Date of Award

Spring 5-28-2014

Document Type


Degree Name

Master of Arts (MA)



First Advisor

Holly R. Barnard

Second Advisor

Mark W. Williams

Third Advisor

Diane M. McKnight


Dissolved organic matter (DOM) is a ubiquitous mixture of compounds formed from the degradation of both terrestrial and microbial materials. It is a key link across the terrestrial-aquatic interface in headwater catchments, and therefore is intimately linked with the hydrologic connectivity of the catchment to the stream. This study uses fluorescence spectroscopy and parallel factor analysis (PARAFAC) to evaluate the mobility of specific chemical constituents of DOM during snowmelt. Monitoring occurred on a daily basis within the shallow soil (10 - 25 cm depth) and the stream during snowmelt and was compared to approximately bi-monthly groundwater samples (~18 m depth). Results suggest that a transition occurred in the stream during snowmelt from DOM dominated by protein-like material to more humic-like material. This transition is indicative of an engagement of DOM originating from shallow soils during snowmelt. Dissolved organic carbon (DOC) normalization of these loadings suggest that the peak in DOC concentration seen in the stream is mainly controlled by the non-fluorescent fraction of DOM. This study identifies a humic-like component fluorophore in the soil and the stream that is traditionally seen only in soil DOM. We propose that the presence of this component in our stream samples during high flow in a small headwater catchment but not in larger systems during variable flow, suggests that this humic-like component is preferentially processed within the stream. These results indicate that shifts in hydrologic connectivity of different watershed units to the stream are a major control on DOM export from the watershed and that DOM mobility is unique to its chemical composition.