| Records |
Author  |
Adolph, G.; KÜlls, C.; Willscheid, A. |
| Title |
Determination and validation of age structures as an improved measure of hydrological dynamics |
Type |
Conference Article |
| Year |
2007 |
Publication |
Geophysical Research Abstracts |
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| Volume |
9 |
Issue |
08013 |
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THL @ christoph.kuells @ Adolph2007determination |
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58 |
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Brook, G.A.; Marais, E.; Srivastava, P.; Jordan, T. |
| Title |
Timing of lake-level changes in Etosha Pan, Namibia, since the middle Holocene from OSL ages of relict shorelines in the Okondeka region |
Type |
Journal Article |
| Year |
2007 |
Publication |
Quaternary International |
Abbreviated Journal |
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| Volume |
175 |
Issue |
1 |
Pages |
29-40 |
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| Abstract |
In 2003 examination of aerial photographs revealed a series of previously unknown relict shorelines on the arcuate ridge, possibly a clay lunette dune, that marks the western boundary of Etosha Pan in Namibia. The shorelines are 120–600m wide and the most prominent extend for tens of km around the lunette dune. The shorelines were examined on the ground in 2004 and an attempt was made to date the three lowest levels at ca. 5, 2.5 and 1m above the present pan surface. The OSL ages obtained indicate higher and more prolonged lake conditions than today at ca. 6.4, 4.0 and 2.1ka with the youngest shoreline sediments resting on an ancient pan surface dating to ca. 13ka. The evidence indicates dry conditions in the pan at ca. 13ka, wetter conditions and higher lake levels in the middle Holocene followed by a decline in lake levels to the present. Periods of inundation were of sufficient duration to produce shorelines at the southwestern end of the pan due to the prevailing northeasterly winds that would have maximized wave action along this section of the pan margin. The Etosha findings, together with other regional paleoclimate data, suggest four periods of increased wetness in SW Africa during the Holocene at 7–5, 4.5–3.5, 2.5–1.7 and ca. 1.0ka. There is widespread evidence for the oldest of these periods suggesting that it was a prominent and widespread interval of wetness. Prior to ca. 8.0ka the climate may have been drier than today. |
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1040-6182 |
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THL @ christoph.kuells @ brook_timing_2007 |
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97 |
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| Author |
Chase, B.M.; Meadows, M.E. |
| Title |
Late Quaternary dynamics of southern Africa’s winter rainfall zone |
Type |
Journal Article |
| Year |
2007 |
Publication |
Earth-Science Reviews |
Abbreviated Journal |
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| Volume |
84 |
Issue |
3 |
Pages |
103-138 |
| Keywords |
Last Glacial Maximum, palaeoenvironment, Quaternary, southern Africa, westerlies, winter rainfall zone |
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Variations in the nature and extent of southern Africa’s winter rainfall zone (WRZ) have the potential to provide important information concerning the nature of long-term climate change at both regional and hemispheric scales. Positioned at the interface between tropical and temperate systems, southern Africa’s climate is influenced by shifts in the Intertropical Convergence Zone, the westerlies, and the development and position of continental and oceanic anticyclones. Over the last glacial–interglacial cycle substantial changes in the amount and seasonality of precipitation across the subcontinent have been linked to the relative dominance of these systems. Central to this discussion has been the extent to which the region’s glacial climates would have been affected by expansions of Antarctic sea-ice, equatorward migrations of the westerlies, more frequent/intense winter storms and an expanded WRZ. This paper reviews the developing body of evidence pertaining to shifts in the WRZ, and the evolution of ideas that have been presented to explain the patterns observed. Dividing the region into three separate axes, along the western and southern margins of the continent and across the interior into the Karoo and the Kalahari, a range of evidence from both terrestrial sites and marine cores is considered, and potential expansions of the WRZ expansions are explored. Despite the limitations of many of the region’s proxy records, a coherent pattern has begun to develop of a significantly expanded WRZ during phases of the last glacial period, with the best-documented being between 32–17 ka. While more detailed inferences will require the recovery and analysis of longer and better-dated records, this synthesis provides a new baseline for further research in this key region. |
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0012-8252 |
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THL @ christoph.kuells @ chase_late_2007 |
Serial |
102 |
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Yabusaki, S.B.; Fang, Y.; Long, P.E.; Resch, C.T.; Peacock, A.D.; Komlos, J.; Jaffe, P.R.; Morrison, S.J.; Dayvault, R.D.; White, D.C.; Anderson, R.T. |
| Title |
Uranium removal from groundwater via in situ biostimulation: Field-scale modeling of transport and biological processes |
Type |
Journal Article |
| Year |
2007 |
Publication |
Journal of Contaminant Hydrology |
Abbreviated Journal |
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93 |
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1 |
Pages |
216-235 |
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Bioremediation, Biostimulation, Field experiment, Iron, Reactive transport, Sulfate, Uranium |
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During 2002 and 2003, bioremediation experiments in the unconfined aquifer of the Old Rifle UMTRA field site in western Colorado provided evidence for the immobilization of hexavalent uranium in groundwater by iron-reducing Geobacter sp. stimulated by acetate amendment. As the bioavailable Fe(III) terminal electron acceptor was depleted in the zone just downgradient of the acetate injection gallery, sulfate-reducing organisms came to dominate the microbial community. In the present study, we use multicomponent reactive transport modeling to analyze data from the 2002 field experiment to identify the dominant transport and biological processes controlling uranium mobility during biostimulation, and determine field-scale parameters for these modeled processes. The coupled process simulation approach was able to establish a quantitative characterization of the principal flow, transport, and reaction processes based on the 2002 field experiment, that could be applied without modification to describe the 2003 field experiment. Insights gained from this analysis include field-scale estimates of the bioavailable Fe(III) mineral threshold for the onset of sulfate reduction, and rates for the Fe(III), U(VI), and sulfate terminal electron accepting processes. |
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0169-7722 |
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THL @ christoph.kuells @ yabusaki_uranium_2007 |
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156 |
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| Author |
Zagana, E.; Külls, C.; Udluft, P.; Constantinou, C. |
| Title |
Methods of groundwater recharge estimation in eastern Mediterranean water balance model application in Greece, Cyprus and Jordan |
Type |
Journal Article |
| Year |
2007 |
Publication |
Hydrological Processes: An International Journal |
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21 |
Issue |
18 |
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2405-2414 |
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John Wiley & Sons, Ltd. Chichester, UK |
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THL @ christoph.kuells @ Zagana2007methods |
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30 |
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