Doo-Ho Kim

Determination of arsenic species in rice grains using HPLC-ICP-MS

Determination of As species in rice is necessary because inorganic As species (arsenate (AsV) and arsenite (AsIII)) are more toxic than organic As (monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA)). This study evaluated the As species in Korean and USA rice grains. Levels were determined using microwave extraction and high performance liquid chromatography coupled with inductively coupled plasma-mass spectrometry (HPLC-ICPMS). Arsenite and DMA were the major species detected in Korean and USA rice. The percentage of inorganic As was 76.94% (54.50–87.86%) for Korean rice and 69.28% (52.94–72.92%) for USA samples. The order and percentage of As species observed in Korean and USA rice were AsIII (70%)>DMA (24%)>AsV (5%)>MMA (1%), and AsIII (64%)>DMA (28%)>AsV(5%)>MMA (3%), respectively. The AsIII concentrations were not significantly different in Korean rice grains, compared to USA grains. The high AsIII predominance indicates an elevated toxic effect of As in rice grains and needs further attention.

Current research trends for heavy metals of agricultural soils and crop uptake in Korea

BACKGROUND: Increase of heavy metals in agricultural ecosystem has become a social issue nationwide as it is related to public health. This review was performed to find out more systematic and integrated future researches on heavy metals using up to date articles published in the Korean journals related to agricultural environment. METHODS AND RESULTS: Researches on heavy metals in agricultural soils and plant uptake were categorized by the establishment of criteria, analytical methods, monitoring, management of source, characteristics and behavior in soil, plant uptake, bioavailability affecting physico -chemical properties in soil, risk assessment and soil remediation. In the early 1990s, the monitoring for heavy metals in soil has been widely performed. Accumulation of heavy metals in contaminated soil and availability to plants has also attracted interests to study the soil remediation using various physico-chemical methods. The phytoavailability and phytotoxicity of heavy metals have been mainly studied to assess the safety of agro-products using risk assessment techniques in the 2000s. CONCLUSION: Future direction of research on heavy metal in agricultural environment must be carried out by ensuring food safety and sustainability. A steady survey and proper management for polluted regions should be continued. Law and regulation must be modified systematically. Furthermore, studies should expand on mitigation of heavy metal uptake by crops and remediation of polluted fields.

Distribution of Microorganisms in Perilla Leaf and Cultivation Area

The prevalence and distribution of hazardous microorganisms were investigated from the major perilla cultivation area at Milyang, Gyeongnam province, Korea. Aerobic plate count (APC) and coliform count of perilla leaves were 4.82 log CFU/g and 3.85 log CFU/g, respectively. E. coli, S. aureus and B. cereus were detected in 3.0% (4/114), 7.9% (9/114) and 46.5% (53/114) of examined perilla leaves. However, E. coli O157:H7, Salmonella spp, and L. monocytogenes were not detected. The distribution of hazardous microorganisms in perilla leaf cultivation environment were compared and the concentration of APC and coliform counts were more than 3.0 log CFU/(mL, g, 100 cm 2 , hand) from most of the samples. S. aureus were detected from irrigation water, packing table, packing vinyl, hand, and clothes. Also, B. cereus was frequently detected from the examined samples. Especially, packing table and collection container were contaminated with maximum 5.5 log CFU/100 cm 2 of B. cereus. Good Agricultural Practice (GAP) system should be

Model Development for Estimating Total Arsenic Contents with Chemical Properties and Extractable Heavy Metal Contents in Paddy Soils

This study was performed to estimate total contents of arsenic (As) by stepwise multiple-regression analysis using chemical properties and extractable contents of metal in paddy soil adjacent to abandoned mines. The soil was collected from paddies near abandoned mines. Soil pH, electrical conductively (EC), organic mater (OM), available phosphorus (), and exchangeable cations (Ca, K, Mg, Na) were measured. Total contents of As and extractable contents of metals were analyzed by ICP-OES. From stepwise analysis, it was showed that the contents of extractable As, available phosphorus, extractable Cu, exchangeable K, exchangeable Na, and organic mater significantly influenced the total contents of As in soil (p) + 0.334 Log (extractable-Cu) + 0.186 Log (exchangeable-K) - 0.593 Log (exchangeable-Na) + 0.558 Log (OM). The estimated value in total contents of As was significantly correlated with the measured value in soil (=0.84196, p

Monitoring of Heavy Metals in Agricultural Soils from Consecutive Applications of Commercial Liquid Pig Manure

Monitoring of Heavy Metals in Agricultural Soils from Consecutive Applications of Commercial Liquid Pig Manure Woo-Ri Go, Ji-Young Kim, Ji-Hyock Yoo, Ji-Ho Lee, Anitha Kunhikrishnan, Jeong-Mi Lee, Kye-Hoon Kim, Doo-Ho Kim and Won-Il Kim (Chemical Safety Division, National Academy of Agricultural Science, Suwon 441-707, Korea, Saemangeum Regional Environmental Office, National Institute Environment Research, Jeonju 560-870, Korea, Department of Environmental Horticulture, The University of Seoul, Seoul 130-743, Korea)

Aqueous Degradation of Imidacloprid and Fenothiocarb using Contact Glow Discharge Electrolysis: Degradation Behavior and Kinetics

Degradation of the pesticides fenothiocarb and imidacloprid in water using contact glow discharge electrolysis (CGDE) achieved rates of 57.8 and 43.2% respectively. Degradation was enhanced using citric or hydrochloric acid to lower the pH to 3.0. Both acids enhanced both the degradation rate and the amount. Fenothiocarb degradation was 77.14% at pH 3 with citric acid, and 100% with HCl. Degradation of imidacloprid at pH 3 was 70.18% with citric acid and 93.02% with HCl. Acidic conditions favor either production of ·OH radicals or enhancement of the degradation of organic compounds by ·OH. Both the degradation rates and amounts for fenothiocarb and imidacloprid were reduced in the presence of methanol due to competition between pesticides and MeOH for ·OH. Degradation of pesticides was not completely inhibited by MeOH. Degradation of both fenothiocarb and imidacloprid using CGDE obeys a first-order rate law with high regression coefficient values (R2>0.99).

Development of Analytical Method for Picoxystrobin in Agricultural Commodities Using GC/ECD and GC/MS

BACKGROUND: This study was conducted to develop analytical method for picoxystrobin in agricultural commodities using GC/ECD and GC/MS. METHODS AND RESULTS: Each steps of analytical method were optimized for determining picoxystrobin residues in various agricultural commodities. The developed methods include acetone extraction, n-hexane/saline water partition and florisil column chromatography for analysis of all samples (apple, potato, green pepper, hulled rice and soybean), and in addition to these steps, solid phase extraction (SPE) was used for analysis of green pepper and n-hexane/acetonitrile partition was used for analysis of hulled rice and soybean. The instrumental conditions were tested for quantitation in GC/ECD and for confirmation in GC/MS. Recovery was in the range of 86~109% with RSD 10.2% and the quantitation limits (LOQ) of method were 0.025 mg/kg in all agricultural commodities. CONCLUSION: The result showed that the developed method can be used to determine picoxystrobin residue in agricultural commodities.

Monitoring and Risk Assessment of Heavy Metals in Edible Mushrooms

BACKGROUND: Many edible mushrooms are known to accumulate high levels of heavy metals. This research was focused on health risk assessment to investigate the mushrooms in Korea, arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg) contaminations in edible mushrooms in cultivated areas were investigated, and health risk was assessed through dietary intake of mushrooms. METHODS AND RESULTS: The heavy metals in mushrooms were analyzed by ICP/MS after acid digestion. Probabilistic health risk were estimated by Monte-Carlo simulation techniques. The average contents of As, Cd, Pb, and Hg were mg/kg, mg/kg, mg/kg, and mg/kg, respectively. The results showed that contents of Cd and Pb did not exceed maximum residual levels established by European Uion regulation (Cd 0.20 mg/kg and Pb 0.30 mg/kg). For health risk assessment, estimated intakes in all age populations did not exceed the provisional tolerable daily intake of As and Hg, provisional tolerable monthly intake of Cd, provisional tolerable weekly intake of Pb. The Hazard Index (HI) were ranged from for As, for Cd, for Pb, and for Hg at general population. CONCLUSION: The HI from the ratio analysis between daily exposure and safety level values was less than 1.0. This results demonstrated that human exposure to heavy metals through dietary intake of mushrooms might not cause adverse effect.

Effect of Electrolyzed Water Combined with Ultrasound and Organic Acids to Reduce Salmonella Typhimurium, Staphylococcus aureus, Bacillus cereus on Perilla Leaves

This study was performed to compared the effectiveness of individual treatments (electrolyzed water: EW, organic acid, and ultrasound) and their combination on reducing foodborne pathogens from perilla leaves. Perilla leaves were innoculated with a cocktail of Salmonella Typhimurium, Staphylococcus aureus, Bacillus cereus. Inoculated perilla leaves were treated with EW combined with different concentration of acetic acid (0.5%, 1.0%, 1.5%, 2.0%) for 1 min at room temperature. Treatment of 3 pathogens on perilla leaves with electrolyzed water com- bined with ultrasound (25 kHz) and 0.5% acetic acid was also performed for 1 min. While the numbers of S. Typhimu- rium and B. cereus showed reduced with increasing acetic acid concentration, there is no difference in the number of S. aureus treated with EW containing 0.5% to 1.5% acetic acid. Discoloration was observed the perilla leaves treated with EW combined with more than 1.0% acetic acid. For all three pathogens, the combined treatment of EW and ultra- sound resulted in additional 0.42 to 0.72 log 10 CFU/g. The maxium reductions of S. Typhimurium and B. cereus were 0.95, 1.23 log 10 CFU/g after treatment with EW combined with 0.5% acetic acid and ultrasound simultaneously. The results suggest that the treatment of EW combined with 0.5% acetic acid and ultrasound increased pathogens reduc- tion compared to individual treatment.

Bioconcentration Factor(BCF) of Perchlorate from Agricultural Products and Soils

BACKGROUND: Perchlorate() is an anion that is extremely water-soluble and environmentally stable. It mostly exists in the form of sodium perchlorate, ammonium perchlorate and potassium perchlorate which are used in rocket fuels, propellants, ignitable sources, air bag inflation systems and explosives. Perchlorate can be taken into the thyroid glands and interfere with iodide uptake. The determination of perchlorate in agricultural products is important due to its potential health impact on humans. The objective of this study was to determine the perchlorate concentrations in the samples of various agricultural products and soils. METHODS AND RESULTS: In this study, samples of cereal(Rice, Barley, Corn, Bean), vegetable(Spinach, Lettuce, Sesame, Chives, Chili, Pumpkin, Tomato), fruit(Apple, Pear, Tangerine, Grape) were analyzed for perchlorate contents. Perchlorate concentrations were analyzed by liquid chromatography-tandem mass spectrometry. The results showed that agricultural products respectively contained perchlorate concentrations in the range of : cereals N.D.~, vegetables , fruits . Bioconcentration factor was in the order of : vegetables > cereals > fruits. Bioconcentration factor was highest follwed by Sesame 37.88, Corn 21.51, Spinach 10.57, Tangerine 4.39, Chives 2.89 and Lettuce 1.90. The recoveries of perchlorate from spiked agricultural products and soils ranged from 87.72~111.26% and 102.09~111.23%. CONCLUSION(S): The health risk assessment results obtained in this study are lower than the RfD(Reference Dose, 0.0007 mg/kg/body weight/day) value as suggested by the Integrated Risk Information System(US IRIS). Our results indicate that, people currently exposed to perchlorate from agricultural products consumption are considered as safe.