Automation and evaluation of three pesticide fate models for a national analysis of leaching risk in Canada

McQueen, D. A. Ross; Farenhorst, Annemieke; Allaire, Suzanne; Cessna, Allan J.

doi:10.4141/s06-065

Cited by 9 publications

(6 citation statements)

References 22 publications

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“…P esticide fate models are being used in regional assessments of the risk of pesticide movement by leaching, runoff, and water‐eroded soil (Stewart and Loague, 1999; Eason et al, 2004; McQueen et al, 2007). Sorption coefficients (measures of pesticide sorption by soil) are among the most sensitive input parameters in pesticide fate models.…”

Section: Description Of Terrain Attributesmentioning

confidence: 99%

Herbicide Sorption Coefficients in Relation to Soil Properties and Terrain Attributes on a Cultivated Prairie

et al. 2008

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The sorption of 2,4-D and glyphosate herbicides in soil was quantified for 287 surface soils (0-15 cm) collected in a 10 x 10 m grid across a heavily eroded, undulating, calcareous prairie landscape. Other variables that were determined included soil carbonate content, soil pH, soil organic carbon content (SOC), soil texture, soil loss or gain by tillage and water erosion, and selected terrain attributes and landform segments. The 2,4-D sorption coefficient (Kd) was significantly associated with soil carbonate content (-0.66; P < 0.001), soil pH (-0.63; P < 0.001), and SOC (0.47; P < 0.001). Upper slopes were strongly eroded and thus had a significantly greater soil carbonate content and less SOC compared with lower slopes that were in soil accumulation zones. The 2,4-D Kd was almost twice as small in upper slopes than in lower slopes. The 2,4-D Kd was also significantly associated with nine terrain attributes, particularly with compounded topographic index (0.59; P < 0.001), gradient (-0.48; P < 0.001), mean curvature (-0.43; P < 0.001), and plan curvature (-0.42 P < 0.001). Regression equations were generated to estimate herbicide sorption in soils. The predicted power of these equations increased for 2,4-D when selected terrain attributes were combined with soil properties. In contrast, the variation of glyphosate sorption across the field was much less dependent on our measured soil properties and calculated terrain attributes. We conclude that the integration of terrain attributes or landform segments in pesticide fate modeling is more advantageous for herbicides such as 2,4-D, whose sorption to soil is weak and influenced by subtle changes in soil properties, than for herbicides such as glyphosate that are strongly bound to soil regardless of soil properties.

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Section: Description Of Terrain Attributesmentioning

confidence: 99%

Herbicide Sorption Coefficients in Relation to Soil Properties and Terrain Attributes on a Cultivated Prairie

et al. 2008

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“…Pesticide fate models are being used in regional assessments of the risk of pesticide movement by leaching, runoff, and water‐eroded soil (Wilson et al, 1996; Stewart and Loague, 1999; Eason et al, 2004; McQueen et al, 2007). For such model simulations, the required pesticide input parameters are obtained from generalized databases of pesticide properties, with each pesticide being assigned single Koc and t½ values regardless of the region in which the simulation is performed.…”

Section: Soil Great Groups Average Climate and Crop Systems Typical mentioning

confidence: 99%

Regional Assessment of Herbicide Sorption and Degradation in Two Sampling Years

Gaultier

Farenhorst

Cathcart³

et al. 2008

J of Env Quality

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Sorption and degradation of the herbicide 2,4-D [2,4-dichlorophenoxyacetic acid] were determined for 123 surface soils (0 to 15 cm) collected in 2002 and in 2004 between 49 degrees to 60 degrees north longitude and 110 degrees to 120 degrees west latitude in Alberta, Canada. The soils were characterized by soil organic carbon content (SOC), pH, electrical conductivity, soil texture, cation exchange capacity, carbonate content, and total soil microbial activity. The 2,4-D sorption coefficients, Kd and Koc, were highly variable with coefficients of variation of 89 and 59%, respectively, at the provincial scale. Both Kd and Koc were well described by regression models with SOC and soil pH as variables, regardless of scale. Surprisingly, variations in 2,4-D mineralization were much smaller than variations in sorption. Variability in total 2,4-D mineralization was particularly low, with a coefficient of variation of only 7% at the provincial scale. Average 2,4-D half-lives in ecoregions ranged from 1.7 to 3.5 d, much lower than the field dissipation half-life of 10 d reported for 2,4-D in general pesticide property databases. Regression models describing degradation parameters were generally poor or not significant because 2,4-D mineralization was only weakly associated with measured 2,4-D sorption parameters and soil properties. As such, regional variations in herbicide sorption coefficients should be measured or calculated based on soil properties, to assign distinct pesticide fate model input parameters when estimating 2,4-D off-site transport at the provincial scale. Spatial variations in herbicide degradation appear less important for Alberta as 2,4-D half-lives were similar in soils across the province. The rapid mineralization of 2,4-D is noteworthy because 2,4-D is widely used in Alberta and perhaps adaptation of soil microbial communities allowed for accelerated degradation regardless of soil properties or the extent of 2,4-D sorption by soil.

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“…The pesticide fate model PRZM version 3.12.3 (Suarez ), developed by the United States Environmental Protection Agency (freely available at http://www2.epa.gov/exposure-assessment-models/przm3-version-3123), simulates the transport of pesticides in water for each simulation unit generated by the stochastic model. The PRZM was selected because it produces reasonably accurate outcomes of pesticide concentrations at edge‐of‐field in a reasonable computational time (Carbone et al ; McQueen et al ). For a detailed description of PRZM, the reader is referred to Suarez ().…”

Section: Methodsmentioning

confidence: 99%

A coupled stochastic/deterministic model to estimate the evolution of the risk of water contamination by pesticides across Canada

Gagnon

Sheedy

Farenhorst

et al. 2014

Integr Envir Assess & Manag

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Periodic assessments of the risk of water contamination by pesticides help decision makers improve the sustainability of agricultural management practices. In Canada, when evaluating the risk of water contamination by pesticides, 2 main constraints arise. First, because the area of interest is large, a pesticide transport model with low computational running time is mandatory. Second, some relevant input data for simulations are not known, and most are known only at coarse scale. This study aims to develop a robust methodology to estimate the evolution of the risk of water contamination by pesticides across Canada. To circumvent the 2 aforementioned issues, we constructed a stochastic model and coupled it to the 1-dimensional pesticide fate model Pesticide Root Zone Model (PRZM). To account for input data uncertainty, the stochastic model uses a Monte Carlo approach to generate several pesticide application scenarios and to randomly select PRZM parameter values. One hundred different scenarios were simulated for each of over 2000 regions (Soil Landscapes of Canada [SLC] polygons) for the years 1981 and 2006. Overall, the results indicated that in those regions in which the risk increased from 1981 to 2006, the increase in risk was mainly attributable to the increased area treated by pesticides or an increase in the number of days with runoff. More specifically, this work identifies the areas at higher risk, where further analyses with finer-scale input data should be performed. The model is specific for Canadian data, but the framework could be adapted for other large countries.

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Automation and evaluation of three pesticide fate models for a national analysis of leaching risk in Canada

Cited by 9 publications

References 22 publications

Herbicide Sorption Coefficients in Relation to Soil Properties and Terrain Attributes on a Cultivated Prairie

Herbicide Sorption Coefficients in Relation to Soil Properties and Terrain Attributes on a Cultivated Prairie

Regional Assessment of Herbicide Sorption and Degradation in Two Sampling Years

A coupled stochastic/deterministic model to estimate the evolution of the risk of water contamination by pesticides across Canada

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