputs of plant-protection agents washed off through vineyard canopy by rainfall.

Soil inputs produced by rainfall waters washed off through a Ribeiro vineyard (Galicia, northwestern Spain) confirmed that levels recovered are <5% of the added fungicides. Laboratory studies showed that some fungicides were degraded in the ODS cartridge used for the collection of fungicides washed off by rainfall. Procymidone wash-off data obtained in the vineyard can be explained by a first-order rate mass transfer model.

Pollution attenuation by soils receiving cattle slurry after passage of a slurry-like feed solution. Column experiments.

Designing soil filtration systems or vegetated filter strips as a means of attenuating water pollution should take into account soil purging capacity. Here we report data on laboratory column trials used to investigate the capacity of a Hortic Anthrosol to attenuate contamination due to downward leaching from cattle slurry applied at the surface. The columns comprised 900 g of soil to a depth of about 20-25 cm, and had been used previously in an experiment involving passage of at least 5 pore volumes of an ion-containing cattle slurry-like feed solution.

Chloride, sodium, potassium and faecal bacteria levels in surface runoff and subsurface percolates from grassland plots amended with cattle slurry.

This study investigated the effectiveness of vegetated buffer strips for removing contaminants in runoff from grassed plots (slope 15%) after application of cattle slurry. Plots (8 x 8 m2 or 8 x 3 m2) received slurry or inorganic fertilizer, and then simulated rainfall (1, 7 and 21 days after slurry/fertilizer application); after each event, runoff and percolates were sampled at various distances downslope (2, 4, 6, and 8 m), and analysed for Cl-, Na+, K+ and faecal bacteria contents. Contaminant concentrations were markedly higher in runoff from the slurry-amended plots than in runoff from the fertiliser-amended plots.