High concentration of labile metals in soil directly affects soil quality, water health and human safety. Decreasing mobility of metals, especially in contaminated soils, by cost-effective amendments may alleviate environmental problems. Natural diatomite was investigated to immobilize toxic elements of zinc, lead, copper and cadmium in a contaminated calcareous soil. The diatomite was characterized using X-ray fluorescence spectrometry and scanning electron microscopy. Contaminated soil was incubated with 0, 2 and 5 weight -% of diatomite at 25 °C for 8 weeks. Tessier sequential extraction method was also used as a suitable method for identification of chemical forms of heavy metals; metal stability index and mobility factor were calculated. Results showed that application of diatomite in soil significantly decreased the metals in the exchangeable fraction and increased them in the residual fraction. The exchangeable metal fractions decreased by 66–88%, and residual fractions increased by 18–94% in the 5 weight -% of diatomite treatment after 8-week incubation. With an increase in the amount of diatomite applied and the incubation time, metal mobility factor values significantly decreased and soil pH values increased. Application of diatomite caused the heavy metals redistribution toward more stable forms and leads to an increase in stability index values. In conclusion, in situ immobilization of heavy metals by application of diatomite, as a low-cost amendment, had a significant potential to stabilize metals in the contaminated calcareous soil.

土壤中不稳定金属的高浓度直接影响土壤质量，水健康和人类安全。通过经济有效的修正降低金属的流动性，特别是在受污染的土壤中，可以减轻环境问题。对天然硅藻土进行了研究，以将锌，铅，铜和镉的有毒元素固定在受污染的钙质土壤中。使用X射线荧光光谱法和扫描电子显微镜对硅藻土进行表征。将污染的土壤与0、2和5重量％的硅藻土在25°C下孵育8周。Tessier顺序萃取法也被用作鉴定重金属化学形式的合适方法。计算了金属稳定性指数和迁移率因子。结果表明，在土壤中施用硅藻土显着减少了可交换部分中的金属，并增加了残留部分中的金属。孵育8周后，硅藻土的5重量％处理时，可交换金属分数降低了66-88％，残留分数增加了18-94％。随着硅藻土施用量和孵育时间的增加，金属迁移率值显着降低，土壤pH值升高。硅藻土的使用导致重金属向更稳定的形式重新分布，并导致稳定性指数值增加。总之，作为一种低成本的改良剂，通过使用硅藻土原位固定重金属具有稳定被污染的石灰质土壤中金属的巨大潜力。