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Choi B.-Y.,Korea University | Choi B.-Y.,Korea Environmental Industry and Technology Institute | Yun S.-T.,Korea University | Yun S.-T.,University of Calgary | And 5 more authors.
Hydrological Processes | Year: 2010

We evaluated sources and pathways of groundwater recharge for a heterogeneous alluvial aquifer beneath an agricultural field, based on multi-level monitoring of hydrochemistry and environmental isotopes of a riverside groundwater system at Buyeo, Korea. Two distinct groundwater zones were identified with depth: (1) a shallow oxic groundwater zone, characterized by elevated concentrations of NO3 - and (2) a deeper (>10-14 m from the ground surface) sub-oxic groundwater zone with high concentrations of dissolved Fe, silica, and HCO3 -, but little nitrate. The change of redox zones occurred at a depth where the aquifer sediments change from an upper sandy stratum to a silty stratum with mud caps. The δ18O and δ2H values of groundwater were also different between the two zones. Hydrochemical and δ18O-δ2H data of oxic groundwater are similar to those of soil water. This illustrates that recharge of oxic groundwater mainly occurs through direct infiltration of rain and irrigation water in the sandy soil area where vegetable cropping with abundant fertilizer use is predominant. Oxic groundwater is therefore severely contaminated by agrochemical pollutants such as nitrate. In contrast, deeper sub-oxic groundwater contains only small amounts of dissolved oxygen (DO) and NO3 -. The 3H contents and elevated silica concentrations in sub-oxic groundwater indicate a somewhat longer mean residence time of groundwater within this part of the aquifer. Sub-oxic groundwater was also characterized by higher δ18O and δ2H values and lower d-excess values, indicating significant evaporation during recharge. We suggest that recharge of sub-oxic groundwater occurs in the areas of paddy rice fields where standing irrigation and rain water are affected by strong evaporation, and that reducing conditions develop during subsequent sub-surface infiltration. This study illustrates the existence of two groundwater bodies with different recharge processes within an alluvial aquifer. © 2009 John Wiley & Sons, Ltd.

Al-Hamadani Y.A.J.,University of South Carolina | Chu K.H.,University of South Carolina | Flora J.R.V.,University of South Carolina | Kim D.-H.,Korea Environmental Industry and Technology Institute | And 4 more authors.
Ultrasonics Sonochemistry | Year: 2016

Sonocatalytic degradation experiments were carried out to determine the effects of glass beads (GBs) and single-walled carbon nanotubes (SWNTs) on ibuprofen (IBP) and sulfamethoxazole (SMX) removal using low and high ultrasonic frequencies (28 and 1000 kHz). In the absence of catalysts, the sonochemical degradation at pH 7, optimum power of 0.18 W mL-1, and a temperature of 15 °C was higher (79% and 72%) at 1000 kHz than at 28 kHz (45% and 33%) for IBP and SMX, respectively. At the low frequency (28 kHz) H2O2 production increased significantly, from 10 μM (no GBs) to 86 μM in the presence of GBs (0.1 mm, 10 g L-1); however, no enhancement was achieved at 1000 kHz. In contrast, the H2O2 production increased from 10 μM (no SWNTs) to 31 μM at 28 kHz and from 82 μM (no SWNTs) to 111 μM at 1000 kHz in the presence of SWNTs (45 mg L-1). Thus, maximum removals of IBP and SMX were obtained in the presence of a combination of GBs and SWNTs at the low frequency (94% and 88%) for 60 min contact time; however, >99% and 97% removals were achieved for 40 and 60 min contact times at the high frequency for IBP and SMX, respectively. The results indicate that both IBP and SMX degradation followed pseudo-first-order kinetics. Additionally, the enhanced removal of IBP and SMX in the presence of catalysts was because GBs and SWNTs increased the number of free OH radicals due to ultrasonic irradiation and the adsorption capacity increase with SWNT dispersion. © 2016 Elsevier B.V. All rights reserved.

Kim H.-J.,Korea Institute of Machinery and Materials | Kim H.-J.,University of Tokyo | Han B.,Korea Institute of Machinery and Materials | Kim Y.-J.,Korea Institute of Machinery and Materials | And 2 more authors.
Building and Environment | Year: 2012

We have developed a new test method for differentiating the gas-removal performance of indoor air cleaners by using Fourier-transfer infrared measurements and a clean-air-delivery-rate (CADR) calculation method in a closed test chamber (4 m3). Eighteen air cleaners were evaluated using both the new method and the current Korean and Japanese test methods, using ammonia, acetic acid, acetaldehyde, and toluene as test gases. The Association of Home Appliance Manufacturers' statistical method for calculating regression line slopes of test chamber gas concentrations during air cleaner operation was used. The standard deviations of CADRs for ammonia, acetic acid, and toluene, gases that were easily removed by the air cleaners in the test chamber, were 3.2, 751.3, and 13.4 times higher, respectively, than the gas-removal efficiencies determined using the current arithmetic calculation method, which uses the ratio of concentrations after 0 and 30 min of air cleaner operation. The new test method clearly differentiated the gas-removal performances of various air cleaners, especially for gases that are quickly removed by indoor air cleaners. Also, the single-pass removal efficiency of the air cleaners was obtained with a simple calculation: CADR/flow rate/0.83. © 2011 Elsevier Ltd.

Chung S.,Gwangju Institute of Science and Technology | Lee J.K.,Gwangju Institute of Science and Technology | Ocon J.D.,Gwangju Institute of Science and Technology | Son Y.-I.,Korea Environmental Industry and Technology Institute | Lee J.,Gwangju Institute of Science and Technology
Applied Chemistry for Engineering | Year: 2014

With the world population's continuous growth and urban industrialization, capacitive deionization (CDI) has been proposed as a next-generation water treatment technology to augment the supply of water. As a future water treatment method, CDI attracts significant attention because it offers small energy consumption and low environmental impact in comparison to conventional methods. Carbon electrodes, which have large surface area and high conductivity, are mainly used as electrode materials of choice for the removal of ions in water. A variety of carbon materials have been investigated, including their adsorption- desorption behavior in accordance to the specific surface area and pore size distribution. In this review, we analyzed and highlighted these carbon materials and looked at the impact of pore size distribution to the overall CDI efficiency. Finally, we propose an optimal condition in the interplay between micropores and mesopores in order to provide the best electrosorption property for these carbon electrodes. © 2014 The Korean Society of Industrial and Engineering Chemistry. All rights reserved.

Yoon H.,Kyungpook National University | You Y.-H.,Kyungpook National University | Kim Y.-E.,Kyungpook National University | Ja Kim Y.J.,Korea Environmental Industry and Technology Institute | And 2 more authors.
Journal of Microbiology and Biotechnology | Year: 2013

The ectomycorrhizal fungus Tricholoma matsutake grows symbiotically with Pinus densiflora. Phenylalanine ammonia-lyase (E.C. catalyzes the conversion of L-phenylalanine to trans-cinnamic acid. The role of fungal phenylalanine ammonia-lyase, however, has not been clear until now. In this study, the gene encoding phenylalanine ammonia-lyase (PAL), which was isolated from T. matsutake, was cloned and characterized. The PAL gene (tmpal) consists of 2,160 nucleotides, coding for a polypeptide containing 719 amino acid residues. The deduced amino acid sequence of tmpal from T. matsutake shows high identity (70%) with that from Laccaria bicolor. Comparative analysis of the PAL genes among T. matsutake and other species of the class Agaricomycetes showed that both active sites and binding sites were significantly conserved among these genes. The transcriptional analysis of the PAL gene revealed a differential gene expression pattern depending on the developmental stages (mycelium, primordium, stipe, pileus, and gills) of T. matsutake. These results suggest that the PAL gene in T. matsutake plays an important role in multiple physiological functions. © 2013 by The Korean Society for Microbiology and Biotechnology.

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