Use of mathematical modeling and its inverse analysis for precise assessment of pesticide dissipation in a paddy environment.

The extrapolability of the lysimeter test as a dissipation simulator in an actual paddy field was evaluated using mathematical models and their inverse analyses for predicting pesticide fate and transport processes in paddy test systems. As a source of experimental data, a four-year comparative experiment in lysimeters and paddy fields was conducted using various paddy pesticides. First, the dissipations for various active ingredients in granule pesticides under submerged applications were statistically compared using simple kinetic modeling.

Separate Analysis of Loquat Fruit Pulp, Peel, and Pits to Calculate Pesticide Residue Levels in the Whole Commodity.

To evaluate the effects of handling "not detectable" residues (ND: <0.01 mg/kg) in the pulp and detectable residues in the pits on the calculation of pesticide residue in the whole fruit, residue levels in the pulp, peel, and pits of loquat fruits were separately analyzed. Following conventional Japanese agricultural practices, 16 pesticides were sprayed at the maximum application rates in three test fields.

Comparison of adherence tendencies of pesticide residues sprayed on small-, medium-, and large-sized tomatoes.

Crop field trials were conducted to investigate the residues of sprayed pesticides on the different sizes of tomatoes. Pesticide residue data in tomatoes varied due to different locations of the three crop fields selected and/or physicochemical properties of the three pesticides tested. The pesticide residue levels in the medium- and small-sized tomatoes were 1.

Inverse modeling of laboratory experiment to assess parameter transferability of pesticide environmental fate into outdoor experiments under paddy test systems.

Background: Extraction of environmental fate parameters for pesticides by inverse modeling in laboratory experiments has evolved to become a common practice in higher tier exposure modeling. This study focuses on flooded paddy soil conditions using a simple container test system. Four active ingredients of paddy herbicide were tested.

Influences of sample homogenization time and standing time before extraction on the determination of incurred pesticide residue levels in grapes.

To estimate the influence of sample processing with a blender, we conducted a homogeneity test using a bulk sample of pre-harvest grapes. Relative standard deviations (RSDs) were calculated from the concentrations of pesticides in the portions from the top, middle, and bottom of the homogenate with fine and rough particles. The results from adequate sample processing showed that the RSDs of the residue levels of all five pesticides in the fine-particle homogenate were lower than 10%.

Development and diffusion of practical technologies for pesticide residue analysis.

We often encounter difficulties in analyzing pesticide residues in food, since the residue level to be measured is infinitesimal but the food samples may contain a variety of matrices, including interferences, for chromatographic analysis. Thus it is important to find out the key points to be checked in the extraction, purification, and determination steps of analysis. We have attempted to develop practical technologies for the analysis of pesticide residues in raw agricultural commodities based on the following studies: The effect of processing and cooking on pesticide residue levels in several crop samples (rice, wheat, soybean, and sesame) was investigated.

Inverse analysis to estimate site-specific parameters of a mathematical model for simulating pesticide dissipations in paddy test systems.

Background: In Japan, while experimental data for the dissipation behavior of paddy pesticides under a standardized test system are available, the application of a mathematical model is limited. This paper proposes a new model calibration procedure for inversely deriving the model parameters from the experimental data. This procedure is tested in the open software R by running an improved Pesticide Concentration in Paddy Field-1 (PCPF-1) model with R packages to analyze the dissipation of simetryn and molinate in flooded lysimeters and paddy fields.

Effect of sample preparation on the estimation of residue levels of sprayed pesticides in separate analyses of turnip roots and leaves: inclusion or exclusion of the root-shoot junction.

The effect of inclusion or exclusion of the root-shoot junction on the estimation of pesticide residue levels in turnip roots and leaves was investigated. Turnips grown at two experimental sites were sprayed with six pesticides. At residue analysis, the turnips were divided in three segments: roots (R), leaves (L), and root-shoot junctions (J).

Influence of various parts of sweet corn ears on pesticide residue levels.

Pesticide residue levels in various parts of sweet corn ears were analyzed. For this purpose, five pesticides were sprayed on corn in two different fields, and the harvested samples were separated into four portions, namely kernels, cobs, silks, and husks. Each of these portions was then separately analyzed.