赤子爱胜蚓对3种污染土壤中Zn及Pb的活化机理研究

以褐土、潮棕壤和酸性棕壤为供试土壤，分别加入100，200和400 mg/kg的w（Zn）或200，400和800 mg/kg的w（Pb）用于模拟污染土壤，通过培养试验，研究了赤子爱胜蚓（Eisenia foetida）对3种土壤中Zn及Pb的活化机理.结果表明:蚯蚓活动显著提高了酸性棕壤和潮棕壤中Zn及Pb处理和褐土中Pb处理的pH；显著降低了褐土中添加w（Zn）为100和200 mg/kg 处理的pH.蚯蚓活动显著提高3种土壤中w（DOC）.蚯蚓活动显著提高了潮棕壤中DTPA提取态w（Pb）〔DTPA-w（Pb）〕，对DTPA提取态w（Zn）〔DTPA-w（Zn）〕的影响不大；显著提高了酸性棕壤分别添加w（Zn）及w（Pb）为200和400 mg/kg处理中土壤DTPA-w（Zn）及DTPA-w（Pb）；对褐土添加w（Zn）低于400mg/kg和添加w（Pb）低于800 mg/kg的处理中DTPA-w（Zn）及DTPA-w（Pb）的影响不明显.蚯蚓粪中DTPA-w（Zn）及DTPA-w（Pb）显著高于土壤，Zn的活化率在52%以上，Pb的活化率在47%以上；而土壤中Zn的活化率低于8%，Pb的活化率低于23%.3种供试土壤中DTPA-w（Zn）及DTPA-w（Pb）与土壤pH均呈线性负相关关系，与土壤w（DOC）和蚯蚓粪中DTPA-w（Zn）及DTPA-w（Pb）均呈线性正相关关系.蚯蚓通过肠道消化和养分富集提高土壤中Zn及Pb的活性，是提高土壤中重金属生物有效性的重要机制之一. 

Mechanism of Mobilization Zn and Pb by Earthworm (Eisenia foetida) in Three Soils

The effects of Eisenia foetida on the mobilization of Zn or Pb were studied using pot experiments in three soils （Cinnamon soil, Aquic brown soil andAcid brown soil） spiked with 100, 200 and 400 mg/kg Zn and 200, 400 and 800mg/kgPb, respectively. The results showed that soil pH was increased by earthworm in Acid brown soil spiked with Zn or Pb and Cinnamon soil with Pb, but decreasedin Cinnamon soil with 100 and 200 mg/kg Zn. Concentrations of dissolved organiccarbon （DOC） in the three soils were significantly enhanced by earthworm. The concentration of DTPA extractable Pb was significantly increased by earthworm in Aquic brown, but no major impact on DTPA-Zn content. The concentration of DTPAextractable Zn or Pb in Acid brown soil with 200 and 400 mg/kg Zn or Pb was significantly enhanced, but no significant difference was found in Cinnamon soil withZn less than 400 mg/kg or Pb less than 800 mg/kg Pb. The concentrationof DTPA extractable Zn or Pb in earthworm casts was higher than that in bulk soils. Themobilization rate of Zn and Pb was over 52% and 47% in earthworm casts and below8% and 23% in bulk soils, respectively. The concentration of DTPA extractable Zn or Pb in soil was in positive linear correlation with it in earthworm casts and with the concentrations of DOC in three soils, but in negative linear correlation with soil pH. The results indicated that earthworm might mobilize heavy metal in soil through gut digestion and metabolism.