Speciation of trace metals and their uptake by rice in paddy soils

Rice (Oryza sativa L.) is the most important staple food in South and Southeast Asia and plays a crucial role in food security. However, with fast urbanization and industrialization and economic growth in these parts of the world, the production and quality of rice has become an increasing concern, because contamination of paddy soils with trace metals in industrialized areas can lead to yield reduction of rice, a decline in the nutritional quality of the rice, and an accumulation of trace metals in rice grains. In this PhD thesis, I used a combination of experimental research and mechanistic modeling to investigate the solubility of trace metals in paddy soils exposed to alternating flooding and drainage conditions and to link trace metal solubility to the uptake by rice plants over time. This work contributes to the understanding of how redox chemistry affects the solubility of trace metals in flooded soil and sediment systems and provides a tool for the measurement of the free trace metal concentrations in flooded soil and sediment systems in situ in the form of the field DMT.