Effects of natural and calcined oyster shells on Cd and Pb immobilization in contaminated soils

• Published in: Environmental earth sciences 2010-09, Vol.61 (6), p.1301-1308
• Main Authors: Ok, Yong Sik, Oh, Sang-Eun, Ahmad, Mahtab, Hyun, Seunghun, Kim, Kwon-Rae, Moon, Deok Hyun, Lee, Sang Soo, Lim, Kyoung Jae, Jeon, Weon-Tai, Yang, Jae E.
• Format: Article
• Language: English
• Subjects: Agricultural land; Aquaculture; Biogeosciences; Cadmium; Calcium carbonate; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental Science and Engineering; Exact sciences and technology; Geochemistry; Geology; Heavy metals; Hydrology/Water Resources; Hydroxides; Lead; Marine; Mine tailings; Mine wastes; Mines; Original Article; Oysters; Pollution, environment geology; Shellfish farming; Shells; Soil amendment; Soil contamination; Soil pH; Soils; Surficial geology; Terrestrial Pollution; X-ray diffraction; X-ray fluorescence
• ISSN: 1866-6280; 1866-6299
• DOI: 10.1007/s12665-010-0674-4

In Korea, soils adjacent to abandoned mines are commonly contaminated by heavy metals present in mine tailings. Further, the disposal of oyster shell waste by oyster farm industries has been associated with serious environmental problems. In this study, we attempted to remediate cadmium (Cd)- and lead (Pb)-contaminated soils typical of those commonly found adjacent to abandoned mines using oyster shell waste as a soil stabilizer. Natural oyster shell powder (NOSP) and calcined oyster shell powder (COSP) were applied as soil amendments to immobilize Cd and Pb. The primary components of NOSP and COSP are calcium carbonate (CaCO 3 ) and calcium oxide (CaO), respectively. X-ray diffraction, X-ray fluorescence and scanning electron microscope analyses conducted in this study revealed that the calcination of NOSP at 770°C converted the less reactive CaCO 3 to the more reactive CaO. The calcination process also decreased the sodium content in COSP, indicating that it was advantageous to use COSP as a liming material in agricultural soil. After 30 days of incubation, we found that the 0.1 N HCl-extractable Cd and Pb contents in soil decreased significantly as a result of an increase in the soil pH and the formation of metal hydroxides. COSP was more effective in immobilizing Cd and Pb in the contaminated soil than NOSP. Overall, the results of this study suggest that oyster shell waste can be recycled into an effective soil ameliorant.