• Economic and Environmental Geology
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• v.54 no.4
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• pp.483-494
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• 2021

This study was carried out to investigate the feasibility of reducing clean cover soil using a flooded column test in arsenic-contaminated farmland reclamation of abandoned coal mine area that shows generally low or about worrisome level (25 mg/kg) of Korea soil environment conservation act unlike abandoned metal mine. During the monitoring period of soil solution for 4 months, chemical properties (pH, EC, ORP, Fe, Mn, Ca, and As) in each layer (clean soil cover and contaminated/stabilized soil) showed different variation. This result revealed that soil solution in stabilized or contaminated soil rarely affected that in cover soil. Whether stabilized or not, arsenic concentrations in the rice roots grown in the soil covers with the thickness of 40 cm decreased by 98% in compared with the that grown in the control soil. In case of the soil covers with 20 cm thickness on stabilized soil, it decreased by 80% and this was 22 percentage point higher than when the soil of lower layer was not stabilized. Thus, reducing clean cover soil could be possible in contaminated farmland soil reclamation if appropriate stabilization of contaminated soil is carried.

• Journal of Korea Soil Environment Society
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• v.3 no.2
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• pp.13-29
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• 1998

Recently, It is increasing popularity to research on the soil remediation in aspect of management by reason of the hazardous impact on the contaminated soil in Korea. It was investigated high levels of arsenic salts in soil near abandoned five mines(Darak, Daduk, Jingok, Dalsung, Ilkwang) located in Youngnam area. Arsenic, classified as group A(Human Carcinogens) from IRIS, have shown statistically significant increment in skin cancer with oral exposure. This paper was conducted to predict excess cancer risk value (to the skin cancer) based on multiple pathway such as soil ingestion, dermal uptake and food(plant) ingestion contaminated by arsenic, and also, to identify the remedial goal regarded in future land use. The mine having the highest arsenic level was Daduk(mean : 1950mg/kg) and the next rank was Jingok(1690mg/kg), Ilkwang(352.37mg/kg), Dalsung(86.08mg/kg), Darak(0.83mg/kg). The chronic daily intake to the multiple exposure were calculated using Monte-Carlo simulation regarded in future land use and used q: value was $1.5(mg/kg/day)^{-1}$ to the oral proposed by IRIS(1997). The computated excess cancer risk 95th value to all the mine regarding future land use as residential and rural area were more than $10^{-4}$. If the level of acceptable risk is aimed for 1$\times$$10^{-6}$, it could be used Darak as commercial and industrial area without soil remediation due to the lowest risk value(6$\times$$10^{-8}$ and 3$\times$$10^{-8}$). Computated remedial goal based on 1$\times$$10^{-6}$ of acceptable risk to the future land use as the residential, rural, commercial and industrial area were 0.02mg/kg, 0.003mg/kg, 97.31mg/kg and 194.62mg/kg, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.2
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• pp.136-142
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• 2012

Various factors affecting on the bioassay were investigated. Experiments with a low mixture ratio (cell to toxicant solution) of 0.5 : 9.5 (v/v) produced observable bioluminescence intensity for assay. Both sodium lactate and potassium nitrate stimulate bioluminescence activity; 2.6~4.0 times of control. Distilled water and MSM, which gave non significant effects on the bioluminescence activity, were determined as proper diluent or extract solutions. A wide range of toxic responses of metals and organics were observed. In general, organics were much less sensitive than metals. Samples collected from eleven sites showed the bioluminescence activity ranging from 29 to 111% of the control. Significant correlation between toxicity and total metal contents was not observed, but the toxicity of two groups, sorted based on the contaminated arsenic concentration in soils, was 44% and 20%, showing considerable differences.

• Journal of the Mineralogical Society of Korea
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• v.21 no.4
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• pp.425-434
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• 2008

Arsenic contamination in soil and groundwater has recently been one of the most serious environmental concerns. This arsenic contamination can be originated from natural or anthropogenic sources. It has been well known that arsenic behavior in geo-environmental is controlled by various oxides or hydroxides, such as those of iron, manganese, and aluminum, and clay minerals. Among those, particularly, iron (oxy)hydroxides are the most effective scavengers for arsenic. For this reason, this study characterized arsenic adsorption of magnetite which is a kind of iron oxide in nature. The physicochemcial features of the magnetite were investigated to evaluate adsorption of arsenite [As(III)] and arsenate [As(V)] onto magnetite. In addition to experiments on adsorption equilibria, kinetic experiments were also conducted. The point of zero charge (PZC) and specific surface area of the laboratory-synthesized magnetite used as an arsenic adsorbent were measured 6.56 and $16.6\;g/m^2$, which values seem to be relatively smaller than those of the other iron (oxy)hydroxides. From the results of equilibria experiments, arsenite was much more adsorbed onto magnetite than arsenate, indicating the affinity of arsenite on magnetite is larger than arsenate. Arsenite and arsenate showed adsorption maxima at pHs 7 and 2, respectively. In particular, adsorption of arsenate decreased with increase in pH as a result of electrical repulsion caused by anionic arsenate and negatively-charged surface of magnetite. These results indicate that the surface charge of magnetite and the chemical speciation of arsenic should be considered as the most crucial factors in controlling arsenic. The results of kinetic experiments show that arsenate was adsorbed more quickly than arsenite and adsorption of arsenic was investigated to be mostly completed within the duration of 4 hours, regardless of chemical speciation of arsenic. When the results of kinetic experiments were fitted to a variety of kinetic models proposed so far, power function and elovich model were evaluated to be the most suitable ones which can simulate adsorption kinetics of two kinds of arsenic species onto magnetite.

• Journal of Soil and Groundwater Environment
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• v.12 no.1
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• pp.103-115
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• 2007

Risk assessment by living indicator species provides the information about the ecosystem disturbance, disapperance of symbiosis and change of living group. In the initial stage of this kind research, the degree of contamination was reported using the level of simple number, but simple number may not represent the risk itself which can be casued in the living organisms. Risk assessment using various indicator species overcomes these limitations and can be expanded to the DNA level. In many developed counties, the government has supervised the researches about the indicator species for the monitoring and its application to ecosystem restoration. Several living indicator species found in the vicinity of the abandoned Au mines such as fern, earthworm, bacteria, rhizosphere-rhizoplane, salamamdor and DNA change of these species are described in this paper.

• The Journal of Engineering Geology
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• v.32 no.4
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• pp.437-448
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• 2022

This work aims to assess the threat to human health of hazardous materials in groundwater that is used domestically and for drinking. Two distinct sub-assessments are considered: cancer and non-cancer risk. The studied groundwater is in an agricultural area of Gyeongnam Province, Korea, and is contaminated by arsenic at a mean level of 16.27 ㎍/L, far greater than the WHO guideline (10 ㎍/L for drinking water). We collected groundwater data from the National Groundwater Information Center (gims.go.kr) and assessed the risk to human health following the methodology of the United States Environmental Protection Agency. We considered three exposure scenarios: domestic use (scenario 1) and drinking use with different doses (scenarios 2 and 3). Scenario 1 had a median hazard quotient (HQ) of 0.77 and a cancer risk (CR) of 0.013. Scenario 2 had a median HQ of 0.08 and a CR of 3.69 × 10^-5, and the values for scenario 3 were 0.11 and 4.82 × 10^-5, respectively. Scenario 1 is likely the most hazardous to human health. Further study of the origin of arsenic in groundwater in the study area is required, as are remedial measures to mitigate its health effects.

• Journal of Soil and Groundwater Environment
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• v.10 no.1
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• pp.58-64
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• 2005

Several tests were conducted to determine the optimum operational conditions of soil washing techniques for floe-forming arsenic-contaminated soils, collected from D abandoned Iron-mine in Korea. The optimum cut-off size was 0.15 mm $(sieve\;\#100)$, about $94\%$ of the mass of soils. Both sodium hydroxide and hydrochloric acid were effective to remove arsenic and the optimum mixing ratio (soil [g] : washing solution [mL]) was 1:5 for both washing agents. Arsenic concentrations, determined by KST Methods, for the dried floe solids obtained from flocculation at pH 5-6 were $990\~1,086\;mg/kg$ dry solids, which were higher concentrations than at the other pH values. Therefore, batch tests for sequential washings with or without removing floc were conducted to find the enhancement of washing efficiencies. After removing floe with 0.2 M HCl, sequential washings of 1 M HCl followed by 1 M NaOH showed the best results (15 mg/kg dry soil). The arsenic concentrations of washing effluent from each washing step were about $2\~3\;mg/L$. However, when these acidic and basic effluents were mixed together, arsenic concentration was decreased to be less than $50\;{\mu}g/L$, due to the pH condition of coagulation followed by precipitation for arsenic removal.

• Journal of the Korean GEO-environmental Society
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• v.13 no.2
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• pp.59-65
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• 2012

Solidification/Stabilization(S/S) is one of the remediation technologies that have been applied for treating inorganic hazardous wastes. This study investigated the reduction of arsenic concentration of arsenic-contaminated soil using by S/S. The binder plays a role in controlling the mobility and solubility of the contaminants in S/S process, so it is important to determine the optimum binder content. Therefore, this study evaluated the effectiveness of S/S using four different binders(cement, zero valent iron, and monosulfate and ettringite(cement-based synthesized materials) at the binder content ranged between 5%(wt.) and 20%(wt.). The leachability of arsenic in 1 N HCl was different depending on the types of binders: cement(71.41%) > monosulfate(47.45%) > ettringite(46.36%) > ZVI(33.08%) at the binder content of 20%. Additionally, three kinds of a mixture binder were prepared using cement and additives(monosulfate, ettringite, calcium sulfoaluminate(CSA)) and tested for arsenic reduction. The highest arsenic removal capacity was found at the mass ratio of cement to the additive, 4:1 in all experiments using a mixture binder, regardless of the additives types. A mixture binder(cement and additives) resulted in higher arsenic removal relative to the arsenic removal when cement was used alone.

• Journal of Food Hygiene and Safety
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• v.13 no.3
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• pp.201-205
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• 1998

In Korea, a small proportion of fishery products are contaminated with a considerable amount of potentially hazardous contaminants. So, there is generally a high risks to consumers. Inorganic contaminants with the greatest potential for toxicity are Sb, As, Cd, Pb, Hg, Se and the Sulfides. As appears to be much more variable than the others. This study was performed to assess the levels of the As in fisheries caught from the waters of the western coast of Korea. The samples included 26 kinds of fishes, 18 kinds of Mollusca, 3 kinds of Crustacea and 7 kinds of salted fishes. The Moisture content of molluscans was significantly higher than that of others (p<0.05). And the As contents of crustaceans were significantly higher than those of fishes, molluscans and salted fishes (p<0.05). The As content of Turban shell was 51.62 ppm, which was the highest among the samples. Also, the As contents of eel, cuttle fish and blue crab were found to be higher than in other fisheries. This variability offers a solution for the reduction of exposure to As through restricting the harvest of aquatic organism from the western coast of Korea.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.445-455
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• 2009

Microbiological sulfate reduction is the transformation of sulfate to sulfide catalyzed by the activity of sulfate-reducing bacteria using sulfate as an electron acceptor. Low solubility of metal sulfides leads to precipitation of the sulfides in solution. The effects of microbiological sulfate reduction on in-situ precipitation of arsenic and copper were investigated for the heavy metal-contaminated soil around the Songcheon Au-Ag mine site. Total concentrations of As, Cu, and Pb were 1,311 mg/kg, 146 mg/kg, and 294 mg/kg, respectively, after aqua regia digestion. In batch-type experiments, indigenous sulfate-reducing bacteria rapidly decreased sulfate concentration and redox potential and led to substantial removal of dissolved As and Cu from solution. Optimal concentrations of carbon source and sulfate for effective microbial sulfate reduction were 0.2~0.5% (w/v) and 100~200 mg/L, respectively. More than 98% of injected As and Cu were removed in the effluents from both microbial and chemical columns designed for metal sulfides to be precipitated. However, after the injection of oxygen-rich solution, the microbial column showed the enhanced long-term stability of in-situ precipitated metals when compared with the chemical column which showed immediate increase in dissolved As and Cu due to oxidative dissolution of the sulfides. Black precipitates formed in the microbial column during the experiments and were identified as iron sulfide and copper sulfide. Arsenic was observed to be adsorbed on surface of iron sulfide precipitate.