Myung Chae Jung

Heavy metal contamination of soils and waters in and around the Imcheon Au-Ag mine, Korea

The heavy metal contamination of soils and waters by metalliferous mining activities in an area of Korea was studied.In the study area of the Imcheon Au–Ag mine, soils and waters were sampled and analyzed using AAS for Cd, Cu, Pb and Zn.Analysis of HCO 3 ,F ,N O 3 and SO4 in water samples was also undertaken by ion chromatography.Elevated concentrations of the metals were found in tailings.The maximum contents in the tailings were 9.4, 229, 6160 and 1640 mg/kg extracted by aqua regia and 1.35, 26.4, 70.3 and 410 mg/kg extracted by 0.1 N HCl solution for Cd, Cu, Pb and Zn, respectively.These metals are continuously dispersed downstream and downslope from the tailings by clastic movement through wind and water.Because of the existence of sulfides in the tailings, a water sample taken on the tailings site was very acidic with a pH of 2.2, with high total dissolved solids (TDS) of 1845 mg/l and electric conductivity (EC) of 3820 mS/cm. This sample also contained up to 0.27, 1.90, 2.80, 53.4, 4,700 mg/l of Cd, Cu, Pb, Zn and SO4 , respectively.TDS, EC and concentrations of metals in waters decreased with distance from the tailings.The total amount of pulverized limestone needed for neutralizing the acid tailings was estimated to be 46 metric tons, assuming its volume of 45,000 m 3 and its bulk density of 1855 kg/m 3 . # 2001 Elsevier Science Ltd.

Heavy metal contamination in the vicinity of the Daduk Au–Ag–Pb–Zn mine in Korea

The heavy metal contamination and seasonal variation of the metals in soils, plants and waters in the vicinity of an abandoned metalliferous mine in Korea were studied. Elevated levels of Cd, Cu, Pb and Zn were found in tailings with averages of 8.57, 481, 4,450 and 753 mg/kg, respectively. These metals are continuously dispersed downstream and downslope from the tailings by clastic movement through wind and water. Thus, significant levels of the elements in waters and sediments were found up to 3.3 km downstream from the mining site, especially for Cd and Zn. Enriched concentrations of heavy metals were also found in various plants grown in the vicinity of the mining area, and the metal concentrations in plants increased with those in soils. In a study of seasonal variation on the heavy metals in paddy fields, relatively high concentrations of heavy metals were found in rice leaves and stalks grown under oxidizing conditions rather than a reducing environment (P<0.05).

Arsenic, Sb and Bi contamination of soils, plants, waters and sediments in the vicinity of the Dalsung Cu-W mine in Korea

The objective of this study is to investigate environmental contamination derived from metalliferous mining activities. In the study area, the Dalsung Cu-W mine, soils, various crop plants, stream waters, sediments and particulates were sampled in and around the mine and analyzed for As, Sb and Bi by ICP-AES with a hydride generator. In addition, soil pH, cation exchange capacity, loss-on-ignition and soil texture were also measured. Concentrations of As, Sb and Bi in surface soils sampled in the mine dump sites averaged 2500, 54 and 436 microg g(-1), respectively. Relatively lower concentrations, however, were found in soils from alluvial and high land sites and household garden sites. Arsenic, Sb and Bi contents in plant samples varied depending upon their species and parts, with higher concentrations in spring onions, soybean leaves and perilla leaves and lower levels in red peppers, corn grains and jujube grains. These results confirm that elemental concentrations in plant leaves are much higher than those in plant grain. Elevated levels of As, Sb and Bi were also found in stream sediments sampled in the vicinity of the mine and decreased with distance from the mine. Concentrations in stream water samples ranged from 0.8 to 19.1 microg As l(-1) and from 0.3 to 8.4 microg Bi l(-1); all the samples contained less than 1.0 microg Sb l(-1). Because of very low particulate loading at the time of sampling, the metal contents in particulates were very low (< 8.2 microg As l(-1), < 0.22 microg Sb l(-1) and 2.8 microg Bi l(-1). This may be mainly due to the low solubility of those elements under moderately acidic and oxidizing conditions of the mining area.

Seasonal Variations and Chemical Forms of Heavy Metals in Soils and Dusts from the Satellite Cities of Seoul, Korea

This research investigated heavy metal pollution of soils and dusts in two representative satellite cities of Seoul, Korea and studied the seasonal variations in metal concentrations through the rainy season and the chemical forms of metals using a sequential extraction analysis. The metal dispersion pattern was illustrated to match with urban structure. Soil and dust samples were collected from the cities of Uijeongbu and Koyang, which are the northern and northwestern satellite cities of Seoul (the capital), before and after rainy season. Concentrations of Cu, Pb and Zn were higher than those of the world averages for soils, and their levels decreased after rain, particularly in highly contaminated samples. Relatively high pH values were found in roadside soils, but no seasonal variation was found after the rainy season. The three metals (Cu, Pb and Zn) in soils and dusts were associated with various chemical fractions of soils and dusts as distinguished by the sequential extraction scheme, and a strong similarity of metal association between soils and dusts was found, which indicates that airborne dust may be a principle source of soil contamination. Copper is uniformly distributed, and Pb is largely associated with the reducible phase. There is an appreciable proportion of total Zn in the exchangeable/water-acid soluble fraction. After the rainy season, the most soluble fractions in soils and dusts were leached away. In terms of mobility and bioavailability of metals in soils and dusts, the order Zn >> Cu > Pb is suggested. Geographical variations of total metals corresponded well with urbanised areas of cities, especially the industrial complex and major motorways.

BBQ charcoal as an important source of mercury emission

In this study, the environmental significance of mercury emission has been investigated with respect to the use of the barbecue (BBQ) charcoal. For this purpose, emission gas samples collected from a total of 11 barbecue charcoal products commonly available in the Korean market were analyzed. All of these products consist of both domestic (4 types) and imported products (7 types from three countries). The emission concentration of Hg varied widely from sample to sample ranging from 114 to 496ngm(-3). The amount of Hg emission appeared to be affected by the diverse nature of raw materials and/or the processes involved in their production. In light of the recent reference exposure limits (REL) of Hg, it can be a potential threat to human health. As such, a proper regulation is desirable from a toxicological viewpoint to reduce the potential risk associated with the use of BBQ charcoal.

Toxic Risk Assessment and Environmental Contamination of Heavy Metals around Abandoned Metal Mine Sites in Korea

In order to investigate the levels of heavy metal contamination and to assess the risk of the adverse health effects on human exposure to toxic heavy metals influenced by past mining activities, environmental geochemical surveys were undertaken around abandoned metal mine sites (Okdong Cu-Pb-Zn, Dokok Au-Ag-Cu and Hwacheon Au-Ag-Pb-Zn mines). High concentrations of heavy metals were found in tailings from the Okdong (72 As mg/kg, 53.6 Cd mg/kg, 910 Cu mg/kg, 1,590 Pb mg/kg, 5,720 Zn mg/kg), the Dokok (254 As mg/kg, 98.2 Cd mg/kg, 2,550 Cu mg/kg, 4,200 Pb mg/kg, 18,020 Zn mg/kg) and the Hwacheon (72 As mg/kg, 12.4 Cd mg/kg, 580 Pb mg/kg, 1,300 Zn mg/kg) mines. Elevated levels of As, Cd, Pb and Zn were also found in agricultural soils from these mine areas. Human risk effects are classified into a cancer effect and a toxic (noncancer) effect. The hazard index representing a toxic risk for As was higher value than 1.0 in the Okdong and the Hwacheon mine sites, as was that for Cd in the Okdong and Dokok mine sites. Therefore, toxic risks for As and Cd exist via exposure (ingestion) to the contaminated soil, groundwater and rice grains in these mine areas. The cancer risk for As by the consumption of groundwater used as drinking water from the Okdong and the Hwacheon mine areas was 7E-4 and 1E-4, respectively. These risk levels exceed the acceptable risk (1 in 100,000) for regulatory purposes.

The impact of mining activities in alteration of As levels in the surrounding ecosystems: an encompassing risk assessment and evaluation of remediation strategies.

A comprehensive field survey was conducted to explore the status of arsenic (As) contamination in soil and water systems surrounding numerous abandoned mine sites in Korea, which were previously applied with soil-topping (15 cm deep) and lime treatment for remediation purposes. This survey also aimed to assess the environmental stability of those reservoirs in relation to their established guidelines for As. To this end, a total of 5837 target soils (TS) were analyzed along with 305 control soils (CS) and 74 tailing (TA) samples. In addition, analyses were also extended to cover 1066 water and 329 sediment samples. Substantial evidence (e.g., differences in the mean As levels between TS (12.7 mg kg(-1)) and CS (0.69 mg kg(-1)) and the strong correlation between TS and TA) suggests a strong effect of previous mining activities. Soil-topping method was successful in confining As at the subsurface soil and restraining its dispersal. Although soil pH level also dropped with increasing As, it was restored to near neutrality by liming treatment. The mean values of As in water samples are comparable between dry (22.2) and wet seasons (21.2 mg L(-1)), while its values frequently exceeded various guideline limits. The pollution status of the current land and water systems needs to be assessed properly along with a removal plan for mine wastes/tailings to limit the dispersion of As in the study area.

Environmental Contamination and Sequential Extraction of Trace Elements from Mine Wastes Around Various Metalliferous Mines in Korea

ABSTRACT This study has focused on the environmental problems of toxic trace elements from mine wastes including tailings around various abandoned metalliferous mines in Korea. 48 mine wastes were sampled in and around 38 abandoned mines classified as 3 groups (Au-Ag, base metal and other mines) with 5 types by their ore minerals and mineralization. Wide ranges of pH values were found in the wastes derived from the weathering process of parent rocks; relatively low pH due to the oxidation of sulfide minerals (mainly pyrite) and high pH related to the interaction with carbonate minerals (mainly calcite) or to absence of sulfide minerals. Based on the 0.1N HCl extraction analysis, elevated levels of Cd, Cu, Pb and Zn were found in a few mine wastes, especially for type 2 (Au-Ag mine mineralized by a hydrothermal vein type with sulfide minerals), and some wastes from types 4 (skarn type) and 5 (others) contained over the guidelines (action level) of Cd and/or Cu under the Soil Environment Preservation Act in Korea. In addition, extremely high concentrations of the metals were also found in the mine wastes extracted by aqua regia compared to soils from uncontaminated natural areas. This was also confirmed by the results of sequential extractions performed on representative samples, which showed high proportions of the metals in exchangeable fractions of the acidic mine wastes. Thus, it can be expected that trace elements in the mine wastes may be dispersed both downstream and downs-lope through water and wind. Eventually they may pose a potential health risk to residents in the vicinity of the mine. Therefore, it is necessary to control the mine wastes with a proper method for their reclamation such as neutralization of the mine wastes using pulverized limestone.

Impact assessment of heavy metal pollution in the municipal lake water, Yaounde, Cameroon

The objectives of this study are to evaluate the extent of heavy metal pollution in water at the Municipal Lake of Yaounde, and to find out their variability and origin. Water from fifteen selected sites of the lake and River Mingoa, Cameroon was sampled in August 16th of 2005 and 2006 and in 30th August 2007 during the minor dry season; and subjected to the analyses of physicochemical parameters and various elements. In addition, multivariate data analysis techniques including principal component analysis (PCA) were utilized to determine the variations in heavy metal content in the Municipal Lake water and their natural or anthropogenic sources. The chemical results indicated that concentrations of Al, Fe, Mn, Cd and Pb in the study area exceeded the drinking water quality and they would pose health risk for users of these waters. This is evidence that River Mingoa, the main tributary to the Municipal Lake is the main collector of pollutants from activities in the sloping side of the Municipal Lake. Based on the multivariate statistical analysis, very high positive correlations were observed between elements, and five factors computed from PCA explained 86.6% of total variance. These factor loadings are mainly controlled by anthropogenic inputs, lithogenic processes during weathering progress of natural parent materials and local geology.

Remediation of soils contaminated with heavy metals with an emphasis on immobilization technology

The major frequent contaminants in soil are heavy metals which may be responsible for detrimental health effects. The remediation of heavy metals in contaminated soils is considered as one of the most complicated tasks. Among different technologies, in situ immobilization of metals has received a great deal of attention and turned out to be a promising solution for soil remediation. In this review, remediation methods for removal of heavy metals in soil are explored with an emphasis on the in situ immobilization technique of metal(loid)s. Besides, the immobilization technique in contaminated soils is evaluated through the manipulation of the bioavailability of heavy metals using a range of soil amendment conditions. This technique is expected to efficiently alleviate the risk of groundwater contamination, plant uptake, and exposure to other living organisms. The efficacy of several amendments (e.g., red mud, biochar, phosphate rock) has been examined to emphasize the need for the simultaneous measurement of leaching and the phytoavailability of heavy metals. In addition, some amendments that are used in this technique are inexpensive and readily available in large quantities because they have been derived from bio-products or industrial by-products (e.g., biochar, red mud, and steel slag). Among different amendments, iron-rich compounds and biochars show high efficiency to remediate multi-metal contaminated soils. Thereupon, immobilization technique can be considered a preferable option as it is inexpensive and easily applicable to large quantities of contaminants derived from various sources.Graphical Abstract