添加天然沸石和石灰对土壤镉形态转化的影响

采用土壤培养实验,研究镉污染土壤中添加沸石、石灰及两者配施对土壤pH值和土壤镉形态变化的影响。结果表明,土壤pH值随沸石用量的增加而增加,随培养时间呈现先增加后下降并逐渐趋于稳定的趋势,但均高于对照。高剂量石灰的处理对土壤pH的影响最大,与对照相比土壤pH提高了3.33个单位。在土壤5~50 d培养过程中,石灰处理的土壤交换态镉含量呈现先逐渐降低而后略有升高的趋势,其余处理均呈下降趋势。培养50 d后,高剂量的沸石、石灰及高剂量沸石与石灰配施处理的土壤交换态镉含量从5 d时的67.54、61.95和55.56 mg/kg降低至54.65、49.93和45.96mg/kg。相关分析表明,不同培养时期交换态镉含量与土壤pH值呈负相关关系。在10个处理中,L2Z3(石灰2 g/kg土和沸石60 g/kg土)组合处理效果最好,使土壤交换态镉含量下降了34.68%,碳酸盐结合态镉含量上升了4.30%,铁锰氧化结合态镉含量上升了16.97%,有机结合态镉含量上升了1.31%,残渣态镉含量上升了12.11%。

Effects of natural zeolite and lime on form transformation of cadmium in soil

The effects of zeolite, lime and the zeolite-lime combination on the soil pH and Cd form transformation from Cd-contaminated soil were studied by soil incubation experiment.The results showed that soil pH increased along with an increase in rates of zeolite. After application of zeolite, the soil pH first increased then decreased and gradually stabilized with incubation time. But the soil pH in treatments was always higher than that of the control.High doses of lime treatment has the greatest impact on soil pH, under high doses of lime the soil pH increased 3.33 units compared with the control.All treatments showed a downward trend on soil exchangeable Cd content from 5 d to 50 d except the lime treatment was gradually decreased and then slightly elevated.After 50 days of incubation, soil exchangeable Cd contents of high-level lime and zeolite and high-level zeolite-lime combination respectively reduced from 67.54, 61.95 and 55.56 mg/kg to 54.65, 49.93 and 45.96 mg/kg.Correlation analysis showed that, different incubation periods for exchangeable Cd content and soil pH were negatively correlated.The L2Z3 (lime 2 g/kg soil and zeolite 60 g/kg soil) was the optimal treatment among 10 treatments, under this treatment, the soil exchangeable Cd content decreased by 34.68% and the content of carbonate-bound, Fe-Mn oxides-bound, organic-bound, residual Cd increased by 4.30%, 16.97%, 1.31%, 12.11%, respectively compared with the control.