不同改良剂对石灰性镉污染土壤的镉形态和小白菜镉吸收的影响

采用盆栽试验,分别在正常土壤(A)、低镉含量土壤(B)、高镉含量土壤(C)三种土壤上种植小白菜,研究4种改良剂(鸡粪、腐植酸、海泡石和生物炭)对小白菜生长、镉含量及土壤各形态含量的影响。结果表明,高施用量的鸡粪能显著提高小白菜的生物量,增加42.7%~79.8%。在B土壤中,除海泡石外,鸡粪、腐植酸和生物炭均增加小白菜地上部的镉含量;在C土壤中,4种改良剂对小白菜吸收镉均有促进作用。施入不同改良剂对土壤中镉形态的影响不同,在A土壤中镉主要以交换态和铁锰氧化态形式存在,在鸡粪和腐植酸处理下,土壤中镉主要以交换态和碳酸盐结合态形式存在,海泡石则增加了土壤中残渣态和有机态的比例。相关分析表明,小白菜镉含量与土壤中交换态镉、碳酸盐结合态镉、铁锰氧化态镉和有机态镉存在极显著正相关关系(P<0.01),与土壤总镉含量的相关性最好。

Effects of Different Amendments on Soil Cd Forms and Cd Uptake by Chinese Cabbage in Cd-contaminated Calcareous Soils

Soil amendments influence the forms and plant bioavailability of Cd in soil. In this pot experiment, Chinese cabbage was grown in different materials amended soils containing 0.3, 1.5, and 3 mg Cd·kg^-1. The amendments were biochar, chicken manure, humic acid, and sepiolite. The growth, biomass and Cd content of plant and the soil Cd forms were measured. Results showed that cabbage biomass increased by 42.7%~79.8% by the highest amount of chicken manure as compared to the control. At 1.5 and 3.0 mg Cd·kg^-1, all amendments increased the Cd content of cabbage, with exception of sepiolite at 1.5 mg Cd·kg^-1. Amendments significantly affected Cd forms. Soil Cd was mainly exchangeable and Fe-Mn oxide-bound forms at 0.3 mg Cd·kg^-1 soil. However, the major forms of Cd were exchangeable and carbonate-bound Cd in both chicken manure and humic acid treatments. The sepiolite treatment increased the proportion of residual Cd and organic matter-bound Cd. Correlation analysis showed that the Cd content of Chinese cabbage was significantly and positively correlated with exchangeable, carbonate-bound, Fe-Mn oxide-bound and organic matter-bound Cd in soil. The Cd content in Chinese cabbage was also highly correlated with soil total Cd.