Sediment Organic Carbon Fate and Transport in a Fluviokarst Watershed in the Bluegrass Region

Document Type

Dissertation

Publication Title

MS Thesis, Department of Civil Engineering, College of Engineering, University of Kentucky

Abstract

Mature karst topography is well recognized within the hydrology and geology communities to include subterranean fluid pathways that act as turbulent conduits conveying fluid from surface stream sinks called swallets to sources called springs. However, we find that little knowledge has been reported with regards to the transport and fate of terrestrially-derived sediment organic carbon (SOC) within karst watersheds. This study investigated the hypothesis that karst pathways could act as biologically active conveyors of SOC that temporarily store sediment, turnover carbon at higher rates than otherwise considered, and recharge depleted SOC back to the surface stream within the fluvial system. Mixed research methods were applied within a mature karst network. Methods included high resolution measurements of water and sediment characteristics of surface streams, carbon and stable carbon isotope measurements of transported sediment, and numerical modeling of water and sediment pathways. The mixing of sediment during net zero deposition and erosion was investigated in this study using a parameter calibrated to SOC data. Results of this study showed that heterotrophic bacteria in the subsurface conduit oxidized 0.05 tCkm-2y-1 resulting from the temporary storage of terrestrial carbon in the karst conduit. The subsurface conduit transports 0.15 tCkm-2y-1 out of the fluviokarst watershed.

Publication Date

2015

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