Dr. Geerd Smidt (PostDoc until 2013)

Dr. Geerd Smidt

I studied biology and soil science at the University of Göttingen and the Free University Berlin in Germany and the University of Warsaw in Poland. Towards the end of my diploma studies, I met Andrea Koschinsky at a workshop on spectroscopic methods in environmental studies. Soon after, I began my PhD studies as part of her workgroup at Jacobs University in Bremen, which was funded through a scholarship provided by the university. 

At Jacobs University Bremen, my research focused on the mobility of fertilizer-derived uranium in arable soils and its contribution to uranium concentrations in groundwater and tap water. Phosphorus mineral fertilizers are found to contain high concentrations of uranium (up to 0.206 mg U kg) and other trace elements, such as cadmium, lead, nickel, copper, zinc, thorium, niobium, strontium, vanadium, and rare earth elements. The content of uranium and other trace elements depends on the sedimentary or igneous origin of the rock phosphate. In my study, the production of phosphorous fertilizers has been shown to contaminate topsoil horizons with uranium and other trace elements in the close vicinity of a factory located in Southern Brazil. In contrast to this point source, agricultural phosphorous fertilization leads to diffuse contamination of the agroecosystem with uranium and other fertilizer-derived trace elements on a large scale. Topsoil horizons of arable land accumulate fertilizer-derived uranium. According to the geochemical behavior of uranium (VI) species under oxidizing conditions, the mobilization capacity for uranium in topsoil horizons is considered to be high, contrary to other fertilizer-derived heavy metals (e.g., cadmium). Hence, it is assumed that uranium can be leached to shallow groundwater and can reach freshwater resources potentially used for drinking water supply. A key objective of my research was therefore to investigate the concentration of uranium and other contaminants in phosphorous fertilizers, identify geochemical processes of fertilizer-derived uranium mobility and mobilization from arable topsoil horizons to the groundwater, and evaluate the origin of uranium in German groundwater and tap water. As part of the project, we also set up a field sampling design for groundwater and soil sampling in cooperation with the Julius-Kühn-Institute in Braunschweig (Germany) and other state authorities in Lower Saxony. 

During my PhD and later in my time as a PostDoc in Andrea Koschinsky’s workgroup, I have developed and taught courses in the Integrated Environmental Studies (IES) program and supervised a number of bachelor theses. Furthermore, I have joined the PROBRAL exchange program with the University of Rio Grande in Brazil. In 2011 we organized the workshop „Better Soils for a better life“ within the German-Brazilian year of science. 

After leaving Jacobs University, I have worked as a project manager in science management and corporate social responsibility management in medium-sized businesses and public services with a focus on greenhouse gas emissions and the management of peatland. Since 2017, I am a project manager for agricultural field management at the Niedersächsische Landgesellschaft.