外源稀土对土壤中稀土和重金属可交换态的影响

通过土壤旱作和淹水2种培养方式,研究了不同时期添加外源稀土对黄褐土中稀土和重金属Fe、Mn、Zn可交换态含量的影响.研究结果表明,稀土处理显著提高土壤中可交换态含量,其分配系数也随之增大,但绝大部分仍维持在10%以下.淹水条件下交换态稀土的含量比旱作高,但随培养时间的延长逐渐降低.随稀土处理浓度的升高,交换态稀土组成逐渐向外源稀土成分靠近,并在200mg·kg^-1以上达到相对稳定土壤中交换态Fe、Mn、Zn的含量随稀土处理浓度的升高呈线性升高,其中稀土对Mn的作用最强.

Effect of Extraneous Rare Earths (REs) on Form of Soil Exchangeable REs and Heavy Metals

The effects of extraneous rare earths (REs) on the form of exchangeable REs and heavy metals Fe, Mn and Zn in yellow cinnamon soil in different terms were studied through soil culture in both dry and inundated condition. The result showed that the treatments of REs enhanced the contents of soil exchangeable REs (EX-REs) and its distribution coefficients also increased while most still remained under 10%. The contents of EX-REs in inundated condition were higher than that in dry condition, but they decreased with the duration of soil culture. The composition of EX-REs in soil gradually approached that in extraneous REs, and it remained relatively steady over the treatment with 200mg·kg^-1 applied REs. Applying REs raised the contents of exchangeable heavy metals, and the contents of exchangeable Fe, Mn and Zn increased with linear trend, of which the effect of REs on Mn was the strongest one.