石灰和海泡石对镉污染土壤的修复效应与机理研究

Effects and Mechanism of Lime and Sepiolite on Remediation of Cd Contaminated Soils

研究了稻作和旱作两种种植制度下,施用石灰、海泡石及两种改良剂配施对镉污染土壤pH值、土壤镉形态变化及作物对镉的吸收等的影响。结果表明,施用改良剂使稻作条件下的土壤pH提高0.3-1.8个单位,旱作条件下土壤pH提高幅度为0.3-2.0个单位;两种种植制度下,作物有效性较高的酸提取态镉含量显著减少,而作物有效性较低的可还原态和残渣态镉含量显著增加,进而引起了水稻和萝卜对镉的吸收量降低。其中以石灰和海泡石配施的效果最好,单施海泡石次之,单施石灰效果最差,且各处理均随改良剂用量的增加效果增强。虽然,施用改良剂可以有效降低土壤中镉的作物有效性,但对水稻产量和生物量及镉在水稻和萝卜两种作物地上部分的分配规律均没有明显的影响。

The effects of lime, sepiolite and lime in combination with sepiolite on soil pH, speciation of cadmium in soil and uptake of Cd by rice and radish by field experiments in a contaminated paddy soil and an arable soil, respecitively. The results indicated. Compared with the CK treatment, amendments significantly increased soil pH by 0.3 to 1.8 units in the paddy soil and by 0.3 to 2.0 units in the arable soil. The percents of acid extractable Cd in soil were significantly decreased, whilst the reducible Cd and residual Cd were significantly increased in both soils. The increasing of soil pH and redistribution of Cd speciation in soils caused the decrease of uptake of Cd by both crops. The efficiencies of different amendments in increasing soil pH and immobilizing Cd in soils was follow the order as： lime in combination with sepiolite 〉 sepiolite 〉 lime, and it was becoming better as long as the applied amount of amendments increased. However, the application of amendments decreased the hioavailability of Cd in soils, no increase of the productivity and biomass of rice was observed and the distribution of Cd in over ground parts of neither rice nor radish was affected.