• 한국환경농학회지
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• 제41권4호
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• pp.355-364
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• 2022

BACKGROUND: Pre-harvest interval and decline pattern of thiamethoxam were determined in kiwifruit using liquid chromatography-tandem mass spectrometry (LCMS/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.

• 한국토양비료학회지
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• 제46권6호
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• pp.510-518
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• 2013

Corn was mainly cultivated in slope land during summer season when heavy rain falls so that soil loss occurs severely. Especially, soil disturbance and exposure of topsoil by conventional tillage intensifies soil loss by heavy rain. The aim of this study was to develop surface covering and tillage methods for reducing soil loss in corn cultivation. The experiment was conducted in 17% sloped lysimeter with 8 treatments including strip tillage after surface covering with rye residue, strip tillage after residue covering of several crops and sod culture, black polyethylene film covering after conventional tillage and control. Amount of runoff water and eroded soil, and corn growth were investigated. Amounts of runoff water in all plots except black polyethylene plot ranged from 152 to 375 $m^3\;ha^{-1}$, accounting for 13~32% of 1,158 $m^3\;ha^{-1}$ in control. Amount of eroded soil decreased by 94 to 99% (3 to 89 kg $ha^{-1}$) in plots of strip tillage after covering with crop residues compared to control with 1,739 kg $ha^{-1}$. Corn yields in plots of strip tillage after covering with crop residues ranged from 6.0 to 6.9 Mg $ha^{-1}$, while that of control was 6.5 Mg $ha^{-1}$. The results suggest that strip tillage methods after surface covering with crop residues are very effective on soil conservation of slope land in corn cultivation.

• Asian-Australasian Journal of Animal Sciences
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• 제16권4호
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• pp.529-533
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• 2003

The intake, dry matter (DM) digestibility, total mean retention time (TMRT) and weight changes were investigated in four fat tailed and four Dorper sheep fed on a maize stover crop residue. Animals were subjected to five dietary treatments, which were: 90, 135 and $180g\;DM/kgBW^{0.75}/day$ of chopped maize stover offered with urea, and in subsequent dietary treatments $180g\;DM/kgBW^{0.75}/day$ of stover supplemented with either dried bean husks or poultry manure. Although not statistically different (p>0.05) fat tailed sheep had higher maize stover intake than the Dorper sheep when expressed per metabolic body weight. The DM intake and digestibility increased significantly (p<0.001) in both sheep breeds when the maize stover offer levels were increased from 90 to $135g/kgBW^{0.75}/day$. Dorper sheep had significantly (p<0.001) higher DM digestibility and longer total mean retention times for both the liquid and solid matter than the fat-tailed sheep. Fat-tailed sheep gained 4.75 kg while Dorper sheep gained 3.75 kg over the entire experimental period. The weight change per dietary treatment was affected by the amount of maize stover and the type and amount of supplement consumed. The higher DM digestibility and longer total mean retention time in Dorper sheep shows that the breed has adapted to utilize the low quality roughage diets. An indigenous fat tailed, has the potential to ingest high volumes of fibrous feed and has higher voluntary intakes relative to its body size. The two sheep breeds are a valuable genetic resource in sub Saharan Africa that is characterized by long dry season with no readily available and affordable conventional feeds for small ruminants.

• 한국환경농학회지
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• 제4권2호
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• pp.95-101
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• 1985

1982년 11월부터 1983년 10월까지 서호를 포함한 수인근교의 저수지 및 한강의 하천수질 시료를 수집, PCBs 및 유기염소계살충제 잔류수준을 평가한 결과는 다음과 같다. 1) PCBs는 거의 모든 수질시료에서 검출되었다. 2) PCBs의 펑균잔류수준은 0.009${\sim}$0.5ppb였고 유기 염소계 살충제의 평균잔류수준은 불검출${\sim}$0.008ppb 였다. 3) PCBs와 총 DDT의 평균잔류수준비는 시료채취 지점에 따라 차이가 있었으며, 이 비는 한강수질시료에서는 500으로 가장 높았고, 원천 수질에서 가장 낮았다. 4) 관개수중 PCBs는 공업 및 도시폐수에서 유래된 것으로 보였다.

• Toxicological Research
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• 제26권2호
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• pp.149-155
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• 2010

The pesticide trichlorfon is readily degraded under experimental conditions to dichlorvos. A method has therefore been developed by which residues of trichlorfon in milk are determined as dichlorvos, using gas chromatography with ${\mu}$-electron capture detection. The identification of dichlorvos was confirmed by mass spectrometry. Milk was extracted with acetonitrile followed by centrifugation, freezing lipid filtration, and partitioning into dichloromethane. The residue after partitioning of dichloromethane was dissolved in ethyl acetate for gas chromatography. Recovery concentration was determined at 0.5, 1.0, and 2.0 of times the maximum permitted residue limits (MRLs) for trichlorfon in milk. The average recoveries (n = 6) ranged from 92.4 to 103.6%. The repeatability of the measurements was expressed as relative standard deviations (RSDs) ranging from 3.6%, to 6.7%. Limit of detection (LOD) and limit of quantification (LOQ) were 3.7 and $11.1{\mu}g/l$, respectively. The accuracy and precision (expressed as RSD) were estimated at concentrations from 25 to $250{\mu}g/l$. The intra- and inter-day accuracy (n = 6) ranged from 89.2% to 91% and 91.3% to 96.3%, respectively. The intra- and inter-day precisions were lower than 8%. The developed method was applied to determine trichlorfon in real samples collected from the seven major cities in the Republic of Korea. No residual trichlorfon was detected in any samples.

• 한국환경농학회지
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• 제23권4호
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• pp.251-257
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• 2004

Analytical methods were developed to determine cyclosulfamuron residues in soil, water, rice grain and straw using high-performance liquid chromatography (HPLC) with ultraviolet absorption detection. In these methods, cyclosulfamuron was extracted with aqueous $Na_2HPO_4$/acetone and acetone/methanol mixture from soil and rice samples respectively. Liquid-liquid partition coupled with ion-associated technique, Florisil column chromatography, and solid-phase extraction (SPE) were used to separate cyclosulfamuron from interfering co-extractives prior to HPLC analysis. For water sample, the residue was enriched in $C_{18}$-SPE cartridge, cleaned up in situ, and directly subjected to HPLC. Reverse-phase HPLC under ion-suppression was successfully applied to determine cyclo-sulfamuron in sample extracts with the detection at its ${\lambda}_{max}$ (254 nm). Recoveries from fortified samples averaged $87.8{\pm}7.1%$ (n=12), $97.3{\pm}7.2%$ (n=12), $90.8{\pm}6.6%$ (n=6), and $78.5{\pm}6.7%$ (n=6) for soil, water, rice grain and straw, respectively. Detection limits of the methods were 0.004 mg/kg, 0.001 mg/L, 0.01 mg/kg and 0.02 mg/kg for soil, water, rice grain and straw samples, respectively.

• 한국유기농업학회지
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• 제5권1호
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• pp.125-135
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• 1996

A study was made to investigate the possibility of treating various organic waste of cattle manure, swine manure, goat manure, apple pomace, chinese medicine residue and coffee less by feeding these to earthworms and then by studying the growth and reproductive efficiency of earthworms, and the chemical composition of worm cast and its production. The results are summarized as follows. 1. When the feed for earthworms were in good condition which were cattle manure, swine manure and apple pomace, the reproductive efficiency of earthworms was improved however in worse condition the feed of which were goat manure and chinese medicine residue, the increasing rate(IR) became faster. 2. Despite the high content of organic matter(OM) in coffee lees, the earthworms fed coffee lees showed significantly lower reproductive efficiency and increasing rate(IR) than those fed other organic waste due mainly to its lower pH and lower total nitrogen(TN) content. Therefore, when coffee lees is considered to be fed to earthworms, it is believed necessary to be mixed with addiveves or other organic waste in order to improve the feed condition. 3. pH in swine manure, goat manure, apple pomace, chinese medicine residue and coffee lees became neutralized by being fed by earthworms. 4. Available P2O5 and exchangeable cation(EC) of earthworm cast were a little increased compared to those of feed. The contents of Mn, Fe and Cu in earthworm cast were a little decreased to compared to those of feed. 5. The contents of Mn, Fe and Cu in earthworm cast were a little a decreased to compared to those of feed. 6. Mean fresh weight of earthworm at final time(FW2) was negatively correlated with number of young worms(NY)(P<0.01), but positively with increasing rate(IR) (P<0.001) and C/N ratio(P<0.05) respectively. Number of cocoons (NC) and fresh weight of cocoons(WC) were positively(P<0.01) correlated with fresh weight of young worms (WY) and digested matter(DI) but negatively(P<0.001) correlated with residual matter(WY) and digested matter(DI) but negatively(P<0.001) correlated with residual matter(RW). Number of young worms(NY) and fresh weigh of young worms(WY) were negatively(P<0.001) correlated with increasing rate(IR), however increasing rate(IR) of earthworm was positively(P<0.05) correlatedd with C/N ratio.

• International Journal of Advanced Culture Technology
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• 제4권1호
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• pp.1-9
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• 2016

The demand for energy in Thailand has been continually increasing as the economic and social country grows. Approximately 60% of Thailand's primary energy is imported, mostly petroleum products. In 2008 Thailand's total energy consumption was 80,971 ktoe and the net price of energy imported was up to 1,161 billion Baht which is equivalent to 12.8% of GDP at the current price. The energy consumption or energy demand has been growing at an annual compounded growth rate of 6.42% and the peak electric power demand and electricity consumption was recorded at 22,568 MW and 148,264 GWh and grew at a rate of 7.0% and 7.5% per annum during the period from 1989 to 2008. The gross agriculture production in 2008 was recorded at 135.4 Mt which represents agriculture residue for energy at 65.73 Mt, which is equivalent to energy potential of about 561.64 PJ or 13,292 ktoe an increase in average of 5.59% and 5.44% per year respectively. The agricultural residues can converted to 15,600 GWh/year or 1,780 MW of power capacity. So, if government sector plan to install small biomass gasification for electricity generation 200 kW for Community. The residue agricultural is available for 8,900 plants nationwide. The small biomass power generation for electricity generation not only to reduce the energy imports, it also makes the job and income for people in rural areas as well. This paper's aim is to report the energy situation in Thailand and has studied 5 main agricultural products with high residue energy potential namely sugarcane, paddy, oil palm, cassava, and maize appropriate for small electricity production. These agricultural products can be found planted in many rural areas throughout Thailand. Finally, discuss the situation, methods and policies which the government uses to promote small private power producers supplying electricity into the grid.

• 한국환경농학회지
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• 제37권2호
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• pp.117-124
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• 2018

본 연구에서는 HPLC-UVD/MS를 이용하여 농산물 중 oxanthiin 살균제인 oxycarboxin의 잔류 분석법을 확립하였다. 대표 농산물은 현미, 콩, 배추, 고추 및 사과를 선정하였고 acetone을 가하여 추출된 oxycarboxin 성분을 dichloromethane 액-액 분배법과 Florisil 흡착크로마토그래피법으로 정제하여 HPLC-UVD/MS 분석대상 시료로 사용하였다. Oxycarboxin의 정량적 분석을 위한 최적 분석 조건을 확립하였으며, 정량한계(LOQ)는 0.04 mg/kg 이었다. 각 대표 농산물에 대해 정량한계, 정량한계의 10배 및 50배 수준에서 회수율을 검토한 결과 모든 처리농도에서 78.3~96.1% 수준을 나타내었으며, 반복 간 변이계수(CV)는 최대 4.7%를 나타내어 잔류분석 기준인 회수율 70~120% 및 분석오차 10% 이내를 충족시키는 만족한 결과를 도출하였으며, LC/MS SIM을 이용하여 실제 농산물 시료에 적용하여 재확인 하였다. 이상의 결과로 신규 oxycarboxin의 HPLC-UVD/MS 분석법은 검출한계, 회수율 및 분석오차 면에서 국제적 분석기준을 만족하는 신뢰성이 확보된 정량 분석법으로 사용 가능할 것이다.

• 한국환경농학회지
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• 제32권2호
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• pp.128-135
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• 2013

BACKGROUND: This study was performed to develop a single residue analytical method for new herbicide metazosulfuron in crops. METHODS AND RESULTS: Brown rice, apple, mandarin, Kimchi cabbage and soybean were selected as representative crops, and clean-up system, partition solvent and extraction solvent were optimized. Instrumental limit of quantitation (ILOQ), linearity of calibration curve and method limit of quantitation (MLOQ) were determined based on the chromatography and whole procedures. For recovery tests, brown rice, apple, mandarin, Kimchi cabbage and soybean samples were macerated and fortified with metazosulfuron standard solution at three levels (MLOQ, 10 MLOQ and 100 MLOQ). And then those were extracted with acetonitrile, concentrated, and partitioned with ethyl acetate. Then the extracts were concentrated again and cleaned-up through $NH_2$ (aminopropyl) SPE cartridge with acetone : dichloromethane (1% acetic acid) (20 : 80, v/v) before concentration and analysis with HPLC. CONCLUSION(S): ILOQ of metazosulfuron was 2 ng (S/N${\geq}$10) and good linearity was achieved between 0.05 and 12.5 mg/Kg of metazosulfuron standard solutions, with coefficients of determination of 0.9999. MLOQ was 0.02 mg/Kg. Good recoveries from 74.1 to 116.9% with coefficients of variation (C.V.) of less than 10% were obtained, regardless of sample type, which satisfies the criteria of Korea Food and Drug Administration (KFDA). Those results were reconfirmed with LC-MS (SIM). The method established in this study is simple, economic and efficient to be applied to most of crops as an official and general method for residue analysis of metazosulfuron.