In order to remediate farmland contaminated with arsenic and heavy metal nearby abandoned metal mines effectively by the stabilization method, this study performed: first, selection of stabilizers (limestone, steel refining slag) for treating farmland soil contaminated with arsenic and heavy metals;...
In order to remediate farmland contaminated with arsenic and heavy metal nearby abandoned metal mines effectively by the stabilization method, this study performed: first, selection of stabilizers (limestone, steel refining slag) for treating farmland soil contaminated with arsenic and heavy metals; second, analysis of the leaching characteristic of arsenic and heavy metals in soil according to the characteristics of farmland; and third, determination of the treatment effect and applicability of selected stabilizers (limestone and steel refining slag) according to the characteristics of farmland. For this study, we selected contaminated farmland nearby the Wondong Mine, the Seosung Mine and the Sangju Mine in Korea. Among the selected areas, the farmland nearby the Seosung Mine is known to be contaminated with arsenic and heavy metals most severely. The results of this study are summarized as follows. 1. The distribution ratio of exchangeable and carbonate fractions, which have high mobility among the forms of heavy metals present in the soil of the subject contaminated farming lands, was high in order of cadmium > zinc > lead. This suggests that, among contaminants present in farming lands under environmental pollution caused by mining, cadmium has the highest impact on surrounding environment and therefore should be monitored very carefully. 2. In the oxidized upland soil condition, heavy metal contents leached highly at the beginning of artificial rainfall injection, and later at the early stage of entering into low pH environment, the leaching of heavy metal contents increased rapidly again. 3. The pH buffer capacity of soil decreased temporarily by acidic environment where even soil with very high pH changes abruptly in upland soil environment, and as a result, a large volume of heavy metals in leachate leached. On the contrary, soil treated with limestone and steel refining slag maintained pH buffer capacity and, as a result, the heavy metal leaching concentration was quite low below the water quality standard compared to untreated soil where leachate exceeding the water quality standard was observed. 4. In the flooded paddy soil condition, at the point of time when iron and manganese were reduced and leached rapidly, heavy metals also leached rapidly, and some leachate samples from untreated soil exceeded the contamination standard. On the contrary, all samples from soil treated with limestone and steel refining slag were below the contamination standard, showing much lower heavy metal concentration than that in untreated soil. 5. In flooded paddy soil environment, arsenic increased continuously during the observation period according to its general characteristics, and along with decreasing redox potential, arsenic was expected to leach as H3AsO3?] of form A (III) with high mobility and strong toxicity. 6. In flooded paddy soil environment, compared to untreated soil showing continuously increasing arsenic leaching concentration, soil treated with limestone and steel refining slag showed a continuous decrease in arsenic leaching concentration, and in particular, the effect of treatment with steel refining slag was higher than that with limestone. 7. Compared to oxidized upland soil condition, flooded paddy soil environment showed a different arsenic and heavy metal leaching characteristic, and arsenic was expected to show continuously increasing leaching concentration and to leach in the form of arsenite (A (III)) with high mobility and strong toxicity. For the effective remediation of contaminated paddy soil, accordingly, it is necessary to develop strategies for applying the stabilization method according to its characteristics. 8. In the results of a field pilot test, the increase of arsenic leaching, which is regarded as a problem in the application of alkali materials like limestone, was observed, but the problem was eased by the application of steel refining slag. In addition, the arsenic and heavy metal contents decreased markedly in soil to which limestone was applied 5%, the maximum mixture ratio, compared to that in untreated soil. 9. Limestone showed a high treatment effect against heavy metals present in soil such as cadmium, lead and zinc, so it was found to be an effective stabilizer in treating heavy metals in soil. 10. Steel refining slag showed not only a high treatment effect against arsenic in soil but also the highest economic efficiency among the considered stabilizers. Accordingly, if steel refining slag is used according to its applicability based on the adsorption selectivity of arsenic and phosphorus (P), which is different according to soil characteristics, it is expected to be very effective as a stabilizer for treating arsenic in soil. 11. This study selected limestone and steel refining slag, alkali materials with high pH, as stabilizers for the subject contaminated soils that showed large differences in soil pH and high heavy metal concentrations. With application ratios to contaminated soil not exceeding 5% (w/w), the treatment effect and applicability of the stabilizers were analyzed. According to the results, the stabilizers did not have an effect on pH, which aggravates soil environment, but lowered the heavy metal leaching concentration effectively. Accordingly, if field applicability to the subject soils is evaluated with application ratios of limestone and steel refining slag not exceeding 5%, we may be able to obtain the optimal mixture ratio of the stabilizers efficiently.
In order to remediate farmland contaminated with arsenic and heavy metal nearby abandoned metal mines effectively by the stabilization method, this study performed: first, selection of stabilizers (limestone, steel refining slag) for treating farmland soil contaminated with arsenic and heavy metals; second, analysis of the leaching characteristic of arsenic and heavy metals in soil according to the characteristics of farmland; and third, determination of the treatment effect and applicability of selected stabilizers (limestone and steel refining slag) according to the characteristics of farmland. For this study, we selected contaminated farmland nearby the Wondong Mine, the Seosung Mine and the Sangju Mine in Korea. Among the selected areas, the farmland nearby the Seosung Mine is known to be contaminated with arsenic and heavy metals most severely. The results of this study are summarized as follows. 1. The distribution ratio of exchangeable and carbonate fractions, which have high mobility among the forms of heavy metals present in the soil of the subject contaminated farming lands, was high in order of cadmium > zinc > lead. This suggests that, among contaminants present in farming lands under environmental pollution caused by mining, cadmium has the highest impact on surrounding environment and therefore should be monitored very carefully. 2. In the oxidized upland soil condition, heavy metal contents leached highly at the beginning of artificial rainfall injection, and later at the early stage of entering into low pH environment, the leaching of heavy metal contents increased rapidly again. 3. The pH buffer capacity of soil decreased temporarily by acidic environment where even soil with very high pH changes abruptly in upland soil environment, and as a result, a large volume of heavy metals in leachate leached. On the contrary, soil treated with limestone and steel refining slag maintained pH buffer capacity and, as a result, the heavy metal leaching concentration was quite low below the water quality standard compared to untreated soil where leachate exceeding the water quality standard was observed. 4. In the flooded paddy soil condition, at the point of time when iron and manganese were reduced and leached rapidly, heavy metals also leached rapidly, and some leachate samples from untreated soil exceeded the contamination standard. On the contrary, all samples from soil treated with limestone and steel refining slag were below the contamination standard, showing much lower heavy metal concentration than that in untreated soil. 5. In flooded paddy soil environment, arsenic increased continuously during the observation period according to its general characteristics, and along with decreasing redox potential, arsenic was expected to leach as H3AsO3?] of form A (III) with high mobility and strong toxicity. 6. In flooded paddy soil environment, compared to untreated soil showing continuously increasing arsenic leaching concentration, soil treated with limestone and steel refining slag showed a continuous decrease in arsenic leaching concentration, and in particular, the effect of treatment with steel refining slag was higher than that with limestone. 7. Compared to oxidized upland soil condition, flooded paddy soil environment showed a different arsenic and heavy metal leaching characteristic, and arsenic was expected to show continuously increasing leaching concentration and to leach in the form of arsenite (A (III)) with high mobility and strong toxicity. For the effective remediation of contaminated paddy soil, accordingly, it is necessary to develop strategies for applying the stabilization method according to its characteristics. 8. In the results of a field pilot test, the increase of arsenic leaching, which is regarded as a problem in the application of alkali materials like limestone, was observed, but the problem was eased by the application of steel refining slag. In addition, the arsenic and heavy metal contents decreased markedly in soil to which limestone was applied 5%, the maximum mixture ratio, compared to that in untreated soil. 9. Limestone showed a high treatment effect against heavy metals present in soil such as cadmium, lead and zinc, so it was found to be an effective stabilizer in treating heavy metals in soil. 10. Steel refining slag showed not only a high treatment effect against arsenic in soil but also the highest economic efficiency among the considered stabilizers. Accordingly, if steel refining slag is used according to its applicability based on the adsorption selectivity of arsenic and phosphorus (P), which is different according to soil characteristics, it is expected to be very effective as a stabilizer for treating arsenic in soil. 11. This study selected limestone and steel refining slag, alkali materials with high pH, as stabilizers for the subject contaminated soils that showed large differences in soil pH and high heavy metal concentrations. With application ratios to contaminated soil not exceeding 5% (w/w), the treatment effect and applicability of the stabilizers were analyzed. According to the results, the stabilizers did not have an effect on pH, which aggravates soil environment, but lowered the heavy metal leaching concentration effectively. Accordingly, if field applicability to the subject soils is evaluated with application ratios of limestone and steel refining slag not exceeding 5%, we may be able to obtain the optimal mixture ratio of the stabilizers efficiently.
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#안정화 공법 비소 중금속 토양오염 석회석 제강슬래그
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