TY  - JOUR
A1  - Aichner, Bernhard
A1  - Makhmudov, Zafar
A1  - Rajabov, Iljomjon
A1  - Zhang, Qiong
A1  - Pausata, Francesco Salvatore R.
A1  - Werner, Martin
A1  - Heinecke, Liv
A1  - Kuessner, Marie L.
A1  - Feakins, Sarah J.
A1  - Sachse, Dirk
A1  - Mischke, Steffen
T1  - Hydroclimate in the Pamirs Was Driven by Changes in Precipitation-Evaporation Seasonality Since theLast Glacial Period
JF  - Geophysical research letters
N2  - The Central Asian Pamir Mountains (Pamirs) are a high-altitude region sensitive to climatic change, with only few paleoclimatic records available. To examine the glacial-interglacial hydrological changes in the region, we analyzed the geochemical parameters of a 31-kyr record from Lake Karakul and performed a set of experiments with climate models to interpret the results. delta D values of terrestrial biomarkers showed insolation-driven trends reflecting major shifts of water vapor sources. For aquatic biomarkers, positive delta D shifts driven by changes in precipitation seasonality were observed at ca. 31-30, 28-26, and 17-14 kyr BP. Multiproxy paleoecological data and modelling results suggest that increased water availability, induced by decreased summer evaporation, triggered higher lake levels during those episodes, possibly synchronous to northern hemispheric rapid climate events. We conclude that seasonal changes in precipitation-evaporation balance significantly influenced the hydrological state of a large waterbody such as Lake Karakul, while annual precipitation amount and inflows remained fairly constant.
KW  - climate
KW  - biomarker
KW  - geochemistry
KW  - modelling
KW  - paleoclimate
KW  - hydrology
Y1  - 2019
U6  - https://doi.org/10.1029/2019GL085202
SN  - 0094-8276
SN  - 1944-8007
VL  - 46
IS  - 23
SP  - 13972
EP  - 13983
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Menges, Johanna
A1  - Hovius, Niels
A1  - Andermann, Christoff
A1  - Dietze, Michael
A1  - Swoboda, Charlie
A1  - Cook, Kristen L.
A1  - Adhikari, Basanta R.
A1  - Vieth-Hillebrand, Andrea
A1  - Bonnet, Stephane
A1  - Reimann, Tony
A1  - Koutsodendris, Andreas
A1  - Sachse, Dirk
T1  - Late holocene landscape collapse of a trans-himalayan dryland
BT  - human impact and aridification
JF  - Geophysical research letters
N2  - Soil degradation is a severe and growing threat to ecosystem services globally. Soil loss is often nonlinear, involving a rapid deterioration from a stable eco-geomorphic state once a tipping point is reached. Soil loss thresholds have been studied at plot scale, but for landscapes, quantitative constraints on the necessary and sufficient conditions for tipping points are rare. Here, we document a landscape-wide eco-geomorphic tipping point at the edge of the Tibetan Plateau and quantify its drivers and erosional consequences. We show that in the upper Kali Gandaki valley, Nepal, soil formation prevailed under wetter conditions during much of the Holocene. Our data suggest that after a period of human pressure and declining vegetation cover, a 20% reduction of relative humidity and precipitation below 200 mm/year halted soil formation after 1.6 ka and promoted widespread gullying and rapid soil loss, with irreversible consequences for ecosystem services.
KW  - geomorphology
KW  - paleoclimate
KW  - human activity
KW  - Tibetan plateau
KW  - late Holocene
Y1  - 2019
U6  - https://doi.org/10.1029/2019GL084192
SN  - 0094-8276
SN  - 1944-8007
VL  - 46
IS  - 23
SP  - 13814
EP  - 13824
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Scheingross, Joel S.
A1  - Hovius, Niels
A1  - Dellinger, M.
A1  - Hilton, R. G.
A1  - Repasch, M.
A1  - Sachse, Dirk
A1  - Grocke, D. R.
A1  - Vieth-Hillebrand, Andrea
A1  - Turowski, Jens M.
T1  - Preservation of organic carbon during active fluvial transport and particle abrasion
JF  - Geology
N2  - Oxidation of particulate organic carbon (POC) during fluvial transit releases CO2 to the atmosphere and can influence global climate. Field data show large POC oxidation fluxes in lowland rivers; however, it is unclear if POC losses occur predominantly during in-river transport, where POC is in continual motion within an aerated environment, or during transient storage in floodplains, which may be anoxic. Determination of the locus of POC oxidation in lowland rivers is needed to develop process-based models to predict POC losses, constrain carbon budgets, and unravel links between climate and erosion. However, sediment exchange between rivers and floodplains makes differentiating POC oxidation during in-river transport from oxidation during floodplain storage difficult. Here, we isolated inriver POC oxidation using flume experiments transporting petrogenic and biospheric POC without floodplain storage. Our experiments showed solid phase POC losses of 0%-10% over similar to 10(3) km of fluvial transport, compared to similar to 7% to >50% losses observed in rivers over similar distances. The production of dissolved organic carbon (DOC) and dissolved rhenium (a proxy for petrogenic POC oxidation) was consistent with small POC lasses, and replicate experiments in static water tanks gave similar results. Our results show that fluvial sediment transport, particle abrasion, and turbulent mixing have a minimal role on POC oxidation, and they suggest that POC losses may accrue primarily in floodplain storage.
Y1  - 2019
U6  - https://doi.org/10.1130/G46442.1
SN  - 0091-7613
SN  - 1943-2682
VL  - 47
IS  - 10
SP  - 958
EP  - 962
PB  - American Institute of Physics
CY  - Boulder
ER  -