Current Issue 2022. Vol.41, Iss.4

Orginal Articles

• Remediation of As-contaminated Soil Using Magnetite and Bottom Ash

  Se Jin Oh, Min Woo Kang, Jong Cheol Lee, Hun Ho Lee, Hyun-Seog Roh, Yukwon Jeon, Dong Jin Kim, Sang Soo Lee / Korean Journal of Environmental Agriculture / 2022 / v.41, no.4, 223-229

  https://doi.org/10.5338/KJEA.2022.41.4.27

  Abstract Full-Text PDF

  Abstract

  

  BACKGROUND:

  Mining activities, smelter discharges, and sludges are the major sources of heavy metal contamination to soils. The objective of this study was to determine the efficiency of magnetite and bottom ash derived from coal ash in remediating As-contaminated soil.

  METHODS AND RESULTS:

  An incubation experiment was conducted for 10 weeks. Magnetite and bottom ash at different rates and ratios were applied to each plastic bottle repacked with 1,000 g of dried As-contaminated soil. After 3-weeks of incubation, the concentrations of available As were measured by using Mehlich-3, SBET, and sequential extraction methods. All of the subjected soil amendments resulted in significant decreases in available As concentration compared to the controls. The addition of magnetite at the highest rate was the best to stabilize As in the soils; however, the values of As concentration varied with the extraction methods.

  CONCLUSION(S):

  To ensure the stabilization accuracy of heavy metals in soil, both single and sequential extractions are recommended. The magnetite derived from fly coal ash can also be applicable as a heavy metal stabilizer for the As-contaminated soil.

• Reducing the Effect of Ammonia Emissions from Paddy and Upland Soil with Deep Placement of Nitrogen Fertilizers

  Sung-Chang Hong, Min-Wook Kim, Jin-Ho Kim / Korean Journal of Environmental Agriculture / 2022 / v.41, no.4, 230-235

  https://doi.org/10.5338/KJEA.2022.41.4.28

  Abstract Full-Text PDF

  Abstract

  

  BACKGROUND:

  Ammonia gas emitted from nitrogen fertilizers applied in agricultural land is an environmental pollutant that catalyzes the formation of fine particulate matter (PM2.5). A significant portion (12-18%) of nitrogen fertilizer input for crop cultivation is emitted to the atmosphere as ammonia gas, a loss form of nitrogen fertilizer in agricultural land. The widely practiced method for fertilizer use in agricultural fields involves spraying the fertilizers on the surface of farmlands and mixing those with the soils through such means as rotary work. To test the potential reduction of ammonia emission by nitrogen fertilizers from the soil surface, we have added N, P, and K at 2 g each to the glass greenhouse soil, and the ammonia emission was analyzed.

  METHODS AND RESULTS:

  The treatment consisted of non-fertilization, surface spray (conventional fertilization), and soil depth spray at 10, 15, 20, 25, and 30 cm. Ammonia was collected using a self-manufactured vertical wind tunnel chamber, and it was quantified by the indophenol-blue method. As a result of analyzing ammonia emission after fertilizer treatments by soil depth, ammonia was emitted by the surface spray treatment immediately after spraying the fertilizer in the paddy soil, with no ammonia emission occurring at a soil depth of 10 cm to 30 cm. In the upland soil, ammonia was emitted by the surface spray treatment after 2 days of treatment, and there was no ammonia emission at a soil depth of 15 cm to 30 cm. Lettuce and Chinese cabbage treated with fertilizer at depths of 20 cm and 30 cm showed increases of fresh weight and nutrient and potassium contents.

  CONCLUSION(S):

  In conclusion, rather than the current fertilization method of spraying and mixing the fertilizers on the soil surface, deep placement of the nitrogen fertilizer in the soil at 10 cm or more in paddy fields and 15 cm or more in upland fields was considered as a better fertilization method to reduce ammonia emission.

• Effects of Liquid Fertilizer of Application from Rendered Livestock Carcass Residues on Maize Cultivation

  Jae-Hyuk Park, Se-Won Kang, Jin-Ju Yun, Han-Na Cho, Seung-Gyu Lee, So-Hui Kim, Seong-Woo Choi, Ju-Sik Cho / Korean Journal of Environmental Agriculture / 2022 / v.41, no.4, 236-244

  https://doi.org/10.5338/KJEA.2022.41.4.29

  Abstract Full-Text PDF

  Abstract

  

  BACKGROUND:

  Liquid fertilizers can provide nutrients to crops effectively and quickly. Amino acid liquid fertilizers produced by decomposing the residues of rendered livestock carcasses are expected to be effective in improving the productivity and quality of crops.

  METHODS AND RESULTS:

  The treatment conditions for maize cultivation were control (Cn), inorganic fertilizer (IF), inorganic fertilizer and rendering residue liquid fertilizer (IF+RALF), compost (CP), compost and rendering residue liquid fertilizer (CP+RALF). Crop productivity, sugar content, and nutrient uptake were investigated after maize harvest in the field applied with liquid fertilizers. Maize yields ranged from 87.6-158 g/plant, and the yield increased by 7.9% and 12.9% in IF+RALF and CP+RALF than in IF and CP, respectively. The maize sugar content increased in the range of 0.1-0.5 brix % by rendering residue liquid fertilizer (RALF) fertilization, and the sugar content was the highest in CP+RALF. There was no significant change in soil chemical properties of the soil due to liquid fertilizer treatment.

  CONCLUSION(S):

  RALF increased yield and sugar content in maize cultivation, and fertilization with organic fertilizers was more effective for maize cultivation than inorganic fertilizers. Residues of rendered livestock carcass can be recycled as amino acid fertilizers, which can be effectively used for crop production and quality improvement.

• Artificial Light Sources Influence Cherry Tomato (Lycopersicon esculentum var. cv. ‘CF Jelly’) Growth and Development

  Jeong-Wook Heo, Jeong-Hyun Baek, Young-Sin Hong / Korean Journal of Environmental Agriculture / 2022 / v.41, no.4, 245-251

  https://doi.org/10.5338/KJEA.2022.41.4.30

  Abstract Full-Text PDF

  Abstract

  

  BACKGROUND:

  Selection an suitable light source is essential in the year-round production of horticultural crops in closed production systems such as plant factory with controlled environments. This study was investigated to confirm the effects of artificial light sources on growth of cherry tomato‘CF Jelly’(Lycopersicon esculentum var.) under high-pressure sodium lamps (HPS), metal-halide lamps (MH), and LEDs.

  METHODS AND RESULTS:

  Light intensity of the light sources was controlled at 220±30 μmol/m²/s with 12 hrs of photoperiod for a day. Flower development was significantly faster in HPS and MH treatments compared to the LEDs. There was no significant difference between the leaf number and leaf shape under the HPS and MH treatments. Reproductive growth of cherry tomato was significantly promoted by the LEDs treatment of blue plus red lights. Fruit yield per plant also increased under the LEDs compared to the others.

  CONCLUSION(S):

  Growth, flowering, and fruit setting of the cherry tomato were accomplished by the artificial lights under plant factory conditions. The HPS treatment showed negative effect on fruit quality in terms of blossom-end rot incidence compared to the LEDs or MH treatment. Effect of the LEDs on promotion of fruit weight and yield was also proved. Additional research should be carried out for improving sugar metabolism or decreasing disease in the fruits under plant factory system using only artificial lights.

• Adsorption Effect of Heavy Metals (Zn, Ni, Cd, Cu) in Aqueous Solution Using Bottom Ash of Biomass Power Plant

  So-Hui Kim, Seung-Gyu Lee, Jin-Ju Yun, Jae-Hyuk Park, Se-Won Kang, Ju-Sik Cho / Korean Journal of Environmental Agriculture / 2022 / v.41, no.4, 252-260

  https://doi.org/10.5338/KJEA.2022.41.4.31

  Abstract Full-Text PDF

  Abstract

  

  BACKGROUND:

  The number of biomass power plants is increasing around the world and the amount of wastes from power plants is expected to increase. But the bottom ash (BA) is not recycled and has been dumped in landfill. This study was conducted to find out functional groups of BA and adsorption rate of heavy metals on BA.

  METHODS AND RESULTS:

  The BA was dried in oven at 105℃ for 24 hours, and characterized by analyzing the chemistry, functional group, and surface area. The adsorption rates of heavy metals on BA were evaluated by different concentration, time, and pH. As a result, the adsorption amount of the heavy metals was high in the order of Zn> Cu> Cd> Ni and the removal rates of Zn, Cu, Cd, and Ni by BA was 49.75, 30.20, 32.46, and 36.10%, respectively. Also, the maximum adsorption capacity of BA was different by the heavy metal in the environmental conditions, and it was suggested that the isotherms for Zn, Ni, Cd, and Cu were adequate to Langmuir model.

  CONCLUSION(S):

  It is suggested that it would be effective to remove heavy metals in aqueous solution by using BA from biomass power plants in South Korea.

• Establishment of Acceptable Daily Intakes (ADIs) and Risk Assessment for Ephedrine, Menichlopholan, Anacolin, and Etisazole Hydrochloride

  Min Ji Kim, Ji Young Kim, Jang Duck Choi, Guiim Moon / Korean Journal of Environmental Agriculture / 2022 / v.41, no.4, 261-275

  https://doi.org/10.5338/KJEA.2022.41.4.32

  Abstract Full-Text PDF

  Abstract

  

  BACKGROUND:

  Prior to implementing a positive list system (PLS), there is a need to establish acceptable daily intake (ADI) and maximum residue limit (MRL) for veterinary drugs that have been approved a few decades ago in South Korea. On top of that, chronic dietary exposure assessment of veterinary drug residues should be performed to determine whether the use of these veterinary drugs would cause health concerns or not.

  METHODS AND RESULTS:

  To establish the ADI, the relevant toxicological data were collected from evaluation reports issued by international organizations. A slightly modified global estimate of chronic dietary exposure (GECDE) model was employed in the exposure assessment owing to the limited residual data. Therefore, only the ADI of ephedrine was established due to insufficient data for the other veterinary drugs. Thus, instead of ADI, the threshold of toxicological concern (TTC) value was used for the other drugs. Lastly, the hazard index (HI) was calculated, except for etizazole hydrochloride, due to the potential of mutagenicity.

  CONCLUSION(S):

  The HI values of ephedrine, menichlopholan, and anacolin were found to be as high as 6.4%, suggesting that chronic dietary exposure to the residues from these uses was unlikely to be a public health concern. Further research for exposure assessment of veterinary drug residues should be performed using up-todate Korean national health and nutrition examination survey (KNHANES) food consumption data. In addition, all relevant available data sources should be utilized for identifying the potentials of toxicity.

• Sorption Characteristics of Tetracycline in Water on Microplastics

  Yu Jin Seo, Ruri Lee, Eun Hea Jho / Korean Journal of Environmental Agriculture / 2022 / v.41, no.4, 276-281

  https://doi.org/10.5338/KJEA.2022.41.4.33

  Abstract Full-Text PDF

  Abstract

  

  BACKGROUND:

  Plastics that are used in our daily lives largely end up in the environment. In agricultural environments, plastic wastes and microplastics can be found due to the uses and improper management of plastic products (e.g., vinyl greenhouses and mulching vinyl). Microplastics can also interact with contaminants in the agricultural environment. Therefore, this study was set to investigate the sorption characteristics of tetracycline, one of widely used antibiotics, on microplastics.

  METHODS AND RESULTS:

  The sorption tests were carried out with the tetracycline solutions (0-30 mg L^-1) and microplastic films prepared from low density polyethylene (LDPE) and polyvinyl chloride (PVC). The residual tetracycline concentrations were analyzed and fitted to the Freundlich and Langmuir isotherm models. The tetracycline sorption patterns on LDPE and PVC films were described better with the Freundlich isotherm model than the Langmuir isotherm model. The isotherm model parameters suggested that the maximum sorption amount of tetracyline was greater for PVC, while the sorption affinity was greater for LDPE.

  CONCLUSION(S):

  Different types of microplastics can have different sorption characteristics of tetracycline. Therefore, there is a need for continuous research on the interaction of various types and shapes of microplastics and contaminants in the environment.

• Application Effect of Chlorella Fusca CHK0059 as a Biofertilizer for Strawberry Cultivation

  Young-Nam Kim, Jun Hyeok Choi, Song Yeob Kim, Hyeonji Choe, Yerim Shin, Young-Eun Yoon, Keum-Ah Lee, Min-Jeong Kim, Yong Bok Lee / Korean Journal of Environmental Agriculture / 2022 / v.41, no.4, 282-287

  https://doi.org/10.5338/KJEA.2022.41.4.34

  Abstract Full-Text PDF

  Abstract

  

  BACKGROUND:

  Green algae (Chlorella spp.) has been widely used as a biofertilizer to improve the crop yield and quality. However, available information is not enough to verify the mechanism of green algae’s beneficial impact on strawberry. This study was conducted to investigate the effect of Chlorella fusca CHK005 application on the growth and nutrient status of strawberry plant and fruit characteristics.

  METHODS AND RESULTS:

  A total of 800 seedlings of strawberry variety ‘Kuemsil’ were planted. Once a week, C. fusca culture solution (1.0 × 10⁷ cells mL^-1) was applied into soil via irrigation in four different concentrations: no application (control), 1/1000 times (× 0.5), 1/500 times (× 1), and 1/250 times (× 2). Result showed that growth of strawberry plant was enhanced by Chlorella application and the highest impact on fresh weight (FW) and chlorophyll content of the plants were observed in × 2 treatment, followed by × 1, × 0.5, and control treatments. The phosphorus (P) concentration in the plant was significantly higher in × 1 and × 2 treatments compared to control. In case of fruit quality, sugar content (°Brix), hardness, and FW were lowest in control, but these values increased as application levels of Chlorella were higher. Also, P and K contents in the fruits increased with increasing the application levels and significant correlation between P content and oBrix in the fruits was found.

  CONCLUSION(S):

  Overall, Chlorella application seemed to improve plant growth and fruit quality by increasing the utilization efficiency of P and K in strawberries.

• Multi-class, Multi-residue Analysis of 59 Veterinary Drugs in Livestock Products for Screening and Quantification Using Liquid Chromatography-tandem Mass Spectrometry

  Yu Ra Kim, Sun Young Park, Tae Ho Lee, Ji Young Kim, Jang-Duck Choi, Guiim Moon / Korean Journal of Environmental Agriculture / 2022 / v.41, no.4, 288-309

  https://doi.org/10.5338/KJEA.2022.41.4.35

  Abstract Full-Text PDF

  Abstract

  

  BACKGROUND:

  The objective of this study was to develop a comprehensive and simple method for the simultaneous determination of 59 veterinary drug residues in livestock products for safety management.

  METHODS AND RESULTS:

  For sample preparation, we used a modified liquid extraction method, according to which the sample was extracted with 80% acetonitrile followed by incubation at -20℃ for 30 min. After centrifugation, an aliquot of the extract was evaporated to dryness at 40℃ and analyzed using liquid chromatography combined with tandem mass spectrometry. The method was validated at three concentration levels for beef, pork, chicken, egg, and milk in accordance with the Codex Alimentarius Commission/Guidelines 71-2009. Quantitative analysis was performed using a matrix-matched calibration. As a results, at least 52 (77.6%) out of 66 compounds showed the proper method validation results in terms of both recovery of the target compound and coefficient of variation required by Codex guidelines in livestock products. The limit of quantitation of the method ranged from 0.2 to 1119.6 ng g-1 for all matrices.

  CONCLUSION(S):

  This method was accurate, effective, and comprehensive for 59 veterinary drugs determination in livestock products, and can be used to investigate veterinary drugs from different chemical families for safety management in livestock products.

• Effect of Saline Soil and Crop Growth with Bottom Ash from Biomass Power Plant Based Wood Pellet

  So-Hui Kim, Seung-Gyu Lee, Jin-Ju Yun, Jae-Hyuk Park, Se-Won Kang, Ju-Sik Cho / Korean Journal of Environmental Agriculture / 2022 / v.41, no.4, 310-317

  https://doi.org/10.5338/KJEA.2022.41.4.36

  Abstract Full-Text PDF

  Abstract

  

  BACKGROUND:

  The salt in soil interrupts crop growth. Therefore, water resources are used to remove any salt found in the soil. However, water resources have been reduced by global warming; thus, a new study is required into reducing the salt in soil. Recently, the bottom ash (BA) of a biomass power plant was found to be similar to biochar. Hence, it can be used to remove heavy metals and wastewater through the adsorption characteristics of BA. The objective of this study was to evaluate the improvement effects on crop growth in saline soil containing the BA from biomass power plants.

  METHODS AND RESULTS:

  The effect on crop growth in the saline soil supplemented with BA was studied with the crop-planted pots, which were packed by reclaimed greenhouse soils collected from Byolyang, Suncheon. The BA application level was 25, 50, 100, 200, and 400 kg/10a (referred as BA25, BA50, BA100, BA200, and BA400, respectively). The BA increased the fresh weights of the leaf and root, while nitrogen uptake increased by approximately 24-102% and 54-77%, respectively for the lead and root. The phosphorous uptake increased by 38%, although only in the leaf of the lettuce. In the case of soil, BA increased water content, pH, EC, CEC, and NH₄⁺ and the SAR of the soil decreased by 5-15%. The bottom ash increased the contents of Ca²⁺ and Mg²⁺, and fixed the amount of Na⁺.

  CONCLUSION(S):

  It was confirmed the bottom ash of a biomass power plant, based on wood pellets, improved crop growth, and increased the nutrient uptake of crops in saline soil. In addition, bottom ash, which has a wide range of porosity and high values of pH and EC, improved properties of the saline soil. However, the BA has a large amount of B, As, and heavy metals. Finally, it may require a study on the safety and contamination of heavy metals contained in the bottom ash, which would be applied in soil for a long time.

• Long-term Elevated Temperature Affects the Growth and Quality of ‘Shiranuhi’ Mandarin Grown in a Green House

  Misun Kim, Young-Eel Moon, Sang Suk Kim, Jaeho Joa, Seok Kyu Yun, YoSup Park / Korean Journal of Environmental Agriculture / 2022 / v.41, no.4, 318-327

  https://doi.org/10.5338/KJEA.2022.41.4.37

  Abstract Full-Text PDF

  Abstract

  

  BACKGROUND:

  The mean annual temperature of the Korean Peninsula will continue to rise due to global warming. ‘Shiranuhi’ mandarin—a late-harvest cultivar —is primarily cultivated in plastic greenhouses where high temperatures cannot be directly avoided. Therefore, growth and fruit quality changes under elevated temperatures must be investigated.

  METHODS AND RESULTS:

  Elevated temperatures were divided into three groups [2℃ (T-I), 4℃ (T-II), and 6℃ (T-III) above the ambient temperature] during the 2019-2020 season. Mean temperatures were 17.1℃, 18.6 ℃, and 20.2℃ in T-I, T-II, and T-III, respectively. The bud bursts in T-II and T-III were earlier than that in T-I at 7 days and 11 days, respectibely. And the full blooms in T-II and T-III were earlier than that in T-I at 11 days and 23 days, respectively. Fruit size significantly increased with increased temperature. The citrus color index in the coloring phase markedly differed across treatments. Further, total soluble solid and acid contents markedly changed with temperature rise but the sugar-to-acid ratio did not. Sucrose content tended to decrease with increase in temperature, but citric acid content remained unaffected.

  CONCLUSION(S):

  Elevated temperature accelerated plant growth and development but delayed rind color development in ‘Shiranuhi’ mandarin. Therefore, rise in ambient temperature by >4.6℃ may negatively affect yield and fruit quality.

• Influence of Summer Pruning Time on Shoot Growth and Fruit Quality of ‘Fuji’/M.9 Apple Tree Damaged by the Low Air Temperature at Flowering Period

  Hun-Joong Kweon, Dong-Hoon Sagong / Korean Journal of Environmental Agriculture / 2022 / v.41, no.4, 328-334

  https://doi.org/10.5338/KJEA.2022.41.4.38

  Abstract Full-Text PDF

  Abstract

  

  BACKGROUND:

  The low temperature at flowering period break the balance between vegetative and reproductive growth of apple tree. Summer pruning has been used to control vegetative growth. So, this study was conducted to investigate the effect of summer pruning time on shoot growth and fruit quality of ‘Fuji’/M.9 apple trees damaged by the low temperature at flowering period.

  METHODS AND RESULTS:

  The following treatments were applied to tree : a) control (no summer pruning), b) pruned 26 June, c) pruned 30 July, d) pruned 28 August, and e) pruned 26 September. The summer pruning significantly increased light penetration and fruit red color by reducing the total shoot growth compared with control. And the summer pruning control the outbreak of apple valsa canker. But the summer pruning at the end of June increased regrowth of shoot and pruning weight compared with the summer pruning at the end of August. The summer pruning at 30 July had the highest fruit weight, but return bloom was the highest in the summer pruning at 28 August.

  CONCLUSION(S):

  These results indicated the optimum summer pruning time of ‘Fuji’/M.9 apple trees damaged by the low temperature at flowering period were the end of August.

• Co-occurrence Analyses of Antibiotic Resistance Genes and Microbial Community in Human and Livestock Animal Feces

  Aprajita Bhandari, Tatsuya Unno, Jiwon Jeong / Korean Journal of Environmental Agriculture / 2022 / v.41, no.4, 335-343

  https://doi.org/10.5338/KJEA.2022.41.4.39

  Abstract Full-Text PDF

  Abstract

  

  BACKGROUND:

  Antibiotics used in animal husbandry for disease prevention and treatment have resulted in the rapid progression of antibiotic resistant bacteria which can be introduced into the environment through livestock feces/manure, disseminating antibiotic resistant genes (ARGs). In this study, fecal samples were collected from the livestock farms located in Jeju Island to investigate the relationship between microbial communities and ARGs.

  METHODS AND RESULTS:

  Illumina MiSeq sequencing was applied to characterize microbial communities within each fecal sample. Using quantitative PCR (qPCR), ten ARGs encoding tetracycline resistance (tetB, tetM), sulfonamide resistance (sul1, sul2), fluoroquinolone resistance (qnrD, qnrS), fluoroquinolone and aminoglycoside resistance (aac(6')-Ib), beta-lactam resistance (bla_TEM, bla_CTX-M), macrolide resistance (ermC), a class 1 integronsintegrase gene (intI1), and a class 2 integrons-integrase gene (intI2) were quantified. The results showed that Firmicutes and Bacteroidetes were dominant in human, cow, horse, and pig groups, while Firmicutes and Actinobacteria were dominant in chicken group. Among ARGs, tetM was detected with the highest number of copies, followed by sul1 and sul2. Most of the genera belonging to Firmicutes showed positive correlations with ARGs and integron genes. There were 97, 34, 31, 25, and 22 genera in chicken, cow, pig, human, and horse respectively which showed positive correlations with ARGs and integron genes. In network analysis, we identified diversity of microbial communities which correlated with ARGs and integron genes.

  CONCLUSION(S):

  In this study, antibiotic resistance patterns in human and livestock fecal samples were identified. The abundance of ARGs and integron genes detected in the samples were associated with the amount of antibiotics commonly used for human and livestocks. We found diverse microbial communities associated with antibiotics resistance genes in different hosts, suggesting that antibiotics resistance can disseminate across environments through various routes. Identifying the routes of ARG dissemination in the environment would be the first step to overcome the challenge of antibiotic resistance in the future.

• Survey of Antibiotic Resistant Bacteria in Ulleungdo, Korea

  Jun Hyung Lee, Hye Won Hong, Dukki Han / Korean Journal of Environmental Agriculture / 2022 / v.41, no.4, 344-354

  https://doi.org/10.5338/KJEA.2022.41.4.40

  Abstract Full-Text PDF

  Abstract

  

  BACKGROUND:

  Although antibiotics have contributed to treatment of bacterial infection, the antibiotic abuse can lead to antibiotic resistant bacteria. Impact of human activities on distribution of antibiotic resistance has been intensively issued and occurrence of antibiotic resistant bacteria in contaminated environments would not be a surprise. Nonetheless, anthropogenic contamination with the dissemination of antibiotic resistance along uncontaminated environments has been less considered. The aim of this study is to investigate antibiotic resistant bacteria across Ulleungdo, known as antibiotic resistance free and anthropogenic pollution free environment in Rep. of Korea.

  METHODS AND RESULTS:

  Antibiotic resistant bacteria in coastal seawater of Ulleungdo were investigated in July 2021. Antibiotic susceptibility test using the disk diffusion method was applied with six drugs according to the Clinical and Laboratory Standards Institute (CLSI) guideline. Total 43 bacterial isolates were tested and 20 isolates among of them showed multidrug resistance. Particularly, the number and ratio of resistant bacteria were relatively high in a densely populated area of Ulleungdo. The bacterial communities were investigated using 16S rRNA gene metabarcoding approach in the coastal seawater and soils of Ulleungdo. In the bacterial communities, Firmicutes were selectively distributed only in seawater, suggesting the possibility of anthropogenic contamination in coastal seawater of Ulleungdo.

  CONCLUSION(S):

  We found antibiotic resistant bacteria in a populated area of Ulleungdo. The occurrence of antibiotic resistant bacteria in Ulleungdo seems to result from the recent anthropogenic impact. Consistent monitoring of antibiotic resistant bacteria in the uncontaminated environment needs to considered for future risk assessment of antibiotics.

• Persistence Study of Thiamethoxam and Its Metabolite in Kiwifruit for Establishment of Import Tolerance

  Il Kyu Cho, Gyeong Hwan Lee, Woo Young Cho, Yun-Su Jeong, Danbi Kim, Kil Yong Kim, Gi-Woo Hyoung, Chul Hong Kim / Korean Journal of Environmental Agriculture / 2022 / v.41, no.4, 355-364

  https://doi.org/10.5338/KJEA.2022.41.4.41

  Abstract Full-Text PDF

  Abstract

  

  BACKGROUND:

  Pre-harvest interval and decline pattern of thiamethoxam were determined in kiwifruit using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The study was carried out to propose import tolerance using OECD maximum residue limit (MRL) calculator for the export promotion of kiwifruit to Taiwan.

  METHODS AND RESULTS:

  The thiamethoxam residue in kiwifruit was determined by using the LC-TriQ-MS/MS with the analytical process to set up the import tolerance under greenhouse conditions for Taiwan. Excellent linearity was observed for all of the analytes with a determination coefficient (R²)≥0.99. The limit of quantification was determined to be 0.01 mg/kg for both thiamethoxam and clothianidin in kiwifruit. Linearity was determined from the co-efficient of determinants (R²) obtained from the seven-point calibration curve. The standard calibration curve showed as follows; 1) Site 1 (Gimje): y = 944,406X + 1,583 (R²=0.9995), 2) Site 2 (Goheung): y = 1,356,205X + 934 (R²=0.9983), and 3) Site 3 (Jangheung): y = 1,239,937X – 3,090 (R²=0.9908). The residue of thiamethoxam in the kiwifruit for three decline trials showed the range of 0.35 to 0.56 mg/kg in site 1 (Gimje), 0.24 to 0.55 mg/kg in site 2 (Goheung), and 0.28 to 0.42 mg/kg in site 3 (Jangheung), respectively. However, clothianidin was not detected in all of the treatments. The maximum residual amounts (decline) in the samples, sprayed according to the safe-use standard for thiamethoxam 10% WG in kiwifruit (30 days before harvest, 3 sprays every 7 days) were 0.56 mg/kg in site 1, 0.55 mg/kg in site 2, and 0.42 mg/kg in site 3, respectively.

  CONCLUSION(S):

  The import tolerance (IT) of thiamethoxam for kiwifruit may be proposed to be 0.9 mg/kg by using the OECD MRL calculator.