Technologies based on zero-valent iron (Fe0) are increasingly being used to immobilize metals in soils and remove metals and nitrate from waters. However, the impact of nitrate reduction on metal immobilization in metal contaminated soils has been poorly investigated so far. Here, different concentrations of Fe0 filings (1%, 2% and 5%; wt%) were applied to a metal contaminated soil. The resulting nitrate reduction and metal (Cd and Zn) immobilization was investigated using a column leaching experiment for 12 weeks. Corrosion of Fe0 filings and precipitation of Fe oxyhydroxydes (FeOOH) on the surfaces of the filings were observed using SEM-EDS and EMPA-WDS at the end of the experiment. Compared to the untreated soil, total nitrate amounts released were lowered by 47%, 59% and 87% in the presence of 1%, 2% and 5% of Fe0, respectively. Concomitantly with nitrate reduction, Cd and Zn concentrations in leachates were strongly alleviated in the presence of Fe0, which was partly attributed to the rise of soil pH subsequent to nitrate reduction. More importantly, biotests with Lupinus albus L. revealed that the mechanisms involved in metal immobilization are stable to root-induced acidification. However, Fe0 was not efficient to reduce Cd concentration in Lolium multiflorum Lam., indicating that root processes other than acidification may re-mobilize metals.

中文翻译：

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用零价铁（Fe0）修正的土壤中的金属固定和硝酸盐还原。

基于零价铁（Fe0）的技术越来越多地用于固定土壤中的金属并从水中去除金属和硝酸盐。然而，迄今为止，对硝酸盐还原对金属污染土壤中金属固定化的影响的研究很少。在此，将不同浓度的Fe0屑（1％，2％和5％； wt％）应用于金属污染的土壤。使用柱浸出实验研究了所得的硝酸盐还原和金属（镉和锌）的固定化，历时12周。在实验结束时，使用SEM-EDS和EMPA-WDS观察到Fe0屑的腐蚀和屑表面Fe羟基氧化物（FeOOH）的沉淀。与未经处理的土壤相比，在1％，2％和5％的Fe0存在下，释放的硝酸盐总量分别降低了47％，59％和87％。伴随硝酸盐还原，在Fe0存在下，渗滤液中Cd和Zn的浓度大大降低，这部分归因于硝酸盐还原后土壤pH升高。更重要的是，用羽扇豆进行的生物测试表明，金属固定化所涉及的机制对于根诱导的酸化是稳定的。但是，Fe0不能有效降低多花黑麦草中Cd的浓度，这表明除酸化作用外的根系过程可能使金属重新迁移。揭示金属固定化涉及的机制对根诱导的酸化是稳定的。但是，Fe0不能有效降低多花黑麦草中的Cd浓度，表明除酸化作用外的根系过程可能使金属重新迁移。揭示金属固定化涉及的机制对根诱导的酸化是稳定的。然而，Fe0不能有效降低多花黑麦草中的Cd浓度，表明除酸化作用外的根系过程可能使金属重新迁移。