• Analytical Science and Technology
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• v.20 no.6
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• pp.460-467
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• 2007

Dose rate conversion factor was calculated to estimate the absorbed effective annual doses for soils for the beta-rays and gamma-rays, which were emitted from $^{238,235}U$, $^{232}Th$, and $^{40}K$ isotopes. The most recent data of the emitted energies per decay, half-lifes, and branching ratios, which were obtained from National Nuclear Data Center, were used. When this factor and the effective annual doses for the beta-rays and the gamma-rays of natural radioisotopes were compared with those of Aitken, these of $^{238}U$, $^{232}Th$ and $^{40}K$ are estimated to have good agreements but a large difference is shown in this for $^{235}U$. Through the calculations of effective annual doses by using these factor and the measurements of gamma-ray spectra for soils, which were extracted from prehistoric remains (Mansuri) on Osong, Chungchengbuk-do, The annual effective doses were obtained to be 3.8~5.9 mGy/yr. Also, when these doses including decay elements upper Rn were compared with those on all isotopes, the differences within 9~30 % were obtained. The analysis method of the annual effective doses for the beta-rays and the gamma-rays of the natural isotopes of soils was established by this dose rate conversion factor.

• The Korean Journal of Pesticide Science
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• v.18 no.3
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• pp.148-155
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• 2014

The transfer pattern of chlorpyrifos present in soil to cucumber plants were assessed and reported with plant growth, concentration dependency, and duration. Cucumber seedlings cultivated in a growth chamber for 30 days and a greenhouse for 120 days. Weight and length of cucumbers cultivated in the chamber increased with the increasing time, while the uptake of chlorpyrifos by cucumber increased a period from 0 to 15 days and decreased after 15 days. Uptake rates of chlorpyrifos into a cucumber plant were 1.0~1.3% to initial amounts treated with 20 and 40 mg/kg to soil. Most chlorpyrifos residues were detected in root, followed by stem and leaf. Results of the greenhouse test showed that chlorpyrifos amounts in cucumber fruits were present less than LOQ (0.02 mg/kg), and chlorpyrifos was mainly found in the root of the cucumber plant. Chlorpyrifos absorbed in a cucumber under greenhouse condition was smaller than that in chamber condition as 0.03~0.04%. Degradation patterns of chlorpyrifos in soils were similar during indoor and outdoor tests with half-lives of 25.8~73.0 days. These results may be useful for establishing the management strategy of residual pesticides in soil environment.

• Applied Biological Chemistry
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• v.25 no.2
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• pp.93-98
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• 1982

Residues of Fujione (Fudiolan, fungicide) and Ortran (Acephate, insecticide) in Korean rice crop were studied. Also the persistencies of the pesticides in rice paddy soil were investigated in field and in laboratory. The residual levels of the pesticides in rice plant, straw, unpolished and polished rice were varied with the application rates of the pesticides. The residues of Fujione and Ortran in unpolished rice were $0.07{\sim}0.09ppm$ and $0.01{\sim}0.53ppm$, respectively. The half life of Fujione was 30 days under aerobic and 150 days under flooded condition in the laboratory system. Whereas in the paddy field it was about 100 days. In the case of Ortran it was $3{\sim}4$ days and $13{\sim}14$ days in aerobic and flooded condition, respectively in laboratory system.

• Current Research on Agriculture and Life Sciences
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• v.11
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• pp.101-110
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• 1993

The residues of combined insecticide of polynactin complex(tetranactin) and BPMC were determined to establish an index for the safety use to apple. Evaluation was made on residual concentration of tetranactin and BPMC in apple as a function of application frequency and date when the combined insecticide of tetranactin and BPMC was sprayed into apple. Their persistence in soil were also studied under the field and laboratory conditions. Recovery percentage from apple was ranged from 74.0 to 77.5 in tetranactin, 87.1 to 83.6 in BPMC, those from soil was 82.3 to 88.4 in tetranactin, 83.6 to 887.1 in BPMC. The minimum detectable limits of tetranactin and BPMC were 0.01ppm in apple pulp and 0.03ppm in apple peel and soil. The residue percentage of tetranactin and BPMC in the peel and pulp part of apple was about 96 in peel part by five sprays up to 3th day before harvest. The residues of tetranactin and BPMC in apple are proved to 0.39ppm and 0.75ppm by five sprays up to 30days before harvest. Maximum residue limit(MRL) of BPMC for fruits was established of 0.3ppm in Environment Protection Agency of Korea, and thus it is suggested that the preharvest intervals of combined insecticide for apple could be 30 days with twice spray. The half life of tetranactin in soil under field and laboratory conditions was 6.9 and 24.4 days, and in case of BPMC was 6.3 and 23.2 days, respectively.

• Korean Journal of Environmental Agriculture
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• v.9 no.1
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• pp.15-22
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• 1990

The efects of application time on the persistence of chlorothalonil in sesame plants and its persistence in soil were studied in the field. A procedure was used which permited the analysis of residues of Chlorothalonil (DACONIL 2787) in sesame(Sesamum indicum L.)and soil. The procedure was based on the multiresidue analytical method using an polarized acetonitrile solution or acidified acetone as the extracting solvent. The DACONIL 2787 is separated from the fat in the extracts by using an activated alumina and Florisil chromatogaphic column. Residues of DACONIL 2787 were determined by subjecting the alternate eluate from the Florisil column to gas chromatographic analysis(ECD). Residue of chlorothalonil in sesame are proved to 0.06 ppm for six sprays, 3rd day before harvest The half-life of chlorothalonil in soil proved to be 8.9 days and residues of chlorothalonil was only 0.03 ppm 100 days after application of 15 ppm.

• Korean Journal of Environmental Agriculture
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• v.16 no.1
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• pp.72-79
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• 1997

Adsorption, leaching, and retention of the Flupyrazofos(KH-502), a new active ingredient for insecticide, in the soils under laborarory and field conditions were investigated to provide the basic data for the safety use and to assess a secondary impact of this insecticide on soil and water environments. A significant power function relation was found between the adsorbed KH-502 and time, representing that 45% of the added KH-502 was adsorbed within 30 min. but a quasiequilibrium was reached after 6 to 12 hr with a slower adsorption. Adsorption phenomena followed th first-order kinetics and time required for 50% adsorption was 5.8 hr. The equilibrium adsorption isotherm was explained by the Freundlich equation and was classified as S-type. The amounts of KH-502 leached through the soil column (C) as compared to initial conc. ($C_0$) were very low and these relative concentrations ($C/C_0$) were 0.073 and 0.017 in SL and CL soils, respectively. The residual conc. of KH-502 in the surface soil was comparatively low and decreased with time. Half-lives of KH-502 in the surface soil was comparatively low and decreased with time. Half-lives of KH-502 under the field conditions were estimated to be 20 and 18 days in the SL and CL soils, respectively. The KH-502 cone, transported to the subsurface soils was extremely low. These results demonstrate that KH-502 has a low pollution risk potential to the surrounding environment as far as it is used following the recommended guideline.

• Korean Journal of Weed Science
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• v.18 no.4
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• pp.325-332
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• 1998

This study was carried out to investigate the adsorption and the movement of herbicide fenoxaprop-P-ethyl in the silty clay soil(SiC) and the sandy loam soil(SL). Fifteen percent of the added herbicide was adsorbed within 30 min after shaking, and a quasi-equilibrium was reached after 8 to 14 h. The time required for 50% adsorption was 15.8 h in the SiC and 19.3 h in the SL. The equilibrium adsorption isotherm was followed by the Freundlich equation and the Kd was 3.86 in the SiC and 2.32 in the SL. The herbicide in the soil columns flooded with 3 cm water depth and eluted at 0.8 cm/day was leached to 6 cm and 8 cm depth at 7 and 21 days after the treatment, respectively. However, the movement was widened with increased amount of leaching water. The herbicide in the field soils was moved up to 6 cm and 8 cm depth at 14 and 56 days after the treatment, respectively. However, the large amount of the applied herbicide was distributed in 0~2 cm profile in all of the soils examined. Half-life of the chemical in soils was shorter than 7 days and the time to 90% degradation was about 4 weeks. The results indicate that the herbicide has relatively small mobility and short persistence.

• Korean journal of applied entomology
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• v.38 no.1
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• pp.47-52
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• 1999

Effects of organic matter content in soil on activity. vertical migration. and persistence of two nernaticides. carbofuran and ethoprophos. to root-knot nematode, Mrloitlog!~iei ~lcognita.w ere investigated. As the organic matter content increased. activity of the nernaticides tended to be reduced. Both nematicides exhibited control values of more than 80'k' to M. iix.o,yilit~iln 0-2 cm depth soil layer from the surface. regi~rdless of organic matter content in soil. In 2-4 cm depth soil layer. however. the control value of the neniaticides varied with the organic niatter content in soil. The control value of carbofuran in the soil layer was ranged from I0 to 30'2,. depending on the soil organic niatter content. In contrast. ethoprophos had no control value against M. i/ic.o,ytlitcr in the \oil layer, except that the nematicide had a control value of 30% when the organic matter content was 0.4%. Furthermore. ethoprophos had no effect on controlling M. i/ic.o,gtiitrr in soil layer of below 4cm. whereas control values of carbofuran were approximately from 5 to 20% in all test soils having different organic matter contents. These results indicate that carbofuran has more vertical migration effect than ethoprophos. Persistence of the two neniaticides was also decreased with increasing soil organic matter content. Half life of carbofuran was 2-3 weeks in soil containing 0.4% organic matter, whereas it was found to be I week in soils containning 0.8 ant1 1.6% of organic matter. On the other hand. activity of ethoprophos was reduced to half in 3-3 weeks and in 2-3 weeks in soil containing 0.4 and 0.8%, and 1.6%) of organic matter, respectively. However, no activity of the both nernaticides was found in soil containing 3.2% of organic matter.

• The Korean Journal of Pesticide Science
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• v.20 no.4
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• pp.349-354
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• 2016

Triazole fungicides occupy an important portion in the global fungicide market and are relatively persistent in soil compared to the other fungicides, suggesting possible adverse effects of the fungicides on human health and environment. In this study, we tried to isolate microorganisms from orchard soils, which can decompose the triazole fungicides, tebuconazole, fluquinconazole, and difenoconazole. Only difenoconazole was completely degraded in the enrichment culture, from which several difenoconazole-degrading bacteria were isolated. They showed the same rep-PCR pattern thus only one strain, C8-2, was further studied. The strain was identified as Sphingomonas sp. C8-2 based on its 16S rRNA gene sequence and decomposed 100 mg/L of difenoconazole in a minimum medium to an unknown metabolite with a molecular weight of 296 within 24 hours. The inhibition effect of the metabolite against representative soil microorganisms significantly decreased compared to that of difenoconazole thus the bacterial strain is expected to be used for the detoxification of difenoconazole in soil and crop.

• Korean Journal of Environmental Agriculture
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• v.14 no.2
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• pp.202-212
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• 1995

In order to elucidate the degrading characteristics of the pyrethroid acaricide-insecticide, acrinathrin in two different types of soils, Soil A(pH, 5.8; organic matter, 3.4%; C.E.C., 115 mmol(+)/kg soil; texture, sandy loam) and Soil B(pH, 5.7; organic matter, 2.0%; C.E.C., 71 mmol(+)/kg soil; texture, sandy loam), residualities of the non-labeled compound under the field and laboratory conditions, extractability with organic solvents and formation of non-extractable bound residues, and degradabilities of [$^{14}C$]acrinathrin as a function of aging temperature and aging period were investigated. The half lives of acrinathrin in Soil A treated once and twice were about 18 and 22 days and in Soil B about 13 and 15 days, respectively, in the field, whereas, in the laboratory, those in Soil A and B were about 36 and 18 days, respectively, suggesting that the compound would be non-persistent in the environment. The amounts of $^{14}CO_2$ evolved from [$^{14}C$]acrinathrin in Soil A and B during the aging period of 24 weeks were 81 and 62%, respectively, of the originally applied $^{14}C$ activity, and those of the non-extractable soil-bound residues of [$^{14}C$]acrinathrin were about 70% of the total $^{14}C$ activity remaining in both soils, increasing gradually with the aging period. Degradation of [$^{14}C$]acrinathrin in both soils increased with the aging temperature. Three degradation products of m/z 198(3-phenoxy benzaldehyde), m/z 214(3-phenoxybenzoic acid), and m/z 228(methyl 3-phenoxybenzoate) as well as an unknown were detected by autoradiography of acetone extracts of both soils treated with [$^{14}C$]acrinathrin and aged for 15, 30, 60, 90, 120, and 150 days, respectively, and the degradation pattern of acrinathrin was identical in both soils. Acrinathrin in soil turned out to be degraded to 3-phenoxybenzaldehyde cyanohydrin by hydrolytic cleavage of the ester linkage adjacent to the $^{14}C$ with a cyano group, the removal of hydrogen cyanide therefrom led to the formation of 3-phenoxybenzaldehyde as one of the major products, and the subsequent oxidation of the aldehyde to 3-phenoxybenzoic acid, followed by decarboxylation would lead to the evolution of $^{14}CO_2$.