• The Korean Journal of Pesticide Science
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• v.8 no.3
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• pp.198-209
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• 2004

In order to elucidate the behavior of the fungicide hexaconazole in soil and rice plants, rice plants were grown for 42 days in a microecosystem (pot) containing fresh and 28 day-aged soil residues of $[^{14}C]$hexaconazole. The amount of $^{14}CO_2$ evolved during 28 days of aging was 0.11 % of total $^{14}C$-radioactivity treated and the averaged weekly degradation rate was 0.03%. Mineralization rates for 42 days of rice cultivation on fresh and aged paddy soils were 0.67% of the total $^{14}C$ in case of non-rice planting on aged soil and 1.17% in case of rice planting on aged soil, whereas 1.25% in non-rice planting on fresh soil and 1.72% in case of rice planting on fresh soil, suggesting that the amounts of $^{14}CO_2$ were evolved higher from fresh soils than aged ones and from rice-planting soils than non-planting ones. The amounts of volatiles collected were very low as background levels. Most of $^{14}C$-Radioactivity was remained in soil after 42 days of rice cultivation and $^{14}C$ absorbed through rice roots was distributed more in shoots than roots and translocated into the edge of shoots of rice plants. Amounts of non-extractable $^{14}C$ in soils were higher in rice planted soil than in non-planting soil. The distribution of non-extractable $^{14}C$ was increased in the order of humin>fulvic acid>humic acid. The amounts of $^{14}C$ translocated into rotational crop Chinese cabbage were 2.36 and 3.69% of the total $^{14}C$ in case of rice planted soil containing fresh and aged residues, respectively, suggesting that small amounts of $[^{14}C]$hexaconazole and its metabolite(s) were absorbed and their bound residues were more available than their fresh ones to Chinese cabbage.

• Korean Journal of Environmental Agriculture
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• v.35 no.4
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• pp.278-285
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• 2016

BACKGROUND: Uptake patterns of ${\alpha}$-, ${\beta}$-isomers and sulfate metabolite of endosulfan (ED) by radishes grown in treated soils with ED concentrations of 2 and 10 mg/kg were investigated to establish soil management guidelines for ensuring the safety of radishes from ED residues. METHODS AND RESULTS: All samples of soils and radish plants separated into shoot and root parts were analyzed for ED residues using a gas-chromatography mass spectrophotometer, and the results were used to calculate the bioconcentration factor (BCF), indicating the ratio of ED concentrations between radishes and soils. During the experimental period, uptake and distribution rates of ED-sulfate in radishes were the highest, followed by ${\alpha}$- and ${\beta}$-ED. The BCF values to initial ED concentrations in soils were greater for root parts (0.0077 to 0.2345) than for shoot parts (0.0002 to 0.0429) and used to obtain regression equations by time. Long-term BCFs estimated by the obtained equations ($R^2$ of 0.86 to 1.00) were evaluated with the maximum residue limit (0.1 mg/kg) of ED for radishes, in order to suggest safe management guidelines of ED for radish-cultivating soils. CONCLUSION: Suggested guidelines showed the significant dependency on duration for radish cultivation and exposed concentration of ED in soil.