Organic carbon storage within in-channel deposits, Talladega Creek, Alabama

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University of Alabama Libraries

River systems play an important role in carbon cycling and geomorphic processes influence rates of carbon storage and export within fluvial systems. Ecological studies have identified the importance of organic carbon (OC) as a food source for aquatic communities and geomorphological studies have identified floodplains as significant carbon sinks. However, information on in-channel OC storage dynamics is lacking. In this study, in-channel depositional landforms within Talladega Creek, located in the Southern Piedmont region of Alabama, were analyzed for OC content and total organic carbon (TOC) loads were estimated for in-channel sediment storage features and extrapolated to the reach scale. Additionally, relationships between OC storage and particle size were explored using Spearman's Rho tests. TOC loads were compared between two in-channel landform types, benches and bars using Mann Whitney U tests. On average, benches were found to have a higher OC content within sediments, and higher TOC loads than bars; however, large in-channel bars stored significant amounts of OC as well. OC content and clay content within benches were positively correlated, while OC content within bars was positively correlated with silt content. Reach-scale TOC was estimated for in-channel deposits to be 16,867 kgC. Overall TOC for all sampled features (14 in total) had a combined total of 143,310 kgC, with the majority of OC sequestered within bench deposits. Comparisons with floodplain data from other studies suggests that in-channel depositional features may be a significant carbon sink within fluvial systems and their TOC loads should be more explicitly incorporated in carbon budgets and carbon cycle models.

Electronic Thesis or Dissertation
Geography, Geomorphology, Environmental science