• Korean Chemical Engineering Research
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• v.52 no.5
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• pp.647-651
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• 2014

Handling of the large quantity of oil, generation of heavy metals at the military blasting range and outworn facilities could cause the environmental accidents. Pollution levels of the former five U.S military bases located in Uijeongbu, Gyeonggi-do were measured. Soil contamination by TPH (Total Petroleum Hydrocarbons), BTEX (Benzene, Toluene, Ethylbenzene, Xylene), and heavy metals and groundwater contamination were detected. In order to purify contaminated soil, a variety of technologies including soil vapor extraction, slurping, landfarming and soil washing were applied. Contaminated soils of five target bases were purified and the results were suitable for the legal standards.

• Journal of Ecology and Environment
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• v.40 no.1
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• pp.5-11
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• 2016

Background: As the decomposition of lignocellulosic compounds is a rate-limiting stage in the nutrient mineralization from organic matters, elucidation of the changes in soil enzyme activity can provide insight into the nutrient dynamics and ecosystem functioning. The current study aimed to assess the effect of thinning intensities on soil conditions. Un-thinned control, 20 % thinning, and 30 % thinning treatments were applied to a Larix kaempferi forest, and total carbon and nitrogen, total carbon to total nitrogen ratio, extractable nutrients (inorganic nitrogen, phosphorus, calcium, magnesium, potassium), and enzyme activities (acid phosphatase, ${\beta}$-glucosidase, ${\beta}$-xylosidase, ${\beta}$-glucosaminidase) were investigated. Results: Total carbon and nitrogen concentrations were significantly increased in the 30 % thinning treatment, whereas both the 20 and 30 % thinning treatments did not change total carbon to total nitrogen ratio. Inorganic nitrogen and extractable calcium and magnesium concentrations were significantly increased in the 20 % thinning treatment; however, no significant changes were found for extractable phosphorus and potassium concentrations either in the 20 or the 30 % thinning treatment. However, the applied thinning intensities had no significant influences on acid phosphatase, ${\beta}$-glucosidase, ${\beta}$-xylosidase, and ${\beta}$-glucosaminidase activities. Conclusions: These results indicated that thinning can elevate soil organic matter quantity and nutrient availability, and different thinning intensities may affect extractable soil nutrients inconsistently. The results also demonstrated that such inconsistent patterns in extractable nutrient concentrations after thinning might not be fully explained by the shifts in the enzyme-mediated nutrient mineralization.

• Applied Chemistry for Engineering
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• v.31 no.4
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• pp.360-367
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• 2020

In this study, the accumulation and distribution routes of microplastics in soil environment were examined, and their analytical methodologies were summarized. Density separation and removal process of inhibition materials were introduced for the separation of microplastics in soil and the basic principles and limitations of quantitative and qualitative analyses including pyrolysis gas chromatography mass spectrometry, µ-Raman spectrometry, fourier transform infrared spectrometry, and microscopes were investigated. Chemical extraction methods for the analysis of mediated hazardous substance (additives and sorbed matters) in microplastics were also discussed with focusing on in vitro bioaccessibility assay for the human oral exposure route. Based on the described methodologies for the analysis of microplastics in soil, it is expected that these methods enable to select appropriate analysis techniques in consideration of medium state, contamination level and sample quantity.

• Journal of Korea Soil Environment Society
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• v.1 no.2
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• pp.91-101
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• 1996

In recent years, phytoremediation, the use of plants to detoxify hydrocarbons, has been a promising new area of research, particularly in situ cleanup of large volumes of slightly contaminated soils. There is increasing need for a mathematical model that can be used as a predictive tool prior to actual field implementation of such a relatively new technique. Although a number of models exist for solute-plant interaction in the vegetated zone of soil, most of them have focused on ionic nutrients and some metals. In this study, we developed a mathematical model for simulation of bioremediation of hydrocarbons in soil, associated with plant root systems. The proposed model includes root interactions with soil-water and hydrocarbons in time and space, as well as advective and dispersive transport in unsaturated soil. The developed model considers gas phase diffusion and liquid-gas mass exchanges. For simulation of temporal and spatial changes in root behavior on soil-water and with hydrocarbons, time-specific distribution of root quantity through soil was incorporated into the simulation model. Hydrocarbon absorption and subsequent uptake into roots with water were simulated with empirical equations. In addition, microbial activity in the rhizosphere, a zone of unique interaction between roots and soil microorganisms, was modeled using a biofilm theory. This mathematical model for understanding and predicting fate and transport of compound in plant-aided remediation will assist effective application of plant-aided remediation to field contamination.

• Magazine of the Korean Society of Agricultural Engineers
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• v.28 no.4
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• pp.66-76
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• 1986

This study was attempted to investigate the effects of delayed compaction on the unconfined compressive strengh and dry density of Soil-cement mixtures. Soil-cement construction is a time-consuming procedure. Time-delay is known as a detrimental factor to lower the quality of soil-cement layer. A laboratory test was performed using coarse and fine weathered granite soils. The soils were mixed with 7% cement at optimum moisture content and excess moisture content in part. Socondary additives such as lime, gypsum-plaster, flyash and sugar were tried to counteract the detri-mental effect of delayed compaction. The specimens were compacted by Harvard Miniature Compaction Apparatus at 0,1,2,4,6 hors after mixing. Two kinds of compactive efforts(9 kgf and 18 kgf tamper) were applied. The results were summarized as follows: 1.With the increase of time delay, the decrease rate of dry density of the specimen compacted by 9 kgf tamper was steeper than that of the specimen compacted by 18kgf tamper. In the same manner, soil-B had steeper decreasing rate of dry density than soil-A. 2.Based on the results of delayed compaction tests, the dry density and unconfined compressive sterngth were rapidly decreased in the early 2 hours delay, while those were slowly decreased during the time delay of 2 to 6 hours. 3.The dry density and unconfined compressive strength were increased by addition of 3% excess water to the optimum moisture content during the time delay of 2 to 6 hours. 4.Without time delay in compaction, the dry densities of soil-A were increased by adding secondary additives such as lime, gypsum-plaster, flyash and sugar, on the other hand, those of soil-B were decreased except for the case of sugar. 5.The use of secondary additives like lime, gypsum-plaster, flyash and sugar could reduce the decrease of unconfined compressive strength due to delayed compaction. Among them, lime was the most effective. 6.From the above mentioned results, several recommendations could be suggested in order to compensate for losses of unconfined compressive strenght and densit v due to delayed compaction. They are a) to use coarse-grained granite soil rather than fined-grained one, b) to add about 3% excess compaction moisture content, c) to increase compactive effort to a certain degree, and d) to use secondary additives like line gypsum-plaster, flyash, and sugar in proper quantity depending on the soil types.

• Journal of the Korean Professional Engineers Association
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• v.19 no.1
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• pp.25-32
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• 1986

The number of visiters to Bukhan Mt. national park, generation quantity of solid waste and collection system were researched to consider a counterplan for the pollution control of the national park and study for developing the effective treatment of solid waste was tried through the proximate analysis of each component containing. Results obtained in this study were summerized as follows; The great part of visitors go on an excursion to the Bukhan Mt. national park during July and August and also, the solid waste was generated nearly a half of the total amount at the same period. The major collection facilities in the national park were waste basket and incineration box. But the incineration box was too large in volume and very far in distance, and its collection period was irregular, so it was cause to the congestion of solid waste and bad smell and dirty. Therefore, to complete collection of solid waste, we must set up the waste basket which able to find within 40～50m from the origination place of solid waste and induce the visitors to throw the solid waste. It was obtained as moisture content: 48.5 wt%, volatile solid: 28.4wt％, fixed solid: 23.1 wt％, lower heating value: 1,320kca1/kg from experimental analysis of solid waste. According to this analysis, the incineration operation is possible, but the generation quantity of solid waste was too small to construct incineration plant for heat recovery. It was found that it is suitable for the aerobic composting by mixing with the night soil which generate in the national park after the recovery of resources such as metals, glasses and plastics.

• Korean Journal of Microbiology
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• v.51 no.2
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• pp.133-140
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• 2015

We have examined the correlation between the physicochemical and microbiological environment variables for the different layers of oak forest soil in Mt. Gyeryong, Korea. The result shows that there is a high correlation in the environment variables between the soil parameters of the fermented (F) layer and humus (H) layer. In particular, the pH level in the F layer shows a high correlation with C and N, while the various organic acids of the H layer turns out to be closely correlated with soil bacteria density. As we evaluated phylogenetic characteristics of bacterial populations by DGGE analysis with DNA extracted. Total of 175 bands including 43 bands from litter (L) layer, 42 bands from F layer, 43 bands from H layer and 47 bands from rhizosphere (A) layer were selected as the major DGGE band of oak forest soil. Based on the 16S rRNA gene sequences, 175 DGGE bands were classified into 32 orders in 7 phylum. The heat map was analyzed in order to compare the quantity of the base sequences of each order and based on the clustering of the different layers of oak forest soil, the result confirms that the F layer and H layer belong to a different cluster from that of L layer and A layer. Furthermore, it also showed that approximately 50% of the total microbial population in different layers is ${\alpha}$-proteobacteria, which indicates that they belong to the dominant system group. In particular, Rhizobiales, Burkholderiales and Actinobacteriales were observed in all the seasons and layers of oak forest soil, which confirms that they are the indigenous soil bacterial community in oak forest soil.

• Journal of The Korean Society of Grassland and Forage Science
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• v.9 no.3
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• pp.168-173
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• 1989

In this report two experiments were carried out. Vertical distribution of exchangeable potassium(K) of soil in the orchardgrass meadow was investigated‘ a and K leaching from soil was monitored under lysimeter condition throughout one year. The results obtained a are as follows; The difference in the exchangeable soil K content b between the soil layers was very small in K-zero plot of the orchard grass meadow, but it was significant in K¬h high plot (Experiment 1). T The volume of leached water from the Iysime ter was a about 471 liters/m2 during a year and the amount of leached water was influenced by the precipitation. D During the investigation the quantity of leached K was 2 22.3 g/$m^2$. About 40 % of the total K in a year leached out during the first two months, May and June, after the start of the experiment. On the other hand, leached K amounted to 13.2 g/$m^2$ (60 % of the total K leached) during the period of ten months from July, 1985 to A April, 1986, when forages were harvested from the soil o of the lysimeter (Experiment 2). From the above results, it was known that K leach¬i ing from grassland soil can be also occurred in consider¬a able amount when the growth stage of forage is not d developed or soil does not become solid on such a p period as immediately after grassland improvement or e establishment. However, unless the K leaching from soil s seems to be little under the condition of permanent g grassland ecosystem with higher grade of soil hardness a and possibly with compact density of forage plants.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.1
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• pp.98-107
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• 2007

Most of plastic film house plots in Korea have salinity problems caused by salt accumulations associated with continuous cropping including the heavy applications of chemical fertilizers, and high evapotranspiration. The objective of this study was to investigate soil properties and watermelon (Citrullus lanatus Thunb.) productivity in plastic film houses as influenced by the short-term crop rotation in the continuous watermelon-cultivated soils. The short-term rotational crops selected were corn, Chinese cabbage, radish, young radish, lettuce, spinach, and onion. Soil pH increased in most plots where a short-term crop was added to the crop rotation, except where radish was added. The content of soil organic matter significantly decreased in the lettuce-cultivated plot. The available phosphorus content in the soils increased with the cultivations of spinach and onion. Exchangeable Ca and Mg tended to increase in most of plots where a short-term rotational crop was grown, whereas the exchangeable K was clearly reduced by more than 50% in the same plots. Cultivation of rotational crops during the post-harvest season significantly decreased the electrical conductivity (EC) and the concentrations of soluble anions, such as chloride ($Cl^-$), nitrate ($NO_3{^-}$), and sulfate ($SO{_4}^{2-}$) in the soils. In particular, the EC decrease was related with the decrease in soil $K^+$ to $Ca^{2+}$ and $Mg^{2+}$ ratio. In all plots cultivated with the shot-term rotational crops, the ratios of bacteria to fungi (B/F) increased. However, the improvement in soil properties after adding a rotational crop did not result in a clear improvement in watermelon quantity or quality as measured by fruit weight and sugar content. Therefore, the addition of short-term rotational crops to a continuous watermelon cropping system would be beneficial to improve target soil properties in plastic film house plots studied.

• Korean Journal of Soil Science and Fertilizer
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• v.8 no.1
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• pp.31-35
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• 1975

In order to gain information on the plant characteristics of high yielding paddy from the point of view of mineral nutrition and to learn more about soil conditions under which high yields are produced a number of soil samples collected from the field experiment carried out in The City College of Seoul were analysed. In addition, a laboratory experiment carried out to support the field experiment was also analysed. Results obtained are as follows: 1. Generally, the higher the yield of paddy, the higher is the potassium content in flag leaves, whereas the reverse is true for the content of Ca and Mg in the leaves. From these facts it can conceivably be said that the high yielding paddy should absorb a large quantity of potassium and a lesser quantity of calcium and magnesium in the reproductive stage. 2. Leaves of paddy which produced yields over 600kg/10a (a comparatively high yield in the experiment) contained 30-35mg/100g of potassium, less than 25me/100g of calcium, and 10me/100g of magnesium which brings the ratio of $K/{\sqrt{Ca+Mg}}$ over 5. 3. Correlation studies indicated a remarkable relationship between the paddy yield and exchangeable potassium in soil samples taken after harvesting. A similar relationship was observed between the yield of paddy and $K/{\sqrt{Cae+Mge}}$ ratio of the soil samples. 4. A regression between yield of padcy (Y) and exchangeable potassium (Ke) or $K/{\sqrt{Ca+Mg}}$ in soil samples taken after harvesting was shown to be; Y=183.95+2135.86Ke $$Y=352.45+3114.454\;K/{\sqrt{Ca+Mg}}$$ 5. The regression between exchangeable potassium (Ke) in soil samples taken after harvesting and the amount of lime (L) and potassium (P) to be applied is; $$Ke=0.1246+0.00007037L+0.004444P+0.000004444L{\cdot}P$$.