State Water Resources Research Institute Program

Project ID: 2007MT147B
Title: Identifying and characterizing sources of dissolved organic carbon in the Big Hole and Clark Fork Rivers, a continued investigation
Project Type: Research
Start Date: 3/01/2007
End Date: 2/28/2008
Congressional District: at large
Focus Categories: Geochemical Processes, Hydrogeochemistry, Water Quality
Keywords: Dissolved organic carbon, dissolved inorganic carbon, carbon isotopes, diel, biogeochemistry
Principal Investigators: Parker, Stephen; Cameron, Douglas
Federal Funds: $ 8,586
Non-Federal Matching Funds: $ 17,177
Abstract: Recent work has identified daily concentration cycles in dissolved organic (DOC) and inorganic carbon (DIC) in the Clark Fork (CFR) and Big Hole (BHR) Rivers in Montana . The DOC in the two rivers showed inverse temporal patterns suggesting that very different mechanisms control the processes in these two rivers. Preliminary study using an isolation chamber on the BHR suggested that the large nighttime increase in DOC observed may have been due to groundwater influx through benthic sediments associated with the daily evapotranspiration cycle. The stable C-isotope composition of the DIC was also investigated. The δ13C-DIC in both the CFR and BHR showed the patterns expected for DIC that is influenced primarily by photosynthesis and respiration. This proposal outlines work to further test the reproducibility of the observed diel cycles in DIC and DOC. Also, the work described will help define the sources and causes of these daily DOC changes using additional laboratory and field experiments. Furthermore, the project will attempt to identify the types and molecular-weight distributions of organic compounds that make-up the DOC using Liquid Chromatography-Mass Spectrometry (LC-MS) analysis.

Progress/Completion Report, PDF

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