骨炭、磷矿粉和生物调理剂对赣南稀土矿区土壤稀土元素淋溶的影响

通过土柱淋溶实验研究了骨炭、磷矿粉与生物调理剂对赣南稀土矿区土壤稀土元素淋溶的影响.结果表明:土壤中添加骨炭、磷矿粉和生物调理剂均显著地提高了淋溶液的p H值.不管是高钇型重稀土土壤还是富镧少钇型轻稀土土壤,添加骨炭均显著地降低了淋溶液中稀土元素的浓度,7 d时淋溶液中15个稀土元素浓度比对照处理降低10.4%~86.7%(重稀土土壤)和4.6%~87.8%(轻稀土土壤),铈、镧、钇、钕、镝、钆等稀土元素浓度降低最明显.培养时间越长稀土元素淋溶量越少,骨炭的降低作用越小.在轻稀土土壤中添加磷矿粉7 d和14 d后,淋溶液中稀土元素浓度均比对照处理有所降低,而在重稀土土壤中添加磷矿粉7~28 d后,均导致淋溶液中稀土元素浓度比对照升高(除了个别元素外).土壤中添加生物调理剂均导致淋溶液中稀土元素浓度急剧提高,7 d时淋溶液中15个稀土元素浓度比对照处理提高0.86~123.4倍(重稀土土壤)和5.4~250.2倍(轻稀土土壤),在重稀土土壤中钇、铒、镱、镝、钆、钕等浓度提高最明显,而在轻稀土土壤中浓度提高最明显的为铈、镧、钕、镨、钆等.另外,还研究了骨炭、磷矿粉和生物调理剂对土壤总稀土元素淋溶的影响.研究表明,骨炭是可以用来修复稀土元素污染土壤的潜力改良剂,而磷矿粉和生物调理剂的应用将提高环境污染的风险.

Effects of bone char, phosphate rock and modifying agent on leaching of rare earth elements in soil

Effects of bone char, phosphate rock and modifying agent on leaching of rare earth elements in the rare earth mining area soil of southern Jiangxi were studied.The result showed that in addition of bone char, phosphate rock and modifying agent could improve pH value of the leaching solution significantly.The addition of bone char reduced concentrations of rare earth elements in leaching solution significantly in both the yttrium-laden heavy rare earth soil and lanthanum-laden light rare earth soil.In comparison with control treatment, concentrations of rare earth elements in the leaching solution of 7 d decreased by 10.4%~86.7% and 4.6%~87.8% for heavy and light rare earth soil, respectively, and the concentrations of Ce, La, Y, Ne, Dy, and Ga decreased most significantly.Both the leaching amount of rare earth elements and the role of bone char decreased with longer incubation time.The addition of phosphate rock in light rare earth soil decreased concentrations of rare earth element in leaching solution in 7 d and 14 d, while addition of phosphate rock in heavy rare earth soil increased concentrations of rare earth element in leaching solution in 7~28 d.The addition of modifying agent resulted in concentrations of 15 rare earth elements in the leaching solution increasing by 0.86~123.4 times and 5.4~250.2 times in 7d for heavy and lLight rare earth soil, respectively.Concentrations of Y, Er, Yb, Dy, Ga and Ne increased most obviously in heavy rare earth soil, while concentrations of Ce, La, Nd, Pr, Gd increased most obviously in the light rare earth soil.In addition, the influences of bone char, phosphate rock and modifying agent on total rare earth elements in the leaching solution were also studied.The results suggested that bone char can be used as a potential material to remediate rare earth elements contaminated soil, and the application of phosphate rock and modifying agent will increase the risk of environmental pollution.