TY - JOUR A1 - Biskaborn, Boris K. A1 - Nazarova, Larisa B. A1 - Pestryakova, Luidmila Agafyevna A1 - Syrykh, Liudmila A1 - Funck, Kim A1 - Meyer, Hanno A1 - Chapligin, Bernhard A1 - Vyse, Stuart A1 - Gorodnichev, Ruslan A1 - Zakharov, Evgenii A1 - Wang, Rong A1 - Schwamborn, Georg A1 - Bailey, Hannah L. A1 - Diekmann, Bernhard T1 - Spatial distribution of environmental indicators in surface sediments of Lake Bolshoe Toko, Yakutia, Russia JF - Biogeosciences N2 - Rapidly changing climate in the Northern Hemisphere and associated socio-economic impacts require reliable understanding of lake systems as important freshwater resources and sensitive sentinels of environmental change. To better understand time-series data in lake sediment cores, it is necessary to gain information on within-lake spatial variabilities of environmental indicator data. Therefore, we retrieved a set of 38 samples from the sediment surface along spatial habitat gradients in the boreal, deep, and yet pristine Lake Bolshoe Toko in southern Yakutia, Russia. Our methods comprise laboratory analyses of the sediments for multiple proxy parameters, including diatom and chironomid taxonomy, oxygen isotopes from diatom silica, grain-size distributions, elemental compositions (XRF), organic carbon content, and mineralogy (XRD). We analysed the lake water for cations, anions, and isotopes. Our results show that the diatom assemblages are strongly influenced by water depth and dominated by planktonic species, i.e. Pliocaenicus bolshetokoensis. Species richness and diversity are higher in the northern part of the lake basin, associated with the availability of benthic, i.e. periphytic, niches in shallower waters. delta O-18(diatom) values are higher in the deeper south-western part of the lake, probably related to water temperature differences. The highest amount of the chironomid taxa underrepresented in the training set used for palaeoclimate inference was found close to the Utuk River and at southern littoral and profundal sites. Abiotic sediment components are not symmetrically distributed in the lake basin, but vary along restricted areas of differential environmental forcing. Grain size and organic matter are mainly controlled by both river input and water depth. Mineral (XRD) data distributions are influenced by the methamorphic lithology of the Stanovoy mountain range, while elements (XRF) are intermingled due to catchment and diagenetic differences. We conclude that the lake represents a valuable archive for multiproxy environmental reconstruction based on diatoms (including oxygen isotopes), chironomids, and sediment-geochemical parameters. Our analyses suggest multiple coring locations preferably at intermediate depth in the northern basin and the deep part in the central basin, to account for representative bioindicator distributions and higher temporal resolution, respectively. Y1 - 2019 U6 - https://doi.org/10.5194/bg-16-4023-2019 SN - 1726-4170 SN - 1726-4189 VL - 16 IS - 20 SP - 4023 EP - 4049 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Kämpf, Lucas A1 - Plessen, Birgit A1 - Lauterbach, Stefan A1 - Nantke, Carla A1 - Meyer, Hanno A1 - Chapligin, Bernhard A1 - Brauer, Achim T1 - Stable oxygen and carbon isotopes of carbonates in lake sediments as a paleoflood proxy JF - Geology / the Geological Society of America N2 - 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) m(3) s(-1) to 79 (110) m(3) 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. KW - detrital carbonate KW - varved sediments KW - record KW - Baldeggersee KW - delta-c-13 KW - alps Y1 - 2019 U6 - https://doi.org/10.1130/G46593.1 SN - 1943-2682 SN - 0091-7613 VL - 48 IS - 1 SP - 3 EP - 7 PB - American Institute of Physics CY - Melville, NY ER - TY - JOUR A1 - Opel, Thomas A1 - Murton, Julian B. A1 - Wetterich, Sebastian A1 - Meyer, Hanno A1 - Ashastina, Kseniia A1 - Günther, Frank A1 - Grotheer, Hendrik A1 - Mollenhauer, Gesine A1 - Danilov, Petr P. A1 - Boeskorov, Vasily A1 - Savvinov, Grigoriy N. A1 - Schirrmeister, Lutz T1 - Past climate and continentality inferred from ice wedges at Batagay Highlands, interior Yakutia JF - Climate of the past : an interactive open access journal of the European Geosciences Union N2 - Ice wedges in the Yana Highlands of interior Yakutia - the most continental region of the Northern Hemisphere - were investigated to elucidate changes in winter climate and continentality that have taken place since the Middle Pleistocene. The Batagay megaslump exposes ice wedges and composite wedges that were sampled from three cryostratigraphic units: the lower ice complex of likely pre-Marine Isotope Stage (MIS) 6 age, the upper ice complex (Yedoma) and the upper sand unit (both MIS 3 to 2). A terrace of the nearby Adycha River provides a Late Holocene (MIS 1) ice wedge that serves as a modern reference for interpretation. The stable-isotope composition of ice wedges in the MIS 3 upper ice complex at Batagay is more depleted (mean delta O-18 about -35 parts per thousand) than those from 17 other ice-wedge study sites across coastal and central Yakutia. This observation points to lower winter temperatures and therefore higher continentality in the Yana Highlands during MIS 3. Likewise, more depleted isotope values are found in Holocene wedge ice (mean delta O-18 about -29 parts per thousand) compared to other sites in Yakutia. Ice-wedge isotopic signatures of the lower ice complex mean delta O-18 about -33 parts per thousand) and of the MIS 3-2 upper sand unit (mean delta O-18 from about -33 parts per thousand to -30 parts per thousand) are less distinctive regionally. The latter unit preserves traces of fast formation in rapidly accumulating sand sheets and of post-depositional isotopic fractionation. Y1 - 2019 U6 - https://doi.org/10.5194/cp-15-1443-2019 SN - 1814-9324 SN - 1814-9332 VL - 15 IS - 4 SP - 1443 EP - 1461 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Wetterich, Sebastian A1 - Rudaya, Natalia A1 - Kuznetsov, Vladislav A1 - Maksimov, Fedor A1 - Opel, Thomas A1 - Meyer, Hanno A1 - Günther, Frank A1 - Bobrov, Anatoly A1 - Raschke, Elena A1 - Zimmermann, Heike Hildegard A1 - Strauss, Jens A1 - Starikova, Anna A1 - Fuchs, Margret A1 - Schirrmeister, Lutz T1 - Ice Complex formation on Bol'shoy Lyakhovsky Island (New Siberian Archipelago, East Siberian Arctic) since about 200 ka JF - Quaternary research : an interdisciplinary journal N2 - Late Quaternary landscapes of unglaciated Beringia were largely shaped by ice-wedge polygon tundra. Ice Complex (IC) strata preserve such ancient polygon formations. Here we report on the Yukagir IC from Bol'shoy Lyakhovsky Island in northeastern Siberia and suggest that new radioisotope disequilibria (230Th/U) dates of the Yukagir IC peat confirm its formation during the Marine Oxygen Isotope Stage (MIS) 7a–c interglacial period. The preservation of the ice-rich Yukagir IC proves its resilience to last interglacial and late glacial–Holocene warming. This study compares the Yukagir IC to IC strata of MIS 5, MIS 3, and MIS 2 ages exposed on Bol'shoy Lyakhovsky Island. Besides high intrasedimental ice content and syngenetic ice wedges intersecting silts, sandy silts, the Yukagir IC is characterized by high organic matter (OM) accumulation and low OM decomposition of a distinctive Drepanocladus moss-peat. The Yukagir IC pollen data reveal grass-shrub-moss tundra indicating rather wet summer conditions similar to modern ones. The stable isotope composition of Yukagir IC wedge ice is similar to those of the MIS 5 and MIS 3 ICs pointing to similar atmospheric moisture generation and transport patterns in winter. IC data from glacial and interglacial periods provide insights into permafrost and climate dynamics since about 200 ka. KW - Cryostratigraphy KW - Ice wedges KW - Stable isotopes KW - Pollen KW - Radioisotope disequilibria dating KW - Beringia Y1 - 2019 U6 - https://doi.org/10.1017/qua.2019.6 SN - 0033-5894 SN - 1096-0287 VL - 92 IS - 2 SP - 530 EP - 548 PB - Cambridge Univ. Press CY - New York ER - TY - JOUR A1 - Nguyen Le Duy, A1 - Nguyen Viet Du, A1 - Heidbüchel, Ingo A1 - Meyer, Hanno A1 - Weiler, Markus A1 - Merz, Bruno A1 - Apel, Heiko T1 - Identification of groundwater mean transit times of precipitation and riverbank infiltration by two-component lumped parameter models JF - Hydrological processes N2 - Groundwater transit time is an essential hydrologic metric for groundwater resources management. However, especially in tropical environments, studies on the transit time distribution (TTD) of groundwater infiltration and its corresponding mean transit time (mTT) have been extremely limited due to data sparsity. In this study, we primarily use stable isotopes to examine the TTDs and their mTTs of both vertical and horizontal infiltration at a riverbank infiltration area in the Vietnamese Mekong Delta (VMD), representative of the tropical climate in Asian monsoon regions. Precipitation, river water, groundwater, and local ponding surface water were sampled for 3 to 9 years and analysed for stable isotopes (delta O-18 and delta H-2), providing a unique data set of stable isotope records for a tropical region. We quantified the contribution that the two sources contributed to the local shallow groundwater by a novel concept of two-component lumped parameter models (LPMs) that are solved using delta O-18 records. The study illustrates that two-component LPMs, in conjunction with hydrological and isotopic measurements, are able to identify subsurface flow conditions and water mixing at riverbank infiltration systems. However, the predictive skill and the reliability of the models decrease for locations farther from the river, where recharge by precipitation dominates, and a low-permeable aquitard layer above the highly permeable aquifer is present. This specific setting impairs the identifiability of model parameters. For river infiltration, short mTTs (<40 weeks) were determined for sites closer to the river (<200 m), whereas for the precipitation infiltration, the mTTs were longer (>80 weeks) and independent of the distance to the river. The results not only enhance the understanding of the groundwater recharge dynamics in the VMD but also suggest that the highly complex mechanisms of surface-groundwater interaction can be conceptualized by exploiting two-component LPMs in general. The model concept could thus be a powerful tool for better understanding both the hydrological functioning of mixing processes and the movement of different water components in riverbank infiltration systems. KW - bank infiltration KW - groundwater KW - lumped parameter model KW - mean transit time KW - Mekong Delta KW - stable isotopes Y1 - 2019 U6 - https://doi.org/10.1002/hyp.13549 SN - 0885-6087 SN - 1099-1085 VL - 33 IS - 24 SP - 3098 EP - 3118 PB - Wiley CY - Hoboken ER -