Assessment of Young Dong tributary and Imgok Creek impacted by Young Dong coal mine,South Korea

An initial reclamation of the Young Dong coal mine site, located in northeastern South Korea, was completed in 1995. Despite the filling of the adit with limestone, acid rock drainage (ARD) enters Young Dong tributary and is then discharged to Imgok Creek. This ARD carries an average of 500 mg CaCO₃/l of mineral acidity, primarily as Fe(II) and Al. Before spring runoff, the flow of Imgok Creek is 3.3–4 times greater than that of the tributary and has an alkalinity of 100 mg CaCO₃/l, which is sufficient to eliminate the mineral acidity and raise the pH to about 6.5. From April through September 2008, there were at least two periods of high surface flow that affects the flow of ARD from the adit. Flow of ARD reaches 2.8 m³/min during spring runoff. This raised the concentrations of Fe and Al in the confluence with Imgok Creek. However, by 2 km downstream the pH of the Imgok Creek is 6.5 and only dissolved Fe is above the Korean drinking water criteria (0.30 mg/l). This suggests only a minor impact of Young Dong Creek water on Imgok Creek. Acid digestion of the sediments in Imgok Creek and Young Dong Tributary reveals considerable abundances of heavy metals, which could have a long-term impact on water quality. However, several water-based leaching tests, which better simulate the bioavailable metals pool, released only Al, Fe, Mn, and Zn at concentrations exceeding the criteria for drinking water or aquatic life.     

Distributions of heavy metals in the sediments of South Korean harbors

Bottom sediments of harbors in the South Korea have been long suspected for metal contamination due to ship-based and urban-based activities for the past several decades. A number of areas have been suspected to impair ecosystem services to the local residents and drawn complaints from main stakeholders. Twelve contamination suspected harbors were subject to evaluate the level of contamination of Cr, Ni, Cu, Zn, As, Cd, Pb and Hg. The level of sediment contamination for each metal was evaluated comparing the relative enrichment of a given metal to pollution-insensitive aluminum. Regional background concentration of a given metal was also determined based on its down core measurement and sediment texture. Ecological risk posed by the presence of heavy metals was evaluated using the sediment quality guidelines (SQGs) developed by United States National Ocean and Atmosphere Administration (US NOAA) as benchmarks for evaluating sediment chemistry to aquatic organisms. Cu, Zn, Cd, Pb and Hg in the surface sediment were found to be higher than a factor of 1.5 than background sediments, and the overall metal contaminations of surface sediment can be regarded as medium-high- to high-priority sites in the sense of SQGs.     

A river water quality management model for optimising regional wastewater treatment using a genetic algorithm

To achieve water quality goals and wastewater treatment cost optimisation in a river basin, a water quality management model has been developed through the integration of a genetic algorithm (GA) and a mathematical water quality model. The developed model has been applied to the Youngsan River, where water quality has decreased due to heavy pollutant loads from Kwangju City and surrounding areas. Pollution source, land use, geographic features and measured water quality data of the river basin were incorporated into the Arc/View geographic information system database. With the database, the management model calculated treatment type and treatment cost for each wastewater treatment plant in the river basin. Until now, wastewater treatment policy for polluted rivers in Korea has been, first of all, to construct secondary treatment plants for untreated areas, and secondarily, to construct advanced treatment plants for the river sections whose water quality is impaired and for which the water quality goal of the Ministry of Environment is not met. Four scenarios that do not use the GA were proposed and they were compared with the results of the management model using the GA. It became clear that the results based on the GA were much better than those for the other four scenarios from the viewpoint of the achievement of water quality goals and cost optimisation.     

A Yeast DNA Microarray for the Evaluation of Toxicity in Environmental Water Containing Burned Ash

Numerous studies on the hazard assessment and epidemiological health responses to burned ash have been reported. However, there is little information on the potential toxicity of unknown chemical complexes in burned ash. For an overall evaluation of the multiple toxicities of burned ash, a DNA microarray was used in this study, as a new attempt to assess these toxicities. Using the global gene expression on yeast DNA chip to reflect the changes in mRNA levels, our study discovered a lot of evidences for the action of cell homeostasis and stress response etc., against the toxic effects on yeast cells. On the genes of 5,117 open reading frames (ORFs), as valid spots in a microarray, 997 were up-regulated, 1,259 were down-regulated and 2,861 remained unchanged. A detailed analysis of the microarray revealed the genes that were dynamically correlated to the function of the subcellular localization, energy/metabolism, various stress responses/cell homeostasis and detoxification. Significantly, the toxicities, caused by reactive oxygen species (ROS), metals and the other xenobiotics, were indicated in burned ash. Also, the possibility of mutagenicity of the burned ash was suggested on the basis of the DNA repair related genes.     

Environmental stress-induced extracellular isoperoxidase RC3 from rice

Effects of various environmental stresses such as heavy metals, salts and low (high) temperature on the secretion of peroxidase isozyme into the medium were examined in rice (Oryza sativa cv. Nak-Dong) suspension culture. The major extracellular peroxidases secreted into the medium by various stresses were cationic isoperoxidases. A far migrating cationic isoperoxidase RC3 was isolated from the medium after application of CaCl2, the effective stimulator for peroxidase secretion. Isolation of extracellular isoperoxidase RC3 was accomplished by ammonium sulfate fractionation, CM-cellulose cation-exchange chromatography, and Sephacryl S-100 gel filtration. The enzyme was a glycoprotein having molecular weight of approximately 34 KDa as determined by SDS-PAGE and 38 KDa by Sephacryl S-100 gel filtration. The pI value of the enzyme was 8.9. Kinetic studies revealed that the optimum pH of the enzyme was 6.0 for guaiacol and H2O2, and the Km values for guaiacol and H2O2 were 10.5 mM and 3.2 mM, respectively.     

Longitudinal‐Vertical Hydrodynamic and Turbidity Simulations for Prediction of Dam Reconstruction Effects in Asian Monsoon Area1

Abstract: This research investigates possible impacts of enlarged water body according to dam reconstruction on the hydrodynamics and water quality of the reservoir using a laterally averaged, two‐dimensional hydrodynamic and transport model, CE‐QUAL‐W2. The lake was formed by the artificial dam in 1983 for agricultural water supply and is currently under consideration of reconstruction so as to expand the volume of reservoir for flood control as well as water supply in downstream areas. To calibrate and validate the model, field‐collected data were compared with model predictions for water level fluctuations and water temperature during the years of 2001 (from January to December) and 2003 (from March to November). The model results showed a good agreement with field measurements both in calibration and verification. Utilizing the model, impacts of dam reconstruction on the thermal hydrodynamics and turbid current were predicted. From the model results, dam reconstruction limited the depth of thermal stratification below 10 meter and formed steep temperature gradient between epilimnion and hypolimnion. The restricted thermal stratification persisted up to the end of September. This result indicated that thermal stratification would become stronger during summer and stay longer after dam reconstruction. In addition, the restricted thermal stratification caused vertical circulation of water mixing lower than 10 meter and isolated the upper water layer from the lower water layer which increased the volume of hypolimnetic water with low temperature. The vertical circulation near the surface also mitigated propagation of density plume within the depth of 10 m which would remain the hypolimnetic water clean.     

Evaluating the effects of granular and membrane filtrations on chlorine demand in drinking water

In this study, chlorine decay experiments were conducted for the raw water from Nakdong river that is treated by Chilseo Water Treatment Plant (CWTP) situated in Haman, Korea as well as the effluents from sand and granular activated carbon (GAC) filters of CWTP and fitted using a chlorine decay model. The model estimated the fast and slow reacting nitrogenous as well as organic/inorganic compounds that were present in the water. It was found that the chlorine demand due to fast and slow reacting (FRA and SRA) organic/inorganic substances was not reduced significantly by sand as well as GAC filters. However, the treated effluents from those filters contained FRA and SRA that are less reactive and had small reaction rate constants. For the effluents from microfiltration, ultrafiltration, and nanofiltration the chlorine demand due to FRA and SRA were further reduced but the reaction rate constants were larger compared to those of sand and GAC filter effluents. This has implications in the formation of disinfection by products (DBPs). If DBPs are assumed to form due to the interactions between chlorine and SRA, then it is possible that the DBP formation potential in the effluents from membrane filtrations could be higher than that in the effluents from granular media filters.     

Removal Efficiency of PM10 via Ventilation with Residential Exhaust Hood and Conditions for Reducing Human Intake Fraction

Environmental Modeling & Assessment - As the number of enclosed residential buildings increases to minimize energy consumption, research on indoor air quality is becoming more important....