Iron isotope fingerprints of redox and biogeochemical cycling in the soil-water-rice plant system of a paddy field

摘要: The iron isotope composition was used to investigate dissimilatory reduction (DIR) processes in an iron-rich waterlogged paddy soil, the uptake strategies of plants and its translocation different parts rice plant along growth. Fe concentration (δ56Fe) irrigation water, precipitates from pore water solution at depths under surface plaque on roots, stems, leaves grains were measured. Over 8.5-10cm vertical profiles investigated, (0.01 24.3mg·l-1) δ56Fe (-0.80 -3.40‰) varied over a large range. significant linear co-variation between Ln[Fe] suggests apparent Rayleigh-type behavior DIR processes. An average net fractionation factor soil substrate Δ56Fe≈-1.15‰ obtained, taking all values weighted by amount for each sample. These results provide robust field study confirmation conceptual model Crosby et al. (2005, 2007) interpreting observed during DIR, established series laboratories experiments. In addition, strong enrichment heavy measured root relative suggest that roots is more likely supplied not plant-available water. Opposite what previously following strategy II soils, -0.9‰ found grains, pointing All these features highlight insights provides into biogeochemical cycling soil-water-rice systems studied nature.