Myrna Simpson

My research in environmental and analytical chemistry involves the development and application of molecular-level analytical tools to improve the fundamental understanding of soil environmental processes. My group uses advanced mass spectrometry (MS) and nuclear magnetic resonance (NMR) methods to characterize, monitor and predict the fate of soil organic matter components in various environments. Soil organic matter is responsible for all life on this planet but its chemistry is poorly understood. Furthermore, soil organic matter plays an important role in the regulation of atmospheric CO₂ and other greenhouse gases. Therefore, we are studying soil organic matter turnover in extreme environments (such as the Arctic and Antarctic) as well as under enhanced warming (ie: climate change). By understanding the fundamental chemistry of soil organic matter, we will be able to better predict its role in the biogeochemical cycling of carbon and nitrogen in a changing world.

We are also studying the sorption of problematic organic contaminants to soils. Sorption often hinders the bioavailability and remediation of contaminants in the environment. Soil organic matter is a major sink for environmental contaminants and the mechanisms of contaminant sorption to organic matter are poorly understood. We study these processes by combining conventional methods (equilibrium sorption and isotherm modeling) with NMR characterization of organic matter. By applying NMR, we have identified mobile organic matter domains that have a large capacity to sequester contaminants. Furthermore, using a special NMR technique (High resolution magic angle spinning NMR), we are able to examine organic matter at the solid-liquid interface. These experiments have also revealed that aliphatic structures, such as those from plant cuticles, predominate at the surface. Aromatic structures, which are visible in 1-D NMR experiments, appear to be buried and not at the surface of soil colloids.

My group is also developing NMR-based metabolomics for studying the sub-lethal toxicity of problematic environmental pollutants in soil. Metabolomics is a rapidly growing field which allows the monitoring of an organisms’ response to an external stressor. Metabolomics is rapid, quantitative and reproducible making it a promising method for improved site assessment. We are currently using metabolomics to identify earthworm responses to environmental pollutants using ¹H NMR. Earthworms are a model organism used in ecotoxicity. Our results to date suggest that NMR-based metabolomics is more sensitive to current methods used to assess toxicity of contaminants in the environment.