• Journal of Applied Biological Chemistry
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• v.60 no.4
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• pp.301-306
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• 2017

This study was carried out to investigate the residual level of 5-methyl-1,2,4-triazolo[3,4-b][1.3] benzothiazole (tricyclazole) and the amount of transfer to Korean cabbage grown in treated soil with tricyclazole. The field trial on Korean cabbage was done at two different green houses located in Gwangju (Field 1) and Yongin (Field 2). Soil and cabbage samples were collected at different days after soil treatment of tricyclazole with two different concentration levels, respectively. Average recoveries of tricyclazole ranged from 83.5 to 92.1% in soil and cabbage and the variation coefficient was 1.3-6.8%. The initial concentrations of tricyclazole in field 1 soil were 4.25 and 8.97 mg/kg and decreased to 2.48 and 4.26 mg/kg at 43 DAT (day after treatment) and 0.88 and 2.02 mg/kg and decreased to 0.43 and 0.98 mg/kg at 36 DAT in field 2, respectively. The half-life of tricyclazole was about 39.6 and 28.1 days for the low and high concentration of tricyclazole treated soils in field 1 and 27.9 and 17.2 days for the low and high concentration of tricyclazole treated soils in field 2, respectively. Residual levels of tricyclazole in Korean cabbage were ranged from 4.03 to 18.26 and from 8.26 to 35.08% of initial concentration in filed 1 and field 2 soils, respectively.

• Applied Biological Chemistry
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• v.26 no.2
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• pp.97-103
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• 1983

To get further information on the behavior of phorate(0,0-diethyl S-ethylthiomethyl phosphorodithioate) in soil under the subtropical conditions, a field experiment has been conducted. Phorate granule (10%) was applied to silt loam soil at the rate of 40kg a.i./ha and incorporated to 10cm soil depth. Residues of phorate and its metabolites in soil were determined with GLC and confirmed qualitatively with TLC. Phorate was rapidly oxidized to its sulfoxide and sulfone. Therefore, main metabolic pathway of phorate in soil was the oxidation of phorate to phorate sulfoxide and sulfone. Phorate sulfoxide and sulfone were relatively more persistent than phorate itself. Phoratoxon was detected at low level only up to 30 days after treatment and its sulfoxide and sulfone were not detected during the whole experimental period. Toluene-acetonitrile-nitromethane(40 : 30 : 30, v/v/v) solvent system separated satisfactorily phorate and its five metabolites. Most of the residues was found in the initial incorporation depth $(0{\sim}10cm)$. Consequently, insecticides showed a little downward movement.

• Korean Journal of Environmental Agriculture
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• v.4 no.1
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• pp.1-5
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• 1985

Fate of tricyclazole in rice paddy system was studied. The effect on soil microorganism as well as the mutagenicity of the compound was also examined. The residues of tricyclazole in crops and soil with two times application before harvest were 0.37 in unpolished rice, 0.29 in polished rice, 0.14 in rice straw, and 0.15 ppm in paddy soil. With three times of application the residues were increased to 0.46, 0.39, and 0.19 ppm, respectively. Until $2{\sim}3$ weeks after treatment of pesticide the degradation of tricyclazole was progressed comparatively but very slowly afterward and the half life of that was about $140{\sim}180$ days. There was no effect for viable count of soil microorganisms and for mutagenic test by Salmonella and Saccharomyces systems.

• Journal of Soil and Groundwater Environment
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• v.6 no.2
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• pp.15-22
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• 2001

Radiocarbon ($^{14}C$) and tritium in water have been applied to hydrogeology as a tool for dating of groundwater. The long half-life of $^{14}C$(5,730 years) makes it useful for evaluation of residence time of groundwater, However, the $^{14}C$ has not been applied to groundwater studies in Korea, owing to the absence of preparation line for $^{14}C$ analysis. By this time $^{14}C$ of groundwater has been analyzed mainly using benzene synthesizer, which is so complicate and time-consuming that has been is limitedly applied to hydrogeology. Recently, the direct $CO_2$ absorption method for $^{14}C$ analysis was developed and introduced to KAERI for the evaluation of domestic groundwater system. The results of $^{14}C$ in groundwater would be usefully applied to hydrogeological studies such as the well understanding of groundwater flow system in depth. The reliability of our $^{14}C$ data was confirmed by inter-comparison with the qualified international isotope laboratory.

• Korean Journal of Environmental Agriculture
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• v.9 no.1
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• pp.9-13
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• 1990

The dissipation of insecticide fenitrothion(O,O-dimethyl O-4-nitro-m-tolyl phosphorothioate), fungicide IBP(S-benzyl O, O-diisopropyl phosphorothioate), and herbicide butachlor(N-butozymethyl-2-chloro-2', 6'-diethylacetanilide) in flooded soil planted with rice plants was investigated in outdoor pot conditions. The half lives of IBP, butachlor and fenitrothion in the flooding water treated with IBP at 98g, butachlor at 352.8g, and fenitrothion at 100g ai/10a, were 3.6, 1.7 and within 1 day, respectively. The concentration of fenitrothion at 5 days after application was found to be less than 0.0lppm. In the case of IBP and butachlor after 20 days, the concentration was 0.025 and 0.004ppm, respectively. The concentration of fenitrothion, IBP, butachlor in a soil depth of 0-3cm was 0.07, 1.45 and 3.37ppm on the 3rd day after application, and below 0.05, 0.18, 0.39ppm after 7 days, respectively. However, 27 days after application concentration of IBP and butachlor at 0-5cm soil depth resulted in 0.04 and 0.05ppm, respectively. The disappearance of pesticides was remarkably rapid, compared to those in the some soil under the laboratory conditions. Differences in the concentration of IBP in different soil profiles were few, but amounts of butachlor were remarkably higher at 0-2cm soil depth than below 2cm soil depth.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.10
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• pp.1825-1832
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• 2000

Column experiments were conducted by using soil columns, to investigate feasibility and efficiency of in-situ ozone enhanced remediation for diesel-contaminated soil. The injection of gaseous ozone into soil column revealed the enhanced decomposition of ozone due to the catalytic reaction between ozone and metal (e.g., Fe, Mn etc.) oxides as evidenced by as much as 25 times shorter half-life of ozone in a sand packed column than in a glass beads packed column. Substantial retardation in the transport of and the consumption of ozone were observed in the diesel contaminated field soil and sand packed columns. After 16 hrs ozonation, 80% of the initial mass of diesel (as diesel range organic) concentration of $800{\pm}50mg/kg$, was removed under the conditions of the flow rate of 50mL/min and $6mg-O_3/min$. Whereas, less than 30% of diesel was removed in the case of air injection. Analysis of the residual TPH(total petroleum hydrocarbon) and selected 8 aliphatics of diesel compounds in the inlet and the outlet of the column confirmed that diesel nonselectively reacted with ozone and then shifted to lower carbon numbered molecules. Water content also was found to be an important parameter in employing ozone to the hydrocarbon-contaminated soil.

• Journal of Radiation Protection and Research
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• v.28 no.4
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• pp.271-279
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• 2003

Soil blocks were taken into culture boxes from 12 paddy fields within 5 km radii of Yonggwang and Ulchin NPPs and $^{90}Sr$ was applied to the surface water at a pre-transplanting stage and $1{\sim}2$ days before the start of heading. Following the pre-transplanting application, transfer factors were investigated for $2{\sim}4$ years. In the year of application, transfer factors $(m^2\;kg^{-1}-dry)\;of\;^{90}Sr$ applied before transplanting, showing no regionally distinguishable trend, varied with soils by a factor of about 2 with averages of $2.6{\times}10^{-4}$ for hulled seeds and $1.3{\times}10^{-2}$ for straw Transfer factors of $^{90}Sr$ applied shortly before heading were about 2 times greater than those applied before transplanting. Transfer factors tended to decrease with increasing soil pH and exchangeable Ca. Generic values of $^{90}Sr$ transfer factors in the year of deposition were proposed for the Korean paddy fields. In the second year compared with the first year, the transfer factor decreased more in Ulchin soils, which were on the whole higher in sand content, than in Yonggwang soils. For Yonggwang soils as a whole, the annual decrease in transfer factor was well described by an exponential equation with a half-life of about 2.2 years.

• Journal of Applied Biological Chemistry
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• v.60 no.4
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• pp.343-349
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• 2017

This study was conducted to investigate the residual level and the amount of transfer to lettuce grown in field condition treated with the 5-methyl-1,2,4-triazolo[3,4-b][1,3]benzothiazole (Azoxystrobin). The field trials on lettuce were carried out at two different green houses located in Gwangju (Field 1) and Yongin (Field 2). Soil and lettuce samples were collected at different days after soil treatment of azoxystrobin with two different concentrations, respectively. Average recoveries for azoxystrobin ranged from 86.9 to 113.6% from soil and lettuce with the variation coefficient of 0.1-4.6%. The initial concentrations of azoxystrobin in Gwangju soil were 9.20, 11.00 mg/kg and decreased to 1.36, 2.70 mg/kg at 43 DAT (days after treatment) in field 1, while 1.06, 2.23 mg/kg decreased to 0.20 and 0.67 mg/kg at 36 DAT in field 2, respectively. The half-lives of azoxystrobin were about 19.4 and 23.3 days for the low and high concentration of azoxystrobin treated soils in field 1 and 11.5 and 17.8 days in field 2 soils, respectively. Residue levels of azoxystrobin in lettuce were not detected in filed 1 and field 2 soils, respectively.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.3
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• pp.181-188
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• 2004

The contaminative influence of beef due to the inhalation of air and the ingestion of soil of livestock, both of which are dealt with as minor contaminative pathways in most radioecological models but may not be neglected, was comprehensively investigated with the improvement of the Korean food chain model DYNACON. As the results, it was found that both pathways can not be neglected at all in the contamination of beef in the case of an accidental release during the non-grazing period of livestock. The ingestion of soil was more influential in the contamination of beef than the inhalation of air over most time following an release. If precipitation is encountered during an accidental release, contaminative influence due to the ingestion of soil was far greater compared with the cases of no precipitation. This fact was more distinct for a long-lived radionuclide $^{l37}Cs$ than a short-lived radionuclide $^{131}I$ (elemental iodine). Compared with the results for milk performed prior to this study, the contaminative pathways due to the inhalation of air and the ingestion of soil were more important in beef because of longer biological half-lives. On the other hand, in the case of an accidental release during the grazing period of livestock, radioactive contamination due to the ingestion of pasture was dominant irrespective of the existence of precipitation during an accidental release. It means that contaminative influence due to the inhalation of air and the ingestion of soil is negligible, like the cases of milk.

• Korean Journal of Environmental Agriculture
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• v.14 no.3
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• pp.302-311
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• 1995

Benfuresate or oxolinic acid, as an experimental pesticide, was applied to the different textural paddy or upland soil respectively under the field condition and the residual concentrations were determined. Six kinetic models were employed to characterize the best-fit kinetic model describing the residual pattern of benfuresate or oxolinic acid and the $t\frac{1}{2}$ estimated from each model was comparatively assessed. All of the six models explained significantly the residual patterns of the pesticides but the empirical models such as PF, EL, and PB were not recommendable for the $t\frac{1}{2}$ estimation. Among theoretical models, the residual patterns were followed in the orders of the second-order(SO)>first-order(FO)>zero-order(ZO) kinetics, judging from the size and significance of coefficient of determination and standard error. However, the multiple FO model, consisting of the fast and slow decomposition steps, was better than the single FO model for the residual pattern and the $r^2$ in this case became similar to that of SO kinetic model. Thus the multiple FO and SO models were represented as the best fit model of the experimental pesticide. The $t\frac{1}{2}$ of benfuresate estimated from the single FO kinetic model in Weolgog and Cheongwon series was 49 and 63 days, respectively, which were 20 and 13% longer than the respective $t\frac{1}{2}$ from the SO kinetic model. The $t\frac{1}{2}$ of oxolinic acid from the FO model in Yonggye and Ihyeon series were 87 and 51% longer than those from the SO kinetic model, respectively. These results demonstrated that the best-fit model representing the residual pattern of a pesticide and the resultant $t\frac{1}{2}$ might be variable with the kinds of pesticides and the environmental conditions. Therefore it is recommended that the half-life of a pesticide be assessed from the best-fit model rather than from the FO kinetic model uniformly.