Molecular and isotopic records of the combustion inputs to the environment over the last 250 yrs
Name
57561892-MIT.pdf
Description
Full printable version
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17.27 MB
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Checksum (MD5)
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Author(s)
Lima, Ana Lúcia Cessel de, 1969-
Advisor(s)
Timothy I. Eglinton and Christopher M. Reddy.
Date Issued
2004
Publisher
Massachusetts Institute of Technology
Abstract
The most ubiquitous source of polycyclic aromatic hydrocarbons (PAHs) to the environment is incomplete combustion. This study generated a high-resolution historical record of pyrogenic PAH emissions since pre-industrial times from anoxic aquatic sediments, allowing for detailed comparison with energy consumption data. We show that an increase in PAH concentrations over the last decade may be due to a rise in emissions from diesel-powered vehicles. Compound-specific radiocarbon measurements demonstrated unequivocally that the proportion of PAHs derived from fossil fuel combustion has increased substantially during the 20th century. [delta]¹³C and [delta]¹⁴C measurements were also used to constrain the relative importance of combustion versus in situ production as sources of perylene. In addition, a comparison of the down-core concentration and isotopic profiles of black carbon (BC) generated by a combination of chemical and/or thermal oxidation methods highlighted the limitations of these methods when applied to sedimentary matrices. Finally, parallel lead and cesium isotopic records revealed two new potential stratigraphic markers in North American sedimentary records. ²⁰⁶Pb/²⁰⁷Pb profiles show a distinct peak in the mid-19th century, while a ¹³⁷Cs peak was found to coincide with the 1986 Chernobyl accident.
Description
Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and, the Woods Hole Oceanographic Institution), 2004.
Includes bibliographical references.
Subjects
Joint Program in Oceanography.
Earth, Atmospheric, and Planetary Sciences.
Woods Hole Oceanographic Institution.
MIT Department
Joint Program in Oceanography
Woods Hole Oceanographic Institution
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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