Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2005. / Includes bibliographical references (p. 229-238). / The fate of trace metals in contaminated coastal sediments is poorly understood, yet critical for effective coastal management. The aim of this thesis is to investigate and quantify the mechanisms leading to the release of silver, lead and copper across the sediment-water interface. Two contrasting sites were investigated, a heavily contaminated site in Boston Harbor and a less impacted, offshore site in Massachusetts Bay. High-resolution porewater and solid phase samples were collected in each season to determine the diagenetic cycles and chemistry controlling the fate of these metals. The trace metals are scavenged by iron oxyhydroxides and released to the porewaters when these oxides are reduced. At the strongly reducing site in Boston Harbor, there is seasonal transfer of trace metals from oxide phases in winter, to sulfides phase in summer. At the Massachusetts Bay site, due to the lack of sulfide, the metals are focused into the surface oxide layer, giving a solid phase enrichment. There is a diffusive flux of copper to the water column throughout the year, while silver is released only in winter. Lead is strongly scavenged and is rarely released to the overlying waters. / (cont.) Analysis of reduced sulfur compounds in the porewaters has shown that there is also a significant flux of these strong ligands to the overlying waters. Polysulfide species enhance the solubility of copper within the porewaters. Sediment resuspension fluxes were quantified using an erosion chamber. Sediment resuspension leads to enhanced release of dissolved metals and is especially important in redistributing contaminants as the first particles to be eroded are enriched in trace metals. The total release of dissolved metals from the sediments by diffusion and sediment resuspension is estimated to be 60% and 10% of the riverine flux for copper and lead respectively. With continued pollution control reducing the discharge of metals from other sources, the benthic release of metals will become increasingly important terms in the metal budget of Boston Harbor. / by Linda H. Kalnejais. / Ph.D.
| Identifer | oai:union.ndltd.org:MIT/oai:dspace.mit.edu:1721.1/33828 |
| Date | January 2005 |
| Creators | Kalnejais, Linda H |
| Contributors | William R. Martin and Roger Francois., Woods Hole Oceanographic Institution., Joint Program in Oceanography, Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences., Woods Hole Oceanographic Institution., Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| Publisher | Massachusetts Institute of Technology |
| Source Sets | M.I.T. Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 238 p., application/pdf |
| Coverage | n-us-ma |
| Rights | M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission., http://dspace.mit.edu/handle/1721.1/33828, http://dspace.mit.edu/handle/1721.1/7582 |
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