TY  - JOUR
A1  - Wolff, Christian Michael
A1  - Kristen-Jenny, Iris
A1  - Schettler, Georg
A1  - Plessen, Birgit
A1  - Meyer, Hanno
A1  - Dulski, Peter
A1  - Naumann, Rudolf
A1  - Brauer, Achim
A1  - Verschuren, Dirk
A1  - Haug, Gerald H.
T1  - Modern seasonality in Lake Challa (Kenya/Tanzania) and its sedimentary documentation in recent lake sediments
JF  - Limnology and oceanography
N2  - 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 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.
Y1  - 2014
U6  - https://doi.org/10.4319/lo.2014.59.5.1621
SN  - 0024-3590
SN  - 1939-5590
VL  - 59
IS  - 5
SP  - 1621
EP  - 1636
PB  - Wiley
CY  - Waco
ER  - 
TY  - JOUR
A1  - Mishrat, Praveen K.
A1  - Anoop, A.
A1  - Jehangir, A.
A1  - Prasad, Sushma
A1  - Menze, R.
A1  - Schettler, Georg
A1  - Naumann, R.
A1  - Weise, S.
A1  - Andersen, N.
A1  - Yousuf, A. R.
A1  - Gaye, Birgit
T1  - Limnology and modern sedimentation patterns in high altitude Tso Moriri Lake, NW Himalaya - implications for proxy development
JF  - Fundamental and applied limnology : official journal of the International Association of Theoretical and Applied Limnology
N2  - We report the results of our investigations on the catchment area, lake surface sediments, and hydrology of the high altitude alpine Tso Moriri Lake, NW Himalayas (India). Our results indicate that the lake is currently alkaline, and thermally stratified with an oxic bottom layer. Results from hydrochemistry and isotopic composition (delta O-18 and delta D) of inflowing streams and lake waters show that Tso Moriri Lake is an evaporative lake with contributions from both westerly source (snow melt) and Indian summer monsoon precipitation. Geochemical and mineralogical investigations on the catchment and lake surface sediments reveal the presence of authigenic aragonite in modern lake sediment. The lithogenic components reflect the inflow and sorting processes during transport into the lake, whereas the authigenic carbonate fraction can be linked to the changes in ([precipitation+meltwater]/evaporation) (I/E) balance within the lake. The spatial variability in grain size distribution within the lake surface sediments shows that the grain size data can be utilised as a proxy for transport energy and shoreline proximity in the lake basin. We have evaluated the applicability of commonly applied environmentally sensitive proxies (isotopes, mineralogy, weathering indices) for palaeoenvironmental reconstruction in the Tso Moriri Lake. Our results show that the commonly used weathering index (Rb/Sr) is not applicable due to Sr contribution from authigenic carbonates. The useful weathering indices in Tso Moriri Lake are the Si/Al and the Chemical Proxy of Alteration (CPA). Since the carbonates are formed by evaporative processes, their presence and isotopic values can be used as indicators of I/E changes in the lake.
KW  - geochemistry
KW  - lake sediments
KW  - palaeoenvironmental proxies
KW  - Tso Moriri Lake
KW  - weathering indices
Y1  - 2014
U6  - https://doi.org/10.1127/fal/2014/0664
SN  - 1863-9135
VL  - 185
IS  - 3-4
SP  - 329
EP  - 348
PB  - Schweizerbart
CY  - Stuttgart
ER  -