铅锌矿区污染土壤的植物淋洗剂筛选研究

Screening of Phyto-eluents for Contaminated Soil in Pb-Zn Mining Area

高效绿色淋洗剂的筛选是土壤淋洗技术开发的重要内容之一。本文以汉源某铅锌矿区污染土壤为对象,将14种植物地上部分风干研磨过2 mm筛后蒸馏水浸提24 h,采用振荡淋洗的方法研究浸提液在不同浓度、pH和作用时间下对铅锌复合污染土壤中铅和锌的提取效果。结果表明,在25℃、200 r·min-1恒温振荡条件下,14种植物淋洗剂对土壤铅锌的淋洗效率不同(P<0.05):随着淋洗剂浓度的增加,其对土壤铅的淋洗率呈逐渐增加和先增后减两种变化趋势,对土壤锌的淋洗率则呈逐渐增加和变化趋势不明显;淋洗率随着p H增加总体降低;14种植物淋洗剂对土壤中铅和锌的淋洗率随淋洗时间的增加均分别呈上升、无显著变化和下降三种趋势。其中马桑浸提液对土壤铅和锌具有较好的淋洗效果,当淋洗剂的浓度为5%、p H为4.0、振荡时间为8 h条件下时,其对铅和锌的淋洗率分别为23.78%和77.03%。因此,马桑提取液是一种对铅锌复合污染土壤修复具有良好运用前景的环境友好型植物淋洗剂。

Soil washing is a frequently used soil remediation technique. The key to this technique is washing agents. The objective of this study is to screen eco-friendly washing agents-phyto-eluents. We collected 14 plant species, ground the aboveground biomass to powders (﹤2 mm), and made washing agents using distilled water. Then the washing efficiencies of Pb and Zn by these washing agents were exam-ined under different concentrations, pH and contact time. At 25℃and 200 r·min-1 rotational oscillation, the washing efficiencies of Pb by these agents showed either continuous increases or initial increase and then decreases as the agent concentrations increased, whereas those of Zn displayed gradual increases or slight changes with the agent concentrations. Increasing pH apparently reduced the removal efficiencies of two metals. The effect of contacting time on the removal efficiencies of two metals showed gradual increase, slight changes or decline pat-terns. Among these 14 plants, Coriaria nepalensis proved to have a better removal efficiency, with the removal efficiencies of Pb and Zn be-ing 23.78%and 77.03%, respectively, at 5%eluent, pH 4.0 and a reaction time of 8 h. Therefore, C. nepalensis could be used as an envi-ronmental-friendly eluent for Pb-Zn contaminated soils.