稻壳生物炭对污染土壤中稀土元素生物有效性的影响

利用农业秸秆制备了污染土壤修复材料稻壳生物炭和稻壳灰，在模拟稀土（REE）污染的酸性土壤中，添加0、5%和10%的稻壳灰（RHA）稻壳生物炭（RHB），通过栽培实验考察RHA和RHB对REEs的形态和生物有效性的影响.春秋两季的盆栽实验结果表明，RHA和RHB的添加有效的降低了稀土的弱酸可提取态，随着添加量的增加效果越明显，10% RHA和10% RHB土壤中REEs的弱酸（乙酸）提取态较对照组分别降低了31.65%、19.915%，弱酸可提取态转化为了可还原态，与对照组相比，RHA和RHB的土壤中稀土元素的可还原态分别增加了26.367%、10.321%.两种修复材料显著降低了胡萝卜和茼蒿对稀土元素的富集，10% RHA处理组胡萝卜和茼蒿REEs含量分别较对照组降低了98.08%、93.41%，10% RHB胡萝卜和茼蒿REEs含量分别较对照组降低了68.61%、66.75%.研究结果表明，稻壳生物炭和稻壳灰的施用，能够有效的改善污染土壤的理化性质，降低稀土元素生物可利用态的含量，从而遏制植物对稀土元素的富集.

Effect of rice husk biochar on bioavailability of rare earth elements in polluted soil

This study was conducted to investigate the effect of Rice hull ash (RHA) and rice hull biochar (RHB) on the bioavailability of rare earth elements (REEs) in the acidic soil. RHA and RHB were mixed into the artificially polluted soil at 0 (W/W), 5% (W/W, and 10% (W/W), respectively. pot experiments were conducted to assess the bioaccumulation of rare earth elements (REEs) by Carrot and chrysanthemum, which sequential extraction was used to analyze the change of REEs' fraction in the soil. The results of pot experiment indicated that the acid extractable of REEs decreased 31.56%, and 19.915% in the soil with 10% RHA and 10% RHB, comparing with the control group. Furthermore, the uptake of REEs by Carrot and chrysanthemum reduced 98.08% and 93.41% in the soil amended by 10% RHA, and decreased 68.61% and 66.75% with 10% RHB. In short, the addition of RHA and RHB can significantly decrease the bioavailability of REEs and restrain the plant's enrichment. Moreover, the amendment effect of RHA was better than the RHB, so the ash of crop straw, as a kind of convenient and effective soil conditioner, need to be valued application on the contaminated soil.