Sediment dynamics in tributaries of the Neuse River estuary, North Carolina / by Katherine J. Marciniak.
| Author/creator | Marciniak, Katherine J. author. |
| Other author | Corbett, D. Reide (David Reide), 1971- degree supervisor. |
| Other author | East Carolina University. Department of Geological Sciences. |
| Format | Theses and dissertations |
| Production | 2008. |
| Description | xvi, 184 leaves : illustrations (some color), color maps ; 29 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | Estuaries along the Atlantic and other coasts are lined with small tributaries which are thought to act as sediment traps and filters for runoff from the surrounding landscape, but better quantification of sedimentation in these areas is needed. The Neuse River Estuary (NRE) is a shallow, micro-tidal estuarine system that has been impacted by development and plagued with symptoms of eutrophication over the past 30 years. Extensive research has been conducted to understand the complex nutrient dynamics, but little information is available on the sediment dynamics of the NRE system, and especially its tributaries. Furthermore, the trapping of sediments may have important implications for the fate of potential pollutants (e.g., trace metals). This study examines several cores collected in two tributaries (Slocum and Hancock Creeks) of the NRE to measure the sedimentation patterns and the trace-metal history. Twelve cores collected from the NRE, Slocum and Hancock creeks were analyzed for radionuclides (210Pb and 137Cs) to evaluate the nature of the material being stored, the site-specific geochronology, and the depositional environment. Metal concentrations were normalized to A1 to account for differences in grain size, organic matter content, and mineralogy for down-core evaluation. Also, these data were normalized by background concentrations (i.e., those from the base of cores) in order to assess the anthropogenic enrichments of the trace metals with time. Grain-size analysis and X- radiography also were used to identify sedimentologcial characteristics and depositional conditions. Sediments accumulating in the creeks are dominantly muds, which are locally well stratified. Sediment accumulation rates ranged from 2.3 to 8.0 mm yr-1 and 2.3 to 3.5 mm yr-1 for Slocum Creek and Hancock Creek, respectively. Sediment budgets constructed for the two tributaries indicate trapping and retention of sediment within the tributaries. Although approximate, the budgets demonstrate that both tributaries are receiving most sediment (~90%) from shoreline erosion. Slocum Creek appears to be storing all of the annually supplied sediment (4600-6300 tonnes), while Hancock Creek stores -1800 tonnes and may export a small amount to the NRE (400 1000 tonnes). The trace-metal concentration and enrichment profiles aid in evaluating the timing of point and non-point-source activities. Largest metal-enrichments (Cr and Cd, particularly) are observed in the upper reaches of Slocum Creek where the inventory of the aluminum- normalized enrichment factor (ANEF1) is over 100, with highest concentrations dated to be from the 1970s. The lowest ANEF1 value of 6.2 is measured in the sandy sediment from the Slocum creek mouth. Greatest metal concentrations in the NRE were associated with recent sedimentation (i.e., last decade). Comparison with an earlier study (Riggs et al., 1991) indicates that sedimentation in Slocum Creek is burying the highest concentrations of trace metals in the sedimentary record. |
| General note | Presented to the faculty of the Department of Geological Sciences. |
| General note | Advisor: D. Reide Corbett |
| Dissertation note | M.S. East Carolina University 2008 |
| Bibliography note | Includes bibliographical references (leaves 108-118). |
| Genre/form | dissertations. |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |