声明
List of Abbreviations
Chapter 1 Introduction
1.1 General introduction
1.2 Aim and specific objectives of the study
1.3 Scope and outline of the thesis
Chapter 2 Literature review
2.1 General background
2.2 Characterisation of iron plaque
2.2.1 The conception of Iron plaque formation: influencing factors
2.2.2 Role of iron plaque in sequestration and uptake of heavy metals
2.2.3 Effect of rice origin on iron plaque formation
2.2.4 Iron plaque: Buffer or Barrier for metal translocation?
2.2.5 Role of iron plaque in plant growth
2.3 Sulphur in plants: Relationship with heavy metals
2.3.1 Sulphur uptake and assimilation in plants
2.3.2 Sulphur speciation and cycling in paddy soils
2.3.3 Sulphur-induced alleviation of heavy metal toxicity: Fe plaque formation/sulphur metabolism
2.4 Chromium (Cr) in the environment and its toxicity to plants
2.4.1 Bioavailability and speciation of Cr in the soil-plant system
2.4.2 Soil- plant Cr transfer: alternative transporting pathways
Chapter 3 Materials and methods
3.1.3 Experimental setup and growth condition
3.1.4 Sample preparation and analysis
3.1.5 Data Analysis
3.1.6 S K-edge XANES analysis
3.1.7 Statistical Analysis
3.2 Study Ⅱ: Influence of sulphur (S) supply in solution culture on the absorption and translocation of iron (Fe) and chromium (Cr) in rice (Oryza sativa L.) seedlings
3.2.1 Rice cultivation and growth condition
3.2.2 Induction of iron plaque, exposure to Cr and biomass assessment
3.2.3 Extraction of iron plaque
3.2.4 Analysis of Fe, S and Cr contents in ACA extractions, roots and shoots
3.2.5 Measurement of thiols (GSH, PCs)
3.2.6 Data processing and statistical analysis
3.3 Study Ⅲ: An insight into speciation and distribution of chromium (Cr) and localisation of micronutrients in the tip and mature zone of rice (Oryza sativa L.) root
3.3.1 Plant culture
3.3.2 Experiment 1: Induction of iron plaque and chemical treatments
3.3.3 Experiment 2: Reductive dissolution of iron oxide and Cr release
3.3.4 Experiment 3: 13C labelling experiments and sample preparation for NanoSIMS analysis
3.3.5 Data analysis and statistics
Chapter 4 Do sulphur addition and rhizoplane iron plaque affect chromium uptake by rice (Oryza sativa L.) seedlings in solution culture?
4.1 Introduction
4.2 Results
4.2.1 Plant growth and iron plaque induction in roots
4.2.2 Cr concentration in iron plaque and plant tissues
4.2.3 Uptake and translocation of Cr
4.2.4 Fe and S concentration in iron plaque and plant tissues
4.2.5 Sulphur K-edge XANES Data
4.3 Discussion
4.4 Concluding remarks
4.4.1 Core findings
4.4.2 Graphical Abstract
Chapter 5 Influence of sulphur (S) supply in solution culture on the absorption and translocation of iron (Fe) and chromium (Cr) in rice(Oryza sativa L.) seedlings
5.1 Introduction
5.2 Results
5.2.1 Growth of rice seedlings under S and Cr treatments
5.2.2 The concentrations of Cr, Fe and S in rice plants
5.2.3 Cr translocation and comparison of its proportional distribution with S and Fe
5.2.4 Formation of iron plaque and Cr adsorption
5.2.5 Effect of sulphur supply on thiol compounds (GSH and PCs) contents in roots
5.3 Discussion
5.3.1 Influence of Cr and S on dry mass and root morphology
5.3.2 Cr implication on Fe distribution and relationships between Fe and Cr in iron plaque
5.3.3 Sulphur implications on Fe plaque formation and distribution of Fe in rice plants
5.3.4 Effects of iron plaque on translocation and uptake of Cr in rice plants
5.3.5 Effect of S supply on Cr and S uptake by rice
5.4 Concluding remarks
5.4.1 Core findings
5.4.2 Graphical Abstract
Chapter 6 An insight into speciation and distribution of chromium (Cr) and localisation of micronutrients in the tip and mature zone ofrice (Oryza sativa L.) root
6.1 Introduction
6.2 Results
6.2.1 Fe and Cr concentrations in different organs of rice
6.2.2 Fe and Cr concentrations in different root regions
6.2.3 Fe and Cr distribution on a cross-section of rice root coated with plaques of iron at two different regions
6.2.4 Spatial mapping of minerals distributions in rice roots
6.2.5 Cr speciation for hotspots of root mature and tip cross-sections using μ-XANES
6.2.6 Release of Cr in the course of reductive dissolution of iron (Ⅲ) precipitates
6.2.7 Carbon isotope results
6.2.8 Distribution mapping of metals and 13C by NanoSIMS
6.3 Discussion
6.3.1 Core findings
Chapter 7 Thesis summary
参考文献
Appendices
致谢
Curriculum Vitae
中国农业科学院;
