Overview
Our environmental geochemistry group is consisting at present of two research fellows and four post graduate students.
Our research themes are:
1. Micronutrient cycling and uptake
2. Aqueous chemistry of metalloids and actinides
3. Global biogeochemical cycles
The Research Themes
1. Micronutrients Cycling and Uptake
The deficiency of micronutrients in crops is one of the major health threats in developing countries. Breeding and crop management are key tools to address this problem. However, to optimize both, a thorough understanding of how micronutrients get into the soil solution and become plant available is needed. We study this problem at several levels. First, we try to understand the role of siderophores and the relevant bioinorganic chemistry of metal-S complexes. We have recently been able to synthesize mugenic acid, the phytosiderophore of importance in rice, and are now studying structural and reactivity details. Second, we are developing the potential of stable isotopes to constrain mechanisms of uptake and translocation in situ. To this end, we are developing models of isotope fractionation and test various individual geochemical processes. Third, we constrain the dynamics of micronutrient release and uptake into rice during flooding of paddy soils. This includes spiked isotope experiments conducted on the International Rice Research Institute in Los Banos (Philippines)
2. Aqueous Chemistry of Metalloids and Actinides
Sustaining clean water resources at low environmental costs is a major challenge to our future society. Concentrated efforts are under way on a global scale to develop low cost and energy efficient technologies that remove major organic and inorganic pollutants from contaminated waters. To this end, we are focusing on the development of mixed metal oxides and of organic based templates for the removal of oxyanion pollutants, in particular arsenic, antimony and radionuclides and on understanding molecular scale processes. We have recently synthesized an organic sorbent that improves the removal for arsenic for a factor of ten compared to conventional commercially used iron oxides. We also have successfully characterized the sorption behavior of arsenic and antimony on mixed iron and titanium oxides and possible interactions
3. Biogeochemical cycles
The atmospheric transport of trace elements and dust is a fundamental process in the Earth System and a key driver of climate and environmental change. Our objective is to constrain what controls atmospheric metal and dust cycles on global and molecular scales with the aim to improve atmospheric models and to understand effects on climate change and air quality. We are addressing in particular the following questions: (i) how has the global dust flux changed during the last glaciation in the Southern Hemisphere, what controlled it and what were the effects of the carbon cycle; (ii) what is the effects of emerging economies such as Brazil, China on global metal cycles, toxic and nutrient metals alike; and (iii) how does air pollution affect the solubility of trace elements from the solid phase and what are the physical chemical controls (kinetic, thermodynamic). Most recently, we were able to calibrate the regional atmospheric climate model REMOTE using experimentally determined atmospheric dust fluxes for Central Asia from a peat core and we demonstrated the potential of metals as novel source tracers for industrial pollution