최근 들어 비소오염에 대한 환경적 관심이 증대되면서, 세계적으로 비소에 대한 음용수 기준이 강화되고 있으며, 국내적으로도 비소로 오열된 지하수 덴 토양의 출현 빈도가 높아지면서 비소 오염과 그에 대한 처리 및 대책이 주요한 환경적 관심사로 대두되고 있다. 지중에서 비소의 거동은 주로 산화물들과 점토광물에 의하여 제어되는데, 특히 철(산)수산화물이 가장 효과적으로 비소를 제어하는 것으로 알려져 있다. 이에 본 연구에서는 다양한 철(산)수산화물들 중 2-line ferrihydrite가 비소의 거동에 어떠한 영향을 미치는가를 파악하기 위하여 수행되어졌다. 다양한 비소 화학종들 중 자연 상에서 발현 빈도수가 가장 큰 3가 비소(아비산염)와 5가 비소(비산염)가 2-line ferrihydritc와 어떠한 흡착 특성을 갖는지 비교하여 연구하였다. 비소의 흡착제로 실험실에서 제조되어 이용된 2-line ferrihydrite는 10~200nm의 작은 나노 크기, 247m2/g의 비교적 큰 비표면적, 다른 철(산)수산화물보다 높은 8.2의 영전하 pH 등을 갖는 것으로 나타났는데, 이러한 2-line ferrihydrite의 대표적인 물리화학적인 특성들은 비소의 흡착제로서 매우 적합한 것으로 조사되었다. 평형흡착 실험결과, 3가 비소가 5가 비소보다 월등히 높은 흡착력을 보였으며, 3가 비소는 pH 7.0, 5가 비소는 pH 2.0에서 가장 놀은 흡착력을 보이는 것으로 나타났다. 3가 비소는 pH 12.2를 제외하고는 pH에 따른 흡착량이 크게 차이를 보이지 않은 반면, 5가 비소는 pH가 증가함에 따라 흡착량이 현격하게 갈소하는 것으로 나타났다. pH에 따른 비소의 흡착특성을 보다 더 자세하게 초찰한 견과, 3가 비소는 pH 8.0까지는 흡착량이 증가하다가 pH 9.2 이상에서는 흡착량이 급격하게 같소하는 것으포 나타났다. 5가 비소의 경우에는 pH가 증가할 수록 비교적 일정하게 흡착량이 갉소하는 것을 알 수 있었다. 이렇게 비소 화학종에 따라서 상이한 흡착특성을 보이는 이유는 pH에 따른 각 비소 화학종의 화학져 존재 형태(chemical speciation)와 2-line ferrihydrite의 표면전하의 변화 등이 복합적으로 작용하기 때문인 것으로 사료된다. 각 비소 화학종과 2-line ferrihyite와의 흡착특성을 반응속도론적 관점에서 고찰한 결과, 대부분의 비소종들이 2시간 이내에 흡착이 거의 완료되는 것으로 나타났으며, 두 종류의 비소 화학종과 2-line ferrihydrite의 흡착 반응속도를 가장 잘 모사하는 반응속도 모댁은 power function과 elovich model인 것으로 조사되었다.

This study has been carried out to examine the feasibility of soil washing process for reducing arsenic contamination level of soil around Dalchên Mine. The results of physicochemical tests of the target soil showed that pH was weak alkalic (pH ~- 7.8), soil texture was coarse sand, and organic contents (5.7%) and CEC (Cation exchange capacity; 21.5 meq/100 g) were similar with those of soils generally found in Korea. Contamination levels of arsenic were found to over 201 mg/kg which exceed the Korea standard levels of countermeasure and concern. To investigate chemical partitioning of heavy metals, sequential extraction procedures were adopted and it was found that arsenic was predominantly associated with the residual fraction among five fractional forms as much as over 85%, which is demonstrating that only less than 15% of all might be vulnerable to a selected washing agents. Among 6 kinds of washing agents applied on the screening for arsenic-contaminated soil, HCl and H3PO4 solution were selected as promising washing agents. In comparison with HCl and H3PO4 solutions for arsenic washing by kinetic experiment in the change of pH, soil-solution ratio, temperature, and washing solution concentration, H3PO4 solution was determined to best one of agents tested, which showed faster washing rate than HCl to accomplish regulatory goal.

Electrokinetic technique was considered in removing arsenic from the abandoned mining tails. In order to estimate the removal characteristics of arsenic, the sequential extraction analysis and desorption experiment were carried out prior to the application of electrokientic process. The result of sequential extraction analysis indicated that the water soluble and exchangeable fraction, easily leachable to ground water, were very low as much as about 2.5% and the fraction except residual (38.3%), possibly extractable under very acidic or alkalic environment, was about 59%. In the result of desorption test using four different kinds of electrolytes, the mixture of citric acid and sodium dodecyl sulfate (SDS) showed the highest desorption efficiency as much as 77.3%. The removal efficiencies of arsenic from mining tailings by electrokinetic process under the different electrolyte environments were slightly low and resulted in the following order: citric acid + SDS (18.6%) > 0.1 NHNO3 (8.1%) > HAc (7.4%) > Distilled water(6.6%). Also, arsenic in soil matrix was moved favorably in the direction of anodic rather than cathodic region, which is opposite trend with cationic metal ions generally existing in soil, because anionic form of arsenic is dominated in acidic soil caused by the movement of acid front form anode.

This experiment was carried out to investigate the effects of mercury and arsenic on the growth of Arabidopsis thaliana when treated with three different concentrations. When treated with mercury, there was no noticeable difference in the growth of the plant between the group treated with 0.5 ㎍/L (the effluent standard established by the Ministry of Environment) and the group treated with the concentration 100 times higher. They both showed almost the same level of growth as that of the normal plant. But the group of the concentration 10 times higher showed significantly 10% more growth compared with the normal plant. When treated with arsenic, the three different groups all showed a little more growth compared with the normal plant. Interestingly, the group of the concentration 10 times higher than the official standard concentration of arsenic (50 ㎍/L) showed the highest level of growth, significantly 20% more than the normal plant. These results show that some amount of mercury and arsenic in the soil do not have much effect on the growth of Arabidopsis thaliana, and that optimum concentrations of mercury and arsenic can even stimulate the growth of the plant.