用放射性同位素1 4 7Nd示踪法 ,以pH8 2的NaAc为交换态Nd的提取剂 ,研究了碳酸盐对土壤中外源Nd的交换态及生物有效性的影响。无论碳酸盐存在与否 ,加入土壤中的Nd ,99%以上均被吸附。碳酸盐在低浓度时 ,能够降低土壤中交换态Nd含量 ;碳酸盐在高浓度时 ,对交换态Nd含量影响作用不明显。实验还表明碳酸盐在 0 8～ 1 6g·kg- 1 范围内有明显降低Nd植物有效性的作用 ,浓度升高到 4 0g·kg- 1时 ,对植物吸收Nd的抑制作用不明显 The effect of carbonate on the exchangeable state and bioavailability of exogenous Nd in soil was studied by radioactive isotope 147Td tracing method and NaAc pH8 2 as exchangeable Nd extractant. Regardless of the presence or absence of carbonate, more than 99% of the Nd added to the soil is adsorbed. Carbonate can reduce the content of exchangeable Nd in the soil at low concentration. However, the effect of carbonate on the exchangeable Nd content is not obvious at high concentration. The experiment also showed that the carbonate could significantly reduce the effectiveness of Nd in the range of 0 8 ~ 1 6g · kg-1. When the concentration was increased to 40g · kg-1, the inhibitory effect on Nd uptake was not obvious