연작으로 인한 토양잔류 Procymidone의 비의도적 후작물 흡수이행

곽세연 ( Se-yeon Kwak ),이상협 ( Sang-hyeob Lee ),( Aniruddha Sarker ),김효영 ( Hyo-young Kim ),신병곤 ( Byung-gon Shin ),김장억 ( Jang-eok Kim ) 한국환경농학회 2021 한국환경농학회지 Vol.40 No.3

BACKGROUND: Pesticides can persist in soil due to multiannual uses. To decrease the concerns for potential carry-over of such residues from treated soil during preceding crop cultivation to non-target crops grown in rotation, an uptake study of procymidone was conducted under the actual cultivation conditions in Korea. METHODS AND RESULTS: Procymidone was sprayed twice by foliar application with recommended and double dose according to the safe use guidelines for Korean cabbage up to 14 days before harvest. Arable land was kept fallow for 4 days after harvesting Korean cabbage, and spinach was cultivated as a succeeding crop. Initial residues in soil were 5.670-14.175 mg/kg that were degraded to 3.098-4.555 mg/kg until harvest of Korean cabbage, and then persisted at 1.026-1.300 mg/kg by spinach harvest. Procymidone residues in edible part of succeeding crops from soil uptake were in range of 0.020-0.048 mg/kg for recommended dose and 0.055-0.116 mg/kg for double dose. Root concentration factor (RCF) values of procymidone at different concentration ranged from 0.053 to 0.123, and translocation factor (TF) ranged from 0.176 to 0.768 for spinach. The value of TF was higher than RCF, indicating that the capability of translocation to shoot was relatively higher than that of root uptake and accumulation. CONCLUSION: Procymidone applied on Korean cabbage can be carried-over to spinach and detected at a level similar to MRL (0.05T mg/kg). Therefore, this study suggests a follow-up study for establishment of plant back interval (PBI) of succeeding crops reflecting the actual agricultural conditions as this study.

전작물 재배를 위해 토양에 혼화처리된 Ethoprophos의 후작물 흡수이행

곽세연 ( Se-yeon Kwak ),이상협 ( Sang-hyeob Lee ),김효영 ( Hyo-young Kim ),신병곤 ( Byung-gon Shin ),김장억 ( Jang-eok Kim ) 한국환경농학회 2021 한국환경농학회지 Vol.40 No.2

BACKGROUND: Unintentional residual pesticide in soil derived from preceding crops and the transfer to succeeding crops was considered a critical barrier for positive list system (PLS). Thus, an uncertain risk is predicted for ethoprophos applied at cultivation of preceding crop (Korean cabbage) to succeeding crop (spinach). METHODS AND RESULTS: Ethoprophos was treated on soil following the recommended dose and 5 times dose according to the safe use guidelines for Korean cabbage after seeding. On the 4 days after harvesting of preceding crop, spinach was sowed. The initial residual amounts of ethoprophos on soil (7.081-19.493 mg/kg) were decreased to 3.832-7.218 mg/kg until the harvest of Korean cabbage, and then finally decreased to 0.011-0.079 mg/kg after spinach cultivation. The uptake rates of ethoprophos from soil by Korean cabbage were 0.01-0.03% and distributed to root (0.150-0.903 mg/kg) and shoot (0.021-0.151 mg/kg), respectively. The residual amounts of uptake and translocation from preceding crop cultivated soil to spinach edible part were found to be below LOQ. CONCLUSION: The plant back internal (PBI) for ethoprophos is not recommended during sequential cultivation of leafy vegetables, since the residual amounts of ethoprophos in spinach were less than MRL (0.02 mg/kg).

살충제 Sulfoxaflor 및 대사체들의 토양 잔류 특성

곽세연(Se-Yeon Kwak),강자군(Ja-Gun Kang),이상협(Sang-Hyeob Lee),남애지(Ae-Ji Nam),이동주(Dong-Ju Lee),허예진(Ye-Jin Heo),김장억(Jang-Eok Kim) 한국농약과학회 2020 농약과학회지 Vol.24 No.3

In order to understand the behavior of the insecticide sulfoxaflor and its metabolites in the soil, the residual patterns, adsorption and desorption properties, and degree of reduction in soil were investigated. To study the role of soil microbes on residual pattern of sulfoxaflor in soil, as the results of the biological half-life of sterilized and non-sterilized soil, it was calculated in the range of 69.3-138.6 days in sterilized soil and 16.5-19.3 days in non-sterilized soil. Sulfoxaflor and its metabolites were found to be higher in the soil with organic matter (sulfoxaflor and X-1 : 99%, X-2 : 98%), and lower amount of tested chemical were found in the soil without organic matter (sulfoxaflor : 76%, X-1 : 79%, X-2 : 67%). Thus, the adsorption of sulfoxaflor and metabolites was affected by soil organic matter. However, the desorption rate of sulfoxaflor was high regardless of the presence or absence of soil organic matter. The results of Fenton reaction to reduce residual sulfoxaflor and its metabolites in the soil was as followed. When Fe<SUP>2+</SUP> (ferrous) was treated, the degradation rate was 2.4% for sulfoxaflor, and 15.7-49.2% for metabolites, which was higher than that of 1.3% of sulfoxaflor and 1.9-9.8% of metabolites when treated with Fe3+ (ferric). Additionally, the reaction kinetics was accelerated when H₂O₂, UV, and persulfate were treated together (with Fe<SUP>2+</SUP> : 40.2-100.0%> with Fe<SUP>3+</SUP> : 1.2-100.0%) and effective degradation has been achieved up to 100%.

살충제 Dinotefuran의 무에 대한 흡수이행 및 잔류 양상

곽세연(Se-Yeon Kwak),황정인(Jeong-In Hwang),이상협(Sang-Hyeob Lee),강민수(Min-Su Kang),류준상(Jun-Sang Ryu),강자군(Ja-Gun Kang),홍성현(Sung-Hyeon Hong),유오종(Oh-Jong You),김장억(Jang-Eok Kim) 한국농약과학회 2017 농약과학회지 Vol.21 No.3

The residual amounts of dinotefuran (DIN) applied to cultivated soil and radish leaf were investigated to assess uptake and residual patterns of DIN through the root and leaf. Recoveries for residual analysis of pesticides spiked with two different concentration on the radish root, leaf and soils were 85.5-104.9%. The degradation half-life of DIN in soils treated with 2.01 and 9.35 mg/kg of initial residues were 6.2-8.9 days and showed rapid degradation patterns. When analyzed radish harvested every 10 days from 40 to 70 days which were cultivated in DIN treated soil, the uptake rates from soil to whole radish by root were 4.9 to 16.7%. Root uptake amounts of DIN were 0.020-0.057 mg/kg for low (2.01 mg/kg) treatment and 0.066-0.256 mg/kg for high (9.35 mg/kg) treatment, respectively. Absorbed DIN were more distributed in the leaf than root at the early stage of harvesting, but the distribution of DIN in root tended to increase as time passage. On the other hand, as a result of foliar spraying with the standard amount, 2 times and 5 times according to the safe use standard of DIN, the initial residual amounts of DIN in leaf were 0.397, 0.788 and 1.172 mg/kg for each treatment level. And leaf uptake rates from leaf to root during experimental period were 1.7 to 7.1%. These results will be useful for determining management criteria for soil persisted pesticides.

토양에 잔류된 Endosulfan의 감자에 대한 흡수 및 잔류특성

곽세연 ( Se-yeon Kwak ),황정인 ( Jeong-in Hwang ),이상협 ( Sang-hyeob Lee ),류준상 ( Jun-sang Ryu ),홍성현 ( Seong-hyeon Hong ),강민수 ( Min-su Kang ),정혜현 ( Hye-hyun Jung ),강자군 ( Ja-gun Kangand ),김장억 ( Jang-eok Kim ) 한국환경농학회 2016 한국환경농학회 학술대회집 Vol.2016 No.-

There have been reports that an organochlorine insecticide endosulfan (ED) consisted of α- and β-isomers is consistently detected in Korean arable soils due to its long-term persistency, and a major metabolite ED-sulfate produced with its degradation is as toxic and persistent as the isomers. This study assessed the uptake amount of ED isomers and ED-sulfate by potato grown on ED-treated soils with concentrations of 2 and 10 mg/kg. Soil samples were collected at 0, 3, 7, 14, 21, 30, 60, and 90 d after planting of potato, and residual amounts of total ED calculated as a sum of isomers and metabolite were halved after 62.4 and 99.5 d in 2 and 10 mg/kg-treated soils, respectively. Potato plants sampled after growth of 60 to 90 d were divided into root, shoot and tuber parts. Most of ED isomers were present in root of potato with mean distribution rate of 57.1%, while ED-sulfate was the greatest in shoot part, with mean distribution rate of 64.5%. The uptake amounts of total ED in tuber of potato were the highest after 60 d of growth, showing concentrations of 0.49-2.34 mg/kg for both treatments. In addition, the distribution rate of ED isomers in potato tubers were 2 times higher than that of ED-sulfate. In Korea, there is no maximum residue limit (MRL) for ED in potato, while Codex and EU has such MRL as 0.05 mg/kg. At the final hervest day of 90 d, uptake amounts (0.2-1.3 mg/kg) of total ED in tuber of potato exceeded the MRL. Therefore, if the potato is cultivated in contaminated soils with concentrations of >2 mg/kg, its final products may be unsafe with exceeding MRL. The results in this study may provide the useful information to establish the management guideline of ED in soil for producing the safe agricultural products.

살충제 Ethoprophos의 비의도적 오염에 따른 후작물 흡수이행

곽세연 ( Se-yeon Kwak ),이상협 ( Sang-hyeob Lee ),이동주 ( Dong-ju Lee ),허예진 ( Ye-jin Heo ),최재원 ( Jae-won Choi ),오지은 ( Ji-eun Oh ),김장억 ( Jang-eok Kim ) 한국환경농학회 2021 한국환경농학회 학술대회집 Vol.2021 No.-

With the implementation of the PLS, the issue of unintentional contamination in soil and the transfer of pesticides used in cultivation of preceding crops to succeeding crop was raised. To assess the safety of succeeding crop, this study was investigated the uptake and translocation of ethoprophos sprayed on Korean cabbage cultivation soil as preceding crop to succeeding crop “spinach”. Ethoprophos(5% GR) was treated on soil with the recommended dose and 5 times of that dose according to the safe use guidelines of Korean cabbage after seeding. On the 4 days after harvesting of preceding crop, spinach was sowed and collected 5 times with 3 days interval during harvesting period. The initial residual amounts of ethoprophos in soil was 7.081-19.493 mg/kg and degraded by 3.832-7.218 mg/kg until the harvest of Korean cabbage, and then finally degraded by 0.011-0.079 mg/kg after spinach cultivation. The uptake rates of ethoprophos from soil by Korean cabbage were 0.01-0.03% and distributed root(0.150-0.903 mg/kg) and shoot(0.021-0.151 mg/kg), respectively. The residual amounts of uptake and translocation from preceding crop cultivated soil to spinach edible part were found to be below LOQ. Since the residual amount of ethoprophos in spinach was less than MRL(0.02 mg/kg) with no concern for the uptake and transfer of succeeding crop. Therefore, it is not necessary to consider the plant back internal(PBI) on ethoprophos for sequential cultivation of leafy vegetables.

토양 중 살충제 Dinotefuran과 대사체의 분해양상

곽세연 ( Se-yeon Kwak ),이상협 ( Sang-hyeob Lee ),류준상 ( Jun-sang Ryu ),홍성현 ( Seong-hyeon Hong ),강자군 ( Ja-gun Kang ),김장억 ( Jang-eok Kim ) 한국환경농학회 2017 한국환경농학회 학술대회집 Vol.2017 No.-

This study was performed to investigate microbial degradation patterns of dinotefuran(DIN) and its metabolites(DN, UF and MNG) in soils under laboratory conditions based on result of field trials. In the field trials, DIN was treated with concentration of 2 mg/kg on the radish cultivated and non-cultivated soil before seeding radish. The initial residue amounts of DIN was 2.01 mg/kg and decreased to below limit of quantitaion (LOQ) at 60 days after treatement which result in the formation of UF upto 0.21 mg/kg for radish cultivated soils. While initial residues of DIN in non-cultivated soils was 2.00 mg/kg and steadily decreased 84% with 0.32 mg/kg at 70 day. UF as well as DN were produced after 50 days in non-cultivated soil. DIN was spiked with 2 mg/kg in each of 20 g sterilized and unsterilized soil and analysed at 0, 1, 3, 7, 14, 21, 30, 45 and 60 day after treatment under laboratory conditions. The residue amounts of DIN at 0 days were 1.97 mg/kg for sterilized soil and 1.99 mg/kg for unsterilized soil and both of them were decreased with a similar decline curve by 45 and 54% at end of experiment day, respectively. The degradation rate of DIN in unsterilized soil was higher than that of sterilized soil, which means mircroorganism was one of the factors that affected the degradation of DIN in soils. As the degradation of DIN by microorganisms in unsterilized soil, DN and UF were detected respectively upto 0.01 and 0.03 mg/kg and MNG was not detect.

소면적 재배 작물 중 살충제 Fluxametamide의 잔류양상

최재원 ( Jae-won Choi ),곽세연 ( Se-yeon Kwak ),이상협 ( Sang-hyeob Lee ),오지은 ( Ji-eun Oh ),김태화 ( Tae-hwa Kim ),김장억 ( Jang-eok Kim ) 한국환경농학회 2022 한국환경농학회 학술대회집 Vol.2022 No.-

Minor crops have limited registered maximum residue limits (MRL) and safety guidelines for pesticides than other major crops because of low economics. However, a positive list system (PLS) was implemented to regulate unregistered pesticides in Korea in 2019, and a recent survey in October 2021 noticed the increased violation rate of Fluxametamide (FM) on crops. In this study, a field experiment was conducted for FM under the greenhouse conditions on two minor crops such as ssam cabbage (SC) and water dropwort (WD) to assess residue patterns and suggest safety guidelines. FM (9% EC) was sprayed 2 times intervals 7 days by foliar application on the crops before harvest (0 days). According to the residue of FM on SC and WD ranged from 0.70∼2.33, and 2.27∼3.91 mg/kg, and the half-lives were 8.41 and 20.69 days, respectively. Whereas, the FM residue on SC did not exceed MRL (5.0 mg/kg), however on WD was exceeded (2.0 mg/kg), therefore it is necessary to suggest a new MRL based on the residue patterns. To validate the recommended MRL (10.0 mg/kg) for WD, theoretical maximum daily intake (TMDI) was considered with food intake and MRL that was registered for FM on 60 crops. It can be estimated the %ADI of FM, through calculation with acceptable daily intake (ADI) (0.0085 mg/kg b.w/day) of FM, TMDI of FM, and average body weight (66.5 kg). Because the sum of %ADI (38.48%) was not over 80% of the tolerable limit, it can be recommended the MRLs of FM for WD. As a result, at the levels of 3 times the residue, the safety guidelines of SC and WD could be proposed as 7 days before harvest following spray schedule 2 times with 7 days interval that does not exceed the MRL of FM on the crops. The findings of this study could be used as the reference data for the evaluation and establishment of MRL for Fluxametamide in minor crops.

토양잔류 농약의 무 흡수양상 및 토양 안전관리기준 설정

황정인 ( Jeong-in Hwang ),곽세연 ( Se-yeon Kwak ),이상협 ( Sang-hyeob Lee ),강민수 ( Min-su Kang ),류준상 ( Jun-sang Ryu ),강자군 ( Ja-gun Kang ),정혜현 ( Hye-hyeon Jung ),홍성현 ( Sung-hyeon Hong ),김장억 ( Jang-eok Kim ) 한국환경농학회 2016 한국환경농학회지 Vol.35 No.4

BACKGROUND: Uptake patterns of α-, β-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 α- and β-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 (R² 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.

시금치에서 살충제 Etoxazole과 Cartap hydrochloride의 잔류양상

허예진 ( Ye-jin Heo ),곽세연 ( Se-yeon Kwak ),이상협 ( Sang-hyeob Lee ),이동주 ( Dong-ju Lee ),최재원 ( Jae-won Choi ),오지은 ( Ji-eun Oh ),김장억 ( Jang-eok Kim ) 한국환경농학회 2021 한국환경농학회 학술대회집 Vol.2021 No.-

Pesticides help in increased yield of agricultural products by controlling pests, pathogens and weeds, but threaten food safety if used incorrectly. Therefore, it is necessary to establish the ‘safe use standards’ for pesticide application to allow pesticide residues be in safe limit. In this study, residual patterns of etoxazole and cartap hydrochloride were investigated in spinach. Etoxazole (10%, SC) and cartap hydrochloride (50%, SP) were diluted 4,000 and 1,000 times, respectively, and sprayed twice with 7 days interval at 21, 14, 10, 7, 3 and 0 days before harvest. Residual amounts of etoxazole and cartap hydrochloride were analyzed by LC-MS/MS. The recovery test was conducted at two levels (0.01 and 0.1 mg/kg), and the recovery rate was 80.8~112.4% with the standard deviation of ≤ 5.8. For cartap hydrochloride, the residual amounts of nereistoxin were analyzed and converted to calculate total residue. The residue of etoxazole decreased from 1.39 mg/kg to 0.01 mg/kg with the reduction rate 99.3% at 21 days after application. On the other hand, cartap hydrochloride (including converted residual amount of nereistoxin) showed 71.3% reduction from 1.72 mg/kg to 0.49 mg/kg. Etoxazole decreased faster than cartap hydrochloride because cartap hydrochloride is converted to nereistoxin prior to decreasing. As each of the pesticides behaves differently in different plant matrics, it is important to know the residue pattern separately to ensure safe application. Hence, the findings of this study will help to establish the safe use standards for field application as well as MRLs for spinach for these two pesticides.