In moist soils, short-range ordered minerals such as iron oxyhydroxides are strong predictors of carbon storage. Therefore, understanding the interactions between organic carbon and iron under various conditions is key to accurate carbon modeling and comprehensive knowledge of nutrient cycling. We have evaluated the impacts of temperature, hydrology, and redox conditions on carbon storage, organo-metal complexation, and iron bioavailability. Investigating these systems involves multiple approaches, including sample collection in mountain wetlands, chromatography and batch experiments in the laboratory, and a host of analytical techniques such as synchrotron-based X-ray absorption spectroscopy, high resolution mass spectrometry, ion chromatography, nuclear magnetic resonance (NMR) spectroscopy, and UV-vis spectroscopy.

Soil organic matter (SOM) is a source of nutrients for microorganisms and plants, and it acts as a binding, stabilizing material that improves water penetration and prevents erosion. It is a major carbon repository, and therefore a major actor in the carbon cycle. Accordingly, the study of SOM formation processes, composition, and degradation is of paramount importance for soil health management as well as for understanding Earth’s carbon cycle, a prerequisite for addressing climate change. It is now known that the remains of dead soil microbes are the main starting material from which SOM is formed. However, how these remains are generated has not been explored deeply. We hypothesize that predatory interactions between microbes are central to necromass production, and thus to carbon sequestering in soil. We will qualitatively and quantitatively measure the contribution of micro-predators to necromass production and its transformation over time under ecological regimes of increasing community complexity. The study will also address the effect of major stressors imposed on soils by human activities like sub-inhibitory concentrations of antibiotics and increased temperatures.