TY  - JOUR
A1  - Dräger, Nadine
A1  - Plessen, Birgit
A1  - Kienel, Ulrike
A1  - Siowinski, Michat
A1  - Ramisch, Arne
A1  - Tjallingii, Rik
A1  - Pinkerneil, Sylvia
A1  - Brauer, Achim
T1  - Hypolimnetic oxygen conditions influence varve preservation and delta C-13 of sediment organic matter in Lake Tiefer See, NE Germany
JF  - Journal of paleolimnolog
N2  - Stable carbon isotopes of sediment organic matter (delta C-13(OM)) are widely applied in paleoenvironmental studies. Interpretations of delta C-13(OM), however, remain challenging and factors that influence delta C-13(OM) may not apply across all lakes. Common explanations for stratigraphic shifts in delta C-13(OM) include changes in lake productivity or changes in inputs of allochthonous OM. We investigated the influence of different oxygen conditions (oxic versus anoxic) on the delta C-13(OM) values in the sediments of Lake Tiefer See. We analysed (1) a long sediment core from the deepest part of the lake, (2) two short, sediment-water interface cores from shallower water depths, and (3) OM in the water column, i.e. from sediment traps. Fresh OM throughout the entire water column showed a relatively constant delta C-13(OM) value of approximately -30.5 parts per thousand. Similar values, about -31 parts per thousand, were obtained for well-varved sediments in both the long and short, sediment-water interface cores. In contrast, delta C-13(OM) values from non-varved sediments in all cores were significantly less negative (-29 parts per thousand). The delta C-13(OM) values in the sediment-water interface cores from different water depths differ for sediments of the same age, if oxygen conditions at the time of deposition were different at these sites, as suggested by the state of varve preservation. Sediments deposited from AD 1924 to 1980 at 62m water depth are varved and exhibit delta C-13(OM) values around -31 parts per thousand, whereas sediments of the same age in the core from 35m water depth are not varved and show less negative delta C-13(OM) values of about -29 parts per thousand. The relation between varve occurrence and delta C-13(OM) values suggests that delta C-13(OM) is associated with oxygen conditions because varve preservation depends on hypolimnetic anoxia. A mechanism that likely influences delta C-13(OM) is selective degradation of OM under oxic conditions, such that organic components with more negative delta C-13(OM) are preferably decomposed, leading to less negative delta C-13(OM) values in the remaining, undegraded OM pool. Greater decomposition of OM in non-varved sediments is supported by lower TOC concentrations in these deposits (similar to 5%) compared to well-varved sediments (similar to 15%). Even in lakes that display small variations in productivity and terrestrial OM input through time, large spatial and temporal differences in hypolimnetic oxygen concentrations may be an important factor controlling sediment delta C-13(OM).
KW  - Carbon stable isotopes
KW  - Hypolimnetic oxygen
KW  - Organic matter degradation
KW  - Varves
Y1  - 2019
U6  - https://doi.org/10.1007/s10933-019-00084-2
SN  - 0921-2728
SN  - 1573-0417
VL  - 62
IS  - 2
SP  - 181
EP  - 194
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Heinrich, Ingo
A1  - Balanzategui, Daniel
A1  - Bens, Oliver
A1  - Blasch, Gerald
A1  - Blume, Theresa
A1  - Boettcher, Falk
A1  - Borg, Erik
A1  - Brademann, Brian
A1  - Brauer, Achim
A1  - Conrad, Christopher
A1  - Dietze, Elisabeth
A1  - Dräger, Nadine
A1  - Fiener, Peter
A1  - Gerke, Horst H.
A1  - Güntner, Andreas
A1  - Heine, Iris
A1  - Helle, Gerhard
A1  - Herbrich, Marcus
A1  - Harfenmeister, Katharina
A1  - Heussner, Karl-Uwe
A1  - Hohmann, Christian
A1  - Itzerott, Sibylle
A1  - Jurasinski, Gerald
A1  - Kaiser, Knut
A1  - Kappler, Christoph
A1  - Koebsch, Franziska
A1  - Liebner, Susanne
A1  - Lischeid, Gunnar
A1  - Merz, Bruno
A1  - Missling, Klaus Dieter
A1  - Morgner, Markus
A1  - Pinkerneil, Sylvia
A1  - Plessen, Birgit
A1  - Raab, Thomas
A1  - Ruhtz, Thomas
A1  - Sachs, Torsten
A1  - Sommer, Michael
A1  - Spengler, Daniel
A1  - Stender, Vivien
A1  - Stüve, Peter
A1  - Wilken, Florian
T1  - Interdisciplinary Geo-ecological Research across Time Scales in the Northeast German Lowland Observatory (TERENO-NE)
JF  - Vadose zone journal
N2  - The Northeast German Lowland Observatory (TERENO-NE) was established to investigate the regional impact of climate and land use change. TERENO-NE focuses on the Northeast German lowlands, for which a high vulnerability has been determined due to increasing temperatures and decreasing amounts of precipitation projected for the coming decades. To facilitate in-depth evaluations of the effects of climate and land use changes and to separate the effects of natural and anthropogenic drivers in the region, six sites were chosen for comprehensive monitoring. In addition, at selected sites, geoarchives were used to substantially extend the instrumental records back in time. It is this combination of diverse disciplines working across different time scales that makes the observatory TERENO-NE a unique observation platform. We provide information about the general characteristics of the observatory and its six monitoring sites and present examples of interdisciplinary research activities at some of these sites. We also illustrate how monitoring improves process understanding, how remote sensing techniques are fine-tuned by the most comprehensive ground-truthing site DEMMIN, how soil erosion dynamics have evolved, how greenhouse gas monitoring of rewetted peatlands can reveal unexpected mechanisms, and how proxy data provides a long-term perspective of current ongoing changes.
Y1  - 2018
U6  - https://doi.org/10.2136/vzj2018.06.0116
SN  - 1539-1663
VL  - 17
IS  - 1
PB  - Soil Science Society of America
CY  - Madison
ER  -