Organic Matter Method Development

In recent decades examining dissolved organic matter (DOM) via ultrahigh resolution mass spectrometry techniques such as Fourier transform-ion cyclotron mass spectrometry (FT-ICR MS) has grown rapidly as it allows resolution of DOM molecular complexity to the level of elemental composition assignment. Improving and assessing insights into the DOM pool through development of solid phase extraction, ionization, dopant, and fragmentation techniques as part of development of FT-ICR MS for examination of DOM remains a core activity in the lab. Ground-truthing and assessing FT-ICR MS molecular-level data with a suite of organic matter from different sources and anthropogenic impacts via statistical analyses, as well as linking to other geochemical analyses, is fundamental to improving the capacity of such techniques and is a continuous theme of research progress in the lab. An enduring limitation to geochemical studies aiming to link climate or land-use change for example, to DOM flux or reactivity in aquatic systems has been the issue of both temporal and spatial scaling. Within the lab we have directed significant effort toward utilizing optical analyses (e.g. absorbance and fluorescence) as proxies for more intensive and expensive analytical analyses (e.g. FT-ICR MS, molecular-level organic biomarkers). Ongoing work has shown the potential of linking such optical measurements to DOM molecular-level composition and age in a host of aqueous settings from permafrost thaw streams in Siberia, to major river systems such as within the Amazon Basin. Such optical measurements also hold great promise for improving spatial scaling of DOM through linkages to watershed features and via remote sensing applications. Ultimately, the lab works from the molecular-scale to the marco-scale characterizing organic matter via a diversity of analytical techniques.