废弃菌棒生物炭对土壤中镉和铅的固持和植物吸收性的影响

Effect of discarded mushroom-stick biochar on immobilization and plant availability of Cd and Pb in contaminated soil

以废弃菌棒为原料,在300,500,800℃缺氧条件下制备菌棒生物炭,结合扫描电镜(SEM)和红外光谱(FTIR)等表征手段,分析热解温度对生物炭性质的影响。将制备的生物炭添加到受到镉(Cd)和铅(Pb)污染的土壤中,探究菌棒生物炭对土壤中Cd和Pb的固定效果,并用盆栽方式评估添加菌棒生物炭对油菜体内重金属含量的影响。结果表明:随热裂解温度的升高,菌棒生物炭的颗粒逐渐变小,空隙逐渐变大,有利于对重金属离子的吸附。高温热解的菌棒生物炭比低温热解的菌棒生物炭碱性物质多,对土壤pH值的提升作用更为显著。油菜盆栽实验表明,生物炭可有效降低有效磷的渗流损失,增加了植物的可利用性。800℃热解下得到的生物炭对土壤中Cd和Pb固定效果最好,土壤中总Cd和总Pb的损失分别仅为6.5%和18. 5%。而500℃热解下得到的生物炭的效果最差。另外,生物炭对Cd的固定效果显著高于对Pb的固定效果。同时与对照值(CK)相比,生物炭可使油菜中的Cd和Pb的含量都显著降低90%以上。菌棒生物炭对重金属Cd和Pb污染土壤具有良好的钝化修复效果。

Discarded mushroom-stick biochar was prepared under anoxic conditions at 300℃,500℃and 800℃by using discarded mushroom-stick as raw materials.Combined with SEM and FTIR,immobilization and remediation effect of discarded mushroom-stick biochar on Pb and Cd were investigated.The experiment of potted vegetable was used to assess the influence of adding discarded mushroom-stick biochar on the heavy metal contents of soil and vegetables.The results showed that with the increase of pyrolysis temperature,and the particles of the biochar gradually become smaller and the gap gradually becomes larger,which was more conducive to the adsorption of heavy metal ions.The biochar prepared at higher temperature had a better effect of increasing the pH of soil because of more alkaline substance on the biochar.The pot experiment showed that discarded mushroom-stick biochar can effectively reduce the P loss caused by the leaching.Meanwhile,the loss in Cd and Pb content in soil were decreased to 6.5%and 18.5%,respectively,by adding the biochar prepared at 800℃,whereas the biochar prepared at 500℃had worst effect.In addition,the fixed effect of biochar on Cd was significantly higher than that of Pb.Compared with the control,discarded mushroom-stick biochar can reduce the content of Cd and Pb in rape by more than 90%.Therefore,discarded mushroom-stick biochar has a good effect of passivation for heavy metal Cd and Pb.