HR: 1340h
AN: H43C-1511    [Abstracts]
TI: Autochthonous dissolved organic matter in karst waters: Evidence from fluorescence spectroscopy
AU: * Birdwell, J E
EM: jbirdw1@lsu.edu
AF: Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA 70803, United States
AU: Schulz, C J
EM: cschulz777@gmail.com
AF: Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803, United States
AU: Engel, A S
EM: aengel@lsu.edu
AF: Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803, United States
AB: Fluorescence spectroscopy provides a rapid, sensitive tool for probing the nature of dissolved organic matter (DOM) without the need for isolation or concentration of the material. This makes it particularly useful for examining waters from environments where collection of large volumes of water is impractical and for large-scale surveying of waters from many sites within a single hydrogeological system. In this study, excitation-emission matrices were collected on waters collected from the Edwards Aquifer (central Texas), Frasassi Caves (Italy), Lower Kane Cave (Wyoming), and other karst sites. The spectral characteristics from the subsurface systems were unlike those observed for surface waters or soil-derived humic substances. Analysis of the data using several different methods suggests that the DOM from these sites is derived primarily from microbial sources with little, if any, terrestrial material present. Because few studies have been conducted with significant microbial contributions to DOM, especially in the absence of allochthonous input, our results provide a unique collection of DOM signatures constrained and controlled by microbial influences. Moreover, our work provides important information about carbon sources and cycling in karst ecosystems.
DE: 0409 Bioavailability: chemical speciation and complexation
DE: 0428 Carbon cycling (4806)
DE: 0448 Geomicrobiology
DE: 0496 Water quality
DE: 1831 Groundwater quality
SC: Hydrology [H]
MN: 2007 Fall Meeting