水肥耦合对海泡石钝化修复镉污染土壤效率的影响

为探讨水肥耦合对海泡石钝化修复镉(Cd)污染土壤效率的影响,采用盆栽试验,以油菜为供试植物,研究了两种水分条件下施用质量分数为0.5%、1.0%和2.0%的蚯蚓粪肥对钝化土壤中有效态Cd含量、油菜根部和可食部分Cd含量的影响。结果表明,土壤水分含量为60%～65%时,施用海泡石能够显著降低土壤中有效态Cd的含量,进一步施用蚯蚓粪肥土壤中有效态Cd的含量为单一海泡石处理的2.24～2.72倍,但是油菜可食部分Cd含量与单一海泡石处理相比变化不显著(P0.05);土壤水分含量为100%时,在钝化修复下施用0.5%、1.0%和2.0%的蚯蚓粪肥,土壤中有效态Cd的含量为单一海泡石处理的1.11、1.17倍和1.26倍,施用0.5%和2.0%蚯蚓粪肥,油菜可食部分Cd含量与单一海泡石处理相比降低了55.9%和56.8%。因此土壤水分含量为60%～65%时,在海泡石钝化修复下施用蚯蚓粪肥,水肥耦合对钝化效应的影响较小;土壤水分含量为100%时,施用0.5%或2.0%蚯蚓粪肥,水肥耦合能够强化海泡石的钝化效应,进一步降低油菜对Cd的吸收和累积。

Coupling effect of water management and fertilizers in remediation of Cd-contaminated soil using sepiolite

In order to investigate the coupling effect of water management and fertilizers on the effectiveness of sepiolite in the remediation of Cd-contaminated soil, a pot experiment was conducted with pak choi as the tested plant. The effects of wormcast with different application ratios on available Cd contents in soils, and Cd contents in roots and shoots of pak choi were studied under two different water conditions. The results indicated that sepiolite reduced the available Cd contents in soils significantly when the soil moisture contents were 60%~65%. Furthermore, the available Cd contents in soils with the addition of wormcast in sepiolite-amended soils were 2.24~2.72 times to single sepiolite-amended treatment, though the Cd contents in edible parts of pak choi did not change significantly (P<0.05). When soil moisture content was 100%, the available Cd contents in sepiolite-amended soils after the addition of 0.5%,1.0% and 2.0% wormcast, 1.0%, and 2.0% were increased by 1.11, 1.17, and 1.26 times, respectively. The application of 0.5% and 2.0% wormcast decreased the Cd contents in edible parts of pak choi by 55.9% and 56.8%, respectively, compared with the application of sepiolite alone. As a consequence, the coupling effect of water management and fertilizer has little impact on the remediation effectiveness of sepiolite with respect to Cd accumulation in plants when soil moisture contents maintained at 60%~65%. When the soil moisture content was 100% and the application ratio of wormcast was 0.5% or 2.0%, the coupling effect of water management and fertilizer could enhance the immobilization effect of sepiolite and further reduce Cd accumulation in pak choi.