Phytoremediation of radiostrontium (90Sr) and radiocesium (137Cs) using giant milky weed (Calotropis gigantea R.Br.) plants

Potential of plants to remove radionuclides/toxic elements from soils and solutions can be successfully applied for removal of important radionuclides such as strontium-90 (90Sr) and cesium-137 (137Cs). When uptake of 137Cs and 90Sr by Calotropis gigantea plants incubated in distilled water spiked with the radionuclides either alone or in combination was studied, it was found to have a high efficiency for the removal of 90Sr, with 90% being removed from solutions (5 × 103 kBq l−1) within 24 h of incubation. However, in case of 137Cs, about 44% could be removed from solutions (5 × 103 kBq l−1) at the end of 168 h of incubation. Accumulation of 90Sr and 137Cs was higher in roots compared to shoots. The plants could remediate both 90Sr and 137Cs when they were added together to the solution. When two months old plants were incubated in low level nuclear waste, 99% of activity disappeared at the end of 15 days. The present study suggests that C. gigantea could be used as a potential candidate plant for phytoremediation of 90Sr and 137Cs.