• Journal of Bio-Environment Control
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• v.20 no.4
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• pp.247-252
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• 2011

Electrical conductivity, drainage, and irrigation amount of nutrient solution are important factors for determination of the mixing ratio of fresh and reused nutrient solutions in closed-loop soilless culture. Generally a fixed mixing ratio is applied in commercial scale greenhouses using solar radiation-based irrigation system. Although it ensures continuous supply of fresh nutrient solution in the mixing process, occasional discharge of the drainage is inevitably required. This study was conducted to compare the nutrient replenishing effect under different mixing processes and to investigate appropriate mixing process. For this experiment, a fixed mixing ratio (FR), modifiable mixing ratio (MR), and open-loop (OP) as control were applied. Mixing ratio was determined by a set value of EC for dilution of collected drainage in FR and the set values of 1.0 and $2.0dS{\cdot}m^{-1}$ were used as treatments (FR 1.0 and FR 2.0), respectively. In MR, mixing ratio was determined based on EC and volume of drainage within irrigation volume per event. The volume of drainage stored in the drainage tank tended to increase in FR 1.0. Although such trend was not observed in FR 2.0 and MR, the volume of drainage stored in MR was lower than that in FR 2.0. The ion balance of $Mg^{2+}:K^+:Ca^{2+}$ or $SO^{2-}_4:NO^-_3:PO^{3-}_4$ in the drainage and reused nutrient solution changed within a narrow range regardless of treatment.

• Horticultural Science & Technology
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• v.16 no.2
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• pp.247-250
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• 1998

This study was carried out to investigate the effects of changes of ionic strength according to growth stage on growth and flowering of Dendranthema grandiflorum (Ramat.) Kitamura 'Seiun' grown hydroponically in perlite. The stage I, II, and III covered early vegetative growth (27-40 days after planting), latter vegetative growth (41-54 days), and reproductive growth (55-80 days), respectively. The 2 strength (1S and 2S) of nutrient solution were treated in stage I, whereas 3 strengths (1S, 1-2S, and 2S) were treated in stage II. Then, total 9 treatments in stage III were designated by 3 treatments (tap water, 1S, and 2S) for each 3 strengths in stage II. Each nutrient solution was applied 8 times per day. At vegetative growth stage (54 days after planting), stem length was highest when irrigated 8 times a day with 1S nutrient solution. Both photosynthesis and transpiration rate were higher in 1S than those in other treatments (1-2S, 2S), whereas leaf chlorophyll content was highest in 2S treatment. Ion content of plant treated with 2S was higher than other treatments. Growth (plant height, leaf area, stem length), fresh weight, and dry weight of each plant organ after flower bud formation were better in tap water treatment (1-1-0) than other 1S treatments (1-1-1, 1-1-2). Regarding the number of days to flowering, tap water treatment was the most effective. Thus, after flower bud formation supplying tap water or lower concentration of nutrient solution than those used during the vegetative growth stage was economical in saving chemical fertilizers, shortening the number of days to flowering, reducing salt accumulation in media, saving efforts of leaching, and reducing ground water contamination.

• Journal of Plant Biotechnology
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• v.39 no.1
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• pp.23-32
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• 2012

Calcium is an essential nutrient for living organisms, with key structural and signaling roles. Its deficiency in plants can result in poor biotic and abiotic stress tolerance as well as reduced crop quality and yield. Calcium deficiency in humans causes various diseases such as osteoporosis and rickets. Biofortification of calcium in various food crops has been suggested as an economic and environmentally advantageous method to enhance human intake of calcium. Recent efforts to increase the levels of calcium in food crops have used calcium/proton antiporters ($CAXs$) and modified one to increase calcium transport into vacuoles through genetic engineering. It has been reported that overall calcium content of transgenic plants has been increased in their edible portions with some adverse effects. In conclusion, biofortification of calcium will add more value in crops as well as will be beneficial for animal and human. Therefore, more fundamental studies on the mechanisms of calcium ion storage and transporting are essential for more effective calcium biofortification.

• Journal of Radiation Industry
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• v.6 no.1
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• pp.75-82
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• 2012

Swine wastewater was treated using a unique sequence of ion exchange membrane bed system (IEBR). Organic matter and nutrient in swine wastewater was pre-treated by electron beam irradiation. The optimal dose for solubilization of organic matter in swine wastewater ranged from 20 kGy to 75 kGy. The carbohydrates, proteins, and lipids were investigated as the solubilized organic fraction of swine wastewater and proteins and lipids mainly contained of the solubilized organic matter. The solubilization of organic matter in swine wastewater was affected by the combination effect of temperature and a dose. The average chemical oxygen demand (COD) removal efficiency under room temperature conditions was 67.1%, while that under psychrophilic conditions was 54.6%. For removal of ammonia, the removal efficiency decreased from 63.6% at $23^{\circ}C$ to 33.5% $16.8^{\circ}C$. On the other hand, the removal of phosphorus was not a function of temperature. Struvite was one of main mechanisms in anaerobic condition.

• Journal of the Korean institute of surface engineering
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• v.56 no.6
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• pp.427-436
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• 2023

In the industry, it is recognized that human activities significantly lead to a large amount of wastewater, mainly due to the increased use of water and energy. As a result, the growing field of wastewater resource technology is getting more attention. The common technology for hydrogen production, water electrolysis, requires purified water, leading to the need for desalination and reprocessing. However, producing hydrogen directly from wastewater could be a more cost-effective option compared to traditional methods. To achieve this, a series of first-principle computational simulations were conducted to assess how waste nutrient ions affect standard electrolysis catalysts. This study focused on understanding the adsorption mechanisms of byproducts related to the oxygen evolution reaction (OER) in anion exchange membrane (AEM) electrolysis, using Co₃O₄ as a typical non-precious metal catalyst. At the same time, efforts were made to develop a comprehensive free energy prediction model for more accurate predictions of OER results.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.5
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• pp.386-390
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• 2013

Recently, special attention has been given to acid rain and its problem to environment such as acid precipitation and air pollution in East Asia. In the present study, rainwater samples were collected from Apr to Nov in 2012. The samples were chemically characterized for the assessment of emission sources. Suwon and Yeoju regions, typical agricultural areas in South Korea, were chosen for study sites. Ion composition and cation-affected neutralization were determined to evaluate the contribution of cations to the acidity of rainwater. Ion and electrical conductivity between the measured and the estimated showed high correlation. The cations observed in Suwon and Yeoju were $Na^+$ > $NH_4{^+}$ > $K^+$ > $Ca^{2+}$ > $Mg^{2+}$ > $H^+$ and $Na^+$ > $K^+$ > $NH_4{^+}$ > $Ca^{2+}$ > $Mg^{2+}=H^+$, respectively. The anions of all sites were $SO{_4}^{2-}$ > $NO_3{^-}$ > $Cl^-$. While the amounts of sulfate, one of the major dissolved components of rainwater, were 77.6 and 75.6 ueq $L^{-1}$ in Suwon and Yeoju, the ones of NSS-$SO{_4}^{2-}$ (Non-Sea Salt sulfate) were 83 and 82% in Suwon and Yeoju, respectively. The comparison of observed pH values ($pH_{obs}$) with the theoretical pH values ($pH_{the}$) showed that the neutralization of rain water considerably went along during the study periods. The highest amounts of rainfall throughout the year in Suwon and Yeoju were 572.3 and 484.6 mm in July, and its corresponding nitrogen loadings in Suwon and Yeoju were 5.28 and 3.50 kg $ha^{-1}$, respectively. The major ion contents for crop growth with $SO{_4}^{2-}$, $Ca^{2+}$, $K^+$ and $Mg^{2+}$ were 51.7, 5.2, 11.8 and 1.8 kg $ha^{-1}$ in Suwon and 34.2, 4.0, 4.2 and 1.1 kg $ha^{-1}$ in Yeoju.

• Korean Journal of Environmental Agriculture
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• v.23 no.3
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• pp.133-137
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• 2004

Recently, saw dust manure has been widely used in horticultural crop production in Korea. Animal manure is produced by decaying of livestock manure mixed with saw dust, and contained higher nutrients and ion concentration than the traditional manure made from rice straw and grasses. Therefore, a continuous application of the animal manure disregarding to soil characteristics may be ruined the soil conditions. This study was conducted to investigate the transportation of the nitrogen, phosphate, potassium, and ion concentration of the animal manure applied to volcanic and non-volcanic soils in Jeju islana Soil chemical analysis were done before and 180 days after animal manure application. After animal manure application, $NO_3$-N moved up to 90cm in volcanic soil, while the movement was limited to 60 cm in non-volcanic soil. Phosphate concentration was high up to 30 cm, where crop roots are mainly distributed, in volcanic soil, however, the phosphate moved up to 60 cm in volcanic soil. Exchangeable potassium moved up to 90 cm in volcanic soil, but the movement wns limited up to 60 cm in non-volcanic soil. For both soil types, no significant different in ion concentrations was observed up to 60 cm in soil depth, though the concentrations were higher in volcanic ash soils as compared to the non-volcanic ash soils.

• Journal of the East Asian Society of Dietary Life
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• v.22 no.5
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• pp.657-666
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• 2012

The purpose of this study was to improve the quality of Korean traditional sauce products by producing short-term green gochujang with cheongyang pepper powder. To determine its antioxidant compounds and activities, we examined vitamin C, capsaicinoid, total phenolic, and total flavonoid contents, as well as electron-donating, SOD-like, ferrous ion-chelating, and nitrite-scavenging activities. Vitamin C content of short-term green gochujang was higher in CON-M than in the sample, whereas capsaicinoid content increased as the amount of cheongyang pepper powder increased. Total phenolic content, total flavonoid content, electron-donating activity, and nitrite-scavenging activity were higher in the sample than in CON-M, and the contents increased as the amount of meju powder increased. Green gochujang containing the highest amount of cheongyang pepper powder showed the highest SOD-like, and ferrous-ion chelating activities as well as superior nutrient contents, compared to red gochujang.

• The Korean Journal of Ecology
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• v.6 no.4
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• pp.243-249
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• 1983

Absorption pattern of potassium, calcium, phosphate and nitrate ions, and the pH change during ion-absorption at pH 3.0-11.0 by Oryza sativa L. were studied to investigate indirectly the evidence of H^+-efflux by ATPase. The rice seedlings which were grown either in $L^{\circ} -dark or in L^+-sunlight$, were used both in each ion-absorption to compare with one another. The uptake rate of these ions appeared to favor more in $L^+than in L^{\circ}$, over all range in pH, nearly with the same pattern. The absorption of potassium resulted in bell shape and that of calcium increased linearly to the alkali range. The shape of phosphate-absorption showed nearly the t-distribution curve with high value in acid range and the uptake of nitrate resulted in the dual peaks, but higher in acid range. The pH of the external solution changed from the range of 3.5-11.0 to 3.5-7.0 after lhr-absorptioin, and further acidified after 3hr-absorption. It is suggested that the pH change of the external solution be affected by $ H^+-efflux$ which may be caused by the ATP-hydrolysis.

• Korean Journal of Agricultural and Forest Meteorology
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• v.4 no.4
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• pp.237-247
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• 2002

Air pollution by acid pollutants is problematic in the whole world. Water acidification has already been deteriorating the forest ecosystem. This study was conducted to analyze the acidity and chemical composition of the open precipitation and throughfall at forests with various geographic locations in Korea. The results of this study are as follows; The open precipitation pH was lowest in Seochun. The throughfall pH showed some buffering capacity in only Quercus mongolica stands. In Pinus rigida(Shingal and Seochun) stands, there was little difference from the open precipitation. Chemical composition of the open precipitation for each sampling site showed that $Ca^{2+}$, N $H_{4}$$^{+}$ and S $O_{4}$$^{2-}$ concentrations had higher value than other ions, and except these ions, the small quantity of ions showed different properties to each site. Changes of ion concentrations in the throughfall showed a tendency to increase. ion concentrations of the throughfall increased with washout and nutrient leaching from the trees. In conclusion, the influence was extended to the pure zone, and the frequency of acid rain is increasing. But, if the deposition of pollutants exceeds the capacity of purification, it would damage forest ecosystem. Further investigations are necessary to identify tolerant tree species to acid pollutants.nts.