• Journal of Microbiology
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• v.42 no.4
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• pp.267-277
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• 2004

Effects of elevated $CO_2$ on soil microorganisms are known to be mediated by various interactions with plants, for which such effects are relatively poorly documented. In this review, we summarize and syn­thesize results from studies assessing impacts of elevated $CO_2$ on soil ecosystems, focusing primarily on plants and a variety the of microbial processes. The processes considered include changes in microbial biomass of C and N, microbial number, respiration rates, organic matter decomposition, soil enzyme activities, microbial community composition, and functional groups of bacteria mediating trace gas emission such as methane and nitrous oxide. Elevated $CO_2$ in atmosphere may enhance certain micro­bial processes such as $CH_4$ emission from wetlands due to enhanced carbon supply from plants. How­ever, responses of extracellular enzyme activities and microbial community structure are still controversy, because interferences with other factors such as the types of plants, nutrient availabilitial in soil, soil types, analysis methods, and types of $CO_2$ fumigation systems are not fully understood.

• Journal of Soil and Groundwater Environment
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• v.16 no.1
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• pp.51-61
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• 2011

Germination tests were conducted to determine the practical concentration levels at which plants can reproduce naturally during the phytoremediation of soils contaminated with a high concentration of petroleum hydrocarbons and heavy metals. The effects of humic acids on plant growth and soil physicochemical properties were also investigated. The results show that phytoremediation can be applied in soils contaminated by multiple contaminants at the former soil contamination potential level of Korean soil quality standards considering successful natural reproduction. It was observed that germination rates of Helianthus annuus and Festuca arundinacea were high after all treatments, and transplantation was more appropriate for Phragmites communis in phytoremediation. Humic acids had a positive effect on the growth of both aboveground and belowground biomass of herbaceous plants. Growth inhibition by multiple contaminants is more severe in the case of aboveground biomass. Germination and growth tests suggest that Helianthus annuus is a suitable phytoremediation plant for soils contaminated with a high concentration of petroleum hydrocarbons and heavy metals. The addition of humic acids also caused changes in the physicochemical properties of contaminated soils. An increase in the carbon and nitrogen content due to the addition of humic acids and a correlation between cation exchange capacity(CEC) and the organic matter content were observed.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.318-322
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• 2004

Arsenic is a toxic and carcinogenic metalloid, whose sources in nature include mineral dissolution and volcanic eruption. Abandoned mines and hazardous waste disposal sites are another major source of arsenic contamination of soil and aquatic systems. To predict concentrations of the toxic inorganic arsenic in aqueous phase. the biogeochemical redox processes and transport behavior need to be studied together and be coupled in a reactive transport model. A new reaction module describing the fate and transport of inorganic arsenic species (As(II)), dissolved oxygen, nitrate, ferrous iron, sulfate, and dissolved organic carbon are developed and incorporated into the RT3D code.

• Korean Journal of Microbiology
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• v.13 no.1
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• pp.1-23
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• 1975

This experiment was designed to elucidate the environmental factors in rhizosphers of bamboo forest that affect the distribution and the population size of Azotobacter, and also to estimate the annual productivities of nitrogen fixed by Azotobacter species. The results of this experiment can be summarized as follows ; The rhizosphere of bamboo forest contained high free sugars as of 3-8 times more than non-rhizosphere (Bacon, 1968), and the contents of organic matter and amino acids of that are reltively higher than this. Because of high content of potassium, average of soil pH is near at 7.0. As above-mentioned enviromental factors, the population sizes of Actinomycetes, general fungi, general bacteria and Azotobacters are larger than those of non-rhizosphere and the ofllowings are general fungi and general bacteria by turns. Azotobacter is dependent upon the antagonistic Actinomycetes. The main carbon source for Azotobacter in nitrogn flxation at the rhizosphere was glucose and minors were fructose, maltose and sucrose by turns. Annual gains of nitrogen by Azotobacters in soil of bamboo forest within 10cm from surface are estimated as of 88.94 kg/ha at site A, 60.4kg/ha at site B and 67.38kg/ha at site C, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.3
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• pp.228-234
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• 2008

The purpose of this study was to predict environmental distribution of anthracene, benzene, benzo[a]pyrene, 1-methylphenanthrene and phenanthrene in a four phase biopile system - air, water, soil and non aqueous phase liquid (NAPL) phase using level I fugacity model. Soil samples used for this study were collected from three sites in the United Kingdom which were historically contaminated with petroleum hydrocarbons. The level I fugacities (f) for the five contaminants were markedly different, however, the fugacities of each contaminant in three soil samples did not show significant difference. NAPL and soil were the dominant phases for all five contaminants. Results of this study indicated that difference in percentage of organic carbon strongly influenced the partitioning behavior of the cntaminants. The presence of benzene calls for an urgent need for risk-based management of air and water phase. Whereas insignificant amount of chemicals leached in the water phase for other organic contaminants showing greatly reduced potential of groundwater contamination. Furthermore, this study helped us to confirm the association of risk critical contaminants with the residual saturation in treated soils. They also can be used to emphasize the importance of accounting for the partitioning behavior of both NAPL and soil phases in the process of the risk assessment of the sites contaminated with petroleum hydrocarbons.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.6
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• pp.371-377
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• 2004

Sulfate adsorption in forest soils is a process of sulfur dynamics playing an important role in plant uptake, cation movement, acid neutralization capacity and so on. The relationship between sulfate adsorption and some physicochemical properties of four forest soils was investigated. Extractable sulfate contents and sulfate adsorption capacity (SAC) in the forest soils varied much among study sites. Extractable sulfate contents were more in sub-surface soils with lower organic matter and greater Al and Fe oxides than in surface soils. The average contents of $Al_d$ and $Fe_d$ in the sub-surface soils were 8.49 and $12.45g\;kg^{-1}$, respectively. Soil pH, cation exchange capacity and clay content were positively correlated with the extractable sulfate contents and SAC. Organic carbon content, however, was negatively correlated with the extractable sulfate contents, implying the competitive adsorption of sulfate with soil organic matter. Considerably significant correlation was found between inorganic + amorphous Al and Fe oxides and the sulfate adsorption, but crystalline Al and other fractions of Fe oxide showed no correlation. Relatively close relationship between the adsorbed sulfates and soil pH, cation exchange capacity, or amorphous Al oxides indicates that the accelerated soil acidification may substantially reduce the potential for sulfate adsorption contributing to sulfur flux in forest ecosystems.

• Journal of the Korea Organic Resources Recycling Association
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• v.30 no.4
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• pp.67-83
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• 2022

Biochar is a carbon material produced through the pyrolysis of agricultural biomass with limited oxygen condition. It has been suggested to enhance the carbon sequestration and mineralization of soil carbon. Objective of this study was to investigate soil potential carbon mineralization and carbon dioxide(CO₂) emissions in different soils cooperated with barely straw and livestock manure biochars in the closed chamber. The incubation was conducted during 49 days using a closed chamber. The treatments consisted of 2 different biochars that were originated from barley straw and livestock manure, and application amounts were 0, 5, 10 and 20 ton ha^-1 with different soils as upland, protected cultivation, converted and reclaimed. The results indicated that the TC increased significantly in all soils after biochar application. Mineralization of soil carbon was well fitted for Kinetic first-order exponential rate model equation (P<0.001). Potential mineralization rate ranged from 8.7 to 15.5% and 8.2 to 16.5% in the barely straw biochar and livestock manure biochar treatments, respectively. The highest CO₂ emission was 81.94 mg kg^-1 in the upland soil, and it was more emitted CO₂ for barely straw biochar application than its livestock biochar regardless of their application rates. Soil amendment of biochar is suitable for barely straw biochar regardless of application rates for mitigation of CO₂ emission in the cropland.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.5
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• pp.434-439
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• 2016

Anthropogenic soil in cropland is formed in the process of subsoil reversal and the refill of soil into cropland. However, there was little information on the chemical properties within soil profiles in anthropogenic soil under rice paddy near the river. In this study, we investigated the chemical properties within soil profiles in the anthropogenic soil located at 4 sites in Gumi, Kimhae, Chungju, and Euiseong to compare with the natural paddy soil near the river. Among particle sizes, the sand content decreased under soil profiles but the silt and clay contents increased compared to the natural paddy soil in soil profiles. Organic matter content in topsoil of anthropogenic soil was lower than in that of natural soil, which was shown the contrary tendency within soil profiles. Also, the soil pH, available $P_2O_5$, and exchangeable cations were higher in anthropogenic soil compared to natural paddy soil at topsoil, which was maintained these tendency into soil depth. Nutrients may be equally distributed in anthropogenic soil during the process of refill in paddy soil near the river. This results indicated that anthropogenic soil would contribute to carbon sequestration, the mitigation of compaction, and reduction of fertilizer application in paddy soil. Therefore, characteristics of anthropogenic soil can be used for the soil management in cropland.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.2
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• pp.107-112
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• 2014

Glomalin has been suggested as an enhancer for soil stability by promoting the aggregation. In this study, we examined the concentrations of glomalin and microbial characteristics in 25 controlled horticultural soils sampled from Gyeongnam Province. Total glomalin had a significant positive correlation with soil organic matter (p < 0.01), soil microbial biomass carbon (p < 0.05), and dehydrogenase activity (p < 0.05) in controlled horticultural soils. In addition, the total glomalin had a significant positive correlation with concentrations of total fatty acid methyl esters, Gram-negative and Gram-positive bacteria, fungi, and arbuscular mycorrhizal fungi in controlled horticultural soils (p < 0.001). In conclusion, the concentration of total glomalin could be an indicator of microbial biomass richness for sustainable agriculture in controlled horticultural soils.

• Korean Journal of Environmental Agriculture
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• v.37 no.1
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• pp.15-20
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• 2018

BACKGROUND: The global mean surface temperature change for the period of 2016~2035 relative to 1986~2005 is similar for the four representative concentration pathway (RCP)'s and will likely be in the range of $0.3^{\circ}C$ to $0.7^{\circ}C$. Climate change inducing higher temperature could affect not only crop growth and yield, but also dynamics of carbon in paddy field. METHODS AND RESULTS: This study was conducted to evaluate the effect of elevated temperature on the carbon dynamics in paddy soil and rice growth. In order to control the elevated temperatures, the experiments were set up as the small scale rectangular open top chambers (OTCs) of $1m(width){\times}1m(depth){\times}1m(height)$ (Type 1), $1 m(W){\times}1m(D){\times}1.2m(H)$ (Type 2), and $1m(W){\times}1m(D){\times}1.4m(H)$ (Type 3). The average temperatures of Type 1, Type 2, and Type 3 from July 15 to October 30 were higher than the ambient temperatures at $0.4^{\circ}C$, $0.5^{\circ}C$, and $0.9^{\circ}C$, respectively. For the experiment, Wagner's pots (1/2,000 area) were placed inside chambers. The pots were filled with loamy soil, and chemical fertilizer and organic compost were applied as recommended after soil test. The pots were flooded with agricultural water and rice (Shindongjin-byeo) was planted. It was observed that TOC (total organic carbon) of the water increased by the elevated temperatures and the trend continued until the late growth stage of the rice. Soil TOC contents were reduced by the elevated temperatures. C/N ratios of the rice plant decreased by the elevated temperature treatments. Thus, it was assumed that the elevated temperatures induced to decompose soil organic matter. Elevated temperatures significantly increased the culm length (P<0.01) and culm weight (P<0.05) of rice, but the number and weight of rice panicle did not showed significant differences. CONCLUSION: Based on the results, it was suggested that the elevated temperatures had an effect on changes of soil and water carbons under the possible future climate change environment.