dc.contributor.author | Street-Perrott, F.A | |
dc.contributor.author | Perrott, R.A | |
dc.contributor.author | Swain, D.L | |
dc.contributor.author | Olago, D.O | |
dc.contributor.author | Eglinton, G | |
dc.contributor.author | Ficken, K.J | |
dc.date.accessioned | 2013-05-30T05:54:52Z | |
dc.date.available | 2013-05-30T05:54:52Z | |
dc.date.issued | 1998 | |
dc.identifier.citation | Organic Geochemistry Volume 29, Issues 5–7, November 1998, Pages 1701–1719 | en |
dc.identifier.uri | http://www.sciencedirect.com/science/article/pii/S0146638098001090 | |
dc.identifier.uri | http://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/27237 | |
dc.description.abstract | The lipid content (n-alkanes, n-alkanols, n-alkanoic acids) and the δ13C values of these lipids were measured in nineteen sediment samples taken from a 21.18 m long core from Lake Nkunga, a high-altitude (1820 m a.s.l.), freshwater lake situated in the montane rain forest on Mt. Kenya. The record spans the early last glacial (marine isotope stages 5a to 4) and the late Holocene (1030±45 14C yr BP to the present day). The intervening hiatus spans the last glacial maximum and the early to mid-Holocene. The molecular biogeochemical results are interpreted in terms of past changes in climate, vegetation and atmospheric CO2 concentration. Three different sources of organic matter input were identified from the n-alkyl lipids, namely terrestrial plants, aquatic plants and algae. Unusual distribution patterns of dominant mid-chain length n-alkanes (C23–25), n-alkanols (C22–24) and n-alkanoic acids (C22–24) are attributed to aquatic macrophytes. An 11‰ decrease in bulk-carbon isotope values between the sediments of early glacial (−17‰) and late Holocene age (−28‰) is also apparent in the individual homologues of the n-alkyl lipids. The observed isotopic shift in terrestrial higher-plant biomarkers is similar to that observed in nearby Sacred Lake and is consistent with an expansion of C4 grasses or sedges during the early glacial. The corresponding vegetation was a dry montane juniper–olive forest with a grassy understorey, representing cold, dry conditions with lower CO2. | en |
dc.language.iso | en | en |
dc.title | Glacial/interglacial variations in carbon cycling revealed by molecular and isotope stratigraphy of Lake Nkunga, Mt. Kenya, East Africa. Organic Geochemist | en |
dc.type | Article | en |