Kraemer Group research

ENVIRONMENTAL BIOGEOCHEMISTRY

Environmental biogeochemistry is an exciting field of research that studies how biotic (organisms) and abiotic constituents (soil, minerals and natural organic material) of the environment interact chemically. These interactions control key processes in the environment such as the mobilisation, transformation or stabilisation of pollutant, mineral weathering and solute acquisition of natural waters and global element cycling. Organisms interact chemically with their surroundings for multiple reasons including the acquisition of nutrients, the generation of energy for metabolic processes and protection against toxins. The nature of the chemistry involved is often complex and diverse, including redox processes, acid base chemistry, dissolution and precipitation processes and complexation reactions. Our group research focuses on clearing up the chemical mechanisms employed by biota on a molecular scale and on quantitatively understanding them.

We do this via field studies and in controlled laboratory experiments, employing various analytical techniques. We investigate the reactivity of biogenic chemical compounds in model systems but we also involve microbial cultures and plants as well as complex soil systems and sediments. Examples are the use of non-traditional isotope geochemistry to complex biogeochemical Hg cycling in contaminated field systems, the investigation of tetravalent uranium (re-)mobilization involving biogenic organic ligands after bioremediation, or the study of phosphorous recycling in agricultural systems. The results of these and other studies are used to construct quantitative thermodynamic and kinetic models that may serve to predict the effect of biogeochemical processes in complex environments.

MINERVA: MINERALOGICAL PRESERVATION OF ANCIENT DNA

While minerals play an important role as electron donors and acceptors in metabolism or as a source of nutrient, they are also interacting with DNA and are therefore agents of information preservation or transmission. For example, ancient human DNA has recently been exracted from sediments. The extraction and sequencing of hundreds of thousand year old ancient DNA has revolutionized the understanding of our human heritage, the movement of our early ancestors, our genetic relationship to extinct groups of ancient humans, and the evolution of human pathogens. From the geochemical perspective, the preservation of DNA recording the full genome of our ancestors over such long timescales poses challenging scientific questions about the geochemical and mineralogical environments that lead to an efficient protection of DNA. We are founding members of the MINERVA research platform at the University of Vienna, where we assembled an interdisciplinary team of evolutionary anthropologists, geochemists, computational biologists and archaeologists in order to elucidate mechanisms of DNA preservation by minerals.