• Geomechanics and Engineering
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• v.34 no.5
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• pp.473-480
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• 2023

Acid rain of soils has a significant impact on mechanical properties. An X-ray diffraction test, scanning electron microscope (SEM) test, laser particle size analysis test, and triaxial unconsolidated undrained (UU) test were carried out in red clay soils with different compaction degrees under the effect of different concentrations of acid. The experiments demonstrated that: the dissolution effect of acid rain on colluvium weakened with the increase in the compacting degree under the condition of certain pH values, i.e., the damage to the structure of red clay soil was relatively light, where the number of newly increased pores in the soil decreased and the agglomeration of soil particles increased; for the same compacting degree, the structural gap decreased, and the agglomeration increased with the increase in the pH value (acidity decreases) of the acid rain; the dissolution rate of Si, Al, Fe, and other elemental minerals and cement in red clay soil was found to be higher under the effect of acid rain, in turn destroying the original structure of the soil body and producing a large number of pores. This is macroscopically expressed as the decrease of the soil cohesion and internal friction angle, thereby reducing the shear strength of the soil body.

• Korean Journal of Environment and Ecology
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• v.7 no.1
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• pp.10-21
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• 1993

Artificial acid rain (pH 3.0, 4.0 and 5.0) and ground was treated on the seeded pots of 4 species to examine its effects on germination and survival rate, seedling growth and contact angles on needle surface. Artificial acid rain was prepared by diluting sulfuric acid with ground water and ground water (pH 6.5) was used as control. Artificial acid rain was sprayed to seeded pots two or three times per week for growing season, one times per week for winter seasons. About 5mm of artificial acid rain was treated each time from early April, 1991 to early October, 1993. Germination and survival rate, soil acidity, seedling growth and contact angles on the needle surface were measured and compared among the treatments. The results were summarized as follows ; Artificial acid rain might have positive effects on growth-related characteristics of the seedlings in the first and second year of acid rain treatment, and the effects were differed among four species. All growth-related characteristics of the seedlings in third year, however, decreased with decrease of pH values of artificial acid rain. This was considered to the results of acidic accumulation over soil buffer capacity. Needle injury and biomass (defoliation) was correlated with the pH values of artificial acid rain, and this character might be a good criteria for early diagnosis of acid rain injury. The differences of soil acidity were significant among the treatments for all species. Contact angles between needle surface and water droplet decreased with decrease of pH values of artificial acid rain. Measuring and comparing contact angles might be very good criteria for early diagnosis of acid rain injury.

• Journal of Biosystems Engineering
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• v.35 no.6
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• pp.450-457
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• 2010

Although cherry tomato is one of major vegetables consumed in fresh vegetable market, the quality grading method is mostly dependant on size measurement using drum shape sorting machines. Using Visible/Near-infrared spectroscopy, apparatus to be able to acquire transmittance spectrum data was made and used to estimate firmness, sugar content, and acidity of cherry tomatoes grown at hydroponic and soil culture. Partial least square (PLS) models were performed to predict firmness, sugar content, and acidity for the acquired transmittance spectra. To enhance accuracy of the PLS models, several preprocessing methods were carried out, such as normalization, multiplicative scatter correction (MSC), standard normal variate (SNV), and derivatives, etc. The coefficient of determination ($R^2_p$) and standard error of prediction (SEP) for the prediction of firmness, sugar, and acidity of cherry tomatoes from green to red ripening stages were 0.859 and 1.899 kgf, with a preprocessing of normalization, 0.790 and $0.434^{\circ}Brix$ with a preprocessing of the 1st derivative of Savitzky Golay, and 0.518 and 0.229% with a preprocessing normalization, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.1
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• pp.38-49
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• 1985

The water soluble organic fractions (WSOF) from an agricultural soil (W), a soil treated with sludge for 6 years ($WS_6$), a sludge-soil mixture incubated for one week ($WS_1$), and sewage sludge (SS) were extracted, purified, and characterized by elemental analysis, functional group determinations, infrared, UV-visible, and proton nuclear magnetic resonance spectrosocpy. The SS was characterized by higher organic H, N, and P contents, a higher H/C ratio, and a lower C/N ratio than W. Total acidity carboxyl and phenolic hydroxyl group contents were generally highest in SS, intermediate in $WS_6$ and $WS_1$, and lowest in W. Overall aromatic character and aromatic carboxyl group contents were highest in W, and lowest in SS. Aliphatic proton, aliphatic carboxyl, and phenolic hydroxyl group contents were highest in SS, and lowest in W. Protein decomposition products were the pronounced components in SS, and decreased in concentration as the sludge component in the mixtures decreased. The $^1H$-NMR spectra suggested that the SS-protons were bound to a wider range of functional groups than W-protons. Structural complexities around the aromatic protons followed the following order: SS>$WS_1$>$WS_6$>W.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.3
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• pp.175-184
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• 2002

Soil chemical parameters of peach orchards and the concentration of nutrients in peach leaves were investigated. Results of soil analysis showed that pH value and content of exchangeable calcium was quite low, required to adjust soil acidity in many investigated soils. Nitrogen and phosphorous contents in leaves were founded to be excessive comparing to RDA's optimal levels(N $29.3{\sim}35.9g\;kg^{-1}$, P $1.7{\sim}2.2g\;kg^{-1}$), while calcium contents were lower than optimal levels($11.2{\sim}21.0g\;kg^{-1}$) in many sites and Potassium content was higher in peach cultivars than nectarine cultivars. Correlation analysis revealed that organic matter contents in subsoils and exchangeable calcium content in soils(top and subsoil) were increased with cultivation year, but available phosphate contents in subsoils were decreased. Organic matter and exchangeable magnesium contents in top soils were positively correlated with potassium and magnesium contents in leaves, whereas were negatively correlated with calcium contents in leaves, impling antagonistic absorption of calcium against potassium and magnesium. The findings indicated that most of soils ought to managed to adjust soil acidity and application amount of nitrogen, phosphorous fertilizer and compost should be controlled properly.

• Korean Journal of Microbiology
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• v.7 no.1
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• pp.29-40
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• 1969

Two kinds of organic materials, powders of Salicornia and Oryza sativa L. wre added as a source of organic matter to the suspensions of saline soils(soil : water = 1:3) to be 4 per cent of dried saline soil grams. And then, the samples were incubated at $28^{\circ}C$ to improve the decomposition of organic materials by soil microflora. Resutls of this experiment are summarized as followings : 1) The pH of soil suspension showed its highest value on the second or third week after the treatments, which were similar to those of the soil microflora. Results of this experiment are summarized as follwings : 1) The pH of soil suspension showed its highest value on the second ot third week after the treatments, which were similar to those of the soil microflora populations. 2) Salinity increased up to the second week and the highest value of it appeared in the samples which were treated with the powder of Salicornia. In general, the salinity of all samples decreased on the third week after the treatment. The fact was assumed the possibilities of desalination from saline soil by the microbial actions. 3) Soil microflora such as bacteria, actinomycetes and fungi, were determined its populations soil microflora is to act as decomposer in soil. Both of the bacteria and actinomycytes population showed in the third weak after the tratment. In general, 30-years old of saline soil contained microbial population much more than those of 5-year old of saline soil. Salicornia powder favored the increase of both the bacteria and fungal population, and Oryza sativa L. seemed to have been a great role in increase of actinomycetes. Especially, fungal population of the untreated soil suspension contained higher microbial populations more than those of the soils treated with both of the organic materials. 4) Sugar contents of soil suspesions decreased remarkably on the first week after the treatments. 5) The amount of nitrate had similar tendency to those of population changes of soil microflora. Total acidity decreased continuously and the amount of potassium showed its highest value on the third week treatment. However, the amount of phosphorus was determined to be insignificant.

• The Korean Journal of Ecology
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• v.19 no.3
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• pp.201-207
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• 1996

Selection of Al tolerant woody plants, and possibility of reforestation with the Al tolerant plants in soil conditions with different Al content, topography and slope exposures were studied on the slopes around Yeocheon Industrial Complex. Root growth in length of plants grown in 1/2 Steinberg solution decreased with increased Al concentrations of the solution. Relative root length showed that Paulownia coreana, Celtis sinensis and Firmiana simplex were sensitive to $500\muM$ Al, Pinus koraiensis, Alnus japonica and Ligustrum japonicum were intermediate, and Pinus rigida, P. densiflora and P. thunbergii were tolerant to $1, 000\muM$ Al. Coniferous plants appeared to be more tolerant to Al than deciduous ones. Soil pH was 4.2 and Al content was 509 ppm in average around the Yeocheon industrial complex. Al content and soil acidity were more deteriorated on the foothill and slope facing to the pollution source from the industrial complex than on the ridge and opposite slope.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.5
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• pp.336-340
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• 2009

The issue of acid precipitation and related environmental problems in East Asia has been emerging. To evaluate the acidity and chemical characteristics of rainwater in Korea, its chemical properties during cultivation season from April to October were investigated at Taean in 2007. Also, to estimate the contribution of ions on its acidity, ion composition characteristics and neutralization effects by cation ions were determined. The ion balance between cations and anions values showed high correlation. The mean values of pH and EC were 4.9 and $32.9{\mu}S\;cm^{-1}$, respectively. The EC of rainwater showed seasonal characteristic, which was $91.4{\mu}S\;cm^{-1}$ with relatively low rainfall compared with other monitoring periods. $Na^+$ was the main cation followed by $NH_4{^+}$ > $Ca^{2+}$ > $H^{+}$ > $Mg^{2+}$ > $K^+$. Among these ions, $Na^{+}$ and $NH_4{^+}$ covered over 70% of total cations. In the case of anion, the order was $SO_4{^{2-}}$ > $NO_3{^-}$ > $Cl^{-}$. The mean value of sulfate, which is main anion component in the samples was $152.1{\mu}eq\;L^{-1}$. Also, 90% of soluble sulfate in rainwater was $nss-SO_4{^{2-}}$(non-sea salt sulfate). With fractional acidity and theoretical acidity of rainwater samples, $NH_4{^+}$ and $Ca^{2+}$ contributed greatly in neutralizing the rain acidity.

• Journal of Korean Society for Atmospheric Environment
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• v.2 no.2
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• pp.66-74
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• 1986

Rain samples were collected at 10 sites in the Seoul area during the period of August through November, 1985. THe concentrations of the major cations $(H^+, Ca^{++}, MG^{++}, Na^+, K^+, NH_4^+)$ and the major anions $(SO_4^=, NO_3^-, Cl^-)$ were measured to characterize the main sources of chemical ions in rainwater. Correlating concentrations of ions to pH, calculated coefficients ranged from 0.1485 to 0/4296. Sulfate shows the largest coefficient indicating that sulfate is more closely associated with hydrogen ion than other ions. This may suggest that sulfuric acid contributes more to the acidity of rainwater in Seoul. It appears that the major chemicals measured in rainwater are from the anthropogenic sources of air pollution. Predominant chemicals are acidic at the Guro-, the Sinseol-, the Yangnam-, and the Ssangmun-dong with sulfate being the most predominant. IT also indicates that alkaline substances resulting from soil and dust have a significant effect on pH values of rainwater by neutralizing actions. According to Granat-model analysis, it is estimated that the relative contributions to the rainwater acidity in Seoul are 84% from sulfuric acid, 8% from nitric acid and 8% from hydrochloric acid.

• Current Research on Agriculture and Life Sciences
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• v.23
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• pp.53-60
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• 2005

This study was carried out in order to produce useful material for the forest multiple use and forest protection management by soil physio-chemical analysis of studied area in Mt. Namsan. The result of soil physio-chemical analysis and statical analysis represented as following. In side of physical properties of forest soil in Mt. Namsan, Soil depth was average 31.4cm and available soil depth was average 20.0cm. Soil type was Brown forest soil that representative soil type in Korea. Soil texture was sandy loom(SL) except valley area. In side of chemical properties, the range of soil acidity was 4.29 ~ 5.19 (average 4.76), organic matter content was 3.17% that compared the lowest value to organic matter content of Korea forest soil. Available phosphorus was 3.64ppm that was lower than others forest soil. Exchangeable cation content was similar to the Korea brown forest soil. Cation exchange capacity(CEC) was $8.22cmol_c/kg$ in Mt. Narnsan.