• Journal of Environmental Impact Assessment
• /
• v.21 no.1
• /
• pp.81-91
• /
• 2012

In this study, it is grasped the status of nutrients through an investigation of release characteristics and physicochemical properties of sediments on reservoir. And then the effect of sediments is evaluated on the water quality in reservoir. In the results of physicochemical analysis, the pollution level of midstream is the highest, which shows the traits that the water is more deeper and takes place a deposition consistently. Then, the pollution level of upstream is higher than downstream's because inflow has influence on the upstream directly. The downstream is located near tidal gate so that the soil particles can be moved easily and are difficult to be deposited due to the distribution of seawater by control of tidal gate. Therefore, the downstream is showed the lowest pollution level than the others. Also, the concentration of SOD(Sediment Oxygen Demand) in the upstream which is influenced on the effect of inflow is highest than the others. When it analyzes under anaerobic and aerobic condition to understand the release characteristic of sediment, it shows that the release rate is low or negative under the aerobic condition. Whereas the release rate is usually positive under the unaerobic condition relatively. According to these results, it is necessary to maintain the proper environmental factors of water body for decreasing the release rate of sediment. Because the release rate is changeable under the different condition of water body. Therefore, proper strategies are required for increasing the self-purification of water as well as keeping the aerobic condition of sediment and managing a sediment layer directly to control the inner-pollution by the sediment of reservoir.

• Journal of Korean Society on Water Environment
• /
• v.18 no.2
• /
• pp.213-220
• /
• 2002

In this study the effects of initial pH, temperature, dissolved oxygen concentration, and sediment depth on the release of phosphorus from sediment in Lake Sihwa were investigated. No phosphorus release occurred at $10^{\circ}C$ for all pH values. DO concentrations were decreased and equilibrium was obtained 4-8 days after phosphorus release started. The DO concentrations were less than 1 mg/L. Sediment depth had little effect on phosphorus release rate. In order to control the released phosphorus, raw sludge and chalk were used. Results showed that a portion of phosphorus was removed by adsorption to chalk and raw sludge. About 90 % phosphorus removal was observed using sludge and calcinated chalk from the water sample in Lake Sihwa.

• Journal of Environmental Impact Assessment
• /
• v.9 no.2
• /
• pp.99-107
• /
• 2000

In order to solve water quality problem of domestic dam reservoir, many projects have been performed in a point of view to restoration of water quality. This study was carried out to evaluate the effect of release from sediment on water quality and release characteristics. Daecheong dam reservoir was investigated for two years, from 1998 to 1999. The nutrient release rates of Daecheong reservoir is less than foreign eutrophic reservoir at anoxic condition. For the evaluation of the effect of nutrient release on water quality, internal and external loading was calculated at Daecheong reservoir. As total phosphorus loading from sediment is calculated 9.3 ton/yr and inflow loading from Daecheong reservoir watershed 118 ton/yr, internal loading shows the portion of 7.88% to external loading. At this study, because sampling point was choosed at the point where much sediment is accumulated, experimental result is more than average release rates. Because Daecheong reservoir shows complete thermal stratification and anoxic condition below 30m from water surface in summer seasons, released phosphorus from sediment can not transfer to epilimnion and eventually resettles. Therefore sediment has insignificant impacts on water quality on Daecheong dam reservoir.

• Journal of Environmental Science International
• /
• v.11 no.12
• /
• pp.1333-1337
• /
• 2002

A significant fraction of nutrients, such as nitrogen and phosphorus released from sediment are utilized by primary production in the shallow water of coast and lake. The purpose of this study is to introduce the mechanism of nutrients release from sediment and to introduce the methods of the measurement of nutrient released from sediment. One approach is to calculate nutrients released from sediment by a concentration gradient between sediment pore waters and overlying water based on the Fick's law. The other approaches of measurement are the undisturbed sediment core experiments and measurement of nutrient released from sediment by the in situ chamber equipment.

• Journal of Korean Society of Water and Wastewater
• /
• v.13 no.2
• /
• pp.89-94
• /
• 1999

In this study small glass columns with 2.5cm inner diameter and 24.5cm length were used as many as the sample numbers to study the effects of initial pH, temperature, dissolved oxygen concentration, and sediment depth on the release of phosphorus from lake sediment. No phosphorus release occurred at $10^{\circ}C$ with all pHs, and release rate at $25^{\circ}C$ was higher than that at $35^{\circ}C$ with pH 4 and reverse trends were observed at pH 7 and 10. Under all conditions, DO concentrations were decreased and equilibrium was obtained after 4-8 days when phosphorus release started and the Do concentrations were less than 1 mg/l. Sediment depth had little effect on phosphorus release rate. It was found that relation between released SRP(Soluble Reactive Phosphorus) concentration and time was zero order reaction and reaction rate coefficients were obtained. The amount of phosphorus release from lake sediment can be predicted by considering these k values.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.57 no.4
• /
• pp.31-38
• /
• 2015

This study aims to assess the effectiveness of limestone, zeolite, and crushed concrete as capping material to block the release of heavy metals (As, Cu, Cr, Ni, and Pb) and reduce the sediment oxygen demand. The efficiency of limestone, zeolite, and crushed concrete was evaluated in a reactor in which a 1-cm thick layer of capping materials was placed on the sediments collected from Inchon north harbor. Dissolved oxygen concentration and heavy metal concentration in seawater above the uncapped sediments and capping material were monitored for 17 days. The sediment oxygen demand was in the following increasing order: crushed concrete ($288.37mg/m^2{\cdot}d$) < zeolite ($428.96mg/m^2{\cdot}d$) < limestone ($904.53mg/m^2{\cdot}d$) < uncapped ($981.34mg/m^2{\cdot}d$). The capping materials could reduce the sediment oxygen demand by blocking the release of biochemical matters consuming dissolved oxygen in seawater. It was also shown that zeolite and crushed concrete could effectively block the release of Cu, Ni, and Pb but those were not effective for the interruption of As and Cr release from marine contaminated sediments.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.56 no.1
• /
• pp.1-9
• /
• 2014

Sediment pollutants have been considered an important source for the eutrophication of estuarine reservoir. In this study, the effects of pollutants released from bottom sediment to water column were investigated. Sediment samples were collected each two station from Namyang and Sukmoon estuarine reservoirs in August 2013. The fractionation result of sediment phosphorus indicated that Adsorbed-P ($36.7{\pm}8.84%$) and Nonapatite-P ($29.3{\pm}12.50%$) are the two dominant phosphorus groups in the sediments. For sediment release test, eight sets of acrylic chamber (0.3 m $diameter{\times}1m$ high, with 0.15 m sediment depth) were used with aerobic and anaerobic environment. Under anaerobic conditions, rates of $NH_4-N$ release from the sediments were highly variable, with final concentrations of $NH_4-N$ in the overlying water varying from between about 0.69~1.04 in Namyang and 2.58~4.23 mg/L in Sukmoon reservoir. The $NH_4-N$ release was active at the upstream around the confluence of tributary compared to downstream near the embankment. The $PO_4-P$ release was more obvious than $NH_4-N$ in anaerobic condition. The final $PO_4-P$ concentrations were approximately from two-fold to eight-fold higher than initial concentration. In terms of reservoir water quality management, not only tributary pollutants but also sediment nutrient loading is necessary to consider the water quality contribution.

• Water Engineering Research
• /
• v.1 no.2
• /
• pp.137-146
• /
• 2000

A windows-based software package, named DREDGE, is developed for estimating sediment resuspension and contaminant release during dredging operations. DREDGE allows user to enter the necessary dredge information, site characteristics, operational data, and contaminant characteristics, then calculates an array of concentration using the given values. The program mainly consists of the near-field models, which are obtained empirically, for estimating sediment resuspension and the far-field models, which are obtained analytically, for suspended sediment transport. A linear equilibrium partitioning approach is applied to estimate particulate and dissolved contaminant concentrations. This software package which requires only a minimal amount of data consists of three components; user input, tabular output, and graphical output. Combining the near-field and far-field models into a user-friendly windows-based computer program can greatly save dredge operator's, planners', and regulators' efforts for estimating sediment transports and contaminant distribution.

• Journal of Environmental Impact Assessment
• /
• v.7 no.2
• /
• pp.5-14
• /
• 1998

This study was performed to estimate interrelation between characteristics of sediment and nutrient releare from sediment in Dae-cheong lake. For the investigations, sediments were sampled in June and October 1997 at fish farms, embayment, and the main stream of Dae-cheong lake. Items for investigation are as follows; water content, weight loss on ignition(IG), porosity of sediment, Total Kjeldahl Nitrogen(TKN), content of element(H, N, C), nutrient release rate. Water content and porosity were measured to conjecture the physical trait and grain size. And weight loss on ignition was measured to determine the contents of organic substance. For the determination of nutrient release rate, $PO_4-P$ and $NH_4-N$ concentration of interstitial water and overlying water were measured. Release rate of nutrients which has direct influenced upon the water quality were 0.05-8.63mg-$P/m^2{\cdot}day$ and 4.99-36.56mg-$N/m^2{\cdot}day$. And it was found that release rate was measured higher in the 1st sampling than in the 2nd sampling. And for determination of the humus level of sediment, carbon and nitrogen content were measured by using elemental analyzer. Generally, C/N ratio is used to determine humus level of lake sediment. As a result of elemental analysis, C/N ratio was determined in the range of 7.64~11.55, so humus level of Dae-cheong lake sediment was estimated from mesohumic state to oligohumic state.

• Journal of Korean Society of Water and Wastewater
• /
• v.26 no.4
• /
• pp.503-512
• /
• 2012

In Yongwon channel, its natural flow of seawater is blocked by the construction of Busan New Port including the container berth. The channel was transformed into a narrow and long one, where it is possible that ships are only allowed to pass through the north-side channel of Gyeonmado located at the point of river mouth to Songjeongcheon. In addition, Yongwon channel is approximately 100 m wide on average and 3,600 m long, and has the highest slenderness ratio (length/width = 36). So it is considered that the changes in the terrain characteristics of Yongwon channel is likely to alter the circulation of sea water, thereby changing its water quality. In this study, the bottom sediment were collected from the 48 points of the Yongwon channel and the long-term leaching characteristics were analyzed. Thus, changes in sediment and water quality were analyzed through the sediment release test to investigate the degree of contamination. The sediment release from the inside region was higher than the outer region, which is due to the pollutant that comes form the downtown area. The results of this study can be used to predict the water quality in the future and prepare the economically optimized countermeasures to improve the water quality of Yongwon channel, Busan New Port.