Particle export and mixing rates in surface waters of the Gulf of Mexico using ²³⁴TH and ²²²RN / by Matthew C. Allen.
| Author/creator | Allen, Matthew C. author. |
| Other author | Corbett, D. Reide (David Reide), 1971- degree supervisor. |
| Other author | East Carolina University. Department of Geology. |
| Format | Theses and dissertations |
| Production | 2002. |
| Description | vii, 91 leaves : illustrations, maps (some color), charts ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | During April and August of 2001, a combination of natural tracers were used to examine particle scavenging and removal and surface water mixing rates in order to evaluate the potential influence of iron deposition associated with Saharan dust on the production and export of biogenic particles. This study builds on earlier work, which demonstrates a direct correlation between iron deposition, primary production and particle export in some water masses. Stations were occupied during spring and summer in the Gulf of Mexico representative of different water masses to evaluate this potential process: open Gulf, coastal waters, and an isolated oligotrophic water mass. At each station, in situ measurements were taken and water samples were collected at varying depths in the water column, focusing on surface waters and the pycnocline. Water samples were analyzed for dissolved and particulate ²³⁴Th and ²²²Rn activities. These two natural tracers have been used extensively in the past to provide insight into particle residence times and surface water mixing rates. Th-234 {t1/2 = 24.1 days) residence times in the water column provide insight as to the efficiency and rate of particle removal processes, while Rn-222 {t1/2 = 3.85 days) profiles provide insight into the time scale of mixing processes in surface waters. Preliminary data received from investigators at FSU indicate that iron deposition was lowest during our spring cruise. However, higher particle export and mixing rates were observed during the spring in open Gulf and oligotrophic water masses. Surface water mixing estimated using Rn indicates much higher rates during the spring cruise, as high as 1 to 2 orders of magnitude. This increased mixing is attributed to adverse weather conditions (high winds and waves) during the April cruise. The increased mixing that occurred in April may have attributed to higher particle export from surface waters. Elevated fluorescence during that same cruise can be attributed to an increase in primary production relative to the summer cruise. The elevated mixing may have been a mechanism in delivering nutrients to surface waters to stimulate production, thus particle export. Collectively, the data indicates that the three water masses sampled are not iron limited. |
| General note | Presented to the faculty of the Department of Geology. |
| General note | Advisor: D. Reide Corbett |
| Dissertation note | M.S. East Carolina University 2002 |
| Bibliography note | Includes bibliographical references (leaves 72-75). |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |