scholarly journals Stable oxygen and carbon isotopes of carbonates in lake sediments as a paleoflood proxy

Geology ◽  
2019 ◽  
Vol 48 (1) ◽  
pp. 3-7 ◽  
Author(s):  
Lucas Kämpf ◽  
Birgit Plessen ◽  
Stefan Lauterbach ◽  
Carla Nantke ◽  
Hanno Meyer ◽  
...  

Abstract Lake sediments are increasingly explored as reliable paleoflood archives. In addition to established flood proxies including detrital layer thickness, chemical composition, and grain size, we explore stable oxygen and carbon isotope data as paleoflood proxies for lakes in catchments with carbonate bedrock geology. In a case study from Lake Mondsee (Austria), we integrate high-resolution sediment trapping at a proximal and a distal location and stable isotope analyses of varved lake sediments to investigate flood-triggered detrital sediment flux. First, we demonstrate a relation between runoff, detrital sediment flux, and isotope values in the sediment trap record covering the period 2011–2013 CE including 22 events with daily (hourly) peak runoff ranging from 10 (24) m3 s−1 to 79 (110) m3 s−1. The three- to ten-fold lower flood-triggered detrital sediment deposition in the distal trap is well reflected by attenuated peaks in the stable isotope values of trapped sediments. Next, we show that all nine flood-triggered detrital layers deposited in a sediment record from 1988 to 2013 have elevated isotope values compared with endogenic calcite. In addition, even two runoff events that did not cause the deposition of visible detrital layers are distinguished by higher isotope values. Empirical thresholds in the isotope data allow estimation of magnitudes of the majority of floods, although in some cases flood magnitudes are overestimated because local effects can result in too-high isotope values. Hence we present a proof of concept for stable isotopes as reliable tool for reconstructing flood frequency and, although with some limitations, even for flood magnitudes.

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3464
Author(s):  
Gabriella Boretto ◽  
Giovanni Zanchetta ◽  
Ilaria Consoloni ◽  
Ilaria Baneschi ◽  
Massimo Guidi ◽  
...  

The stable isotope composition of living and of Holocene Mytilidae shells was measured in the area of Camarones (Chubut, Argentina). The most striking results were the high δ18O values measured in samples older than ca. 6.1 cal ka BP. In the younger samples, the δ18O values remained substantially stable and similar to those of living specimens. Analysis of the data revealed the possibility for this isotopic shift to be driven mainly by changes in temperature probably accompanied by minor changes in salinity, suggesting cooler seawater before 6.1 cal ka BP, with a maximum possible temperature shift of ca. 5 °C. A possible explanation of this change can be related to a northward position of the confluence zone of the Falkland and Brazilian currents. This is consistent with the data obtained in marine cores, which indicate a northerly position of the confluence in the first half of the Holocene. Our data are also in line with the changes in wind strength and position of the Southern Westerlies Wind, as reconstructed in terrestrial proxies from the Southernmost Patagonia region.


2009 ◽  
Vol 25 (2) ◽  
pp. 135-145 ◽  
Author(s):  
Clara Mangili ◽  
Achim Brauer ◽  
Birgit Plessen ◽  
Peter Dulski ◽  
Andrea Moscariello ◽  
...  

2010 ◽  
Vol 300 (1-2) ◽  
pp. 125-138 ◽  
Author(s):  
Paolo Ballato ◽  
Andreas Mulch ◽  
Angela Landgraf ◽  
Manfred R. Strecker ◽  
Maria C. Dalconi ◽  
...  

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Cory J. D. Matthews ◽  
Fred J. Longstaffe ◽  
Jack W. Lawson ◽  
Steven H. Ferguson

AbstractKiller whales (Orcinus orca) are distributed widely in all oceans, although they are most common in coastal waters of temperate and high-latitude regions. The species’ distribution has not been fully described in the northwest Atlantic (NWA), where killer whales move into seasonally ice-free waters of the eastern Canadian Arctic (ECA) and occur year-round off the coast of Newfoundland and Labrador farther south. We measured stable oxygen and carbon isotope ratios in dentine phosphate (δ18OP) and structural carbonate (δ18OSC, δ13CSC) of whole teeth and annual growth layers from killer whales that stranded in the ECA (n = 11) and NWA (n = 7). Source δ18O of marine water (δ18Omarine) at location of origin was estimated from dentine δ18OPvalues, and then compared with predicted isoscape values to assign individual distributions. Dentine δ18OPvalues were also assessed against those of other known-origin North Atlantic odontocetes for spatial reference. Most ECA and NWA killer whales had mean δ18OPand estimated δ18Omarinevalues consistent with18O-depleted, high-latitude waters north of the Gulf Stream, above which a marked decrease in baseline δ18O values occurs. Several individuals, however, had relatively high values that reflected origins in18O-enriched, low-latitude waters below this boundary. Within-tooth δ18OSCranges on the order of 1–2‰ indicated interannual variation in distribution. Different distributions inferred from oxygen isotopes suggest there is not a single killer whale population distributed across the northwest Atlantic, and corroborate dietary and morphological differences of purported ecotypes in the region.


2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Christopher J. Pollock ◽  
Pablo Capilla-Lasheras ◽  
Rona A. R. McGill ◽  
Barbara Helm ◽  
Davide M. Dominoni

2019 ◽  
Vol 569 ◽  
pp. 423-435 ◽  
Author(s):  
Guofeng Zhu ◽  
Huiwen Guo ◽  
Dahe Qin ◽  
Hanxiong Pan ◽  
Yu Zhang ◽  
...  

2020 ◽  
Author(s):  
Arne Ramisch ◽  
Alexander Brauser ◽  
Mario Dorn ◽  
Cecile Blanchet ◽  
Brian Brademann ◽  
...  

Abstract. Varved lake sediments provide long climatic records with high temporal resolution and low associated age uncertainty. Robust and detailed comparison of well-dated and annually laminated sediment records is crucial for reconstructing abrupt and regionally time-transgressive changes as well as validation of spatial and temporal trajectories of past climatic changes. The VARved sediments DAtabase (VARDA) presented here is the first data compilation for varve chronologies and associated palaeoclimatic proxy records. The current version 1.0 allows detailed comparison of published varve records from 95 lakes. VARDA is freely accessible and was created to assess outputs from climate models with high-resolution terrestrial palaeoclimatic proxies. VARDA additionally provides a technical environment that enables to explore the database of varved lake sediments using a connected data-model and can generate a state-of-the-art graphic representation of multi-site comparison. This allows to reassess existing chronologies and tephra events to synchronize and compare even distant varved lake records. Furthermore, the present version of VARDA permits to explore varve thickness data. In this paper, we report in detail on the data mining and compilation strategies for the identification of varved lakes and assimilation of high-resolution chronologies as well as the technical infrastructure of the database. Additional paleoclimate proxy data will be provided in forthcoming updates. The VARDA graph-database and user interface can be accessed online at https://varve.gfz-potsdam.de, all datasets of version 1.0 are available at http://doi.org/10.5880/GFZ.4.3.2019.003 (Ramisch et al., 2019).


2013 ◽  
Vol 10 (7) ◽  
pp. 8789-8839
Author(s):  
S. R. Lutz ◽  
H. J. van Meerveld ◽  
M. J. Waterloo ◽  
H. P. Broers ◽  
B. M. van Breukelen

Abstract. Compound-specific stable isotope analysis (CSIA) has, in combination with model-assisted interpretation, proven a valuable approach to quantify the extent of organic contaminant degradation in groundwater systems. CSIA data may also provide insights into the origin and transformation of diffuse river pollutants such as pesticides and nitrate at the catchment scale. While CSIA methods for pesticides have increasingly become available, they have not yet been deployed to interpret isotope data of pesticides in surface water. We applied a coupled subsurface-surface reactive transport model (HydroGeoSphere) at the hillslope scale to investigate the usefulness of CSIA in the assessment of pesticide degradation. We simulated the transport and transformation of a pesticide in a hypothetical but realistic two-dimensional hillslope transect. The steady-state model results illustrate a strong increase of isotope ratios at the hillslope outlet, which resulted from degradation and long travel times through the hillslope during average hydrological conditions. In contrast, following an extreme rainfall event that induced overland flow, the simulated isotope ratios dropped to the values of soil water in the pesticide application area. These results suggest that CSIA can help to determine whether pesticides enter the stream via groundwater exfiltration or via surface runoff. Simulations with daily rainfall and evapotranspiration data and one pesticide application per year resulted in small seasonal variations of concentrations and isotope ratios at the hillslope outlet, which fell within the uncertainty range of current CSIA methods. This implies a good reliability of in-stream isotope data in the absence of transport via surface runoff or other fast transport routes, since the time of measurement appears to be of minor importance. The analysis of simulated isotope ratios also allowed quantifying the contribution of two different reaction pathways to the overall degradation, which gave further insight into transport routes in the modelled system. The simulations supported the use of the commonly applied Rayleigh equation for the interpretation of CSIA data, since this led to an underestimation of the real extent of degradation of less than 12% at the hillslope outlet. Overall, the model results emphasize the applicability and usefulness of CSIA in the assessment of diffuse river pollution.


Sign in / Sign up

Export Citation Format

Share Document