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Modern seasonality in Lake Challa (Kenya/Tanzania) and its sedimentary documentation in recent lake sediments

  • From November 2006 to January 2010, a sediment trap that was cleared monthly was deployed in Lake Challa, a deep stratified freshwater lake on the eastern slope of Mt. Kilimanjaro in southern Kenya. Geochemical data from sediment trap samples were compared with a broad range of limnological and meteorological parameters to characterize the effect of single parameters on productivity and sedimentation processes in the crater basin. During the southern hemisphere summer (November-March), when the water temperature is high and the lake is biologically productive (nondiatom algae), calcite predominated in the sediment trap samples. During the "long rain" season (March-May) a small amount of organic matter and lithogenic material caused by rainfall appeared. This was followed by the cool and windy months of the southern hemisphere winter (June-October) when diatoms were the main component, indicating a diatom bloom initiated by improvement of nutrient availability related to upwelling processes. The sediment trap data support theFrom November 2006 to January 2010, a sediment trap that was cleared monthly was deployed in Lake Challa, a deep stratified freshwater lake on the eastern slope of Mt. Kilimanjaro in southern Kenya. Geochemical data from sediment trap samples were compared with a broad range of limnological and meteorological parameters to characterize the effect of single parameters on productivity and sedimentation processes in the crater basin. During the southern hemisphere summer (November-March), when the water temperature is high and the lake is biologically productive (nondiatom algae), calcite predominated in the sediment trap samples. During the "long rain" season (March-May) a small amount of organic matter and lithogenic material caused by rainfall appeared. This was followed by the cool and windy months of the southern hemisphere winter (June-October) when diatoms were the main component, indicating a diatom bloom initiated by improvement of nutrient availability related to upwelling processes. The sediment trap data support the hypothesis that the light-dark lamination couplets, which are abundant in Lake Challa cores, reflect seasonal delivery to the sediments of diatom-rich particulates during the windy months and diatom-poor material during the wet season. However, interannual and spatial variability in upwelling and productivity patterns, as well as El Nino-Southern Oscillation (ENSO)-related rainfall and drought cycles, exert a strong influence on the magnitude and geochemical composition of particle export to the hypolimnion of Lake Challa.show moreshow less

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Metadaten
Author:Christian Wolff, Iris Kristen-Jenny, Georg Schettler, Birgit Plessen, Hanno MeyerORCiDGND, Peter Dulski, Rudolf Naumann, Achim BrauerGND, Dirk Verschuren, Gerald H. Haug
DOI:https://doi.org/10.4319/lo.2014.59.5.1621
ISSN:0024-3590 (print)
ISSN:1939-5590 (online)
Parent Title (English):Limnology and oceanography
Publisher:Wiley
Place of publication:Waco
Document Type:Article
Language:English
Year of first Publication:2014
Year of Completion:2014
Release Date:2017/03/27
Volume:59
Issue:5
Pagenumber:16
First Page:1621
Last Page:1636
Funder:European Science Foundation Collaborative Research (ESF-EUROCORES) program EuroClimate [CRP28-CHALLACEA]; Deutsche Forschungsgemeinschaft (DFG); Leibniz Center for Earth Surface Process and Climate Studies; Kenyan Ministry of Education, Science and Technology (MOEST) [13/001/11C]
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Erd- und Umweltwissenschaften
Peer Review:Referiert