• Title/Summary/Keyword: Leaching potential

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Potential Element Retention by Weathered Pulverised Fuel Ash : II. Column Leaching Experiments (풍화 석탄연소 고형폐기물(Pulverised Fuel Ash)의 중금속 제거가능성 : II. 주상용출실험)

  • Lee, Sanghoon
    • Economic and Environmental Geology
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    • v.28 no.3
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    • pp.259-269
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    • 1995
  • Column leaching tests were conducted using fresh and weathered pulverised fuel ash of some 17 and 40 years old from two major British power plants, with deionised water and simulated synthetic industrial leachate. The former was to see the leaching behaviour of weathered ash and the latter was to see if the formation of secondary products from water and PFA interaction and ameliorating effect in removing metals from industrial leachates. Fresh PFA liberates elevated concentrations of surface-enriched inorganics, including Ca, Na, K, B, $Cr_{total}$, Li Mo, Se and $SO^{2-}_4$. This might indicate their association with the surface of PFA particles. In the column leaching tests using weathered ash and deionised water, elements are not readily leached but are released more slowly, showing relatively constant concentrations. For the case of weathered ash, some readily soluble surface-enriched elements appears to have been liberated in their early stage of leaching and the liberation of glass associated elements are thought to be more important function in controlling the element concentration. The result from column leaching tests exceed for a number of elements when compared with various Water Standards and suggests the leachate from PFA disposal mound needs dilution to achieve target concentrations. PF A shows element retention effect for many elements, including B, Fe, Zn, Hg, Ni, Li and Mo, in the order of fresh Drax ash > weathered Drax ash > Weathered Meaford ash in retaining capacity. Geochemical modelling using a computer program WATEQ4F reveals some solubility controlling secondary solid products. These include $CaSO_4{\cdot}2H_2O$ for Ca, $Al(OH)_3$ for Al and $Fe(OH)_3$ for Fe.

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Effect of Activated Carbon, Orpar or Zeolite on Leaching Loss of Fenitrothion, Triadimefon and Diniconazole in Model Green of Golf Course (골프장 모형그린에서 활성탄, Orpar또는 Zeolite의 처리가 Fenitrothion, Triadimefon, Diniconazole의 용탈에 미치는 영향)

  • Oh, Sang-Sil;Koh, Yong-Ku;Chung, Jong-Bae;Hyun, Hae-Nam
    • Applied Biological Chemistry
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    • v.44 no.2
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    • pp.97-102
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    • 2001
  • Cheju island depends on a hydrogeologically vulnerable aquifer system as its principle source of drinking water. Most of golf courses are located in the area which is important for the ground water recharge, and pesticides are applied to golf courses often at relatively high rates. Therefore, turf pesticides in golf course should be applied without adversely impacting ground water. In this experiment, downward movement of pesticides was monitored in model greens of golf course, where different adsorbents were layered in 3-cm thickness at 35-cm depth, and effect of the adsorption layer on the leaching loss of pesticides was investigated. Major leachings were observed in the periods of heavy rain and very limited leaching was observed under artificial irrigation. Fenitrothion and triadimefon, which have relatively short persistence and high adsorption coefficient, were found in the leachate in low concentrations only at the first rainfall event, around 20 days after the pesticide application. However, diniconazole, which has a relatively long half-life (97 days), was detected in the leachate during the whole period of experiment and concentration was much higher than those of the other pesticides. Maximum leachate concentrations were 1.9, 10.3, and 84.5 ${\mu}l^{-1}$ for fenitrothion, triadimefon, and diniconazole, respectively. Therefore, in golf course green which allows rapid water percolation and has extremely low adsorption capacity, persistence in soil could be more important factor in determination of leaching potential of pesticides. Total quantity of pesticides leached from the model green was <0.2% for fenitrothion and triadimefon and 1.8% for diniconazole. Adsorption layers significantly reduced pesticide leaching, and active carbon and Orpar were more effective than zeolite. In the model green having adsorption layer of active carbon or Orpar, leaching loss of pesticides was reduced below 0.01% of the initial application.

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Mineralogical and chemical characterization of arsenic solid phases in weath-ered mine tailings and their leaching potential (풍화광미내 고상 비소의 광물학적${\cdot}$화학적 특성 및 용출 가능성 평가)

  • 안주성;김주용;전철민;문희수
    • Economic and Environmental Geology
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    • v.36 no.1
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    • pp.27-38
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    • 2003
  • Arsenic contamination around Au-Ag mining areas occurs mainly from the oxidation of arsenopyrite which is frequently contained in mine tailings. In weathered tailings, oxidation of sulfide minerals typically results in the formation of abundant ferric (oxy)hydroxides or (oxy)hydroxysulfates near the tailings surface, and arsenic may be associated with these secondary precipitates. In this study, solid phases of arsenic in weathered tailings of some Au-Ag mines were investigated through the SEM/EDS and sequential extraction analyses. The stability of As solid phases and the leaching potential were assessed with the variation of pH and Eh conditions. Oxidation of sulfides in the tailings samples was indicated by depletion of S molar concentrations compared to As and heavy metals. Under XRD examinations, jarosite as an Fe-oxyhydroxysulfate was found in the tailings of Deokeum, Dongil and Dadeok, and scorodite as an As-bearing crystalline mineral was identified from Dadeok which has the highest concentration of As (4.36 wt.%). Beudantite-like phases and some Pb-arsenates were also found under SEM/EDS analysis, and most of As phases were associated with Fe-(oxy)hydroxides and (oxy)hydroxysulfates despite a few arsenopyrite from Samgwang and Gubong. Sequential extraction analysis also showed that As was present predominantly as coprecipitated with Fe hydroxides from Dongil, Dadeok and Myungbong (72∼99%), and as sulfides (58%) and Fe hydroxide-associated forms (40%) from Samgwang and Gubong. In the tailings leaching experiment, As was released with high amounts by the dissolution of As-bearing Fe(oxy)hydroxysulfates in the lowest pH (2.7) conditions of Deokeum, and by desorption under alkaline conditions of Samgwang and Gubong. Higher leaching rates of arsenite(+3) were found under acidic conditions, which pose a higher risk to water quality. Changes in pH and Eh conditions coupled with microbial processes could influence the stabilities of the As solid phases, and thus, time amendments or landfilling of weathered tailings may result in enhanced As mobilization.

Movement for the Various Coated and Uncoated Potassium(K) Fertilizers in the Turfgrass Soils of Golf Course (골프장의 잔디 토양에서 다양한 코팅 및 비코팅 칼륨(K) 비료의 이동성 평가)

  • Kim, Hong-Ki;Han, Seok-Soon;Kwon, Sang-Moon;Kim, Hee-Jung;Woo, Sun-Hee;Lee, Moon-Soon;Baek, Ki-Tae;Lee, Bong-Gyu;Lee, Sang-Sung;Kim, In-Su;Chung, Keun-Yook
    • Asian Journal of Turfgrass Science
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    • v.23 no.1
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    • pp.133-142
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    • 2009
  • This study was initiated to evaluate the K leaching potential in the green soils and K uptake by the turfgrass in the golf course using the K fertilizers. The turfgrass, Floradwarf bermudagrass(Cynodon dactylon L. $P_{ERS}$.) was planted and grown in the mixture of sand and peat moss in this lysimeter study. Eight representative K fertilizers, such as, monopotassium phosphate (MKP), KCL, $K_2SO_4$, $KNO_3$, CKCl, $CK_2SO_4$, $CKNO_3$, and 0-20-20(liquid) were used in this study. Based on the total K quantity of leachate collected during the whole 12 weeks, 0-20-20 is the K fertilizers the most contributing to the leaching of K, then MKP, the second, KCL, the third, and finally $KNO_3$ are K fertilizers contributing to the K leaching. However, most amount of K applied and collected in the lysimeter were leached during the first period of two and four weeks, compared to that of K leached during the second period of six, eight, ten, and twelve weeks. Application of CKCL and $CK_2SO_4$ producted the largest amount of total dry matter, then MKP and KCL, $KNO_3$ and $CKNO_3$, 0-20-20 in second group. However, except $K_2SO_4$, most K fertilizer sources such as MKP, KCL, $KNO_3$, CKCL, $CK_2SO_4$, $CKNO_3$, 0-20-20 showed the largest amount of K uptake, except $K_2SO_4$. Therefore, based on the K leaching, dry matter production, and plant K uptake, it appears that the coated fertilizers, CKCL, $CKNO_3$, and $CK_2SO_4$ are the environmentally sound fertilizers recommended in the turfgrass green soil of golf course.

Information on Movement of the Phosphorus(P) Fertilizers in the Turfgrass Soils of Golf Course (골프장의 잔디 토양에서 인산 비료의 이동성 평가를 위한 정보 구축)

  • Chung, Keun-Yook;Baek, Ki-Tae;Ko, Seong-Hwan;Noh, Jae-Goan;Lee, Kyung-Ho;Woo, Sun-Hee
    • The Journal of the Korea Contents Association
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    • v.8 no.8
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    • pp.285-292
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    • 2008
  • This study was initiated to evaluate the Phosphorus(P) leaching potential in the putting green soils and P uptake by the turfgrass in the golf course using the P fertilizers. The turfgrass, Floradwarf bermudagrass(Cynodon dactylon L. PERS,) was planted and grown in the mixture of sand and peat moss in this lysimeter study. Five representative P fertilizers, such as, ammonium polyphosphate (APP), monopotassium phosphate (MKP), MAP(monoammonium phosphate), 0-20-20(liquid), and concentrated superphosphate(CSP, solid) were used in this study. Based on the total P quantity of leachate collected during the whole 12 weeks, MKP and APP are the first group of P fertilizers contributing to the leaching of P, then MAP and 0-20-20 are the second group of P fertilizers causing the P leaching. Finally, CSP is the third group of P fertilizer resulting in the P leaching. However, most of P applied and collected in the lysimeter were leached during the first period of two and four weeks, compared to that of P leached during the second period of six, eight, ten, and twelve weeks. Applications of MAP, APP and CSP, MKP and 0-20-20 in order produced the largest amount of total dry matter. However, APP, MKP and MAP, CSP and 0-20-20 in order showed the largest amount of P uptake. Therefore, based on the data of P leaching, dry matter production, and plant P uptake, it appears that CSP, 0-20-20, and MAP are the environmentally sound fertilizers recommended in the turfgrass putting green soil of golf course.

The Development of Mathematics Teacher Education Program Using Explorative Computer Softwares (탐구형 소프트웨어를 활용한 수학 교사교육 프로그램 개발 탐색)

  • 류희찬;조민식;장경윤;유공주
    • School Mathematics
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    • v.5 no.1
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    • pp.97-114
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    • 2003
  • This study is a basic step research for developing mathematics teacher education program using the potential power of explorative softwares for learning geometry. This study investigates the characteristics of the softwares and noteworthy points in its applying process. Analizing an impact of this softwares on the mathematics leaching and learning, this study presents the desirable direction for developing the teacher education program for mathematics teachers to be ableto teach successfully. Focusing on GSP as an to manage classrooms of the 21st century successfully. Focusing on GSP as an excellent explorative software used widely in the current mathematics classrooms, this study investigates the potential contents to be used in the teacher education program for mathematics teachers to get new kinds of experiences about the softwares and suggests implications for choosing contents and instructional methods of the program using the softwares.

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Effect of Soil Water Contents on Urea Hydrolysis and Nitrification in a Newly Reclaimed Tidal Soils

  • Park, Mi-Suk;Kim, Hye-Jin;Chung, Doug-Young
    • Korean Journal of Soil Science and Fertilizer
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    • v.44 no.1
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    • pp.48-52
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    • 2011
  • The effect of soil water content on the transformation potential of N compounds derived from hydrolysis of urea applied in a reclaimed tidal soils which was saline-sodic was observed to evaluate nitrification rates of urea. Soil samples were collected from Moonpo series at the newly reclaimed area in Saemanguem. For the transformation potential of N compounds from urea (46% N), newly reclaimed tidal soils (RS) were amended with urea at the rates of 0, 10, and 20 kg $10a^{-1}$. With leachate obtained from the incubated RS in a leaching tube at $25^{\circ}C$, urea hydrolysis and nitrification were measured for a total of 30days. The cumulative amounts of $NO_3{^-}$-N in each of the four soils treated with urea was linear with time of incubation. Results showed that increase in pH occurred with increasing application rate of urea and volumetric water content due to hydrolysis of urea. The total N in the RS was decreased with incubation time, indicating that rates of urea hydrolysis was influenced by soil moisture conditions. Also, the cumulative amount of nitrate in RS gradually increased with increase in time of incubation.

Corrosion Behavior of Casting Aluminum Alloys in H2SO4 Solution (H2SO4 수용액에서의 주조용 알루미늄 합금들의 부식거동)

  • Woo, Sang-Hyun;Son, Young-Jin;Lee, Byung-Woo
    • Journal of Power System Engineering
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    • v.20 no.3
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    • pp.17-21
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    • 2016
  • The corrosion behavior of aluminum alloys in the $H_2SO_4$ solution was investigated based on potentiodynamic techniques. Electrochemical properties, such as corrosion potential($E_c$), passive potential($E_p$), corrosion current density($I_c$), corrosion rate(mpy), of Al-Mg-Si, Al-Cu-Si and Al-Si alloys were characterized at room temperature. Passive aluminum oxide film, which including $Al_2(SO_4)_3$ and $3Al_2O_34SO_38H_2O$, were uniformly formed on the surface via the reaction of Al with $SO{_3}^{2-}$ or $SO{_4}^{2-}$ ions in the $H_2SO_4$ solution and the dependence of the corrosion behavior on the alloying element was discussed. The selective leaching of alloy element increased with increasing Cu content in the aluminum alloys.

Evaluation of the Pilot Village Project of Environment-Friendly Agriculture for a Rice Farming (친환경농업 시범마을 조성사업의 성과분석)

  • Kang, Choong-Kwan;Jung, Man-Chul
    • Korean Journal of Organic Agriculture
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    • v.12 no.2
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    • pp.121-134
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    • 2004
  • Crop inputs in excess of the yield potential of the soil type reduce profitability and increase pollution problems from leaching and runoff. Inaccurate fertilizer and pesticide application can also result in profit loss. Current farming practices plan only for the dominate soil in the field. A government-supported program titled "Pilot village project for the environment-friendly agriculture" was proceeded from 1999 to 2001 to tackle the problems with which our agriculture is faced by introducing IPM, INM and others. The objective of this study is to consider the potential input savings of agricultural chemicals and economic feasibility of the project compared with the conventional farming. The results of the analysis indicate the followings: (1) organic or no-pesticide farming size was increased from 9% in 1999 to 20% in 2001 ; (2) crop yield was a link bit lower than that of the conventional farming, but the sal6 price, gross income and income of the pilot village were 6%, 10% and 9% higher than that of the conventional farming, respectively; and (3) fertilizer and pesticide use also showed decreasing trend gradually.

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Stabilization of fluorine in soil using calcium hydroxide and its potential human health risk

  • Jeong, Seulki;Kim, Doyoung;Yoon, Hye-On
    • Environmental Engineering Research
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    • v.24 no.4
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    • pp.654-661
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    • 2019
  • This study assessed the stabilization of fluorine (F)-contaminated soil using calcium hydroxide (Ca(OH)2) and the consequent changes in human health risk. The bioavailable F decreased to 3.5%, (i.e., 57.9 ± 1.27 mg/kg in 6% Ca(OH)2-treated soil sample) from 43.0%, (i.e., 711 ± 23.4 mg/kg in control soil sample). This resulted from the conversion of water-soluble F to stable calcium fluoride, which was confirmed by XRD spectrometry. Soil ingestion, inhalation of fugitive dust from soil, and water ingestion were selected as exposure pathways for human health risk assessment. Non-carcinogenic risks of F in soils reduced to less than 1.0 after stabilization, ranging from 4.2 to 0.34 for child and from 3.0 to 0.25 for adult. Contaminated water ingestion owing to the leaching of F from soil to groundwater was considered as a major exposure pathway. The risks through soil ingestion and inhalation of fugitive dust from soil were insignificant both before and after stabilization, although F concentration exceeded the Korean soil regulatory level before stabilization. Our data suggested that substantial risk to human health owing to various potential exposure pathways could be addressed by managing F present in soil.