• Korean Journal of Soil Science and Fertilizer
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• v.43 no.4
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• pp.430-437
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• 2010

The continuous release of nutrient sources into natural water resource can be a continuing problem in eutrophication, as well as severe reductions in water quality. However, any desirable measure is not developed yet even though so many researches and efforts have been done to solve this problem. Forest as one of troublesome nonpoint sources may contributes most to nutrient loading, but the loading of N and P from forest in order to grasp the eutrophication potential of nonpoint sources has not been evaluated. The nutrient sources from the organic litter accumulated on the surface of forest soils can be a critical factor in continuity of eutrophication of a lake. The decomposition rate of litter can be estimated to predict release of N and P from the forest stand. The loss rate of nitrogen is complicated but depends in part upon the physical matrix of the element. Therefore, long-term nutrient budget and flux estimates at stand would be useful tools in calculating potential nutrient fluxes into the watercourses in a sustainable way. The present investigation can give insight to the actual situation of the eutrophication potentials of forest as the practical nonpoint sources.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.3
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• pp.67-74
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• 2012

Bio-char, obtained from biomass as a by-product of the pyrolysis process, is used successfully as a soil amendment and carbon sequester in this limited study. Recent and active research from literatures has extended the application of bio-char in the industry to promote sustainability and help mitigate the negative environmental impacts caused by carbon emissions. This study aims to investigate the feasibility of high-carbon bio-char as a carbon sequester and/or admixture in mortar and concrete to improve the sustainability of concrete. This paper presents the experimental results of an initial attempt to develop a cement admixture using bio-char. In particular, the effects of the water retention capacity of bio-char in concrete are investigated. The chemical and mechanical properties (e.g., the chemical components, microstructure, concrete weight loss, compressive strength and mortar flow) are examined using sample mortar mixes with varying replacement rates of cement that contains hardwood bio-char. The experimental results also are compared with mortar mixes that contain fly ash as the cement substitute.

• Journal of the Korean Geosynthetics Society
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• v.14 no.4
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• pp.79-86
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• 2015

Korean territories has formed about 70% of mountainous areas that have acidified serious level to average pH 4-5. There are a number of abandoned metal mines about 1,000 in Korea. However, mine tailings and waste rock included heavy metals are exposed to long-term environment without prevention facility or treatment system. Thus, ongoing management and monitoring of soil environment are required. Most of abandoned mine scattered in forest areas of slopes. Soil erosion due to continuous rainfall in the slopy areas can cause the secondary pollution by the influence eutrophication of water system and the productivity loss of the plant. Therefore, this study would like to estimate pH leaching rate by artificial rainfall using waste neutralization-agent in lysimeter. Moreover, the potentially of secondary pollution related to precipitation is figured out through the experiments, and the optimal planting methods would examinate after neutralizing treatment in soil. Experiments composed three kinds of lysimeter; lysimeter 1 had filled only acidic soil, lysimeter 2 had neutralized soil, and lysimeter 3 had planting plants after neutralized soil. In the results, lysimeter 2 showed the lowest pH leaching, and there is not specific relativity with pH leaching of the seasonal characteristics.

• Applied Biological Chemistry
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• v.40 no.4
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• pp.323-328
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• 1997

Runoff of phorate, soil insecticide, were measured under simulated rainfall conditions in field using small test plot$(120\;cm{\times}120\;cm)$ at the loam area and loamy sand area. Fish acute toxicity tests were performed with runoff water to elucidate its toxicological effect on organisms in ecosystem. The average concentrations of phorate in runoff water from loam and loamy sand soil were 11.3 ppb and 4.8 ppb, respectively. However, there was no significant concentration difference between the heavy and the light rain. With loam soil, average runoff rates were 1.31 and 0.18%, while with loamy sand soil those were 0.48 and 0.012% under the heavy and the light rain conditions, respectively. Total average runoff rate was 0.50%. With killifish, no mortality was observed in runoff water from loamy sand soil, whereas half of the population was dead in runoff water from loam soil when it was diluted to 54.4% content.

• Korean Journal of Environmental Agriculture
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• v.28 no.1
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• pp.15-19
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• 2009

Ammonia in atmosphere has a negative effect on the natural ecosystems, such as soil acidification and eutrophication, by wet and dry deposition. Livestock manure, compost, and fertilizer applications to arable land have been recognised as a major source of atmospheric ammonia emissions. The objective of this study was to evaluate the efficiency of compost application techniques in reducing ammonia loss in upland soil. The reductions in ammonia emission were 70 and 15% for immediate rotary after application (IRA) and rotary at 3 day after application (RA-3d) in comparison with surface application (SA). Total ammonia emissions for 13 days, expressed as % ammonia-N applied with compost, were 42, 35.7, and 12.7% for SA, RA-3d, and IRA treatments, respectively. The ammonia emission rate fell rapidly 6 h after application and 61 % of total ammonia emission occurred within the first 24 h following surface application. The lime application along with compost significantly enhanced the total ammonia emission. Total ammonia emission for 22 days were 40.1, 31.4, and 27.7 kg/ha for immediate incorporation in soil after lime and compost application, lime incorporation in soil following 3 days after compost surface application, and compost incorporation in soil following 3 days after lime surface application, respectively. Therefore, lime and livestock manure compost application at the same time was not recommended for abatement of ammonia emission in upland soil.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.1
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• pp.111-117
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• 2015

We investigate the influence of spatial rainfall distribution on hillslope soil erosion through laboratory experiments. Two distinct spatial distributions are examined in this study, i.e., rainfall concentrated on central area versus upper area of hillslope. During the entire period of 8 hours for each experiment, direct runoff, subsurface flow, and sediment yield are measured at high temporal resolution (10 minutes). Compared to the case that rainfalll concentrated on central area, upstream concentrated rainfall results in lower peak of the sediment yield curve while greater cumulative sediment yield. Cumulative sediment yield increases over time linearly but its growth rate shows a sudden decrease at around 2 hours. This should be taken into consideration when temporal variability of sediment yield is estimated from observed total amount, and demonstrates the necessity of measuring sediment yield at high temporal resolution.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.6
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• pp.1013-1020
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• 2018

With the rapid industrialization and increase in population, more and more people are moving to live in cities. This urbanization trend is resulting in increased construction and development activities which associates with escalation of impervious surface. This in turn causes problems like groundwater depletion, higher flood peaks, and increased rate of soil loss from the watershed. Watershed management projects are being implemented around the globe concerning with the application of soil and water resources conservation practices. It is desirable that an entire watershed be evaluated based on soil and water conservation practices applied. In this study, water management categories of green building rating systems (GBRS) of South Korea, Taiwan, and the Philippines were discussed. The water management practices rating criteria of G-SEED (South Korea), BERDE (Philippines), and EEWH (Taiwan) were explored and compared. The insights of this study are expected to be projected to establish a comprehensive rating system for the evaluation of watersheds. The quantification of watershed management practices will help future planners to identify areas of potential water-related risks and counter the hazards more effectively.

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.3
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• pp.163-168
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• 1981

The studies were carried out to examine the effect of soil improvement agents, such as lime, wollastonite and phosphate, in reducing the damage caused by hydrogen fluoride gas to the vegetative growth of rice. The yield loss, damage rate of the plant leaves, the fluoride and silicate concentrations of the plants were measured. The results obtained are summarized as follows : 1. Of various levels of added lime and wollastonite, the best were found to be neutralized lime plus lime 150kg/10a, and wollastonite 150kg/10a. 2. Added fluoride increased the fluoride content of the plant and the damage rate of the plant leaves, and the yield was greatly decreased. 3. The silicate concentration at harvesting period was also increased by high amounts of fluoride in the plant during vegetative growth. 4. Increasing the amount of added lime increased the watersoluble silicate concentration in the soil. The silicate content of the plant showed the same tendency.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.1
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• pp.77-82
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• 2007

Volatilization of ammonia from N fertilizer is the major mechanism of N losses that occur naturally in all soils and is influenced by numerous soils, environmental and N fertilizer management factors. Vegetables are often damaged by $NH_3$ gas volatilized from the high rates of N fertilizer. We determined the rate of $NH_3$ volatilization from urea applied to surface of the alluvial soil (coarse silty, mixed, mesic family of Dystric Fluventic Eutrochrepts, Ihyeon series) as affected by fertilizer management factors such as rate of urea application, irrigation schedule and temperature. The $NH_3$ volatilization was triggered about 3 d after urea application and reached at maximum level in general within 15 days. Cumulative amounts of 3.0, 4.4, and 8.0 kg of $NH_3$ N after 17 d were volatilized at application rates of 200, 400, and $600kg\;N\;ha^{-1}$, respectively, which were equivalent to the N losses of 15.0, 10.9, and 13.0% of N applied. Masses of N volatilization were 5, 21, 75 and $87kg\;NH_3\;N\;ha^{-1}$ at 5, 8, 22, and 28, respectively. Total amounts of 21.3, 21.2, and $16.6kg\;N\;ha^{-1}$ were volatilized at control, 5 and 10 mm water irrigation before fertilization, respectively. However, those at 5 mm irrigation after fertilization were only $10.44kg\;N\;ha^{-1}$. Results showed that urea loss can be avoided by incorporating with the recommended level, applying when temperatures are low or irrigating immediately to carry the urea into soil.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.6
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• pp.399-406
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• 2003

The application of potassium above the optimum level may cause the inhibition of plant growth, fertilizer loss, and environmental pollution. Therefore, application rate of K fertilizer should be recommended on the basis of soil test. In order to determine critical K content in soils causing growth inhibition of vegetables, $1m^2-pot$ experiments with Chinese cabbage and radish were accomplished with various K-application rates. The threshold concentrations of exchangeable potassium causing the inhibition of plant growth were $0.96cmol_c\;kg^{-1}$ for Chinese cabbage in spring, and $1.28cmol_c\;kg^{-1}$ for radish in autumn. Above those concentration levels, the yields of them were decreased with the increase of potassium levels in soils. Germination rate of Chinese cabbage in spring decreased with increase of the electrical conductivity (EC) of soils due to application of potassium fertilizer. In the harvesting stage, the potassium contents of plant were increased with the increase of K application rate while plant uptake of nutrients was decreased at the K adjustment level of over $2.0cmol_c\;kg^{-1}$.