• Journal of Korean Society on Water Environment
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• v.31 no.5
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• pp.533-542
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• 2015

In order to investigate the effect of internal loading from sediment on algal blooming at Chusori area in Daechung Reservoir, the amount and contamination level of sediment and the release rate of total phosphorus were analyzed. The sedimentary layer was consisted with two layers, and the average depth of upper and lower ones were 0.35 and 1.44 m, respectively. The fraction of inorganic phosphorus in the sediment was higher than that of organic phosphorus, and the fractions of phosphorus which responsible for internal loading were very high as in the range of 72.7 and 80.2% of inorganic phosphorus. The C/N ratio of sediment taken with core sampler indicated the organic compounds are originated from settled algae from water body. The average release rate of total phosphorus from sediment was $6.74({\pm}0.50)mg/m^2/day$. These results indicated that the internal loading from sediment contributes the excessive algal growth at Churosi area, and the countermeasures to improve the quality of sediments are required to manage algal blooming in Daechung Reservoir.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.984-993
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• 1993

land application of sewage sludge requires careful monitoring because of its potential for contamination of surface water and groundwater. A rainfall simulator was used to investigated the effects of freshly applied sludge on runoff of sediment and nutrients from agricultural crop lands. Rain was applied to 16 experimental field plots. A three run sequence was used to simulate different initial moisture conditions. Runoff, sediment and nutrient losses were monitored at the base of each plot during the simulated rainfall events. Sludge was surface applied and incorporated at conventionally -tilled plots and surface applied at no-till plots, at rates of 0, 75, 150 kg-N/ha. No-till practices greatly reduced runoff, sediment , and nutrient losses form the sludge treated plots, relative to the conventional tillage practices. Incorporation of the sludge was effective in reducing nutrient yields at the conventionally-tilled plots. This effect was more pronounced during the third rain torm, with wet initial conditions. Peak loadings of nutrients appeared during the rainstorm with wet initial conditions.

• Journal of Environmental Science International
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• v.11 no.9
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• pp.851-855
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• 2002

A comparison of Daphnia magna, Ceriodaphnia dubia and Simocephalus mixtus toxicity test was performed to study the relative sensitivities and discrimination abilities with both pore and elutriate water of Woopo wetland sediments. Sediment risk assessment has been done by standardized preparation method of pore and elutriate water described in the joint US EPA-US Army Crops of Engineers manual. Simocephalus mixtus which was obtained from Woopo wetlands in Korea was cultured and applied to sediment toxicity test. Water quality in Woopo wetland had great site and seasonal variations. S. mixtus was more sensitive than D. magna in heavy metal toxicity test. The toxicity results with S. mixtus reflected the water quality of elutriate and pore water. The results also suggested that S. mixtus could be used as a test organism in estimating potential risk of contaminated sediments.

• Journal of Environmental Impact Assessment
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• v.18 no.6
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• pp.435-443
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• 2009

Ba Ria - Vung Tau province in Southern Vietnam is one of the fastest economic growing areas in the country, characterized by the rapid port and industrial development along the Thi Vai river. The socio-economic situation of the area has generally been improved; however, its part of the local inhabitants has not gained benefits from the changes. 35 surface water samples and 25 sediment samples were analysed with the interpretation of the SPOT images for 1995 and 2005. The data showed that rapid port and industrial development have resulted in significant losses of mangroves and agriculture land. The surface water was seriously polluted, particularly in terms of organic materials and suspended solids. It contained high and increasing oil concentrations. The river sediment was saline and slightly alkaline. It was heavily reduced, organic-rich, and contaminated with oil and heavy metals (Cu, Pb, and Cr).

• Magazine of the Korean Society of Agricultural Engineers
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• v.42
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• pp.38-49
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• 2000

Two application rates (9 and 18 t/ha) of poultry litter and a recommended rate of commercial fertilizer were studied to determine their effects on nutrient (N and P) losses in surface and subsurface runoff and loadings in soil layers from conventionally-tilled com by the treatments. The model predicted higher sediment losses than observed data from all treatments. The overpredicted sediment losses resulted in overprediction of organic-N and sediment-P losses in surface runoff. Simulated soluble-P losses in surface runoff were close to observed data, while NO3-N losses in surface runoff were underpredicted from all treatments. Observed NO3-N concentrations in leachate at 1.0-m depth from commercial fertilizer treatment were fairly well predicted. But the concentratins were overpredicted from poultry litter treatments due to high simulation of organic-N mineralization simulated by the model.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.2 no.2
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• pp.169-179
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• 1998

This paper was performed to estimate interrelations between humus level of sediments and nutrient release from sediments in Dae-cheong reservoir. For investigations, sediments were sampled in June and October, in 1997 at fish farms, embayment, and the main stream of Dae-cheong reservoir. Items for investigation are as follows; water content, weight loss on ignition(IG), porosities of sediments, contents of element such as hydrogen, nitrogen, carbon, and nutrient release rates. Water contents and porosities were measured to conjecture the physical trait and grain size trait. Weight loss on ignition was measured to determine the contents of organic substance. For determination of the humus level of sediments, carbon and nitrogen contents were measured by elemental analyzer. As a result of elemental analysis, C/N ratio was determined in the range of $3.0\~13.1$. From the elemental analysis, humus level of Dae-cheong reservoir sediment was estimated from mesohumic state to oligotrophic state. For the determination of nutrient release rate, $PO_4-P$ and $NH_4-N$ concentrations of interstitial water and overlying water were measured. By using the concentration difference between interstitial water and overlying water and using the Fick's diffusion law, the release rates of phosphorus and nitrogen from the sediment samples were calculated. Release rates of nutrients which directly influence to the water quality were $0.05\~8.63mgP/m^2day$ and $4.99\~36.56mgP/m^2day$. It was found that release rate was measured higher in the 1st sampling period than in the 2nd sampling period. For the determination of phosphorus content in sediment, TPs were measured in 807\~1542{\mu}g/g$ in the 1st samling period and $677\~5238{\mu}g/g$ in the End samling period. Phosphorus release rate and phosphorus content were not interrelated each other.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.3
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• pp.349-357
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• 2011

This study has an objective to estimate effect on water-quality enhancement by removal of contaminated river-bed material using a two-dimensional numerical modeling in the Seonakdong River, the Pyunggang River and the Maekdo River. RMA2 and RMA4 models were used for flow and contaminant transport simulation, respectively. After the analysis of the effects of flow restoration plan for the Seonakdong River system made by Lee et al (2008), simulation have been performed about scenarios which contains operations of the Daejeo Gate, the Noksan Gate, the Makdo Gate (on planning), and the Noksan Pumping Station. Because there is no option for elution from bed sediment in the RMA4 model, a simple technique has been used for initial condition modification for elution. The analyses revealed that the effect on water quality improvement due to dredging of bed sediment seemed to be less than 10 % of the total effect. The most efficient measure for the water quality improvement of the river system was the linked operation of water-gates and pumping station.

• Journal of Environmental Science International
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• v.7 no.5
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• pp.591-598
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• 1998

This study was conducted to evaluate water quality in the Keum River estuary using principal component analysis. The results was summarized as follow; Water quality in the Keum River estuary could be explained up to 70.40% by three factors which were included in the inffluent loading by the Keum River and Kyungpo cheon(38.99%), seasonal variation and organic matter pollution(19.05%), sediment resuspension and internal metabolism(12.35%). For spatial variation of factor score, artificial pollutant loading is highest at st.1, below Keum River barrage, and decreases toward the outer sea. For annual variation of factor score, factor 1 was highly related to artificial pollutant leading, and it was gently increased in 1994. Also, organic matter pollution, sediment resuspension and internal metabolism were increased to every year. It is necessary to control the nutrient leading by Keum river and Kyongpo cheon for Water quality management of estuary.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.5
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• pp.576-588
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• 2017

Some of the mariculture grounds near Ongjin-gun, Korea, were designated as mariculture management areas in 2007. Areas are so designated when the environmental quality of the mariculture ground deteriorates or there is an outbreak of hypoxia or harmful red tide that kills mariculture organisms. We surveyed the water and sediment quality and examined the mortality of mariculture organisms in the Ongjin-gun mariculture area. In a survey conducted in 2016, the water quality was better than the environmental quality standards for mariculture grounds, excepts for dissolved inorganic nitrogen, and the sediment quality was good. However, there was still mortality of mariculture organisms in some of the designated management areas. The areas that met the environmental quality standards should be delisted and the areas in which we observed mortality should be classified as management areas. This will enable the sustainable development of aquaculture and preserve healthy mariculture grounds.

• Journal of Soil and Groundwater Environment
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• v.18 no.1
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• pp.123-128
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• 2013

Water quality and contamination of sediment is a growing concern in the Iksan stream of Korea. Heavy metal contamination and changes in the physicochemical properties of the stream were evaluated. Water and sediment samples were collected from six sites during the dry and rainy seasons; pH, DO, EC, ORP, turbidity, $PO_4$-P, $NO_3$-N and selected heavy metals (Cu, Pb, Ni, As, Zn, Cd, Hg) were measured. Results showed almost no change in pH between seasons. DO was highest at site 2 (~2.63 mg/L) in the dry season; EC (1,540 ms/m) was greatest at site 1 in both seasons. The ORP gradually increased from the dry to rainy season at most of the sites and was highest at site 5. Turbidity was highest at site 1 and gradually decreased from the dry to rainy season at all sites except site 3. $PO_4$-P ranged from a high of 1,193mg/L at site 1 to in the dry season to a low of ~1.2 mg/L at site 4. In contrast, $NO_3$-N was highest at site 3 in the rainy season (12,531 mg/L). Among the heavy metals measured, Cu and Zn concentrations were highest at all sediment sites. Cu and Zn are added to livestock feed to improve reproductive rates and can be carried to the stream with manure. Transport of sediment and heavy metals during the rainy season is the major source of stream contamination and it is important to continue monitoring and take necessary action in these areas.