Characterization of water chemistry in the presence of Didymosphenia geminata in boulder creek

This study explores water chemistry associated with the growth of Didymosphenia geminata. This diatom, once believed to be native to cool, oligotrophic waters in North America and Europe, has demonstrated nuisance behavior beyond this range over the last decade. From May through August 2008, one-liter whole water samples were collected weekly at four hydraulically variable sites along Boulder Creek in Colorado, USA. Additionally, periphyton samples, analyzed for their D. geminata content, and other water nutrient samples were collected weekly. Chromatographic separation of the whole water samples was completed to isolate the hydrophobic organic acid components, primarily fulvic acid. Once separated, these fractions were analyzed for dissolved organic carbon (DOC) concentration. Further, the characterization process involved collecting excitation emission matrixes (EEMs) for the dissolved organic matter (DOM) fractions, modeling with parallel factor analysis (PARAFAC), and identifying the quinone-like fluorophores. The Fluorescence Index (FI) and Specific UV absorbance (SUVA²⁵⁴), were calculated to understand the source, either terrestrial or microbial, and the aromaticity of the DOM. Cumulatively, these results will be used to gain an understanding of the relationship between water chemistry and varying presence of D. geminata.