碳酸钙与氢氧化钙修复重金属污染土壤效果差异研究

Different Effects of CaCO_3 and Ca(OH)_2 on Heavy Metals Remediation in Contaminated Farmland Soil

土壤固化是修复重金属污染农田的有效措施,它可在一定程度解决土壤污染与农产品安全之间的矛盾,因此受到广泛青睐。碳酸钙与氢氧化钙是常见且廉价的固化材料,应用十分广泛。该研究通过室内实验,研究两者在土壤重金属污染修复效果的差异,筛选出最佳的改良剂及添加量,为受污染农田的大面积修复提供理论依据与指引。试验结果表明,碳酸钙与氢氧化钙均能显著提高土壤pH值,但碳酸钙的效果较温和,添加量为4 g/kg可使pH值上升1.83个单位,土壤接近中性,相当于2 g/kg的氢氧化钙用量;2种固化剂对Cd、Cu、Pb和Zn均有良好的改良效果,并对其赋存形态造成明显影响,其中添加4或8 g/kg碳酸钙的效果可显著降低可交换态含量,并将其转化为残渣态,修复效果优于同样添加量的氢氧化钙。在实际应用中,应优选碳酸钙作为修复材料,建议添加量为4~8 g/kg。

Soil stabilization is an effective measure for remediation of heavy metal contaminated farmland, it can solve the contradiction between the soil pollution and the safety of agricultural products in a certain degree, so it is widely popular.Calcium carbonate and calcium hydroxide as common and cheap materials, are widely applied. Through lab experiment, their differences in heavy metal contaminated soil remediation effect were studied, to screen out the best and the dosage of amendments, for the purpose to provide a theoretical basis and guidance for the remediation of large area of contaminated farmland. Experimental results showed that the calcium carbonate and calcium hydroxide can significantly increase soil pH value, but the effect of calcium carbonate was more moderate, adding amount of 4 g/kg could make the pH value increased by1.83 units, with the soil close to neutral, and equivalent of 2 g/kg calcium hydroxide dosage. Two kinds of amendments on the remediation effect of Cd, Cu, Pb and Zn were good, with obvious influence on the geometrical state; with the addition of 4 or8 g/kg, the effect of calcium carbonate can significantly reduce the amount of exchangeable, and transform into residual state,the repair effect was better than that the same amount of calcium hydroxide. In practical application, calcium carbonate should be preferably as the repair materials, and recommended dosage is 4~8 g/kg.