Fate of metolachlor under subirrigation in a sandy soil: A lysimeter study

Jebellie, S.J.; Prasher, Shiv O.; Bassi, R.

doi:10.1080/03601230009373251

Cited by 3 publications

(1 citation statement)

References 14 publications

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“…A rainfall simulator with rainfall intensity of 30 mm h −1 was used to investigate the metolachlor leaching potential. Soil and water samples were collected from the soil columns after each 60 mm rainfall event ( Jebellie et al, 2000). Samples were analyzed using a gas chromatography unit and the average values were plotted for comparison with simulated results from the PRZM2 model.…”

Section: Methodsmentioning

confidence: 99%

Computer Simulation of Fate and Transport of Metolachlor in a Soil Column Study

Jebellie¹,

Madani²,

Prasher³

2004

Canadian Water Resources Journal / Revue canadienne des ressour

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PRZM2 is a computer model developed to simulate pesticide transport through the soil profile under saturated and unsaturated conditions. The ability of PRZM2 to simulate the fate and transport of metolachlor will be examined and the simulation results from a soil column study will be evaluated. The input parameters and the measured data were obtained from a soil column study. The model outputs were compared to the measured values and statistical analyses were performed using the coefficient of performance approach. Based on the simulated results, metolachlor did not leach below 0.2 m depth, however, herbicide residue was detected in the soil solution at deeper depths in the soil columns. Although the simulated metolachlor results at 0.1 m depth followed the observed time and depth pattern, the model did not perform well in simulating metolachlor concentration at other depths. The statistical analyses show that the simulated metolachlor concentration was in poor agreement with the corresponding measured data over the entire experimental period. Higher or lower estimation of metolachlor concentrations by the model may be due to a simplistic treatment of matrix flow and the absence of a realistic macropore flow component. The existing mathematical formulation to handle transport and transformation processes may not adequately reflect the realistic fate and transport of metolachlor in soil. This may imply the need for further research and validation of PRZM2 for herbicides. Résumé : Le modèle PRZM2 consiste en un modèle informatique conçu afin de simuler le transport des pesticides à travers le profil pédologique dans des conditions de sol saturé et de sol non saturé. La capacité de PRZM2 à simuler le transport et le sort du métolachlore sera examiné et les résultats de simulation obtenus à partir d'une étude sur des colonnes de sol seront évalués. Les paramètres d'entrée et les données mesurées ont été obtenus à partir d'une expérimentation sur des colonnes de sol. Les données de sortie du modèle ont été comparées aux valeurs mesurées et des analyses statistiques ont été faites à l'aide de la méthode de coefficient de performance. D'après les résultats simulés, le métolachlore n'a pas été lessivé au-dessous de 0,2 m de profondeur. Cependant, des résidus d'herbicides ont été détectés dans la solution du sol à des profondeurs plus grandes dans les colonnes de sol. Bien que les résultats simulés quant au

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Section: Methodsmentioning

confidence: 99%

Computer Simulation of Fate and Transport of Metolachlor in a Soil Column Study

Jebellie¹,

Madani²,

Prasher³

2004

Canadian Water Resources Journal / Revue canadienne des ressour

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Soil Column Leaching of Pesticides

Katagi

2012

Reviews of Environmental Contamination and Toxicology Volume 221

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In this review, I address the practical and theoretical aspects of pesticide soil mobility.I also address the methods used to measure mobility, and the factors that influence it, and I summarize the data that have been published on the column leaching of pesticides.Pesticides that enter the unsaturated soil profile are transported downwards by the water flux, and are adsorbed, desorbed, and/or degraded as they pass through the soil. The rate of passage of a pesticide through the soil depends on the properties of the pesticide, the properties of the soil and the prevailing environmental conditions.Because large amounts of many different pesticides are used around the world, they and their degradates may sometimes contaminate groundwater at unacceptable levels.It is for this reason that assessing the transport behavior and soil mobility of pesticides before they are sold into commerce is important and is one indispensable element that regulators use to assess probable pesticide safety. Both elementary soil column leaching and sophisticated outdoor lysimeter studies are performed to measure the leaching potential for pesticides; the latter approach more reliably reflects probable field behavior, but the former is useful to initially profile a pesticide for soil mobility potential.Soil is physically heterogeneous. The structure of soil varies both vertically and laterally, and this variability affects the complex flow of water through the soil profile, making it difficult to predict with accuracy. In addition, macropores exist in soils and further add to the complexity of how water flow occurs. The degree to which soil is tilled, the density of vegetation on the surface, and the type and amounts of organic soil amendments that are added to soil further affect the movement rate of water through soil, the character of soil adsorption sites and the microbial populations that exist in the soil. Parameters that most influence the rate of pesticide mobility in soil are persistence (DT50) of the pesticide, and its sorption/desorption(Koc) characteristics. These parameters may vary for the same pesticide from geographic site-to-site and with soil depth. The interactions that normally occur between pesticides and dissolved organic matter (DOM) or WDC are yet other factors that may complicate pesticide leaching behavior.The soil mobility of pesticides is normally tested both in the laboratory and in the field. Lab studies are initially performed to give researchers a preliminary appraisal of the relative mobility of a pesticide. Later, field lysimeter studies can be performed to provide more natural leaching conditions that emulate the actual field use pattern. Lysimeter studies give the most reliable information on the leaching behavior of a pesticide under field conditions, but these studies are time-consuming and expensive and cannot be performed everywhere. It is for this reason that the laboratory soil column leaching approach is commonly utilized to profile the mobility of a pesticide,and appraise how it behaves in diffe...

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Leaching of S-metolachlor, terbuthylazine, desethyl-terbuthylazine, mesotrione, flufenacet, isoxaflutole, and diketonitrile in field lysimeters as affected by the time elapsed between spraying and first leaching event

Milan

Ferrero

Fogliatto

et al. 2015

Journal of Environmental Science and Health, Part B

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The effect of elapsed time between spraying and first leaching event on the leaching behavior of five herbicides (terbuthylazine, S-metolachlor, mesotrione, flufenacet, and isoxaflutole) and two metabolites (desethyl-terbuthylazine and diketonitrile) was evaluated in a 2011-2012 study in northwest Italy. A battery of 12 lysimeters (8.4 m(2) long with a depth of 1.8 m) were used in the study, each filled with silty-loam soil and treated during pre-emergence with the selected herbicides by applying a mixture of commercial products Lumax (4 L ha(-1)) and Merlin Gold (1 L ha(-1)). During treatment periods, no gravity water was present in lysimeters. Irrigation events capable of producing leaching (40 mm) were conducted on independent groups of three lysimeters on 1 day after treatment (1 DAT), 7 DAT, 14 DAT, and 28 DAT. The series was then repeated 14 days later. Leachate samples were collected a few days after irrigation; compounds were extracted by solid phase extraction and analyzed by high-performance liquid chromatography and gas chromatography-mass spectrometry. Under study conditions, terbuthylazine and S-metolachlor showed the highest leaching potentials. Specifically, S-metolachlor concentrations were always found above 0.25 µg L(-1). Desethyl-terbuthylazine was often detected in leached waters, in most cases at concentrations above 0.1 µg L(-1). Flufenacet leached only when irrigation occurred close to the time of herbicide spraying. Isoxaflutole and mesotrione were not measured (<0.1 µg L(-1)), while diketonitrile was detected in concentrations above 0.1 µg L(-1) on 1 DAT in 2011 only.

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Fate of metolachlor under subirrigation in a sandy soil: A lysimeter study

Cited by 3 publications

References 14 publications

Computer Simulation of Fate and Transport of Metolachlor in a Soil Column Study

Computer Simulation of Fate and Transport of Metolachlor in a Soil Column Study

Soil Column Leaching of Pesticides

Leaching of S-metolachlor, terbuthylazine, desethyl-terbuthylazine, mesotrione, flufenacet, isoxaflutole, and diketonitrile in field lysimeters as affected by the time elapsed between spraying and first leaching event

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