Liming Effects on Cadmium Stabilization in Upland Soil Affected by Gold Mining Activity

Abstract

To reduce cadmium (Cd) uptake of plants cultivated in heavy metal-contaminated soil, the best liming material was selected in the incubation test. The effect of the selected material was evaluated in the field. In the incubation experimentation, CaCO(3), Ca(OH)(2), CaSO(4).2H(2)O, and oyster shell meal were mixed with soil at rates corresponding to 0, 400, 800, 1600, 3200 mg Ca kg(-1). The limed soil was moistened to 70% of field moisture capacity, and incubated at 25 degrees C for 4 weeks. Ca(OH)(2) was found to be more efficient on reducing soil NH(4)OAc extractable Cd concentration, due to pH increase induced net negative charge. The selected Ca(OH)(2) was applied at rates 0, 2, 4, 8 Mg ha(-1) and then cultivated radish (Raphanus sativa L.) in the field. NH(4)OAc extractable Cd concentration of soil and plant Cd concentration decreased significantly with increasing Ca(OH)(2) rate, since alkaline-liming material markedly increased net negative charge of soil induced by pH increase, and decreased bioavailable Cd fractions (exchangeable + acidic and reducible Cd fraction) during radish cultivation. Cadmium uptake of radish could be reduced by about 50% by amending with about 5 Mg ha(-1) Ca(OH)(2) without adverse effect on radish yield and growth. The increase of net negative charge of soil by Ca(OH)(2) application may suppress Cd uptake and the competition between Ca(2+) and Cd(2+) may additionally affect the suppression of Cd uptake.

Lime and Phosphate Amendment Can Significantly Reduce Uptake of Cd and Pb by Field-Grown Rice

“…Many pot and field experiments have demonstrated that soil amendments such as lime, silicon fertilizer and phosphate could reduce rice uptake of heavy metals [16][17][18]. However, the inhibition effects varied according to the type and dose of soil amendments, experimental conditions and heavy metals.…”

Assessment of Cadmium Contamination of Soils in Sewage Disposal Areasof Coimbatore District, Tamil Nadu, India.

“…The nearby Amaranthus field (irrigated by well water as well as direct sewage water) and Marigold field (fertilized with treated sludge) were found with increasing level of cadmium Cadmium in soils can be immobilized by increasing the soil pH through addition of liming materials 20 . Decrease in cadium uptake arise from increased Cd 2+ adsorption caused by pH, increase in negative charge, thereby decreasing its bioavailability.…”

Liming Effect on Cadmium Immobilization and Phytoavailability in Paddy Soil Affected by Mining Activity

“…소석회의 시 용량을 최대 8 Mg/kg으로 시용하였을 때 무처리에 비해 각 부위별 카드뮴 흡수량은 알곡에서 64%, 볏짚에서 63.5%, 뿌 리에서 40%로 현저히 감소되어 졌다. 몇몇 연구자들이 밭토 양의 조건에서 소석회의 처리에 의해 식물체 내 카드뮴의 흡 수농도가 저감된다는 사실을 보고하였다 (Basta and Sloan, 1999;Gray et al, 1999;Hong et al, 2007). …”

“…석회를 시용하여 토양 내 카드뮴의 용해도와 식물체 흡수를 저감시키기 위한 연구는 과거부터 오랜 기간 연구되어 왔으며 이미 국내외적으로 여 러 연구에서 석회의 효과를 입증해 왔다 (오왕근, 1981;이민효 등, 1984;정구복 등, 1999;김민경 등, 2004;Anderson and Siman, 1991;Kreutzer, 1995;Gray et al, 1999;Bolan et al, 2003;Hong et al, 2007). 그러나 토양 내 석 회처리에 의한 카드뮴의 부동화 기작에 대한 의견이 다양하 며 현장조건에서 석회처리에 의한 카드뮴의 식물이용성 저감 효과는 늘 의문시 되어왔다.…”