期刊
SOIL SYSTEMS
卷 4, 期 2, 页码 -出版社
MDPI
DOI: 10.3390/soilsystems4020028
关键词
paddy fields; iron plaque; microaerophilic Fe(II) oxidation; Fe(III) reduction; contaminant (im)mobilization
类别
资金
- DFG [SCHM 2808/2-1, SCHM 2808/4-1]
- Margarete von Wrangell grant
Iron plaque on rice roots represents a sink and source of iron in paddy fields. However, the extent of iron plaque in impacting paddy field iron cycling is not yet fully deciphered. Here, we followed iron plaque formation during plant growth in laboratory-controlled setups containing a transparent soil matrix. Using image analysis, microsensor measurements, and mineral extractions, we demonstrate that radial oxygen loss (ROL) is the main driver for rhizosphere iron oxidation. While O(2)was restricted to the vicinity of roots, root tips showed highest spatio-temporal variation in ROL (<5-50 mu M) following diurnal patterns. Iron plaque covered >30% of the total root surface corresponding to 60-180 mg Fe(III) per gram dried root and gradually transformed from low-crystalline minerals (e.g., ferrihydrite) on root tips, to >20% higher-crystalline minerals (e.g., goethite) within 40 days. Iron plaque exposed to an Fe(III)-reducingGeobacterspp. culture resulted in 30% Fe(II) remobilization and >50% microbial transformation to Fe(II) minerals (e.g., siderite, vivianite, and Fe-S phases) or persisted by >15% as Fe(III) minerals. Based on the collected data, we estimated that iron plaque formation and reductive dissolution can impact more than 5% of the rhizosphere iron budget which has consequences for the (im)mobilization of soil contaminants and nutrients.
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