声明
Acknowledgements
CONTENTS
LIST OF TABLES
LIST OF FIGURES
ABSTRACT
摘要
CHAPTER 1 General Introduction and Review of Literature
1.1 Heavy metals in the environment
1.2 Bioavailability of heavy metals in the soil
1.3 Uptake of heavy metals by food crops
1.4 Health risks related to heavy metals
1.5 Environmental quality standards for soils
1.6 Heavy metals and soil microbial community
1.7 Objectives of the study
CHAPTER 2 Cadmium Phytoavailability to Rice (Oryza sativa L.) Grown in Representative Chinese Soils.A Model to Improve Soil Environmental Quality Guidelines for Food Safety
2.1 Introduction
2.2 Materials and methods
2.2.1 Soil collection and analysis
2.2.2 Cd spiking
2.2.3 Green house experiment
2.2.4 Soil and rice grain analysis
2.2.5 Statistical analysis
2.3 Results and discussion
2.3.1 Charaeteristics of soils
2.3.2 Mehlich-3-extractable Cd in soils after aging of 6 months
2.3.3 Biomass yield of rice
2.3.4 Accumulation of Cd in polished rice grain
2.3.5 Relationship between Mehlich-3-extractable Cd in soils and grain Cd content
2.3.6 Multiple regression model for predicting cadmium phytoavailability to polished rice
2.3.7 Soil Cd thresholds for potential dietary toxicity in rice
CHAPTER 3 Phytoavailability of Cadmium (Cd) to Pak Choi (Brassica chinensis L.) Grown in Chinese Soils:A Model to Evaluate the Impact of Soil Cd Pollution on Potential Dietary Toxicity
3.1 Introduction
3.2 Materials and methods
3.2.1 Ethies statement
3.2.2 Soil collection and analysis
3.2.3 Cadmium spiking and aging
3.2.4 Containerized experiment
3.2.5 Plant sample collection
3.2.6 Total Cd of soil and plant
3.2.7 Mehlich-3-extractable Cd in soils
3.2.8 Quality control for Cd analysis
3.2.9 Derivation soil Cd thresholds for potential dietary toxicity in Pak choi
3.2.10.Statistical analysis
3.3 Results
3.3.1 Charaeteristies of soils
3.3.2 Mehlich-3-extractable Cd in soils after aging of 1 year
3.3.3 Biomass yield of Pak choi
3.3.4 Accumulation and distribution of cadmium in Pak choi
3.3.5 Relationship between Mehlich-3-extractable Cd in soils and Pak choi Cd content
3.3.6 Soil Cd thresholds for potential dietary toxicity in Pak choi
3.4 Discussion
3.4.1 Biomass yield of Pak choi
3.4.2 Accumulation and distribution of cadmium in Pak choi
3.4.3 Relationship between Mehlich-3-extractable Cd in soils and Pak choi Cd content
3.4.4 Soil Cd thresholds for potential dietary toxicity in Pak choi
3.4.5 Stepwise regression model for predicting cd phytoavailability to Pak choi
CHAPTER 4 Lead Phytoavailability to Rice (Oryza sativa L.) Grown in Representative Chinese Soils.A Model to Improve Soil Environmental Quality Standards for Food Safety
4.1.Introduction
4.2 Materials and methods
4.2.1 Soil collection and analysis
4.2.2 Lead spiking
4.2.3 Containerized experiment
4.2.4 Soil and rice Pb analysis
4.2.5 Extraetable Pb in soils
4.2.6 Statistical analysis
4.3 Resuits
4.3.1 Mehlich-3-extractable Pb in soils after aging of 6 months
4.3.2 Accumulation and distribution of lead in rice
4.3.3 Biomass yield of rice
4.3.4 Correlation between Pb concentration in rice and different forms of Soil Pb
4.3.5 Soil Pb thresholds for potential dietary toxicity in rice
4.3.6 Stepwise regression model for predicting Pb phytoavailability to rice
4.4 Discussion
CHAPTER 5 Lead Phytoavailability to Pak Choi (Brassica chinensis L.) Grown on Representative Chinese Soils:A Model for Assessment of Soil and Food Safety
5.1 Introduction
5.2 Materials and methods
5.2.1 Soil collection and analysis
5.2.2 Lead spiking
5.2.3 Pot experiment
5.2.4 Soil and plant Pb analysis
5.2.5 Extractable Pb in soils
5.2.6 Statistical analysis
5.3 Resuits
5.3.1 Mchlich-3-extractable Pb in soils after aging of 1 year
5.3.2 Distribution of Pb in Pak choi
5.3.3 Biomass yield of Pak choi shoots
5.3.4 Correlation between Pb contents in the edible Pak choi shoots and different forms of Pb in various soils
5.3.5 Soil Pb thresholds for potential dietary toxicity in Pak choi shoots
5.3.6 Stepwise Regression Model for Predicting Pb Phytoavailability to Pak choi
5.4 Discussion
CHAPTER 6 Changes in Microbial Biomass and Community Structure due to Cd and Pb Contamination in Acid and Alkaline Soils Growing Rice
6.1 Introduction
6.2 Material and methods
6.2.1 Soil collection and analysis
6.2.2 Soil spiking
6.2.3 Pot experiment
6.2.4 Microbial biomass carbon(MBC)
6.2.5 PLFA extraction
6.2.6 Dehydrogenase activity
6.2.7 Statistical analysis
6.3 Results
6.3.1 Effect of Cd and Pb on microbial biomass carbon(MBO
6.3.2 The microbial community pattern in soils with different Cd and Pb loading rates
6.3.3 Dehydrogenase activity
6.4 Discussion
CHAPTER 7 Major Findings and Future Perspectives
7.1 Major findings
7.2 Future perspectives
References
List of Publications