Abandoned Metal Mines Research Articles

Microcosm Experiment for Evaluating Efficiency of Chemical Amendments on Remediation of Heavy Metal Contaminated Soil

Heavy metal pollution in agricultural field near the abandoned metal mines is a critical problem in Korea. General remediation technique is to apply chemical amendments and soil covering. However, there is no specific guidelines for conducting soil covering. Therefore, main objective of this research was to determine optimum soil covering technique with microcosm experiment. Three different chemical amendments, lime stone (LS), steel slag (SS), and acid mine drainage sludge (AMDS), were examined and varied soil covering depth, 20, 30, 40cm, was applied to determine optimum remediation technique. Bioavailable heavy metal concentration in soil and total concentration of heavy metals in crop were monitored. Result showed that average heavy metal concentration in varied soil covering depth was ordered as 40 cm (14.5 mg kg -1 ) -1 ) -1 ) and also heavy metal concentration in crop was ordered as 40 cm (100 μg kg -1 ) -1 ) -1 ). In terms of chemical amendments, average heavy metal concentration was decreased as AMDS (150 μg kg -1 ) -1 ) -1 ). Overall, depth of soil covering should be over 30 cm to minimize bioaccumulation of heavy metals and SS and LS could be applied in heavy metal contaminated soil for remediation purposes.

Immobilization of Cd, Zn, and Pb from Soil Treated by Limestone with Variation of pH Using a Column Test

Decades of mining in South Korea have resulted in the contamination of large amounts of soil by metals. The most feasible approach to site restoration requires the use of a stabilization agent to reduce metal mobility. This study examined the leaching characteristics of limestone used as a stabilization agent when subjected to solutions of differing pH. In a laboratory-scale column test, solutions with pH values of 3.5, 4.6, and 5.6, representing acidic to nonacidic rainfall, were applied to soil mixed with limestone. Test results indicate that metal components can be released with the addition of acidic solutions, even if the soil is highly alkaline. Cd and Zn, in particular, exhibited abrupt or continuous leaching when exposed to acid solutions, indicating the potential for contamination of water systems as metal-laden soils are exposed to the slightly acidic rainfall typical of South Korea. Treatment using stabilization agents such as limestone may reduce leaching of metals from the contaminated soil. Stabilizing metal-contaminated farmland is an economical and feasible way to reduce pollutants around abandoned metal mines.

Comparison of Bioavailability and Biological Transfer Factor of Arsenic in Agricultural Soils with Different Crops

Heavy metal pollution in agricultural field near at the abandoned metal mines has been a critical issue in Korea. In particular, bioaccumulation in plants can have detrimental effect on human health. Main objective of this research was to examine arsenic (As) concentration in soil with varied extraction methods and to determine bioaccumulation and biological transfer factor in different crops. Results showed that bioaccumulation ratio of As for total contents in soil was ordered leafy and stem vegetables (1.19%) > fruit bearing vegetables (0.79%) > pulses (0.40%) > root vegetables (0.36%) with different crop species. Among 6 different extraction methods, all of extraction methods showed high correlation (R² = 0.87 - 0.97) except DTPA (R² = 0.25) when comparing As concentration in soil extracted with different extractants and As concentration in each crops. Calculated biological transfer factor was ranged 0.002-0.018 depending on crop species. Overall, concentration of As in crops can be varied and best management practice for minimizing bioaccumulation of As should be considered depending on crop species.

폐광산지역 토양에서 중금속과 PAHs 농도 분포 상관관계

BACKGROUND: Heavy metals contamination of soils in the vicinity of abandoned mines in South Korea has been investigated. However, PAHs contamination rarely has been studied. Both heavy metals and PAHs concentrations have been measured in this study. METHODS AND RESULTS: The samples of soil and sediment were collected from the vicinities of three abandoned coal mines and two abandoned metal mines for analysis of heavy metals contaminants and PAHs concentration from April to September 2012. After preparation of these samples following the Korean standard test method for soils, the concentrations of heavy metals contaminants and PAHs were measured using ICP-OES and GC-MS, respectively. It was observed that the concentration of Arsenic was above the concern level based on ‘area 1’ suggested by Korean soil conservation law, resulting that Arsenic is the main contaminant in these areas. Also Cd, Cu, Pb and Zn were observed as a partial contaminants. The concentrations of other investigated components including benzo(a)pyrene were less than the concern level. CONCLUSION: The correlation observed between Arsenic (as main contaminant) and PAHs concentrations suggested that the contaminant source and pathway are different for each other. The effect of mine activity on PAHs concentration was rarely observed.

A model for prioritizing sites and reclamation methods at abandoned mines

Abandoned mines present numerous safety and environmental problems due to altered topography and poor management of mine waste. Few guidelines are available for selecting reclamation methods to address these problems, and many existing decision models lack transparency, leave out important parameters and reclamation methods, and/or lack model calibration. Consequently, a decision model was developed that includes: (1) a mine hazard index for prioritizing sites for reclamation, (2) a reclamation method screening table for narrowing viable reclamation methods, and (3) a reclamation method ranking matrix for ranking the applicability of reclamation methods at a site. These three processes form the abandoned mine decision model, optimized for topographic reconstruction and waste disposal at abandoned mines. The hazard index quantifies geologic and hydrologic hazards using measurable parameters, sub-parameters, and a range of sub-parameter conditions. Main and sub-parameter weighting factors were determined using the analytic hierarchy process and Delphi method. Reconciling differences between initial parameter weighting factors for the two methods resulted in an improved decision-making technique. The decision model was calibrated with 25 abandoned metal mines in the western USA. Mine hazard index thresholds were determined for mines having low, medium, and high priority. The screening table and ranking matrix were effective at narrowing the number of viable reclamation methods. Further validation of the decision model was evident by the implemented reclamation method being among the four highest scoring alternatives 80 % of the time. This model provides a quantitative and transparent process that overcomes the deficiencies found in many existing mine reclamation decision models.

Bioremediation of lead by ureolytic bacteria isolated from soil at abandoned metal mines in South Korea

Lead (Pb) is one of the most widely present heavy and toxic metals in the environment. Application of Pb-resistant bacteria to biomineralize this toxic metal could be utilized in the Pb bioremediation process. In this study, 93 ureolytic bacteria were newly isolated from the soil of abandoned metal mines. Among the isolates, Enterobacter cloacae KJ-46 and KJ-47 were selected for subsequent studies. When the biomineral samples were analyzed using an inductively coupled plasma, high removal rates (ca. 60%) of Pb were observed, following 48h of incubation. Scanning electron microscopy showed PbCO3 precipitates with a diameter of approximately 5μm. Energy dispersive X-ray spectroscopy confirmed the presence of Pb along with carbon (C) and oxygen (O) within the PbCO3 crystals. The results demonstrated that application of the biomineralization process based on stimulation of urea hydrolysis could be possible and potentially useful for soil bioremediation applications.

Stabilization of Metals-contaminated Farmland Soil using Limestone and Steel Refining Slag

The metals contamination of farmland soil nearby abandoned metal mine was serious problem in Korea. Stabilization of contaminated soil was reported using various stabilizers. Application of limestone and steel refining slag was reported as effective stabilizers in the stabilization of metals. The batch studies confirmed that the mixture of limestone and steel refining slag was suitable for stabilization of metals in contaminated soil. The limestone and steel refining slag mixture (2 : 1 and 3 : 2) were used in column studies and it was confirmed that the stabilizers effectively stabilized heavy metals in contaminated soil. The pH of the soil was increased with the addition of stabilizers. Total leached concentration of metals from the column study was reduced 44, 17, and 93% in comparison to the control at arsenic, cadmium and copper, respectively. The sequential extraction studies showed that the exchangeable fraction was changed into carbonate bound fraction (Cd and Cu) and Fe-Mn oxide bound fraction (As). Based on the results we confirmed that 2:1 ratio of limestone and steel refining slag effectively stabilizes the heavy metals. The mixed treatment of lime stone with steel refining slag would be an effective and feasible method for controlling metals leaching in contaminated soil.

Human exposure and risk assessment of cadmium for residents of abandoned metal mine areas in Korea.

The objective of this study is to find the Cd levels in agricultural crops compared to soil, to evaluate the relationship between daily intake dose through the multimedia/multi-pathway of human exposure and biomarker levels of the residents in mine vicinity area. We collected and cited the data of four out of ten health impact assessments for the residents of abandoned mine areas undertaken by the Korea Ministry of Environment in 2008. The Cd levels in soil were significantly decreased by the separation distance from the mines. The Cd levels in blood were significantly different between residents in mine areas and in comparative areas, but urinary Cd levels did not differ. The Cd levels in blood were related to the age; the separation distance from mine to residence; the daily intake dose via ingestion of drinking water, crops, and surface soil; and inhalation of ambient air of Cd, but urinary Cd levels were not relevant with various sociodemographic characteristics and exposure factors. The average hazard quotient (HQ) value of Cd in the mining site was below 1.0, but the maximum HQ was closed to 1.0. The results indicated that the ingestion of Cd-contaminated soil and agricultural crops by local inhabitants could pose potential adverse health effects to long-term residents consuming rice grown near to the mining areas.

Acidibacter ferrireducens gen. nov., sp. nov.: an acidophilic ferric iron-reducing gammaproteobacterium.

An acidophilic gammaproteobacterium, isolated from a pit lake at an abandoned metal mine in south-west Spain, was shown to be distantly related to all characterized prokaryotes, and to be the first representative of a novel genus and species. Isolate MCF85 is a Gram-negative, non-motile, rod-shaped mesophilic bacterium with a temperature growth optimum of 32-35 °C (range 8-45 °C). It was categorized as a moderate acidophile, growing optimally at pH 3.5-4.0 and between pH 2.5 and 4.5. Under optimum conditions its culture doubling time was around 75 min. Only organic electron donors were used by MCF85, and the isolate was confirmed to be an obligate heterotroph. It grew on a limited range of sugars (hexoses and disaccharides, though not pentoses) and some other small molecular weight organic compounds, and growth was partially or completely inhibited by small concentrations of some aliphatic acids. The acidophile grew in the presence of >100 mM ferrous iron or aluminium, but was more sensitive to some other metals, such as copper. It was also much more tolerant of arsenic (V) than arsenic (III). Isolate MCF85 catalysed the reductive dissolution of the ferric iron mineral schwertmannite when incubated under micro-aerobic or anaerobic conditions, causing the culture media pH to increase. There was no evidence, however, that the acidophile could grow by ferric iron respiration under strictly anoxic conditions. Isolate MCF85 is the designated type strain of the novel species Acidibacter ferrireducens (=DSM 27237(T) = NCCB 100460(T)).

Characteristics of hydrochemical variations and contaminant load during rainfall in an acid mine drainage-impacted watershed, Korea

Acid mine drainage (AMD) refers to the outflow of acidic water from usually abandoned metal mines. Since AMD is closely related to the rainfall–runoff process, it is important to monitor rainfall events for its characterization. This work aims to study the characteristics of hydrochemical variations of metals during rainfall in the Geopung Mine Watershed, Korea. Eleven dry-weather and five rainfall event monitorings were conducted in 2010 at two locations (GP-1 and GP-2). At GP-1, concentrations significantly increased during the fifth event, which was the largest one (As from 0.0003 to 0.0046 mg/l; Cd from 0.0114 to 0.2188 mg/l; Cu from 0.0206 to 3.1512 mg/l; Pb from 0.0006 to 0.1857 mg/l; Zn from 0.5823 to 15.9194 mg/l; Ni from 0.0011 to 0.0294 mg/l). Similar though less-marked trend of increase in metal concentration was found at GP-2 during the fifth rainfall event. As for the load, as much as 62–97% of the annual metal loads were accounted for by rainfall at GP-1 and GP-2. This pattern implies that most of the metals in AMD are brought into the stream by rainfall.

Characteristics of Arsenic and Heavy Metal Leaching for Paddy Soils Around Abandoned Metal Mines

Characteristics of Arsenic and Heavy Metal Leaching for Paddy Soils Around Abandoned Metal Mines

Blood levels of cadmium and lead in residents near abandoned metal mine areas in Korea.

We analyzed national data on blood lead levels (BLL) and blood cadmium levels (BCL) in residents living near 38 abandoned metal mining areas (n = 5,682, 18-96years old) in Korea that were collected by the first Health Effect Surveillance for Residents in Abandoned Metal mines (HESRAM) from 2008 to 2011. The geometric mean BCL and BLL were 1.60μg/L (95% CI = 1.57-1.62μg/L) and 2.87μg/dL (95% CI = 2.84-2.90μg/dL), respectively, notably higher than levels in the general population in Korea and other countries. We found significantly higher BLL and BCL levels in people living within 2km of an abandoned metal mine (n = 3,165, BCL = 1.87μg/L, BLL = 2.91μg/dL) compared to people living more than 2km away (n = 2,517, BCL = 1.31μg/L, BLL = 2.82μg/dL; P < 0.0001) and to the general population values reported in the literature.

NON-CANCER HUMAN HEALTH RISK ASSESSMENT FROM EXPOSURE TO HEAVY METALS IN SURFACE AND GROUNDWATER IN IGUN IJESHA, SOUTHWEST NIGERIA

Non-cancer hazard index for inhabitants exposed to heavy metals in surface and groundwater of the abandoned metal mine in Igun-Ijesha area were evaluated. A total of thirty-eight water samples were collected from surface and ground water sources in the study area between September 2012 and February 2013 and the concentrations of heavy metals were determined using Atomic Absorption Spectrophotometer. Non-cancer risk assessments from possible exposure to heavy metals were evaluated using the United States Environmental Protection Agency’s human health risk assessment guidelines. Simple random sampling was used to administer questionnaires to investigate demographic characteristics and public health status of residents. Data obtained were subjected to descriptive statistics and ANOVA using SPSS for Windows version 16. Results indicated elevated levels of Cadmium (Cd), Chromium (Cr), Copper (Cu), lead (Pb), Manganese (Mn), Nickel (Ni) and Zinc (Zn) ranging from 0.01-1.20, 0.05-0.52, 0.80-34.80, 0.09-4.30, 0.09-8.30, 0.05-3.94, 0.05-19.60 and 1.80-29.90 mg L-1 respectively which exceeded national recommended limits with few exceptions. Hazard Quotients (HQ) and Hazard Index (HI) of heavy metals were calculated and results greater than 1 indicate non-carcinogenic adverse health effects of the observed metals. A daily intake of water by the local residents could pose a potential health threat from long-term heavy-metal exposure. The risk assessment provided by this study can be beneficially used and applied for risk communication to avoid negative public health impact. Similarly, Water Safety quality assurance strategic plan should be developed to safeguard source, water and public health within the mining community.

Blood cadmium concentration of residents living near abandoned metal mines in Korea.

The purpose of this study was to investigate demographic and lifestyle variables and blood cadmium concentrations in residents living near abandoned metal mines in Korea. Blood cadmium concentrations were measured in 15,161 subjects living around abandoned metal mines (exposed group, n = 14,464) and compared with those living in designated control areas (control group, n = 697). A questionnaire was provided to all subjects to determine age, gender, mine working history, times of residence, smoking habits and dietary water type. The geometric mean (95% confidence intervals) of blood cadmium concentration (1.25 [1.24-1.27] µg/L) in the exposed group was significantly higher than in the control group (1.17 [1.13-1.22] µg/L). Mean residence time and mine working history in the exposed group were significantly higher than in the control group. Blood cadmium concentrations increased with increasing age, and residence time in both groups, and blood cadmium concentrations were higher in current-smokers than in non-smokers in both groups. This study shows the geometric mean of blood cadmium concentration in abandoned mining areas are higher than in non-mining areas in the general adult Korean population.

The investigation of arsenic and heavy metal concentrations in soil, water and crops around abandoned metal mines

Soils, water and crops around abandoned metal mines can be contaminated by heavy metals from adjacent tailings and waste rocks accumulated during mining operations. The results indicate that the As, Zn, Cd, and Cr concentrations exceed the soil contamination standard in many soil samples of the nearby farmlands as well as the tailings sites. In the case of water quality, the As concentrations in the Okgae and Youngchen Mines show a decreasing trend with increasing distance from the mine, which is similar to that of the soil samples. The Cd and Pb concentrations in the crops near the Okgae Mine show a decreasing trend with increasing distance from the mine which is also similar to that of soil samples. In addition, the Cd and Pb concentrations in the rice samples and the Cd concentration in the corn samples increase with the Cd and/or Pb concentrations in the soil.

Study of the Stabilization of As and Heavy Metals Contaminated Farmland Soils nearby Abandoned Metal Mines, Korea

Study of the Stabilization of As and Heavy Metals Contaminated Farmland Soils nearby Abandoned Metal Mines, Korea

폐금속광산 지역의 비소오염토양 처리를 위한 선별 기술 적용

After the law has been enacted for the prevention and recovery of mining damage in 2005, efforts of remediation have been started to recover heavy metal contaminated soils in agricultural land near mining sites. As part of an effort, the upper part of cultivation layer has been treated through covering up with clean soil, but the heavy metal contamination could be still spreaded to the surrounding areas because heavy metals may be remained in the lower part of cultivation layers. In this study, the most frequently occurring arsenic (As) contamination was selected to study in agricultural land nearby an abandoned metal mining site. We applied separation technologies considering the differences in the physical characteristics of soil particles (particle size, density, magnetic properties, hydrophobicity, etc.). Based on physical and chemical properties of arsenic (As) containing particles in agricultural lands nearby mining sites, we applied sieve separation, specific gravity separation, magnetic separation, and flotation separation to remove arsenic (As)-containing particles in the contaminated soil. Results of this study show that the removal efficiency of arsenic (As) were higher in the order of the magnetic separation, flotation separation, specific gravity separation and sieve separation.

Biological monitoring of metal mine residents in Korea

Heavy metal contamination near abandoned metal mines caused health risks to nearby inhabitants and 936 mines were existed in Korea. Aims of this study were to measure human exposure level of enviro...

폐금속광산 주변 논토양 및 벼작물의 비소함량과 계절적 변화

이 연구는 국내 휴폐금속광산 주변의 논토양과 식물(벼)의 비소 오염과 계절적 변화를 고찰하고, 토양과 식물의 유기적 관계규명을 위해 토양시료를 왕수, 1 M <TEX>$MgCl_2$</TEX>, 0.01 M <TEX>$CaCl_2$</TEX> 및 0.05 M EDTA 등 다양한 추출제로 전처리하여 비소를 분석하였다. 화학분해 방법에 따른 함량 변화는 통계적으로 유의한 양의 상관관계를 보이며(p<0.01), 1 M <TEX>$MgCl_2$</TEX> >0.01 M <TEX>$CaCl_2$</TEX> >0.05 M EDTA 순으로 나타났다. 벼줄기의 생물학적 농축계수는 산화환경보다 환원환경에서 높았으며, 백미시료에서는 농축계수가 0.02로 낮게 나타났다. 농가의 1일 평균 쌀소비량인 315 g을 적용하여 세계보건기구의 미량원소 1일 섭취 최대허용량과 비교한 결과 농가에서는 65%의 높은 섭취량을 보여, 이들 쌀 소비에 의한 비소의 인체섭취도에 중요한 역할을 하고 있음을 확인하였다. The objective of this study is to investigate the contents and seasonal variation of arsenic in soils and crop plant(rice) in paddy fields around the abandoned metal mines in Korea. The soils were extracted by various methods including aqua regia, 1 M <TEX>$MgCl_2$</TEX>, 0.01 M <TEX>$CaCl_2$</TEX> and 0.05 M EDTA to evaluate the relationships between soils and crop plants(rice). According to correlation analysis, statistically significant correlation with the four methods(p<0.01) were found in soils extracted by various chemical solutions and arsenic contents in soils were decreased in the order of 1M <TEX>$MgCl_2$</TEX> > 0.01M <TEX>$CaCl_2$</TEX> > 0.05 M EDTA. Biological accumulation coefficients(BACs) of rice stalks were higher than those of rice grain, and the coefficients under reducing(August) environment were higher than those under oxidizing conditions(October). Assuming the rice consumption of 315 g/day by farm households in Korea, the amount of daily intake of arsenic were estimated to be 77.8 <TEX>${\mu}g/day$</TEX>. The daily intake of arsenic from the rice estimates up to 65% of ADI(acceptable daily intake) that the FAO/WHO Joint Food Additive and Contaminants Committee has set to evaluate their safeties.

폐금속 광산의 유형별 오염특성에 관한 연구

This study is aimed to prepare the effective detail survey methods(Phase II) of abandoned metal mines through the contamination assessment for mine types and facilities in the abandoned metal mine areas. The study sites of 12 abandoned mines are located in Gyeonggi-do and Gangwon-do and those were chosen among 310 sites that the Phase II survey was conducted from 2007 to 2009 after considering the results of Phase I for abandoned mines scattered all over the country. 12 study sites were classified into four types; Type I sites only have pit mouth. Type II sites have pit mouth and mine-waste field. Type III sites have pit mouth and tailing sorting field. Type IV sites have pit mouth, tailing sorting field and concentrator(s). In forest land, paddy soil and farm land of Type I, As and Cd were showed average concentration, and Cu and Pb were high on the pit mouth area in one mines where the pit mouth was developed within 500 m. In the mines of Type II, Cu and Pb were showed average concentration too, but As and Cd were slightly high in pit mouth and mine-waste field. The mines of Type III which had grinding particle process through physical separation milling or hitting showed similar tendency with Type II. However, mines of Type IV pit mouth, mine-waste field and showed various results depending on defining the contamination sources. For example, if contamination source was pit mouth, the mixed results of Type I, II, II were showed. In tailing sorting field which was regarded as the most important source and having high mobility, however, if there were no facilities or it was difficult to access directly, field sampling was missed occasionally during phase I and phase II survey. For that reason, the assessment for tailing sorting field is missed and it leads to completely different results. In the areas of Type I mines, the concentration of heavy metals exceeded precautionary standards of soil contamination or not within 1,000 meters of pit mouth. Nickel(Ni) was the largest factor of the heavy metal contamination in this type. The heavy metals except Arsenic(As) were shown high levels of concentration in Type II areas, where pit mouth and mine-waste field were operated for making powder in upriver region; therefore, to the areas in the vicinity of midstream and downstream, the high content of heavy metals were shown. The tendency of high level of heavy metals and toxic materials contained in flotation agent used during sorting process were found in soil around sorting and tailing field. In the abandoned-pit-mouth area, drygrinding area and tailing sorting field area, the content of Cupper(Cu) and Zinc(Zn) were higher than other areas. Also, the contaminated area were larger than mine reclamation area(2,000 m) and the location of tailing sorting field was one of the important factors to estimate contaminated area.