Iron Isotope Fractionation during Fe Uptake and Translocation in Alpine Plants
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- 作者：Mirjam Kiczka ; Jan G. Wiederhold ; Stephan M. Kraemer ; Bernard Bourdon ; Ruben Kretzschmar
- 刊名：Environmental Science & Technology
- 出版年：2010
- 出版时间：August 15, 2010
- 年：2010
- 卷：44
- 期：16
- 页码：6144-6150
- 全文大小：333K
- 年卷期：v.44,no.16(August 15, 2010)
- ISSN：1520-5851
文摘
The potential of stable Fe isotopes as a tracer for the biogeochemical Fe cycle depends on the understanding and quantification of the fractionation processes involved. Iron uptake and cycling by plants may influence Fe speciation in soils. Here, we determined the Fe isotopic composition of different plant parts including the complete root system of three alpine plant species (Oxyria digyna, Rumex scutatus, Agrostis gigantea) in a granitic glacier forefield, which allowed us, for the first time, to distinguish between uptake and in-plant fractionation processes. The overall range of fractionation was 4.5‰ in δ56Fe. Mass balance calculations demonstrated that fractionation toward lighter Fe isotopic composition occurred in two steps during uptake: (1) before active uptake, probably during mineral dissolution and (2) during selective uptake of Fe at the plasma membrane with an enrichment factor of −1.0 to −1.7‰ for all three species. Iron isotopes were further fractionated during remobilization from old into new plant tissue, which changed the isotopic composition of leaves and flowers over the season. This study demonstrates the potential of Fe isotopes as a new tool in plant nutrition studies but also reveals challenges for the future application of Fe isotope signatures in soil−plant environments.