土壤中植物凋落物的分解改变了土壤养分含量,在调节土壤pH值和潜在有毒元素(PTE)的有效性方面起着重要作用。然而,关于凋落物在生态恢复过程中影响PTEs迁移的机制的研究仍然有限。这项研究研究了植物凋落物分解介导的铁和硫成分还原对汞-th矿山废物中PTE迁移的影响。结果表明,4种凋落物均能缓解垃圾的酸度,尤其是Bpa和Tre垃圾。垃圾分解产生的硝基和亚硝基被吸附到废物上,从而为铁还原微生物提供电子转移介质,比如Geobacter.这促进了Fe3向Fe2的还原和释放,并降低了废物的电负性(El)值。还原的El促进金属阳离子如Hg和Tl的吸附以保持电中性。然而,不利于As和Sb含氧阴离子的吸附。凋落物的增加导致汞-th矿山废物的还原性增加。这维持了Fe3+向Fe2+的还原,改变或破坏了硅酸盐矿物的结构。PTE,比如Tl,Hg,As,Sb,被释放,导致其残余分数的减少。然而,强还原条件,特别是Bpa的分解,导致部分释放的Hg(II)与SO42-还原产生的S2-结合形成不溶性HgS,从而减少其迁移。研究结果可为指导废渣场PTEs的原位控制和生态修复提供理论依据。
The decomposition of plant litter in soil changes soil nutrient content and plays an important role in regulating soil pH and availability of potentially toxic elements (PTEs). However, there remains limited studies on the mechanism under which litter influences the transport of PTEs in the process of ecological restoration. This study examined the effect of plant litter decomposition mediated reduction of iron and sulfur components on migration of PTEs from mercury-thallium mine waste. The results showed that the four kinds of litter alleviated the acidity of the waste, especially the Bpa and Tre litter. The nitro and nitroso groups produced by the decomposition of the litter were adsorbed onto the waste, thereby providing an electron transfer medium for iron reducing microorganisms, such as Geobacter. This promoted the reduction and release of Fe3+ to Fe2+ and reduced the electronegativity (El) value of waste. The reduced El promoted the adsorption of metal cations such as Hg and Tl to maintain electrical neutrality. However, it was not conducive to the adsorption of oxygen containing anions of As and Sb. An increase in litter resulted in an increase in reductivity of mercury-thallium mine waste. This maintained the reduction of Fe3+ to Fe2+ and changed or destroyed the structure of silicate minerals. PTEs, such as Tl, Hg, As, and Sb, were released, resulting in reductions in their residual fraction. However, the strong reduction conditions, especially the decomposition of Bpa, caused part of the released Hg(II) combining with S2- produced by the reduction of SO42- to form insoluble HgS, thereby reducing its migration. The findings could provide a theoretical basis to guide the situ-control and ecological restoration of PTEs in waste slag site.