高浓度汞污染土壤低温工程性修复复垦的可行性

Reclamation feasibility of high mercury-contaminated soil repaired by low-temperature pyrolysis technology

低温热解技术修复高浓度汞污染土壤(≥100 mg·kg^(-1))工程除汞效果可达70%以上,仍残留20%~30%的惰性汞,是否对农作物安全存在一定风险仍属未知。为此,以低温热解工程性修复前的高浓度汞污染农田土壤为对照,研究修复后土壤在原位大田条件下残留汞的形态变化及对几种常见作物生物产量、质量及汞在植物组织间迁移的影响。结果表明:低温热解过程未对土壤肥力造成影响,经低温热解修复后土壤中有机结合态汞降低64.07%,残渣态汞降低56.38%;高浓度汞污染抑制了作物生长,修复后土壤耕种作物生长状况得以明显改善,作物产量提高了2~3倍;所研究作物可食部分土豆肉、玉米粒及稻米,汞含量分别降低了51.2%、43.8%和53.79%;汞在植株中的分布情况为:根>叶>茎,残留汞对植株根系的胁迫最为严重,且植株的根和叶汞含量,相比修复前明显降低了2~5倍。

Low-temperature pyrolysis technology was used to remedy high levels of mercury-contaminated soil （≥100 mg·kg^-1 ）. More than 70% of mercury was removed from the contaminated soil by the technology. However,20% to 30% of mercury still remained in the soil. A field planting experiment was conducted to inves- tigate the effects of residual mercury on crop growth, economic yield, and quality. Mercury transportation between plant tissues were also investigated. The results can be summarized as follows. First, the low-temperature pyroly- sis technology does not reduce soil fertility. The organically bound fraction and the residual fraction were reduced by 64.07% and 56. 38% ,respectively. Second ,the low-temperature pyrolysis technology had no damage on soil fertility. Third, high levels of mercury pollution inhibited the growth of crops. After the low-temperature pyrolysis treatment,there was a significant improvement in plant height and the economic yield increased from 2 to 3 times. In addition,the mercury content in potatoes,corn,and rice reduced by 51.2% ,43.8% ,and 51.2% ,re- spectively. Finally,the mercury distribution in the body of the three crops were in the following order：root 〉 leaf 〉 stem. The mercury content in root and leaf significantly decreased （2 to 5 times） after the treatment.