• Korean Journal of Environmental Agriculture
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• v.37 no.3
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• pp.213-220
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• 2018

BACKGROUND: This study was carried out to determine characteristics of residual pesticides in time-dependent manner and calculate half-lives of the residual pesticides in fresh and dried Chinese matrimony vine. In addition, processing factors were calculated based on the residual concentrations in them. METHODS AND RESULTS: The test pesticides, etofenprox and fenitrothion, were sprayed onto the Chinese matrimony vine plants at once or twice (at seven-day interval) and then samples were collected at 0 (after 3 hours), 1, 3, 5 and 7 days after the last spraying. Dried samples were prepared in hot-air drying oven at $60^{\circ}C$ for 48 hours until water content of less than 20%. Residual concentrations of etofenprox in fresh and dried samples decreased by 54.0-60.9% after 7 days of the last pesticide-application. In case of fenitrothion, the concentrations were found to have decreased by 69.2-76.5%. Processing factors of etofenprox were 2.6-3.0 for the one-time spraying and 2.5-3.0 for the two-time spraying and those of fenitrothion were found to be 1.5-22 for the one-time spraying and 1.6-2.0 for the two-time spraying. First half-lives of etofenprox and fenitrothion in fresh and dried samples ranged from 5.0 to 6.3 and from 3.4 to 4.0 days, respectively. The third half-lives were found to be 15.0-18.9 and 10.2-12.1 days, respectively. CONCLUSION: Residual concentrations of the tested pesticides in the studied crop decreased, but those in the dried samples appeared to have increased. In addition, processing factor and half life were constant regardless of spraying times.

• The Korean Journal of Pesticide Science
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• v.10 no.1
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• pp.15-21
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• 2006

In order to monitor the pesticide residues in/on peppers and pepper powder and to assess their risk, pesticides in/on green pepper from 10 farmgates and fresh red pepper from 9 farmgates in Chungbuk area and pepper powder from 6 wholesale markets in Cheongju city were analyzed with a GLC and an HPLC. Also, pepper powder made by pulverization of the dried red pepper was analyzed to elucidate the change of pesticide residues in fresh red pepper by oven-drying. The number of pesticides detected from peen pepper, fresh red pepper, dried red pepper and pepper powder were 9, 12, 12, and 17, respectively, including 10 pesticides (one fungicide and nine insecticides) which were exceeded the maximum residue limits (MRLs). The exceeding rate of the MRL were higher in dried red pepper and pepper powder than in green pepper and fresh red pepper. Although some pesticides in peppers and pepper powder exceeded the MRLs, their estimated daily intake(EDI) were less than 1.6% of their acceptable daily intakes(ADIs), suggesting that it would be estimated to safe. By oven-drying of fresh red pepper at $65^{\circ}C$ for 72 hours, the weight of dried red pepper was from 1/5.9 from 1/7.8 of fresh red pepper, while the concentration of pesticide residue in dried red pepper increased from 1.7 to 8.2 times, suggesting that further reconsideration was required for the MRL of pepper powder.

• Korean Journal of Environmental Agriculture
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• v.39 no.2
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• pp.83-88
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• 2020

BACKGROUND: This study was carried out to investigate residual characteristics of diethofencarb during ginseng cultivation and processing, and to establish the maximum residue limits (MRL) of ginseng and its processed products. METHODS AND RESULTS: Supervised field trials were conducted from three fields located at Seosan, Goesan and Jeongeup in Korea. Diethofencarb 25% WP was diluted by 500 times and sprayed 4 times onto the ginseng with 10 days interval. The samples were collected at 80 days after final application. The residual amounts of diethofencarb ranged from 0.074 to 0.460 mg/kg in fresh ginseng, from 0.292 to 0.720 mg/kg in dried ginseng, and from 0.208 to 0.557 mg/kg in red ginseng. These data exceeded the ginseng's MRL, 0.3 mg/kg. The processing factors of diethofencarb in processed products were found to be 2.64 and 1.99, respectively for dried and red ginseng. CONCLUSION: Given the lower residual concentration of red ginseng that goes through a more complicated process than dried ginseng, the residual concentrations of diethofencarb in processed ginseng products were found to be dependent on processing method. Therefore, it is necessary to reconsider the MRL of diethofencarb in fresh ginseng and its processed products.

• Journal of Applied Biological Chemistry
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• v.56 no.1
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• pp.29-35
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• 2013

This study was performed to analyze 48 kinds of pesticide residues using gas chromatography (GC)/nitrogen phosphorous detector, GC/micro electron capture detector, GC/mass selective detector, and high performance liquid chromatograph/diode array detector in 186 fresh ginseng samples collected in the Seoul area from 2010 to 2011. Fresh ginseng dietary intakes were estimated using the data from the 2009 Korea National Health and Nutrition examination survey. Residual pesticides were detected in 79 samples (42.5%) with eight different fungicides. Only 20 samples (10.8%) exceeded the maximum residue limits (MRLs) for pesticides registered by the Korea Food & Drug Administration. Among them, tolclofos-methyl residues (10.2%) exceeded the MRL for fresh ginseng in 18 ginseng seedlings and one of the two-year old fresh ginseng plants, and the residual level in just one ginseng seedling violated the MRL for pyrimethanil. The results showed that residual pesticides levels in marketable fresh ginseng around Seoul were relatively safe. The percent acceptable daily intake (%ADI) was calculated using pesticide residues in fresh ginseng and dietary intakes of fresh ginseng. The risk caused by pesticide residues in fresh ginseng was very low.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.4
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• pp.682-686
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• 1998

To use onion(Allium cepa L.) residue as raw materials of food products, contents and stability of quercetin-related substance in onion were investigated. The amount of quercetin-related substance of onion was richer in the inedible portion(317.99mg%) than the edible protion(4.10mg%). Total quercetin-related substances of juice and residue from fresh onions were 2.26mg% and 1.57mg%, respectively, but they were changed to 1.50mg% and 2.96mg% by heating at 8$0^{\circ}C$ for 10min. Quercetin was found to be stable at 20$0^{\circ}C$ for 60 min, but it was unstable to light. When it was illuminated with 30W, the content was decreased and reached to 80~85% of the original content after 48 hours. Quercetin was not affected by pH, but quercitrin and rutin were unstable below pH 5.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.1
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• pp.43-52
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• 2016

The coniferous fallen leaf is one of the major forestry residues. Since the coniferous fallen leaf would not be easily decayed, the large amount of the coniferous fallen leaves in forestry could be the source of forest fire. The applicability of the fallen leaves to the pulp mold were evaluated for developing new utilization of coniferous fallen leaves. The morphological properties and the chemical composition of the fallen leaves of Pinus densiflora and Pinus koraiensis were evaluated by the comparison with those of fresh leaves. The applicability of the coniferous fallen leaves to the pulp mold and the effects on the pulp mold properties including the scent diffusion were investigated. The fallen leaves showed the shrunk structure by losing the hot water extract component, which leaded to better grinding properties than that of fresh leaves. The pulp mold with fallen leaves showed higher strength properties than the pulp mold with fresh leaves. Although the scent of the pulp mold with fresh leaves was stronger, the pulp mold with fallen leaves had coniferous scent too. The application of fallen leaves to pulp mold for the functional properties could be possible by improving the mechanical properties and the scent lasting treatments.

• The Korean Journal of Pesticide Science
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• v.16 no.2
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• pp.131-136
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• 2012

This study was carried out to elucidate residual characteristics of azoxystrobin and difenoconazole in fresh ginseng. Test pesticides were sprayed onto ginseng both in 2009 for 3-year-old ginseng and in 2010 for 4-year-old ginseng according to their pre-harvest intervals (PHIs). Limit of quantitation (LOQ) of both azoxystrobin and difenoconazole was 0.003 mg/kg. Analytical methods set up for the test pesticides were considered to be suitable for the analysis of their residues in fresh ginseng, considering that their recoveries ranged from 87.58 to 112.79%. Concentration of azoxystrobin in 3-year-old ginseng ranged from 0.004 to 0.011 mg/kg and that in 4-year-old ginseng ranged from 0.007 to 0.016 mg/kg. Amounts of difenoconazole in 3- and 4-year-old ginsengs were from 0.003 to 0.007 and from 0.007 to 0.01 mg/kg, respectively, representing no accumulation effect observed in residue amount between them.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.4
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• pp.211-217
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• 2005

Fresh hairy vetch (HV) as a green manure equivalent to $240kg\;N\;ha^{-1}$ were incorporated into soil at corn planting in 1997 and 1998 to clarify the effects on changes of nitrogen (N) content in soil and corn plant. The influences of HV for the N of soil and plant were compared with those of ammonium nitrate (AN) in terms of mineralization and microbial biomass. During early decomposition of HV residue, the content of $NO_3-N$ in HV plot was as much as 60-70% of that in AN plot in surface soil of 0-15 cm depth. In addition, soil microbial biomass N (SMBN) by HV residue was increased up to $10-20mg\;kg^{-1}$ more than that by AN. Some mineral N from HV seemed to be released slowly until late corn growth stage judging from high content of $NO_3-N$ in both corn stem at silking stage and soil at harvest. There were no difference of N accumulations in corn plant at silking stage between HV and AN plots in both 1997 and 1998. At harvesting stage, a total of plant N accumulation in HV plot in 1997 was 8% less than that in AN plot while in 1998 it was 19% more. It was concluded that fresh HV green manure equivalent to $240kg\;N\;ha^{-1}$ was good enough to substitute the same amount with chemical N fertilizer by slow releasing of mineral N from HV residue in soil.

• Korean Journal of Environmental Agriculture
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• v.25 no.2
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• pp.174-179
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• 2006

Chinese cabbage, Braccica campestris has long been consumed as a staple food for Koreans in various forms of fresh, salted, and fermented Kimchi. Cultivation of the crop under greenhouse has become a general practices to fulfill its off-seasonal consumer's demand. However, agricultural practices of the crop have always accompanied with heavy applications of pesticides caused by severe outbreaks of diseases and pose under warm and humid circumferences. Since dissipation patterns of pesticide residues in/on the crop under greenhouse conditions ate quite different from those in the open-air, changes of diazinon, O,O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphornthioate, in/on the Chinese cabbage applied by foliar spraying under greenhouse were studied. Diazinon 34% EC was applied with dilution of recommended and double dose to the crop. The shoots of crop were harvested immediately after this application and at regular intervals over a 10-day. After sample preparations, the diazinon residue was analyzed using gas chromatography equipped with electron capture detector (GC/ECD). Initially deposited amount of the chemical in/on the crop right after applications with recommended and double doses were 8.3 and 15.2 mg/kg, respectively. The residue levels after 10 days of application were 0.03 and 0.09 mg/kg with 1.3 and 1.5 days of half-life in/on the crop, respectively. In consequent 10 days of pre-harvest interval (PHI) for diazinon EC formulation in/on Chinese cabbage under greenhouse condition was fulfill maximum residue level set by Korea Food and Drug Administration (KFDA, 0.1 mg/kg).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.3
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• pp.285-294
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• 1994

Dried top and root extracts of seven different weed species, fresh top and root extracts, and various concentrations of extract (0, 5, 10 and 15%, W/V) and residue rate (0.0, 0.25. 0.5, 0.75 and 1.0%) of velvetleaf (Abutilon theophrasti Medic.) were used to study their allelopathic effects on alfalfa in the laboratory and greenhouse. Top and root aqueous extracts of common lambsquarter (Chenopodium album L.), giant foxtail (Setaria faberii Herrm), redroot pig-weed (Amaranthus retroflexus L), velvetleaf, large crabgrass (Digitaria sanguinalis L), canada thistle (Cirsium arvense L.) and prostrate knotweed (Polygonium aviculare L.) significantly inhibited germination, seedling length, weight, and vigor in alfalfa. Top growth extracts of weeds exhibited greater allelopathic effects than root extracts. Alfalfa test species, WL-320, responded significantly different to the various weed species extracts in terms of allelopathic effect. The regression slopes of various top extracts showed significant variation with respect to germination percentage. Velvetleaf (b=3.69) extracts were the most inhibitory, while large crabgrass (b=2.39) extracts had the least allelopathic effect on alfalfa. When compared the activity of fresh velvetleaf extract to that of dry velvetleaf extract, dry extract was more inhibitory to alfalfa germination and seedling growth. Germination, seedling length and weight of alfalfa were inversely proportional to the concentration of dried velvetleaf extracts. Seedling emergence and survival percentage was inhibited by velvetleaf residue mixture treatment. Also, more of the toxic effects were observed from the dried top extracts, as compared to extracts from fresh top and root. These results demonstrate the allelopathic activity of different weed species extracts and suggest that weeds may affect crop growth and development due to the inhibitory effects of allelochemicals present in weed tissue.