Hi! I’m Jess Smith and I worked in Dr. Jim McClelland’s lab this summer. Here’s a snippet of my abstract:
Dissolved organic matter (DOM) is a little explored field in Texas rivers, which can be described in part by dissolved organic carbon (DOC) and colored DOM (CDOM). The degradation of river water by light and microbial sources can indicate the fate of the matter in the estuary. Three rivers were sampled for this experiment: the Nueces, the San Antonio, and the Guadalupe. There were three methods of analysis were utilized in this experiment: directly measuring the DOC content for an estimate of quantity of DOM, utilizing the CDOM absorbance scan between 275 and 295nm for spectral slope which is an indication of molecular weight, and finally using the DOC content and absorbance at 254 nm for SUVA (a measure of aromaticity). The larger the molecular weight, the more difficult it is for microbial sources to break down the matter. Similarly, the more aromatic the matter, the more difficult it is to break down. The Nueces watershed contains a lake creating autochthonous DOC, easier to break down and less aromatic, while the Guadalupe watershed contains more allochthonous DOC which is recalcitrant and aromatic. The San Antonio follows the Nueces’ pattern in the DOC and S275-295 results, while acting more like the Guadalupe in the SUVA results, having anthropogenic DOC sources that act differently feeding into its watershed. These three rivers along the Texas coast show that, under normal conditions, DOM lability and quality varies greatly, owing to the diverse characteristics of the watersheds.
This has been a great summer, and much different than staying in Pennsylvania or Connecticut. There’s always a lovely breeze and the beach is so close. I’ve grown close to everyone here, and will miss hanging out in the perpetually sunny Southern Texas!