TY  - JOUR
A1  - Warken, Sophie Friederike
A1  - Fohlmeister, Jens Bernd
A1  - Schröder-Ritzrauh, Andrea
A1  - Constantin, Silviu
A1  - Spötl, Christoph
A1  - Gerdes, Axel
A1  - Esper, Jan
A1  - Frank, Norbert
A1  - Arps, Jennifer
A1  - Terente, Mihai
A1  - Riechelmann, Dana Felicitas Christine
A1  - Mangini, Augusto
A1  - Scholz, Denis
T1  - Reconstruction of late Holocene autumn/winter precipitation variability in SW Romania from a high-resolution speleothem trace element record
JF  - Earth & planetary science letters
N2  - We present the first high-resolution trace element (Mg/Ca, Sr/Ca, Ba/Ca) record from a stalagmite in southwestern Romania covering the last 3.6 ka, which provides the potential for quantitative climate reconstruction. Precise age control is based on three independent dating methods, in particular for the last 250 yr, where chemical lamina counting is combined with the identification of the 20th century radiocarbon bomb peak and Th-230/U dating. Long-term cave monitoring and model simulations of drip water and speleothem elemental variability indicate that precipitation-related processes are the main drivers of speleothem Mg/Ca ratios. Calibration against instrumental climate data shows a significant anti-correlation of speleothem Mg/Ca ratios with autumn/winter (October to March) precipitation (r = -0.61, p < 0.01), which is statistically robust when considering age uncertainties and auto-correlation. This relationship is used to develop a quantitative reconstruction of autumn/winter precipitation. During the late Holocene, our data suggest a heterogeneous pattern of past regional winter hydroclimate in the Carpathian/Balkan realm, along with intermittent weakening of the dominant influence of North Atlantic forcing. In agreement with other regional paleo-hydrological reconstructions, the observed variability reveals periodically occurring strong NW-SE hydro-climate gradients. We hypothesize, that this pattern is caused by shifts of the eastern edge of the area of influence of the NAO across central eastern Europe due to the confluence of North Atlantic forcing, and other climatic features such as the East Atlantic/Western Russia (EAWR) pattern. (C) 2018 Elsevier B.V. All rights reserved.
KW  - speleothem
KW  - trace elements
KW  - proxy calibration
KW  - precipitation reconstruction
KW  - Romania
KW  - North Atlantic forcing
Y1  - 2018
U6  - https://doi.org/10.1016/j.epsl.2018.07.027
SN  - 0012-821X
SN  - 1385-013X
VL  - 499
SP  - 122
EP  - 133
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Fohlmeister, Jens Bernd
A1  - Arps, Jennifer
A1  - Spoetl, Christoph
A1  - Schroeder-Ritzrau, Andrea
A1  - Plessen, Birgit
A1  - Günter, Christina
A1  - Frank, Norbert
A1  - Trüssel, Martin
T1  - Carbon and oxygen isotope fractionation in the water-calcite-aragonite system
JF  - Geochimica et cosmochimica acta : journal of the Geochemical Society and the Meteoritical Society
N2  - The precise determination of the stable C and O isotope fractionation between water and calcite (CC) and water and aragonite (AR) is of special interest for climate reconstructions, e.g. paleotemperatures. Previous studies reported results from both laboratory and field experiments, but their results are only partly consistent. Here we present C and O isotope data of a stalagmite from the Swiss Alps, which shows CC-AR transitions along individual growth layers. Using detailed analyses both laterally and perpendicular to such layers we examined the difference in the C and O isotope fractionation factor of the HCO3- - CC and the HCO3- - AR system. For O this difference is similar to the water-CC and water-AR offset provided in experimental studies. The O isotope fractionation difference in the water-CC and water-AR system is comparable to those determined in laboratory studies but shows a statistically significant correlation with the CaCO3 precipitation rate. For C we found a fractionation difference, which is independent of CaCO3 precipitation rate and with slightly smaller values for the fractionation offset between HCO3- - CC and HCO3- - AR compared to literature values. However, we also found an unexpected decrease in delta C-13 along growth layers, which contradicts the widely used concept of Rayleigh fractionation during CO2 degassing and CaCO3 precipitation. The results of this study can be used e.g., to correct stable isotope time series of stalagmites showing CC-AR transitions along their growth axes. (C) 2018 Elsevier Ltd. All rights reserved.
Y1  - 2018
U6  - https://doi.org/10.1016/j.gca.2018.05.022
SN  - 0016-7037
SN  - 1872-9533
VL  - 235
SP  - 127
EP  - 139
PB  - Elsevier
CY  - Oxford
ER  -