AGRO-2014: A time dependent model for assessing the fate and food-web bioaccumulation of organic pesticides in farm ponds: Model testing and performance analysis.

A time-dependent environmental fate and food-web bioaccumulation model is developed to improve the evaluation of the behaviour of non-ionic hydrophobic organic pesticides in farm ponds. The performance of the model was tested by simulating the behaviour of 3 hydrophobic organic pesticides, i.e.

Evaluation of AGRO-2014 for Predicting Hydrophobic Organic Chemical Concentrations in Ponds.

Highly hydrophobic organic chemicals (HOCs), like pyrethroids, adsorb strongly to eroded soil and suspended sediment. Therefore, total suspended solids (TSS) concentration in the water column of receiving waters is important for determining the proportion of chemical in the sediment-sorbed vs. the dissolved (bioavailable) state.

Use of quantitative structural analysis to predict fish bioconcentration factors for pesticides.

The focus of this research was to develop a model based solely on molecular descriptors capable of predicting fish bioconcentration factors (BCF). A fish BCF database was developed from high-quality, regulatory agency reviewed studies for pesticides based on the same laboratory protocol and the same fish species, Lepomis macrochirus. A commercially available software program was used to create a quantitative structure-activity relationship (QSAR) from 93 BCF studies based on unique molecules.

Statistical tools for determining appropriate selection of regression models for analysis of environmental fate datasets.

Background: In the NAFTA regulatory community, a currently consistent methodology used to estimate dissipation times for environmental fate data is not applied.

Results: This work demonstrates through a case study that the inappropriate use of pseudo-first-order regression models can result in inaccurate estimates of soil degradation rates, and it proposes some statistical tools that can be used to identify an appropriate statistical model to fit a particular environmental fate dataset. Diagnostic procedures have been proposed to identify the appropriate scale, and statistical testing procedures have been proposed to select the appropriate model within that scale.

PLUS: a regional groundwater assessment and ranking tool.

There has been interest within the pesticide regulatory community in developing a tool that can provide estimates of potential pesticide exposure in shallow groundwater across an intended use area. Therefore, industry initiated an investigative project based on the PRZM 3.12 model, which uses regional soils and weather in an easy to use interface.

Comparison of leaching predictions based on PRZM3.12, LEACHP, and RZWQM98 using standard scenario modeling.

Regulatory agencies in the NAFTA region use ground water leaching models to help determine risks to ground water resources. The results of three models for leaching predictions are compared using a standard soil and weather scenario currently used by the New York Department of Environmental Conservation (NYDEC) to simulate the Riverhead soil found on Long Island, New York. The three models, PRZM3.

Use of PRZM-3 to validate a laboratory to field degradation conceptual model.

The test substance, boscalid, was applied at two field sites, but, depending on how kinetic calculations were performed, the time required for 50% of the initial compound concentration to dissipate (half-life) ranged from 27 to 200 days. Laboratory aerobic soil studies indicated that the DT50 for the compound was about 108 days, and since compound dissipation rates are typically shorter in the field than those observed in the laboratory, confidence in the field half-life calculations was questioned. Researchers have asked whether exposure models might be useful for relating laboratory to field behavior, especially when results are difficult to reconcile between the two systems.

A degree-day concept for estimating degradation time under field conditions.

Development of degradation rate information for crop protection products in soil is typically a time consuming and costly process. Therefore, development of methodology that would allow extrapolation of limited degradation information to wider field conditions in a predictive fashion would be desirable. This study presents an approach that uses a modified heat unit model to estimate organic compound degradation time using limited datasets.