Reconstruction of the late Quaternary paleoenvironments of the Nussloch loess paleosol -- Response to comments by G. Wiesenberg and M. Gocke

Zech, Michael; Rass, Simon; Buggle, Björn; Löscher, Manfred; Zöller, Ludwig

doi:10.1016/j.yqres.2012.12.010

Cited by 4 publications

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“…Concerning degradation effects on n -alkane patterns, two possible correction procedures were suggested by Buggle et al (2010) and Zech et al (2009, 2013a). There is also a discussion as to whether n -alkane biomarkers in loess sequences are significantly affected by postdepositional root and rhizomicrobial sources (e.g., Wiesenberg and Gocke, 2013 vs. Zech et al, 2013b). This controversy stimulated compound-specific as well as bulk n -alkane 14 C dating in loess research.…”

Section: Methodological Approaches To the Study Of Loessmentioning

confidence: 99%

Approaches and challenges to the study of loess—Introduction to the LoessFest Special Issue

et al. 2018

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In September 2016, the annual meeting of the International Union for Quaternary Research’s Loess and Pedostratigraphy Focus Group, traditionally referred to as a LoessFest, met in Eau Claire, Wisconsin, USA. The 2016 LoessFest focused on “thin” loess deposits and loess transportation surfaces. This LoessFest included 75 registered participants from 10 countries. Almost half of the participants were from outside the United States, and 18 of the participants were students. This review is the introduction to the special issue forQuaternary Researchthat originated from presentations and discussions at the 2016 LoessFest. This introduction highlights current understanding and ongoing work on loess in various regions of the world and provides brief summaries of some of the current approaches/strategies used to study loess deposits.

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Section: Methodological Approaches To the Study Of Loessmentioning

confidence: 99%

Approaches and challenges to the study of loess—Introduction to the LoessFest Special Issue

et al. 2018

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“…In general, long-chain (C 27 -C 31 ) n-alkanes are derived from epicuticular plant waxes of terrestrial plants (Galy et al, 2011;Puttock et al, 2014), medium chain-length (C 21 -C 25 ) n-alkanes are produces by lower plants and aquatic 123 macrophytes (Fang et al, 2014;Meyers, 2003;Tolosa et al, 2013), while short chain-length (C 15 -C 19 ) n-alkanes are typically derived from aquatic algae (Meyers, 2003). Both individual n-alkanes as well as different chain-length ratios have been used in paleo-ecological studies to attribute OM sources over decadal to millennial timescales (Ranjan et al, 2015;Zech et al, 2013Zech et al, , 2012. As n-alkane signatures are altered by land use change, they are ideally suited to track changing OM sources from eroded soils and sediments over time (Chen et al, 2016).…”

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Tracing of particulate organic C sources across the terrestrial-aquatic continuum, a case study at the catchment scale (Carminowe Creek, southwest England)

Glendell

Jones

Dungait

et al. 2018

Science of The Total Environment

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Soils deliver crucial ecosystem services, such as climate regulation through carbon (C) storage and food security, both of which are threatened by climate and land use change. While soils are important stores of terrestrial C, anthropogenic impact on the lateral fluxes of C from land to water remains poorly quantified and not well represented in Earth system models. In this study, we tested a novel framework for tracing and quantifying lateral C fluxes from the terrestrial to the aquatic environment at a catchment scale. The combined use of conservative plant-derived geochemical biomarkers n-alkanes and bulk stable δC and δN isotopes of soils and sediments allowed us to distinguish between particulate organic C sources from different land uses (i.e. arable and temporary grassland vs. permanent grassland vs. riparian woodland vs. river bed sediments) (p<0.001), showing an enhanced ability to distinguish between land use sources as compared to using just n-alkanes alone. The terrestrial-aquatic proxy (TAR) ratio derived from n-alkane signatures indicated an increased input of terrestrial-derived organic matter (OM) to lake sediments over the past 60years, with an increasing contribution of woody vegetation shown by the C/C ratio. This may be related to agricultural intensification, leading to enhanced soil erosion, but also an increase in riparian woodland that may disconnect OM inputs from arable land uses in the upper parts of the study catchment. Spatial variability of geochemical proxies showed a close coupling between OM provenance and riparian land use, supporting the new conceptualization of river corridors (active river channel and riparian zone) as critical zones linking the terrestrial and aquatic C fluxes. Further testing of this novel tracing technique shows promise in terms of quantification of lateral C fluxes as well as targeting of effective land management measures to reduce soil erosion and promote OM conservation in river catchments.

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δ2Hn-alkane and δ18Osugar biomarker proxies from leaves and topsoils of the Bale Mountains, Ethiopia, and implications for paleoclimate reconstructions

et al. 2021

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The hydrogen isotopic composition of leaf wax–derived n-alkane (δ2Hn-alkane) and oxygen isotopic composition of hemicellulose–derived sugar (δ18Osugar) biomarkers are valuable proxies for paleoclimate reconstructions. Here, we present a calibration study along the Bale Mountains in Ethiopia to evaluate how accurately and precisely the isotopic composition of precipitation is imprinted in these biomarkers. n-Alkanes and sugars were extracted from the leaf and topsoil samples and compound–specific δ2Hn-alkane and δ18Osugar values were measured using a gas chromatograph–thermal conversion–isotope ratio mass spectrometer (GC–TC–IRMS). The weighted mean δ2Hn-alkane and δ18Osugar values range from − 186 to − 89‰ and from + 27 to + 46‰, respectively. Degradation and root inputs did not appear to alter the isotopic composition of the biomarkers in the soil samples analyzed. Yet, the δ2Hn-alkane values show a statistically significant species dependence and δ18Osugar yielded the same species–dependent trends. The reconstructed leaf water of Erica arborea and Erica trimera is 2H– and 18O–enriched by + 55 ± 5 and + 9 ± 1‰, respectively, compared to precipitation. By contrast, Festuca abyssinica reveals the most negative δ2Hn-alkane and least positive δ18Osugar values. This can be attributed to “signal–dampening” caused by basal grass leaf growth. The intermediate values for Alchemilla haumannii and Helichrysum splendidum can be likely explained with plant physiological differences or microclimatic conditions affecting relative humidity (RH) and thus RH–dependent leaf water isotope enrichment. While the actual RH values range from 69 to 82% (x̄ = 80 ± 3.4%), the reconstructed RH values based on a recently suggested coupled δ2Hn-alkane –δ18Osugar (paleo–) hygrometer approach yielded a mean of 78 ± 21%. Our findings corroborate (i) that vegetation changes, particularly in terms of grass versus non–grassy vegetation, need to be considered in paleoclimate studies based on δ2Hn-alkane and δ18Osugar records and (ii) that the coupled δ2Hn-alkane –δ18Osugar (paleo–) hygrometer approach holds great potential for deriving additional paleoclimatic information compared to single isotope approaches.

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Reconstruction of the late Quaternary paleoenvironments of the Nussloch loess paleosol -- Response to comments by G. Wiesenberg and M. Gocke

Cited by 4 publications

References 12 publications

Approaches and challenges to the study of loess—Introduction to the LoessFest Special Issue

Approaches and challenges to the study of loess—Introduction to the LoessFest Special Issue

Tracing of particulate organic C sources across the terrestrial-aquatic continuum, a case study at the catchment scale (Carminowe Creek, southwest England)

δ2Hn-alkane and δ18Osugar biomarker proxies from leaves and topsoils of the Bale Mountains, Ethiopia, and implications for paleoclimate reconstructions

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