• Korean Journal of Environmental Agriculture
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• v.12 no.1
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• pp.27-34
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• 1993

This experiment was conducted to determine the residual amount of dimepiperate (S-1-methyl-1-phenylethyl piperidine-1-carbothioate) and dimepiperate-OH(S-1-methyl-1-phenylethyl-4-hydroxy piperidine-1-carbothioate) in surface water and leachate using a lysimeter system. In surface water, the concentration of dimepiperate was 851-897 ppb in the treatment of 3.0 Kg prod/10a. 1,755-1,781 ppb in the treatment of 6.0 Kg prod/10a 1 day after the treatment. The amount of dimepiperate gradually decreased and was infinitesimal from 35 days after the treatment. In leachate dimepiperate was detected from the 45 days, but its concentration was very low, below 1 ppb, compared to that in surface water. The metabolite of dimepiperate, dimepiperate-OH in surface water was detected after the application of dimepiperate. The highest level of 88-173 ppb occurred 2 day after the treatment of dimepiperate and then decreased gradually. The residual concentration was below 2.13 ppb during 28-63 days. In leachate, the concentration of dimepiperate-OH in the different treatments in the range of 0.5-11 ppb from the 21 days, although each treatment showed different detected date and concentration. The detected concentration showed a little change until 63 days.

• Korean Journal of Weed Science
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• v.3 no.1
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• pp.75-99
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• 1983

The herbicidal properties of perfluidone [1,1,1-trifluoro-N-2-methyl-4-(phenylsulponyl) phenyl methanesulfonamide] were investigated in pots and paddy fields. At the rate of 2.0kg prod./10a, perfluidone did not cause any injury to the 4 leaf stage (LS) rice seedlings. Although the crop injury increased with increasing the application rate, the injury caused by 16kg prod. perfluidone/10a gave rise to only 30% yield reduction. The crop injury was greatest when perfluidone was applied 2 days before transplanting and decreased as the application time delayed. Perfluidone showed greater crop injury to the 3 LS seedlings, at more than 7cm water depth, and at high temperature than to the 4 LS seedlings, at 3-5cm water depth, and at low temperature. Indica and indica ${\times}$ japonica rice varieties were generally more sensitive to perfluidone than japonica rice variety. Perfluidone effectively controlled most of annual weeds and such perennial weeds as Sagittaria pygmaea MIQ., Potamogeton distinctus A. BENN, Cyperus serotinus ROTTB, Scirpus maritimus L., Eleocharis kuroguwai OHWL, and Scirpus hotarui OHWL, whereas Sagittaria trifolia L. and Polygonum hydropiper SPACH. were tolerent to perfluidone. The weeding effect decreased with increasing the leaching amount of water and the overflowing of irrigated water within 24 hours after the herbicide application. When the application time was done later than 8 days after transplanting, the perennial weeds were shown at deeper soil layers, and the standing water was deeper than 7cm, the effect tended to decrease. However, there was no difference in the weeding effect between soil types. Downward movement of perfluidone in flooded soil ranged from 2 to 8cm deep. The movement increased with increasing the leaching amount of water and the application rate and at a sandy loam soil which possessed less adsorptive capacity. Residual effect of perfluidone was found at 35 to 80 days after application, which varied such factors as Soil types. Increase in the leaching amount of water resulted in decrease in the period of the residual effect. The period was shorter at non-sterilized soil than at sterilized soil. The 0.75kg ai perfluidone + 1.5kg ai SL-49 (1,3-dimethyl-6-(2,4-dichlor-benzoyl)-5-phenacyloxy-pyrazole)/ha and 1.5kg ai perfluidone + 1.05kg ai bifenox (2,4-dichlorophenyl-3-methoxy carbonyl-4-nitro phenyl ether)/ha showed less crop injury than 1.5kg ai/ha perfluidone alone. However, the weeding effect of the former was similar to that of the later.

• Applied Biological Chemistry
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• v.22 no.2
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• pp.109-122
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• 1979

Present study was carried out to reduce residual toxicity of BHC insecticides inherent in the organochlorine pesticides. For This end, r-isomer, the most potent insecticidal component among the BHC stereoisomers, was isolated and thus fortified by means of solvent precipitation. In parallel, 3-(2,4,5-trichlorophenyl)-1-methyl urea was prepared in good yield from technical BHC via 1,2,4-trichlorobenzene, 1,2,4,-trichloronitrobenzene, and 2,4,5-trichloroaniline. In addition, certain merit of the compound which make it possible to use as a herbicide is discussed. The results are summarized as follows; 1. Recrystallizing technical BHC from methanol-water binary solvent system, r-isomer was enriched to 49.7% at 95% recovery of r-isomer. 2. By partitioning technical BHC in 85% of methanolic solution into chloroform, r-isomer was fortified to 89.6% at 90.5% recovery of r-isomer. 3. Yield of 1,2,4-trichlorobenzene from technical BHC was greatly dependent upon concentration of alkalies and to less degree on the alkalies. 4. Surfactants, in particular cationic a quartenary ammonium salt, increased yield of 1,2,4-trichlorobenzene from technical BHC by alkaline hydrolysis. 5. Conversion of 1,2,4-trichlorobenzene to 2,4,5-trichloronitrobenzene was effected almost quantitatively utilizing $HNO_3-H_2SO_4$ nitrating agent at low temperature. 6. Yield of 91.4% was observed for the synthesis of 2,4,5-trichloroaniline by reducing 2,4,5-trichloronitrobenzene in the presence of iron turning and hydrochloric acid. 7. Overall yield based on BHC of 3-(2,4,5-trichlorophenyl)-1- methyl urea was 60.8%. 8. Inhibition effects, both germination and growth, 3-(2,4,5-trichlorophenyl)-1-methyl urea on several crops were found comparable to or more potent than those of $linuron{\circledR}\;and\;diuron{\circledR}$. In addition, it was also noted that susceptibility to the prepared compound depended upon the crops as well as specific part (shoots, roots) of the plant exposed to the chemicals.

• Korean Journal of Environmental Agriculture
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• v.14 no.3
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• pp.312-318
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• 1995

Residues of benfuresate in rice and oxolinic acid in Chinese cabbage were determined through the field experiments in order to establish the safe use and the maximum residue limit(MRL) of these pesticides in Korea. The herbicide benfuresate powder was sprayed into the paddy field with a level of 0.6kg(active ingredient)/ha and rice (Oryza sativa L.) was grown. At harvest, residues of benfuresate in brown rice and stem were analyzed using gas chromatograph. The residue of oxolinic acid in Chinese cabbage (Brassica campestris subsp. napus var pekinesis MAKINO) was analyzed using HPLC after foliar-spraying this fungicide into the cabbages at a level of 15kg/ha. The recovery efficiencies of benfuresate and oxolinic acid were 87-89% and 90-95%, respectively. The respective residues of benfuresate in rice and oxolinic acid in Chinese cabbage were in the range of 0.27-0.46 mg/kg and 0.23-1.53kg/kg. Residual concentrations of these pesticides in crops increased with the increased application frequencies, followed the first-order kinetics and linearly decreased with time. The highest residue of 1.53 mg/kg of oxolinic acid was observed when this fungicide was sprayed six times until three days prior to harvest, but this level was far lower t㏊n 5 mg/kg, which is the maximum residue limit(MRL) set by FAO/WHO.

• Korean Journal of Environmental Agriculture
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• v.13 no.2
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• pp.199-208
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• 1994

Analytical methods for the determination of the derivatives of the herbicide (${\pm}$)-2-(4-chloro-2-methylphenoxy)propionic acid (MCPP) by capillary column gas chromatography with mass spectrometer (GC-MS) and electron-capture detection (GC-ECD) were studied. A successful procedure was introduced for the ester preparation using $H_2SO_4$, as the catalyst and the alcohol 2,2,2-trichloroethanol (TCE) or 2,2,2-trifluoroethanol (TFE). The identificaiton and elucidation of MCPP by GC-MS spectrometry following the esterification with diazomethane, $BF_3$/methanol, $H_2SO_4$/methanol, TCE, TFE, or pentafluorobenzyl bromide (PFB) were carried out. A comparison of the response-sensitivities among those MCPP esters was made with GC-ECD. Although the methylation product of MCPP was confirmed by GC-MS, its low sensitivity to the ECD limited the detection of MCPP. TCE, TFE, and PFB derivatization methods resulted in a high rate of MCPP esterifications and very sensitive ECD molecular responses. Based on efficiency, convenience, worker safety, and least sample contamination, TFE esterificaiton was considered as the superior method for MCPP analysis to the other methods of derivatization. An accurate method is described for quantifying MCPP in soil leachates by GC-ECD at very low concentrations without the requirement of a complicated clean-up process. As a result, MCPP residues at concentrations of less than $0.1{\mu}g$ in 100ml soil leachate were detected.

• Journal of Soil and Groundwater Environment
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• v.11 no.4
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• pp.33-40
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• 2006

Residual pesticides discharged from diffuse sources at agricultural area in association with suspended solid will be settled at downstream, and may degrade surface water quality. This research studied dechlorination kinetic of atrazine, one of triazine-category herbicide, using zero-valent iron (ZVI) in sediment. It can be observed from the experiments that buffer capacity of sediment helped pH maintained beutral, resulted in continuous dechlorination. Sediments were spiked with atrazine at 10, 30, and 50 mg atrazine/L of total sediment for batch experiments. Dechlorination constants were $1.38x10^{-1}/d$ for the initial concentration of 10 mg/L, $1.29x10^{-l}/d$ for 30 mg/L, and $7.43x10^{-2}/d$ for 50 mg/L while dechlorination constants of initial concentration of 50 mg/L without ZVI adding were estimated as $3.05x10^{-2}/d. Half lifes atrazine by ZVI were estimated as 5.03 d fur 10 mg/L, 5.38 d for 30 mg/L, and 9.33 d for 50 mg/L, respectively.

• Korean Journal of Weed Science
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• v.4 no.1
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• pp.52-61
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• 1984

Pot and laboratory tests were undertaken to investigate the influence of silicate fertilization on butachlor phytotoxicity to rice. Growth of rice seedlings at 150 ppm of $SiO_2$ was stimulated, while adverse effect was observed over 300 ppm of $SiO_2$ and growth reduction was enhanced with combination of butachlor and $SiO_2$ Rice growth in pot trial at 150kg/10a of silicate fertilization was not influenced by recommended amounts of butachlor and nitrofen, however, the growth of Seokwang byeo at 300kg/10a of silicate was markedly retarded by butachlor in the initial stage of growth. Growth reduction of Seokwang byeo caused by combined application of silicate and butachlor was recovered 50 days after herbicide application. Growth reduction from butachlor was not influenced by pH level and also degradation behaviors of butachlor in submerged soil was not altered by silicate fertilization. Adsorbed amount of butachlor on rice root was increased with addition of $SiO_2$ and its amount in Seokwang byeo was higher than that of Jinju byeo. Butachlor absorption by Seokwang byeo was accelerated by 150 ppm of $SiO_2$ applied simultaneously, but those effect was not encountered in Jinju byeo. Butachlor absorption of rice seedlings was also increased by 150 ppm of $K_2O$, while CaO hindered the absorption and $Na_2O$ had no effect on the absorption. Residual level of butachlor in Seokwang byeo treated with combined solution of butachlor and $SiO_2$ was continued higher than that with butachlor alone during 10 days after transplantation to culture solution.