CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China.
CAS Center for Excellence in Comparative Planetology, Hefei 230026, China.
J Agric Food Chem. 2020 Aug 5;68(31):8143-8150. doi: 10.1021/acs.jafc.0c02515. Epub 2020 Jul 22.
In paddy soils, iron (Fe) forms are highly influenced by the seasonal redox changes and leave detectable isotope signals because of fractionation between different Fe forms. Here, we present Fe concentrations and Fe isotope compositions (expressed as δFe values) in a paddy soil profile from Suzhou, China. Light Fe isotopes were enriched in two iron-accumulation layers (Br3 and G1) with high Fe concentrations. In particular, large shifts in both Fe concentrations and δFe values were found at the Br2 and Br3 boundaries, showing fast and efficient transformation between these horizons. With sequential extraction, we show that Fe isotopes in the short-range-ordered Fe minerals and crystalline Fe oxides were lighter than those in the residual silicate minerals. Iron enriched in light isotopes was leached from the Ap horizon and subsequently moved to Br horizon, quickly precipitating there as Fe oxides.
在稻田土壤中，铁（Fe）形态受季节性氧化还原变化的强烈影响，并由于不同 Fe 形态之间的分馏而留下可检测的同位素信号。在这里，我们展示了来自中国苏州的一个稻田土壤剖面的 Fe 浓度和 Fe 同位素组成（表示为 δFe 值）。轻 Fe 同位素在两个高 Fe 浓度的铁积累层（Br3 和 G1）中富集。特别是，在 Br2 和 Br3 边界处发现 Fe 浓度和 δFe 值都发生了较大的变化，表明这些层之间存在快速而有效的转化。通过连续提取，我们表明短程有序的 Fe 矿物和结晶 Fe 氧化物中的 Fe 同位素比残余硅酸盐矿物中的更轻。富含轻同位素的铁从 Ap 层中淋滤出来，随后迁移到 Br 层，迅速在那里沉淀为 Fe 氧化物。
