• Journal of Environmental Science International
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• v.8 no.1
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• pp.19-26
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• 1999

The degree of pesticides accumulation in tap water in Taejon from June 1995 to Apr 1996 was measured by Ellman's coupled enzyme assay. Since organic phosphate and carbamate pesticides specifically inhibit the neurotransmitter modulating enzyme acetylcholinesterase(AChE), the enzyme activity can be used as a diagnosis for the pesticides accumulation in water and various samples. During the period of this study, the enzyme activity was changed almost every week. The lowest enzyme activity was 64 % of that of the control reaction and there are several days showing about 100 % enzyme activity. In general, the enzyme activity is higher in summer than other seasons especially early spring times. The pH value of tap water was very close to neutral(pH 7.0) and it seems that the enzyme activity was not affected by the small pH changes. Either boiling of tap water or addition of NaOH solution decomposed the pesticide components. These results show that AChE assay is a convenient, sensitive, and reliable method for detection of pesticides in water samples.

• Journal of Food Hygiene and Safety
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• v.17 no.2
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• pp.87-93
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• 2002

The removal of three pesticides which were residued in chinese cabbage was investigated during making process of Kimchi. When chinese cabbage was washed by water, the removal rates of three pesticides were 62.0%, 54.8% and 61.1% for pirimiphos-methyl, chlorpyrifos and prothiofos, respectively. Pesticides remaining in chinese cabbage after washing by water were also removed from 22.4% to 23.8% by salting. During the fermentation of kimchi for 24 days at 4。C, the pH was lowered 4.5 from 5.8 and the residual amount of pesticides was decreased by 51.4% to 69.4% for three Pesticides remaining after washing and salting On the other hand, when Kimchi was fermented under various temperature for 11 days, the residual amount of chlorpyrifos was decreased up to 29.2%, 45.0% and 77.3% of initial concentration at 4, 10 and 20 。C, respectively. The residual amount of chlorpyrifos in Kimchi was decreased up to 16.3% by heating at 100 。C for 6.5 minutes.

• The Korean Journal of Pesticide Science
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• v.16 no.1
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• pp.11-20
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• 2012

As increasing the use of pesticides both in number and amount to boost crop production, consumer concerns over food quality and safety with respect to residual pesticides are also continuously increasing. However, there is still lacking of information that can effectively help to remove residual pesticides in foods. In recent years, contaminant removal by gas (or) glow discharge plasma (GDP) attracts great interests on environmental scientists because of its high removal efficiency and environmental compatibility. It was shown to be effective for the removal of some organophosphorus pesticides, phenols, benzoic acid, dyes, and nitrobenzene on solid substrate or in aqueous solution. This work mainly focuses on the removal of wide range of residual pesticides from fresh fruits and vegetables. As for preliminary study, the experiments were carried out to investigate whether GDP can be used as an effective tool for degrading target pesticides or not. With this objective, 60 selected pesticides drop wised onto glass slides were exposed to two types of GDP, dielectric barrier discharge plasma (DBDP) and low pressure discharge plasma (LPDP), for 5 min. Then, they were washed with 2 mL MeCN which were collected and used for determination of remaining concentration of pesticides using LC-MS/MS. Among selected pesticides, degradation of 18 pesticides (endosulfan-total was counted as one pesticide) by GDP could not be examined because control treatments, which were left in ambient environment, of those pesticides recovered less than 70% or even did not recover. However, majority of tested pesticides (42) were degraded by both types of GDP with satisfactory recovery (>80%) of control sample. Pesticides degradation ranged from 66.88% to 100% were achieved by both types of plasma except clothianidin which degradation in LPDP was 26.9%. The results clearly indicate that both types of gas discharge plasma are promising tools for degrading wide range of pesticides on glass substrate.

• The Korean Journal of Pesticide Science
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• v.9 no.1
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• pp.41-50
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• 2005

For the removal of residual pesticides in ginseng extracts, we estabilished the removal process using pilot plant system, the characteristic components of ginseng maintains only. According to the agricultural chemical removal process, we monitored residual pesticides of 155 species, compraing the characteristic components of ginseng. The process of 4 types of agricultural chemical removal process compared to the control test was appeared that the residual pesticides were eliminated. As results above, the most efficient method of the possibility of raising the removal ratio of the agricultural chemical construction process was dried process of hexane after dipping and also remaining quality of the hexane appeared lowly. Besides, the removal process had an effected on the ginsenocide os ginseng, only the residual pesticides will be able to remove.

• Journal of Ecology and Environment
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• v.41 no.11
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• pp.318-327
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• 2017

Background: A typical sewage treatment plant is designed for organic and nutrient removal from municipal sewage water and not targeted to eliminate micropollutants such as pesticides, pharmaceuticals, and nano-sized metals which become a big concern for sustainable human and ecological system and are mainly discharged from sewage treatment plant. Therefore, despite contaminant removal by wastewater treatment processes, there are still remaining environmental risks by untreated pollutants in STP (sewage treatment plant) effluents. This study performed aquatic toxicity tests of raw wastewater and treated effluents in two sewage treatment plants to evaluate toxicity reduction by wastewater treatment process and analyze concentration of contaminants to reveal potential toxic factors in STP effluents. Methods: Water samples were collected from each treatment steps of two STPs, and acute and chronic toxicity tests were conducted following USEPA (United States Environmental Protection Agency) and OECD (Organization for Economic Cooperation and Development) guidelines. Endpoints were immobility for mortality and reproduction effect for estrogenicity. Results: Acute $EC_{50}s$ (median effective concentration) of influents for Seungki (SK) and Jungnang (JN) STPs are $54.13{\pm}32.64%$ and $30.38{\pm}24.96%$, respectively, and reduced to $96.49{\pm}7.84%$ and 100%. Acute toxicity reduction was clearly correlated with SS (suspended solids) concentration because of filter feeding characteristics of test organisms. Chronic toxicity tests revealed that lethal effect was reduced and low concentration of influents showed higher number of neonates. However, toxicity reduction was not related to nutrient removal. Fecundity effect positively increased in treated wastewater compared to that in raw wastewater, and no significant differences were observed compared to the control group in JN final effluent implying potential effects of estrogenic compounds in the STP effluents. Conclusions: Conventional wastewater treatment process reduced some organics and nutritional compounds from wastewater, and it results in toxicity reduction in lethal effect and positive reproductive effect but not showing correlation. Unknown estrogenic compounds could be a reason causing the increase of brood size. This study suggests that pharmaceutical residues and nanoparticles in STP effluents are one of the major micropollutants and underline as one of estrogenic effect factors.

• Korean Journal of Environmental Agriculture
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• v.39 no.3
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• pp.246-252
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• 2020

BACKGROUND: Pesticides are broadly used to control weeds and pests, and the residues remaining in crops are managed in accordance with the MRLs (maximum residue limits). Therefore, an analytical method is required to quantify the residues, and we conducted a series of analyses to select and validate the quick and simple analytical method for tolpyralate in five agricultural products using QuEChERS (quick, easy, cheap, effective, rugged and safe) method and LC-MS/MS (liquid chromatography-tandem mass spectrometry). METHODS AND RESULTS: The agricultural samples were extracted with acetonitrile followed by addition of anhydrous magnesium sulfate, sodium chloride, disodium hydrogencitrate sesquihydrate and trisodium citrate dihydrate. After shaking and centrifugation, purification was performed with d-SPE (dispersive-solid phase extraction) sorbents. To validate the optimized method, its selectivity, linearity, LOD (limit of detection), LOQ (limit of quantitation), accuracy, repeatability, and reproducibility from the inter-laboratory analyses were considered. LOQ of the analytical method was 0.01 mg/kg at five agricultural products and the linearity of matrix-matched calibration were good at seven concentration levels, from 0.0025 to 0.25 mg/L (R²≥0.9980). Mean recoveries at three spiking levels (n=5) were in the range of 85.2~112.4% with associated relative standard deviation values less than 6.2%, and the coefficient of variation between the two laboratories was also below 13%. All optimized results were validated according to the criteria ranges requested in the Codex Alimentarius Commission (CAC) and Ministry of Food and Drug Safety (MFDS) guidelines. CONCLUSION: In conclusion, we suggest that the selected and validated method could serve as a basic data for detecting tolpyralate residue in imported and domestic agricultural products.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.3
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• pp.185-191
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• 2001

To obtain the basic information for degradation of remaining pesticide accumulated in cultivated soil of Honam area, the resistant bacterial strains were investigated in Chlorothalonil(TPN). Mancozeb, Bentazone, and Butachlor levels of 100, $500{\mu}g\;ml^{-1}$, and degradation of TPN by TPN-resistant bacteria in sterilized soil was studied under TPN levels 0, 10, 50 and $100{\mu}g\;g^{-1}$. A number of resistance strains were decreased with higher at concentration level of pesticide, and were higher in greenhouse than upland or paddy soil. The resistance of bacteria was strong in other of Bentazone> Butachlor> TPN> Mancozeb. The percentage of bacterial strains of resistance for pesticides isolated from the cultivated soil were the highest in Acinetobacter spp. and Corynebacterium spp., and the lowest in Moraxella spp. A number of TPN-resistant strains were the highest at the TPN level of $10{\mu}g\;g^{-1}$, and 5 days after strains inoculation, and were higher in Pseudomonas spp. TD-25 than TC-23 or strains in non-sterilized soil. The degradation of TPN was fast in order of strain TD-25>strain in non-sterilized soil >TC-23.