Submarine groundwater discharge and recirculated seawater may provide important chemical constituents to the ocean, but the dispersed nature of this process makes locating and quantifying its input difficult. Two approaches were taken to evaluate subsurface fluid discharge into an area of the northeastern Gulf of Mexico: (1) direct measurements of seepage; and (2) use of naturally-occurring $\sp{222}$Rn as a tracer of this flow. / The response of seepage meters to water motion effects was evaluated in the nearshore study area through time-series experiments using empty and 1000-mL prefilled collection bags. It was confirmed that prefilling the plastic bags effectively alleviated an anomalous, short-term influx. Control experiments demonstrated that water motion did not cause artifacts in seepage measurements. Temporal and spatial variations in seepage fluxes were found along an 7-km stretch of coastline in this study area. Tidal cycle influences on seepage rates were negligible, but long-term temporal variations in seepage proved substantial. / Concentrations of $\sp{222}$Rn in groundwater are 3 to 4 orders of magnitude higher than seawater. Integrated concentrations in the nearshore waters overlying a seepage meter transect showed a significant positive relationship to direct seepage measurements. These waters receive only a small contribution of $\sp{222}$Rn by diffusion based on flux measurements. Radon inventories in these shallow waters are consistent with the input of radon-bearing groundwaters and suggest that $\sp{222}$Rn is an excellent tracer of this process. / Factors influencing the concentration of radon in the inner continental shelf waters (i.e., production-decay, horizontal transport, and benthic advection and diffusion) were evaluated using a linked benthic exchange-horizontal transport model. Simulations of $\sp{222}$Rn activities in a water mass moving across the seafloor demonstrate that inventories are relatively insensitive to horizontal flow, at least when a strong pycnocline is present and net current velocities are slow. The regional subsurface fluid flow into the 620-km$\sp2$ study area is estimated to be 180 to 710 $\rm m\sp3\cdot sec\sp{-1}$, equivalent to at least 50 first magnitude springs. / Source: Dissertation Abstracts International, Volume: 57-04, Section: B, page: 2444. / Major Professor: William C. Burnett. / Thesis (Ph.D.)--The Florida State University, 1996.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_77723 |
| Contributors | Young, Jaye Ellen., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 286 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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