Award Date

1-1-2004

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

First Committee Member

Spencer M. Steinberg

Number of Pages

60

Abstract

Lignin distribution in sediment is a useful tool for tracing the transport of land derived organic matter in an aquatic environment. Tetramethylammonium hydroxide (TMAH) thermochemolysis at sub-pyrolysis temperatures of 300°C followed by GC-MS analysis showed a great promise in being able to semi quantitatively assess the nature of organic carbon in sediments. TMAH chemopyrolysis produces methylated syringyl (S), vanillyl (V), and cinnamyl (C) phenols from lignin, these methylated phenols are an indirect measure of lignin in sediment. The concentration of lignin phenols is indicative of the contribution of terrestrial runoff to lake sediments because lignin is exclusively a product of land plants. The S/V ratio is a powerful tool to trace the terrestrial origin of organic matter in sediment; Two chemolysis methods (on-line and off-line) were examined and compared. Organic carbon and lignin in several cores from Lake Mead were investigated. The results from sediment cores indicate significant variations in the sources of sedimentary materials. The concentration of organic carbon and the composition and amount of lignin provides an interpretable record of historical changes.

Keywords

Carbon; Lake; Lignin; Mead; Measurement; Organic; Sediment

Controlled Subject

Chemistry, Analytic; Soil science

File Format

pdf

File Size

1658.88 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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