Soil samples contaminated with heavy metals such as lead (Pb), copper (Cu) and zinc (Zn) were leached with citric acid solution. A five step-sequential extraction method involving "exchangeable", "bound to carbonate", "bound to FeMn oxide", "bound to organic matter" and "residue" fractions was also carried out to investigate the leaching behavior of Pb, Cu and Zn with citric acid.The leaching efficiencies of Pb, Cu and Zn increased with increasing citric acid concentration. About 86.5, 88.9 and 83.3% leaching efficiencies were obtained for Cu, Zn and Pb, respectively, under the following leaching condition: 2 kmol·m ¹3 in citric acid concentration, 120 min in leaching time, 10% in pulp density, 50°C in temperature, and 80 rpm in shaking speed. In the sequential extraction test, the heavy metal contaminants were extracted more in "bound to carbonate" and "bound to FeMn oxide" fractions than in "bound to organic matter" and "residue" fractions. When the leaching efficiencies of Pb, Cu and Zn with 2 kmol·m ¹3 citric acid solution were compared with the results of the sequential extraction, a good agreement with the summation of amount leached in "exchangeable", "bound to carbonate" and "bound to FeMn oxide" fractions was noted.

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The effect of pH on the citrate leaching behavior of heavy metal ion was investigated to develop an eco-friendly process for removing heavy metals from soil contaminated with copper, zinc, and lead. The leaching tests were performed using citrate solution with pH adjusted by mixing citric acid and sodium citrate under the following leaching conditions: particle size, under 75 µm; temperature, 50 o C; citrate concentration, 1 kmol/m 3 ; pulp density, 5%; shaking speed, 100 rpm; leaching time, 1 hour. The difference of pH before and after the leaching test was not observed, and this result indicates the direct effect of hydrogen ion concentration on the leaching of metals was insignificant. The removal ratios of copper, zinc, and lead from the contaminated soil decreased with increasing pH. The thermodynamic calculation suggests that the leaching behaviors of metal ions were determined by two reactions; one is the reaction to form complex ions between heavy metal ions and citrate ion species, and the other is the reaction to form metal hydroxide between heavy metal ions and hydroxide ion.

Purpose: Posterior tibialis tendon dysfunction (PTTD) is one of the most common causes of acquired flatfoot deformity in western countries. But it was known that they were very rare in eastern countries. So we want to report the clinical features and outcomes of 12 patients with PTTD. Materials and Methods:We evaluated the results of 12 patients using clinical features and results from March 2000 to January 2007 and mean follow up periods is 32 months. Results: Average age was 45 years, 8 of 12 patients were female, 2 patient with hypertension and 1 with rheumatoid arthritis. 5 patients were overweighted and 5 patients were obese. 4 patients has a history of last trauma. 4 patients experienced progression of flatfoot. On behalf of Johnson and Strom classifications 6 cases were grade I, 4 cases were grade II, grade III, and grade IV was 1 case, relatively. As a treatment we used tenosynovectomy for 3 cases of grade I, additional FDL transfer was done for 2 cases of grade I and 2 cases of grade II. For other 2 patients of grade II flexor digitorum longus transfer and Medial displacement calcaneal osteotomy was done. Pathologic findings of tendon showed degenerative tendinitis. Lastly conservative treatment group was 3 cases of grade I, III, IV each. Average preoperative and postoperative American Orthopedic Foot and Ankle Society's hindfoot/ankle scoreFAS score was 58 and 90. Initial and follow up AOFAS scores of the conservative group was 38 and 57, relatively. Conclusion: As a cause of acquired flatfoot in adult, PTTD is not a rare disease any more in Korea. To prevent the disability and progression of flatfoot, careful clinical evaluation and proper treatment is important.