Papers by Dana Riechelmann
Isotopes in Environmental and Health Studies, 2016
δ(13)C and δ(18)O values from sapwood of a single Pinus uncinata tree, from a high elevation site... more δ(13)C and δ(18)O values from sapwood of a single Pinus uncinata tree, from a high elevation site in the Spanish Pyrenees, were determined to evaluate the differences between whole wood and resin-free whole wood. This issue is addressed for the first time with P. uncinata over a 38-year long period. Results are also compared with published isotope values of α-cellulose samples from the same tree. The differences in δ(13)C and δ(18)O between whole wood and resin-free whole wood vary within the analytical uncertainty of 0.3 and 0.5 ‰, respectively, indicating that resin extraction is not necessary for sapwood of P. uncinata. Mean differences between cellulose and whole wood are 0.9 ‰ (δ(13)C) and 5.0 ‰ (δ(18)O), respectively. However, further analyses of different species and other sites are needed to evaluate whether the findings reported here are coherent more generally.
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Climate of the Past Discussions, 2016
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Palaeogeography, Palaeoclimatology, Palaeoecology, 2016
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Bunker Cave (N 51° 22'03', E 7° 39'53') is located in the Rhenish Slate Mountains... more Bunker Cave (N 51° 22'03', E 7° 39'53') is located in the Rhenish Slate Mountains in the western part of Germany and is part of a giant cave system in the area of Iserlohn (Hammerschmidt et al., 1995).As part of the DAPHNE (Dated Speleothems - archives of the paleoenvironment) project Bunker Cave is being monitored since the end of 2006. The ongoing monitoring program is performed on a monthly base. Surface climate parameters are measured and samples of rain water, cave air, drip water at eight different drip sites and modern calcite precipitates from watch glasses placed beneath drip sites are collected. Data sets include temperature, precipitation, calculated infiltration, drip rates, electric conductivity, pH, alkalinity, cations, anions and stable isotopes. Bunker Cave shows a constant temperature throughout the year. Active calcite precipitation is higher in winter than in summer, which is due to lower cave pCO2 in winter. The generally low pCO2 values, however,...
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Chemical Geology, 2014
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ABSTRACT Only very few studies exist dealing with the reproducibility of stable isotope data from... more ABSTRACT Only very few studies exist dealing with the reproducibility of stable isotope data from tree rings. In this study, we show that within-tree variability of d13C is significant and has to be considered for the design of sampling strategies and interpretation of results. We analyzed tree rings from European larch (Larix decidua) growing at 1,700 m above sea level in the Simplon area, Switzerland. Samples were taken at seven height levels between 1m and 13m above ground, from a single tree. At each height, we analyzed tree rings representing the 1991-2010 AD period, along six radii every 60 degrees around the stem. Results show that the circumferential d13C variability, i.e. the difference between maximum and minimum isotope values within a tree ring, is in the order of 0.5 to 2.8 per mil. A comparison of isotope data between different height levels revealed a rather consistent gradient of ~0.1 per mil d13C per meter, with increasing values with stem height. A comparison of tree-ring d13C with climate data from nearby weather stations revealed that summer temperature explains most of the d13C variability, but also summer (JJA) precipitation from the previous year shows some correlation. We conclude that it is important to be aware of the vertical isotope gradient, especially when studying sub-fossil material with unknown and differing height levels. The large circumferential variability we found for Larix decidua at our sampling site suggests that more than only two cores should be analyzed in order to get a reliable isotope signal from each tree. Our results also highlight the need for a better understanding of intra-plant processes which lead to isotope fractionation.
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Geochimica et Cosmochimica Acta, 2014
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Rapid Communications in Mass Spectrometry, 2014
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Journal of Hydrology, 2011
... Bunker Cave (NW Germany): A prerequisite to interpret geochemical proxy data of speleothems f... more ... Bunker Cave (NW Germany): A prerequisite to interpret geochemical proxy data of speleothems from this site Dana Felicitas Christine Riechelmann*1,5 ... PCP is a common process in karst aquifers (Fairchild et al., 2000; Johnson et al., 2006; Verheyden et al., 2008), whereby ...
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Journal of Hydrology, 2010
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Geochimica et Cosmochimica Acta, 2013
ABSTRACT Speleothem proxy data provide important information in continental palaeo-climate resear... more ABSTRACT Speleothem proxy data provide important information in continental palaeo-climate research due to their precise chronology and wide geographic distribution. Despite a continuously growing number of field and numerical studies designed to study stable isotope fractionation effects, many aspects remain a matter of debate. Here, carbon and oxygen isotope ratios from cave drip water and calcite precipitates sampled on watch glasses in the Bunker Cave (Western Germany) are compared with the values expected for isotopic equilibrium. Furthermore, the field data are compared with the results of a numerical model simulating stalagmite growth and stable isotope ratios.Two drip sites with different drip rates were investigated. Drip site TS 1 is characterised by a high drip rate, and drip water of this site is characterised by a high saturation index with respect to calcite. TS 1 shows no evidence of prior calcite precipitation. Conversely, drip site TS 8 shows a low drip rate, and drip water from this site is characterised by a low saturation index. TS 8 shows evidence of prior calcite precipitation. Whereas the mean δ13CDIC values of the drip water are significantly different between the two drip sites, the mean δ18Odrip water values are similar. Calcite precipitation rates are higher at watch glass site U I corresponding to drip site TS 1. This is probably due to the higher SIcalcite and drip rate. The δ18O and δ13C values of the calcite precipitated on watch glasses U IV corresponding to drip site TS 8 are significantly higher than those of the calcite collected on watch glasses U I. Calcite precipitation occurs close to isotopic equilibrium at watch glass site U I, whereas the calcite precipitated at watch glass site U IV shows clear evidence of isotopic disequilibrium.The results suggest that cave calcites precipitated at lower drip rates have higher δ13C and δ18O values than predicted by equilibrium precipitation. Furthermore, our data show that stalagmites from the same cave, which are fed by drip water with similar δ18O values, may have different δ18Ocalcite values.The δ13C and δ18O values predicted by the numerical model are generally lower by 1.9‰ and 0.8‰, respectively, than those of the natural cave calcite. Nevertheless, the first-order trends observed in the cave data are well reproduced by the model. The offset between cave and model data is probably due to the fractionation factors used in the model.
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Geochimica et Cosmochimica Acta, 2010
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Climate of the Past, 2012
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Abstracts by Dana Riechelmann
High-resolution palaeoclimate reconstructions are essential to identify possible influences of cl... more High-resolution palaeoclimate reconstructions are essential to identify possible influences of climate variability on landscape evolution and landscape-related cultural changes (e.g., shifting settlement patterns and long-distance trade relations). Northwestern Europe is an ideal research area for comparison between climate variability and cultural transitions given its geomorphological diversity and the significant cultural changes that took place in this region during the last two millennia (e.g., the decline of the Roman Empire and the transition to medieval kingdoms). We compiled climate reconstructions for sites in Northwestern Europe from the literature and its underlying data. The compilation of the different temperature reconstructions shows similar trends in most of the records. Colder conditions since AD 300 for a period of approximately 400 years and warmer conditions after AD 700 become apparent. The compilation of the different precipitation reconstructions also show similar trends. Dry periods are indicated by all records around AD 400 and 600, although precipitation records do not show the same spatial continuity as the temperature proxies. This study shows that clear climate changes occurred over Northwestern Europe in the period between AD 300 and 700, which are partly reflected by changes in seasonality.
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Papers by Dana Riechelmann
Abstracts by Dana Riechelmann