• Korean Journal of Organic Agriculture
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• v.5 no.1
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• pp.45-66
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• 1996

In Korea there is still no basic standard for organic agriculture and organic farmers in Korea do not follow the minimum requirements of IFOAM basic standard Most of them just practice the organic agriculture applying organic fertilizer, commercial seed without legume, rotation and green manure. But they believe this system is a absolutely environmental friendly agricultural system and it produce a safe agricultural product since they are not aware of the basic standard of organic agriculture at all. The overuse of organic fertilizer by some organic farmer have caused some severe problems risk for nitrate and phosphate leaching. In soil profile showed the potential risk for nitrate and phosphate leaching. In the paper, it is discussed on the environmental friendly function and the safe vegetable production by european organic agriculture which keeps the internationally recognized basic standards of organic agriculture. Therefore it is strongly recommended that korean organic farmer have to follow the IFOAM it is strongly in order to practice the environmental agriculture and produce the safe food. And it is also necessary to introduce to Korea the basic standard of organic agriculture which coincides with IFOAM's and Codex of FAO/WHO immediately if they really want to practice an organic agriculture in the country.

• Korean Journal of Materials Research
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• v.21 no.9
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• pp.502-508
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• 2011

The goal of the present work was to investigate the development of a geopolymeric ceramic material from a mixture of mine residue, coal fly ash, blast furnace slag, and alkali activator solution by the geopolymer technique. The results showed that the higher compressive strength of geopolymeric ceramic material increased with an increase in active filler (blast furnace slag + coal fly ash) contents and with a reduction of mine residue contents. The geopolymeric ceramic had very high early age strength. The compressive strength of the geopolymeric ceramic depended on the added active filler content. The maximum compressive strength of the geopolymeric ceramic containing 20 wt.% mine residue was 141.2 MPa. The compressive strength of geopolymeric ceramic manufactured by adding mine residue was higher than that of portland cement mortar, which is 60 MPa, when cured for 28 days. SEM observation showed the possibility of having amorphous aluminosilicate gel within geopolymeric ceramic. XRD patterns indicate that the geopolymeric ceramic was composed of amorphous aluminosilicate, calcite, quartz, and muscovite. The Korea Standard Leaching Test (KSLT) was used to determine the leaching potential of the geopolymeric ceramic. The amounts of heavy metals were noticeably reduced after the solidification of mine residue with active filler.

• Journal of the Korean earth science society
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• v.42 no.4
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• pp.412-424
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• 2021

Understanding the distribution of heavy metals in sediment is necessary because labile heavy metals can partition into the water column and bioaccumulate in aquatic organisms. Here we investigated six heavy metals (Co, Cu, Mn, Ni, Pb, and Zn) in sediment cores using a five-step sequential leaching method to examine the occurrence of heavy metals in the sediment. The results showed that all elements, except Mn, are depleted in the exchangeable and carbonate fractions. However, heavy metal concentrations are much higher in the Fe-Mn oxide and organic matter fractions, especially for Cu, indicating enrichment in the organic matter fraction. Furthermore, contamination parameters (contamination factor and geoaccumulation index) indicate that Mn contamination is high, primarily derived from anthropogenic sources, presenting a potential risk to ecosystems in the Nakdong River.

• Advances in environmental research
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• v.7 no.3
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• pp.225-237
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• 2018

The sorption of metal ions with low-cost adsorbents plays an important role in sustainable development. In the present study, the efficacy of sugarcane bagasse, rain tree fruits (samaneasaman), banana stem and their mixtures, used as bio-sorbents, in the removal of Cu(II) and Pb(II) ions from aqueous solution is evaluated. Batch studies are conducted, and residual ions were measured using Inductively Coupled Plasma (ICP)-atomic spectrometer. Effect of pH, initial metal ion concentration, reaction time and adsorbent dosage are studied. The Pb(II) removal efficiency was observed to be 97.88%, 98.60% and 91.74% for rain tree fruits, banana stem and a mixture of adsorbents respectively. The highest Cu(II) ion removal was observed for sugarcane bagasse sorbent with an efficiency of 82.10% with a pH of 4.5 and a reaction time of 90 min. Finally, desorption studies were carried out to study the leaching potential of adsorbent, and it was found that the adsorbent is stable in water than the other leaching agents such as HCl, ammonium acetate, Sodium EDTA. Hence, these adsorbents can be effectively used for the removal of these heavy metals.

• Corrosion Science and Technology
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• v.7 no.3
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• pp.179-181
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• 2008

With nano-$SiO_2$ and sulphate acid, a kind of colloid electrolyte is synthesized by sol-gel method. It is placed outside the reference electrode as a layer of gel electrolyte so as to decrease the leaching of $Cu^{2+}$ and increase the life of the reference electrode. The performance of the gel electrode in simulating soil solution is measured as follows: the potential of the electrodes ranging from 60 mV to 80 mV (vs. SCE) with potential variation no more than $\pm10mV$, enough resistance to polarization. The $Cu^{2+}$ effusion rate of the reference electrode without gel electrolyte is 3 times that with colloid electrolyte, which means that gel electrolyte can extend the life of the reference electrode significantly.

• Journal of Environmental Health Sciences
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• v.30 no.2
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• pp.167-172
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• 2004

In this study, we carried out the research for the recycling potential of the dyeing wastewater treatment sludges as construction materials. The incineration ash of sludges were solidified as interlocking block in condition of sludge/cement ratio 2.5%, 5.0% and 10%, respectively. Those interlocking blocks were cured for 3days, 7days and 28days in ambient air condition, respectively. The results of this research were summarized as follows: The dyeing wastewater treatment sludges was below the Korea Leaching Limit. After incineration, the ash was manufactured as interlocking block. Bendable strength over 50kg$_{f}$/$\textrm{cm}^2$ suitable for interlocking block was obtained only when the sample was cured for 7days at sludge/cement ratio 2.5% and 5.0%. Hygroscopic ratio of interlocking block was above the Korea Industry Standard. We think that recycling of the incineration ash from dyeing wastewater treatment sludges to interlocking block will have high potential possibility.y.

• Korean Journal of Environmental Agriculture
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• v.21 no.1
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• pp.7-16
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• 2002

Contamination of groundwater by agrochemicals used in the regional-scale Is now a major environmental problem, and this is especially true for Cheju island where virtually all potable water is from groundwater. The objective of this study was to assess leaching potential of eight pesticides in soils of citrus orchards using groundwater ubiquity score (GUS), retardation factor (RF) and attenuation factor (AF). Considering GUS estimated in 30 citrus orchard soils, metribuzin and metolachlor were classified as leacher, alachlor in volcanic ash soils and linuron in non-volcanic soils were classified as leacher, but chlorothalonil and chlorpyrifos were classified as non-leacher. For RF values, metribuzin was classified to be mobile in soils of low organic carbon, metolachlor and alachlor were classified to be moderately immobile in most soils, but linuron, diuron, diniconazole, chlorothalonil and chlorpyrifos were all classified to be very immobile. For AF values, diniconazole, chlorothalonil, and chlorpyrifos were classified to be very unlikely leachable in all of the soils, metribuzin was classified to be likely leachable, and metolahclor, alachlor, linuron and diuron were classified to be leachable only in non-volcanic soils. Although there were some variations in the relative potential of teachability of pesticides estimated with the three different indices, the ranking was essentially determined on the base of the intrinsic properties of the chemicals and environmental properties. Among the eight pesticides, metribuzin, metolachlor, and alachlor, which have high water solubility and low $K_{oc}$ values, have a significant leaching potential especially in non-volcanic ash soils of low organic carbon. But diniconazole, chlorothalonil, and chlorpyrifos, which have low water solubility and high $K_{oc}$ values, were classified to be very immobile in all of the soils. Therefore, to lower the possibility of pesticide contamination of the groundwater in Cheju island, those pesticides which have high water solubility and low $K_{oc}$ values should be used with care in soils of low organic carbon including non-volcanic ash soils.

• The Korean Journal of Pesticide Science
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• v.8 no.1
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• pp.46-53
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• 2004

Adsorption and leaching characteristics of hexaconazole were investigated to estimate the mobility potential of the compound in the soil environment. As well fitted to Freundlich adsorption isotherm, adsorptivity of hexaconazole, ranged 10.56-18.01 of Kf values, seemed high enough to be immobile in soil. This chemical leached more faster from fresh soil with rice plants. Most of $^{14}C$ (86-99% of originally applied $^{14}C$) was distributed within 5 cm soil depth from surface. Considering Koc values of 1,400-1,552 and Groundwater Ubiquity Score (GUS) indices of 1.25-1.35 as well as results from leaching experiment with soil column, hexaconazole falls into the category of improbable leacher, suggesting little mobility in soil.

• Journal of Soil and Groundwater Environment
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• v.9 no.1
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• pp.95-103
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• 2004

This study has been assessed the influence of applying sewage sludge to soil amendments on the sorption properties, and leaching potential of three commonly used organophosphorus pesticides, Diazinon, Fenitrothion, and Chlorpyrifos. A sandy soil with a low content of organic carbon was treated with sewage sludge with a ratio sandy soil sludge ratio of 30:1. The sorption was determined with the batch equilibrium technique. The sorption isotherms could be described by Freundlich equation. The Freundlich constant, K value which measures sorption capacity, were 3.97, 9.94, 22.48 for Diazinon, Fenitrothion, Chlorpyrifos in non-amended soil. But in amended soil, K value was 12.58, 28.47, and 61.21 for Diazinon, Fenitrothion, and Chlorpyrifos. The overall effect of sewage sludge addition to soil was to increase pesticides adsorption, due to the high sorption capacity of the organic matter. The effect of sludge on the leaching of pesticides in the soil was studied using packed soil columns. Total recoveries of pesticides in soil and leachate with leaching in soil column, were in the range of about 73∼84%, was reduced with the passage of time. Diazinon moved more rapidly than Chlorpyrifos in the unamended soil due to greater sorption and lower water solubility of Chlorpyrifos. Total amounts of pesticides leached from the sewage sludge amended soils were significantly reduced when compared with unamended soils. This reduction may be mainly due to and increase in sorption in amended soils, as a consequence of the increase in the organic matter content.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.2926-2936
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• 2021

Rare-earth (RE) industries generate a massive amount of radioactive residue containing high thorium concentrations. Due to the fact that thorium is considered a non-economic element, large volume of these RE processed residues are commonly disposed of without treatment. It is essential to study an appropriate treatment that could reduce the volume of waste for final disposition. To this end, this research investigates the applicability of carbon-based adsorbent in separating thorium from aqueous phase sulphate is obtained from the cracking and leaching process of solid rare-earth by-product residue. Adsorption of thorium from the aqueous phase sulphate by carbon-based electrodes was investigated through electrosorption experiments conducted at a duration of 180 minutes with a positive potential variable range of +0.2V to +0.6V (vs. Ag/AgCl). Through this research, the specific capacity obtained was equivalent to 1.0 to 5.14 mg-Th/g-Carbon. Furthermore, electrosorption of thorium ions from aqueous phase sulphate is found to be most favorable at a higher positive potential of +0.6V (vs. Ag/AgCl). This study's findings elucidate the removal of thorium from the rare-earth residue by carbon-based electrodes and simultaneously its potential to reduce disposal waste of untreated residue.