Runoff of Aerially Applied Phthalide from Paddy Fields

The daily variations in the insecticides, i.e., buprofezin, etofenprox, fenitrothion, fenobucarb and pyridaphenthion, and fungicides, i.e., flutolanil, isoprothiolane, mepronil, pencycuron, phthalide and tricyclazole, were investigated in order to evaluate the short periodic variations in the pesticide concentrations of small river waters. The mean and maximum concentrations were 0.05 microg/L (pyridaphenthion)--1.2 microg/L (isoprothiolane) and 0.30 microg/L (pyridaphenthion)--13 microg/L (flutolanil), respectively. The concentration at 10:00 a.m. could be regarded as the representative daily concentration of the day. However, the concentration could markedly vary during the day or the day following the pesticide application. Therefore, the mean concentrations at 10 a.m., 2 p.m. and 6 p.m. were recommended as the best representative values of the day.

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Daily Variation of Pesticides in Surface Water of a Small River Flowing Through Paddy Field Area

Tanabe

Kawata

2009

“…Although radio-controlled helicopters have recently been used for pesticide spraying instead of manned helicopters, few reports have been published on the behavior and runoff ratios of pesticides applied by these radio-controlled helicopters. Therefore, we have previously investigated variations in the concentrations of phthalide in paddy field waters, drainage channel waters and river waters after application by a radio-controlled helicopter in August 2005, and evaluated the runoff ratios of phthalide (Shiota et al 2006). The investigation in 2005 was conducted for 9 days after the application, because the concentrations in the water samples significantly decreased over this the period.…”

mentioning

confidence: 99%

Variation of 4,5,6,7-Tetrachlorophthalide in Water After Aerial Application to Rice Cultivation Area

Maeda

Iwashita

Hori

et al. 2008

Self Cite

Variation in the fungicide, 4,5,6,7-phthalide, in water was investigated in order to evaluate the runoff of the fungicide after aerial application to paddy fields by a radio-controlled helicopter. The survey was conducted for 4 months after the application. The average and maximum concentrations of phthalide were 3.7-4.4 microg/L and 30.5-33.8 microg/L in the paddy fields, 0.37-0.64 microg/L and 2.7-7.5 microg/L in the drainage channels, and 0.18 and 0.83 microg/L in a river, respectively. The runoff ratios of the aerially applied phthalide from the paddy fields into the drainage channels were calculated to be 1.7-2.4%.

“…The experiments were carried out at two paddy fields (paddy fields 1 and 2) located in Agano City, Niigata, Japan (Shiota et al 2006). Paddy fields 1 and 2 had areas of 1,470 and 1,200 sq m, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…We have previously investigated variations in the concentrations of phthalide in paddy field water, drainage channel water and river water after application by a radiocontrolled helicopter, and evaluated the runoff ratios of phthalide from the paddy fields (Shiota et al 2006;Maeda et al 2008). The runoff ratios of the applied phthalide from the paddy fields were 1.6%-2.4%.…”

mentioning

confidence: 99%

Decrease of 4,5,6,7-Tetrachlorophthalide in Paddy Field Soil After Aerial Application

Iwashita

Maeda

Hori

et al. 2008

Self Cite

Variation in the fungicide, 4,5,6,7-tetrachlorophthalide (phthalide), in paddy field soil was investigated in order to evaluate its decrease after aerial application by a radio-controlled helicopter. The maximum concentrations of phthalide were 309-320 microg/kg dry, which were 83%-96% of the applied phthalide. The organic carbon normalized soil sorption coefficient (K(oc)) was calculated to be 94-96 mL/g at 1 h after the application. The calculated K(oc) values increased to 620-1,300 mL/g from 1 through 9 days after the application and then 4,700-7,200 mL/g 14 days after the application. The half-life of the phthalide was calculated to be 20-31 days.