• Journal of the Korean Society for Marine Environment & Energy
• /
• v.13 no.4
• /
• pp.288-295
• /
• 2010

Metal exposure experiments using polychaete (Perinereis nuntia) as a bio-indicator of trace metals contamination were conducted to evaluate the bioaccumulation and the biomarkers responses such as metallothionein-like protein (MTLPs) and glutathione S-transferase (GST) which was simultaneously exposed to Cadmium (Cd) and Copper (Cu). Cu and Cd concentrations in polychaete were enhanced with increasing exposure time and their concentrations of aqueous medium. Initial accumulation of Cd was higher than that of Cu. Our results showed that the bioaccumulation of Cu and Cd were prohibited, especially at higher Cu levels, suggesting the different cellular uptake mechanisms when Cu and Cd are co-exist. Net accumulation rate of Cu was declined with exposure time but it did not show any significant change for Cd. Although the highest MTLPs concentration was observed at 6 hr of exposure time, it did not show any significant change related to exposure times and metals concentrations. An increase of GST activity tended to increase as a function of exposure time and metals concentrations. And GST activities in P. nuntia have similar tendency with bioconcentration factors in high concentration of Cu (treatment group IV) at post 24 h of exposure. Our results provide new information of the bioaccumulation and biomarker responses to understand the effects of co-existing contaminants (Cu and Cd) using polychaete. Further studies are required to elucidate the bioaccumulation and biomarkers responses for various contaminants.

• Economic and Environmental Geology
• /
• v.37 no.1
• /
• pp.21-33
• /
• 2004

The objective of this study is to review of environmental assessment of heavy metals derived from various metalliferous mines in Korea. As a results of national wide research for heavy metal contaminations in the vicinity of metalleferous mines, the main contaminants are mine waste materials including tailings. From the materials, toxic elements including As, Cd, Cu, Pb and Zn can be dispersed into downstream through wind and water. Thus, soils around the mines contain elevated levels of those elements, which are over the guide values for environmental regulation of soils in Korea. Arsenic is one of the most important elements contaminated by mining activities, to a less extent, Cd, Cu, Pb and Zn. In spite of remediation works for some metal mines by the government, there are still lots of abandoned mines which are necessary for reclamation of mining sites. This study also includes that metal concentrations in soils and tailings can be varied upon various decomposition methods including 0.1N HC1 and aqua regia and sequential extraction scheme, with differences in each element, too. This may be due to geochemical characteristics of the elements, such as solubility, mobility and chemical forms in the geochemical environment. Finally, it is suggested that a certain organization should be runned by Korean government for management of abandoned mines.

• Journal of Environmental Science International
• /
• v.27 no.11
• /
• pp.1059-1072
• /
• 2018

Bioremediation has been recognized as a suitable alternative to conventional methods of removing contaminants, and it uses fungi, bacteria and microalgae. In contrast to other organisms, microalgae are unique in that they have the ability to perform photosynthesis like plants and to utilize organic/inorganic carbon substrates, in a process called phytoremediation. Microalgae can populate a reaction site rapidly and enhance the bioremediation efficiency. In this study, Chlorella vulgaris was used to evaluate the removal potentials of the nutrients (N and P) and heavy metals (Cu and Zn) from swine wastewater. The optimum growth conditions for Chlorella vulgaris and the removal potentials of N, P, Cu, and Zn from synthetic wastewater using Chlorella vulgaris were investigated. Based on the results, the applicability of this microalga to on-site wastewater treatment was examined. Optimal growth conditions for Chlorella vulgaris were established to be $28^{\circ}C$, a pH of 7, and light and dark cycles of 14:10 h. As the concentrations of the nutrients were increased, the efficiencies of N and P removal efficiencies by Chlorella vulgaris were decreased in the single and binary mixed treatments of the nutrients, respectively. Further, the efficiencies of Cu and Zn removal also decreased as the heavy metals concentrations added were increased, both in the single and binary mixed treatments. In addition, the efficiency of Cu removal was higher than that of Zn removal. Our results indicate that Chlorella vulgaris could be used in treatment plants for the removal of nutrients and heavy metals from swine wastewater.

• Journal of the Mineralogical Society of Korea
• /
• v.16 no.4
• /
• pp.283-293
• /
• 2003

Domestic water treatment plants operate the rapid and slow filtering system using the filtering sands. Most of them are composed of beach sands, which have less sorption capacity of heavy metals as well as organic contaminants. Therefore, the development of fortified functional filtering materials with high removal capacity of organic and inorganic contaminants is needed to prevent the unexpected load of contaminated source water. This study aims to test the hydrochemical change and the removing capacity of heavy metals such as Cd, Cu, and Pb on the Jumunjin sand, feldspathic sand(weathering product of Jecheon granite), feldspathic mixing sand I(feldspathic sand mixed with 10 wt% zeolite), and feldspathic mixing sand II (feldspathic sand mixed with 20 wt% zeolite). Feldspathic mixing sand I and II showed the eruption of higher amounts of cations and anions compared with the Jumunjin sand and feldspathic sand. They also showed higher eruption of Si, Ca, $SO_4$ ions than that of Al, $NO_3$, Fe, K, Mg, and P. Feldspathic mixing sand II caused higher eruption of some cations of Na, Ca, Al than feldspathic mixing sud I, which is the result controlled by the dissolution of zeolite. Jumunjin sand and feldspathic sand showed very weak sorption of Cd, Cu and Pb. In contrast to this, feldspathic mixing sand I and II showed the high sorption and removal capacity of the increasing order of Cd, Cu and Pb. Feldspathic mixing sand II including 20% zeolite showed a fortified removal capacity of some heavy metals. Therefore, feldspathic mixing sand mixed with some contents of zeolite could be used as the fortified filtering materials for the water filtering and purification in the domestic water treatment plants.

• Journal of Environmental Science International
• /
• v.21 no.1
• /
• pp.57-67
• /
• 2012

The midge samples were undertaken at three streams, representing different surrounding environments, to investigate the contaminant exposure of midge. The content of heavy metals in midge collected in Singil stream were generally higher as a result of input to the industrial effluents with respect to other streams. Adsorption experiments were done to evaluate the possibility of removing contaminants from water with midge. Diazinon and heavy metals were contaminant target compounds in this study. The removal rate of diazinon in water by midge was 60-75%. In the case of Cu, the removal rate was reached around 90% at the lower initial concentration of 1.87 and 0.81 ppm rather than 4.25 ppm. The reduction of concentration of Cr and Cd according to the lapse of time was similar to the Cu, but their removal rates were shown 50% and 60-74%, respectively. The removal rate of Zn by midge represented relatively high level within the experimental condition. No change in concentration of Cr and As with time were occurred at all experimental conditions. It accounts for the fact that the reduction of Cr and As could not be achieved through the adsorption process, using midge.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.05a
• /
• pp.735-738
• /
• 2000

The characteristics of wire electrical discharge machining (WEDM) are governed by many factors such as the power supply type, operating condition and electrode material. This work deals with the effect of wire electrode materials on the machining characteristics such as, metal removal rate, surface characteristics and surface roughness during WEDM A wire's thermal physical properties are melting point, electrical conductivity and vapor pressure. One of the desired qualities of wire is a low melting point and high vapor pressure to help expel the contaminants from the gap. They are determined by the mix of alloying elements (in the case of plain brass and coated wire) or the base core material(i.e. molybdenum). Experiments have been conducted regarding the choice of suitable wire electrode materials and influence of the properties of these materials on the machinability and surface characteristics in WEDM, the experimental results are presented and discussed from their metallurgical aspect. And the coating effect of various alloying elements(Au, Ag, Cu, Zn, Cr, Mn, etc.) to the Cu or 65-35 brass core on them was reviewed also. The removal rate of some coated wires are higher than that of 65-35 brass electrode wire because the wire is difficult to break due to the wire cooling effect of Zn evaporation latent heat and the Zn oxide on the surface is effective in preventing short circuit. The removal rate increases with increasing Zn content from 35, 40 and Zn coated wire

• Journal of Soil and Groundwater Environment
• /
• v.23 no.1
• /
• pp.63-73
• /
• 2018

Rice is a staple food source in Asian countries. In paddy field, rice plant can take up toxic elements through its roots from contaminated soils, and its leaves and grain can absorb the toxic elements deposited on the soil surface. A totla of 40 soil and polished rice samples were collected around four abandoned metal mines in Korea and analyzed for As, Cd, Cu, Pb and Zn by atomic absorption spectrophotometer (AAS). The average contents of As, Cd, Cu, Pb and Zn in rice grain grown on the contaminated soils were 0.247, 0.174, 4.694, 0.804 and 16.78 mg/kg, respectively. These levels are higher than worldwide average concentrations. Assuming the rice consumption of 169 g/day by overall households in Korea, the estimated daily intakes from the rices were found to be 33, 48, and 63% for As, Cd, and Pb, respectively, of the acceptable daily intake (ADI) suggested by the FAO/WHO Joint Food Additive and Contaminants Committee.

• Journal of Applied Biological Chemistry
• /
• v.57 no.2
• /
• pp.131-136
• /
• 2014

An attempt was made to assess metal ionic toxicity levels of different fishes in the polluted rivers viz., Buriganga and Turag. Fish samples collected from two polluted rivers were analyzed for the levels of metals such as Cd, Cr, Cu, Mn, Pb, and Zn in order to elucidate the status of these contaminants in fish meant for human consumption. The detected concentrations of Cr, Cu, Mn, and Zn ions in fish species collected from the polluted rivers were below the toxic levels and did not appear to pose a threat. Among the analyzed metals, Cd and Pb ions were detected above the permissible levels in liver and muscle tissues of stinging catfish (Heteropneustesfossilis), spotted snakehead (Channapunctata) and wallago (Wallagoattu) collected from the polluted rivers causing toxicity for human consumption. Stinging catfish (Heteropneustesfossilis) was the species found to highly bioaccumulate these metals. Fish species bioconcentrated appreciable amounts of Cd and Pb as toxic metals in the liver as compared to the muscle. Levels of these toxic metals varied depending on different tissues in fish species.

• Korean Journal of Materials Research
• /
• v.27 no.12
• /
• pp.672-678
• /
• 2017

In the production of zirconium cladding tube, a pickling acid solution is used to remove surface contaminants, which generates tons of pickling acid waste. The waste pickling solution is a valuable resource of Hf-free Zr. Many studies have investigated separating the Hf-free Zr source from the waste pickling acid. The results showed that $Ba_2ZrF_8$ precipitates prepared from the waste pickling acid were useful as an electrolyte for the electrorefining of Zr in molten salt. In the present work, electrorefining was performed in a $Ba_2ZrF_8-LiF$ binary electrolyte to recover Zr from a Hf-free CuZr ingot anode prepared by electroreduction. Before electrorefining, two pretreatments are performed. First, electrolyte melting was carried out to determine the eutectic temperature, and second, the electrolyte was treated to eliminate impurities, mainly hydride. After electrorefining, the cathode deposits were analyzed by $O_2$ gas analyzer and SEM-EDX to explore the possibility of recovering nuclear-grade Zr metal. Moreover, the anode was analyzed by SEM-EDX to determine the Zr dissolution depth.

• Environmental Engineering Research
• /
• v.24 no.3
• /
• pp.427-433
• /
• 2019

Sakarya is famous for cucurbit productions in Turkey and cucurbits can grow as big as 560 kg of weight per fruit in its agricultural areas. There is no or limited information about contaminant levels and profiles of the agricultural fields in Sakarya. The purpose of this study is to investigate the levels of polycyclic aromatic hydrocarbons (PAHs) (naphthalene, phenanthrene, pyrene, and fluoranthene) and heavy metal (As, Cd, Cu, Cr, Ni, Pb, Zn) concentrations of the selected fields. Total 33 soil samples were collected from 12 counties of Sakarya where both cucurbits have been produced and organochlorine pesticides have been applied to the fields for more than 30 y during the historical plantation periods. Heavy metal and PAH contents in the soil samples were measured by an Inductively Coupled Plasma Emission Spectroscopy and a Gas Chromatography-Mass Spectrometry. The highest phenanthrene, pyrene, and fluoranthene concentrations were measured as 63.50 ng/g, 134.34 ng/g, 140.0 ng/g, respectively in the soil samples from Geyve County. Cu, Ni, and Cr concentrations were measured as 108.2 mg/kg, 219.9 mg/kg, and 173.1 mg/kg, respectively in Geyve's samples which were also the highest and 2-7 times more than the limit values given in the Turkish Soil Pollution Control Regulation. Precautions need to be taken for Sakarya's agricultural fields which are an important milestone of Turkey's cucurbit and fruit productions since the contaminants can be accumulated in the fruits and edible parts of the plants.