硅和生物炭互作对空心菜-土壤系统中重金属生物有效性的影响

The interactive effects of silicon and biochar on heavy metal bioavailability in a water spinach-soil system

通过盆栽实验研究了两种复合污染(中度污染土壤S1和重度污染土壤S2)条件下硅(Si)、皇竹草生物炭(BC)单施和复配对空心菜生长和吸收重金属以及土壤中重金属有效性的影响。结果显示:单施Si、BC及其二者复配均可显著促进空心菜的生长,其中复配组对空心菜生长的促进效果最好,S1和S2土壤中复配组空心菜的株高相较于对照组分别提高了131.72%和123.08%,根长分别提高了117.66%和165.66%;单施Si、BC及其二者复配均可显著提高土壤的pH值0.48—2.06个单位,其中Si+BC复配组的提高效果最显著;单施Si、BC以及Si+BC复配均能显著降低土壤中各重金属元素的有效态含量以及空心菜体内的各元素含量,其中复配组的降低效果最为显著,对S1和S2中Cd、Pb、Zn、Ni、Cu、Cr有效态含量的降低幅度分别为29.82%、57.72%、64.97%、71.37%、44.63%、82.85%和42.37%、52.18%、69.48%、49.45%、37.98%、62.75%,对S1和S2中空心菜地上部六种重金属元素含量的降低幅度分别为60.36%、47.07%、74.74%、68.90%、62.14%、34.19%和66.32%、65.48%、51.97%、94.47%、68.59%、72.83%。因此,硅和生物炭互作可以协同降低土壤重金属有效性和空心菜体内重金属的含量,二者互作可用于菜地土壤重金属复合污染的钝化修复。

A pot experiment was conducted to investigate the effects of application of silicon(Si)and Pennisetum sinese Roxb biochar(BC),singly or in combination,on the growth of Ipanoea aquatica Forsskal in two heavy metal-polluted soils,one moderately polluted(S1)and the other severely polluted(S2).Heavy metal availability in soil and accumulation characteristics in plant were also investigated.The results showed that application of Si and BC,singly or in combination,significantly promoted the growth of Ipanoea aquatica Forsskal,and the promotion effect of the combined addition of Si and BC was the most obvious.Plant height was increased by 131.72% and 123.08% in S1 and S2,respectively,and plant root was increased by 117.66% and 165.66% in S1 and S2,respectively by combined application of Si and BC,as compared to control(no Si or BC).Soil pH increased by 0.48-2.06 unit in the treatments with addition of Si and BC,and the largest increase was observed in the treatment with combined amendment of Si and BC.Application of Si and BC,singly or in combination,significantly decreased heavy metal bioavailability in soil and accumulation in plant.The biggest reduction in Cd,Pb,Zn,Ni,Cu,and Cr bioavailability by 29.82%,57.72%,64.97%,71.37%,44.63%,and 82.85%,respectively,in S1 and 42.37%,52.18%,69.48%,49.45%,37.98%,and 62.75%,respectively,in S2 was achieved by combined application of Si+BC as compared to control.Similarly,the largest reduction in Cd,Pb,Zn,Ni,Cu,and Cr accumulation in plant aboveground parts was achieved by combined addition of Si and BC,by 60.36%,47.07%,74.74%,68.90%,62.14%,and 34.19%,respectively,in S1 and 66.32%,65.48%,51.97%,94.47%,68.59%,and 72.83%,respectively,in S2.Thus,the results indicated that the combined application of the Si and BC can synergically reduce heavy metal availability in soil and their accumulation in Ipanoea aquatica Forsskal,and combined amendment of Si and BC can be used to remediate heavy metal-polluted vegetable soils.