Molecular and isotopic fingerprinting of aliphatic hydrocarbons in Conception Bay, Newfoundland
The distributions and isotopic compositions of the aliphatic hydrocarbons of plankton, sediments and biota of a typical northern fjord (Conception Bay, Newfoundland) were studied by standard gas chromatography-mass spectrometry (GC-MS), and by the novel technique of compound-specific isotope ratio m...
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| Format: | Thesis |
| Language: | English |
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Memorial University of Newfoundland
1992
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| Online Access: | https://research.library.mun.ca/6871/ https://research.library.mun.ca/6871/1/TilmanBieger.pdf https://research.library.mun.ca/6871/3/TilmanBieger.pdf |
| Summary: | The distributions and isotopic compositions of the aliphatic hydrocarbons of plankton, sediments and biota of a typical northern fjord (Conception Bay, Newfoundland) were studied by standard gas chromatography-mass spectrometry (GC-MS), and by the novel technique of compound-specific isotope ratio mass spectrometry (IRMS). Sediments contained compounds of terrestrial, marine biogenic, and bacterial origins, with petroleum appearing to contribute primarily an unresolved complex mixture (UCM), occasional pristane and phytane, and typical trace cyclic terpenoids. A suite of eight C₂₅ highly branched isoprenoid alkenes containing 3 to 5 degrees of unsaturation was the dominant feature in plankton, sediments, and some benthic biota in Conception Bay, as well as in samples from other coastal and offshore areas around Newfoundland. Although attempts to isolate the source of these compounds by culturing common local diatom species were unsuccessful, the molecular distribution and isotopic signature of these alkenes suggest that these hydrocarbons are synthesized by one particular organism during the spring bloom. Measurement of the δ¹³C (or carbon isotopic composition) of individual compounds proved to be a useful tool in recognizing the input of different sources of compounds to sedimentary organic matter pools. For example, variations in the isotopic compositions of even chain-length n-alkanes in sediments suggest the input of at least three main sources of n-alkanes (terrestrial leaf debris, marine algae, and a third source, proposed to be marine bacteria). The δ¹³C of biogenic hydrocarbons appeared to be relatively unchanged during early degradation in the water column and surface sediments. Although the existence of kinetic isotope fractionation during biosynthesis was indicated by co-variations in the distribution and isotopic signature of algal products in cultures, biochemical isotope effects generally appeared to be masked in the complex environmental samples analyzed. Compounds from distinct sources were ... |
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