Choosing a suitable ε w-p by distinguishing the dominant plant sources in sediment records using a new Pta index and estimating the paleo-δD p spatial distribution in China

Wang, Zheng; Hu, Liu; Cao, Yunning

doi:10.1016/j.orggeochem.2018.01.002

Cited by 15 publications

(10 citation statements)

References 37 publications

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“…is dominated by n-C 29 . Those findings are in line with previous regional studies, which report n-C 31 being mainly produced by grasses/herbs and n-C 29 by deciduous trees and shrubs (Cheung et al, 2015;Wang et al, 2018c;Liu et al, 2018;Bliedtner et al, 2018a). Although Artemisia spp.…”

Section: N-alkane Pattern In Plantssupporting

confidence: 93%

Leaf wax n-alkane pattern and compound-specific δ13C of plants and topsoils from semi-arid Mongolia

Struck¹,

Bliedtner²,

Strobel³

et al. 2019

Preprint

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Abstract. n-Alkane pattern and their compound-specific &#948;13C signatures are valuable proxies for paleoenvironmental reconstructions. So far, their potential has not been investigated in semi-arid to arid regions. We have therefore analysed the leaf wax n-alkanes and their compound-specific &#948;13C of five plant species (Poaceae, Cyperaceae, Artemisia spp., Caragana spp. and Larix sp.), and topsoils (0&#8211;5&#8201;cm) along two transects in central and southern Mongolia. Grasses depict a distinct dominance of the n-C31 homologue, whereas Caragana spp. and Artemisia spp. are dominated by n-C29. Larix sp. is characterized by the mid-chain n-alkanes n-C23 and n-C25. From plant to soil, n-alkane homologue pattern show the potential to differentiate between grass covered sites from those covered by Caragana spp. n-Alkane concentrations and OEP values of the topsoils are distinctly influenced by mean annual temperature, mean annual precipitation and aridity, likely reflecting the degree of n-alkane degradation and biomass production. In contrast, the n-alkane average chain-length and the n-alkane ratio (n-C31&#8201;/&#8201;n-C29&#8201;+&#8201;n-C31) are not affected by climatic parameters. The compound-specific &#948;13C signatures are strongly corelated to climate, showing a significant enrichment with increasing aridity, indicating the effect of water use efficiency. Our calibration results suggest that long-chain n-alkanes and their compound-specific &#948;13C signatures have great potential to reconstruct paleoenvironmental and -climatic conditions when used in sediment archives from Mongolia.

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Section: N-alkane Pattern In Plantssupporting

confidence: 93%

Leaf wax n-alkane pattern and compound-specific δ13C of plants and topsoils from semi-arid Mongolia

Struck¹,

Bliedtner²,

Strobel³

et al. 2019

Preprint

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“…The εC29/MAP distribution of grasses deviate from either angiosperm or gymnosperm trees, and a change from either source to grasses (or vice versa) would produce a significant shift in the δ 2 H of sedimentary C29. Our data support previous findings (Sachse et al, 2012;Bush and McInerney et al, 2013;Wang et al, 2018) and show that the mean εC29/MAP in grasses (-162 ‰) is ~29 ‰ lower than in angiosperm and gymnosperm trees, respectively (Figure 5). A shift favoring grass inputs to the sediments would decrease C29…”

Section: εApp As a Function Of Vegetation Typesupporting

confidence: 92%

“…However, a dominant submerged aquatic source of C29 alkane is unlikely (Figure 2), except in the absence of higher terrestrial plants around the lakes as is the case with desert lakes (Wang et al, 2018).…”

Section: εApp As a Function Of Vegetation Typementioning

confidence: 99%

“…The difference in the most common chain lengths between aquatic and terrestrial plants has led to the use of the mid-chain alkane C23 as proxy for lake water δ 2 H and evapotranspiration (Ficken et al, 2000;Seki et al, 2011;Rach et al, 2014;Rach et al, 2017;Curtin et al, 2019;Puleo et al, 2020) and to the use of the long-chain alkane C29 as proxy for precipitation δ 2 H (Sachse et al, 2004;Sachse et al, 2012;McFarlin et al, 2019). A challenge with this approach has been that most plants produce varying amounts of both mid-and long-chain nalkanes (Ficken et al, 2000;Gao et al, 2011;Feakins et al, 2016;Wang et al, 2018;Dion-Kirschner et al, 2020;He et al, 2020), and the high production rates of all n-alkanes by terrestrial plants may dominate over aquatic sources even for mid-chain lengths (Freimuth et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

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Mid- and long-chain leaf wax δ2H values in modern plants and lake sediments from mid-latitude North America

Stefanescu¹,

Macdonlad²,

Cook³

et al. 2022

Preprint

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Compound-specific δ2H composition of leaf-wax n-alkanes are increasingly being used to infer past hydroclimates. However, differences in n-alkane production and apparent fractionation factors (εapp) among different plant groups complicate the relationships between n-alkane and environmental water δ2H. Mid- and long-chain n-alkanes in sedimentary archives (i.e., C23 and C29) are thought to derive from aquatic and terrestrial plants, respectively, and track the isotopic composition of either lake water or precipitation. Yet, the relationship between the δ2H composition of alkane C23 and that of lake water is not well constrained. Moreover, recent studies show that n-alkane production is greater in terrestrial plants than in aquatic plants, which has the potential to obscure n-alkane aquatic inputs to sedimentary archives. Here, we investigated n-alkane contributions to sedimentary archives from both aquatic and terrestrial plants by analyzing their distributions and δ2H signatures in plants and lake sediments at 29 sites across mid-latitude North America. We find that both aquatic and terrestrial plants synthesize alkane C23 and that sedimentary C23 δ2H values parallel those of terrestrial plants and differ from those of aquatic plants. Our results indicate that across mid-latitude North America, and globally, both mid- and long-chain n-alkanes in lake sediments commonly derive from terrestrial higher plants challenging the assumption that submerged aquatic plants produce the C23 alkane preserved in lake sediments. Moreover, angiosperms and gymnosperms exhibit similar εapp values between the δ2H of alkane C29 and mean annual precipitation. Therefore, vegetation shifts between angiosperms and gymnosperms do not strongly affect the εapp between alkane C29 and MAP. Our results show that both mid- and long-chain alkanes track the isotopic composition of mean annual precipitation in the temperate region of North America.

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“…The stability of the IRMS was checked with nine groups of reference gas tests, and was better than 0.04‰. Precision of isotope analyses was routinely checked by injection of the laboratory isotope standards (mixed C 21–C33 odd carbon number n ‐alkanes with known δD values calibrated using Indiana University FAME reference substances) after every ∼4–6 sample injections, and was generally within ±2‰ (1σ) (Z. Wang et al., 2018). We also analyzed duplicated samples every other five or six samples to verify the stability of our analyses, the resulted uncertainties are consistent with that of laboratory standards.…”

Section: Methodsmentioning

confidence: 99%

Paleoclimate Significance of Reconstructed Rainfall Isotope Changes in Asian Monsoon Region

Cheng

Wang

Yan

et al. 2021

Geophysical Research Letters

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Speleothem oxygen isotope (δ18Oc) records have been regarded as a critical reference to study past Asian monsoon variability. However, existing δ18Oc records in the Indian monsoon region are fragmented in time coverage and/or sampling resolution since the last deglaciation. Also, the climatic interpretation of δ18Oc is still obscure. Here, we report a continuous and centennial‐resolved leaf wax hydrogen isotope (δDwax) record over the past ∼28 ka from Lugu Lake in Indian‐monsoon influenced southwestern China. Our new record shows striking consistency with the well‐established δ18Oc record in East Asian monsoon‐influenced southeastern China, revealing a spatially coherent change and thus a similar physical process in rainfall isotopes in the broader Asian monsoon region. Based on the combination with the TraCE21ka simulation, we propose reconstructed long‐term and millennial‐scale isotope changes could be influenced by the intensity of local convection along the monsoon trough, which extends from the Indian subcontinent across to the Philippines in summer.

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Choosing a suitable ε w-p by distinguishing the dominant plant sources in sediment records using a new Pta index and estimating the paleo-δD p spatial distribution in China

Cited by 15 publications

References 37 publications

Leaf wax <i>n</i>-alkane pattern and compound-specific δ<sup>13</sup>C of plants and topsoils from semi-arid Mongolia

Leaf wax <i>n</i>-alkane pattern and compound-specific δ<sup>13</sup>C of plants and topsoils from semi-arid Mongolia

Mid- and long-chain leaf wax δ2H values in modern plants and lake sediments from mid-latitude North America

Paleoclimate Significance of Reconstructed Rainfall Isotope Changes in Asian Monsoon Region

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Choosing a suitable ε w-p by distinguishing the dominant plant sources in sediment records using a new Pta index and estimating the paleo-δD p spatial distribution in China

Cited by 15 publications

References 37 publications

Leaf wax &lt;i&gt;n&lt;/i&gt;-alkane pattern and compound-specific δ&lt;sup&gt;13&lt;/sup&gt;C of plants and topsoils from semi-arid Mongolia

Leaf wax &lt;i&gt;n&lt;/i&gt;-alkane pattern and compound-specific δ&lt;sup&gt;13&lt;/sup&gt;C of plants and topsoils from semi-arid Mongolia

Mid- and long-chain leaf wax δ2H values in modern plants and lake sediments from mid-latitude North America

Paleoclimate Significance of Reconstructed Rainfall Isotope Changes in Asian Monsoon Region

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Leaf wax <i>n</i>-alkane pattern and compound-specific δ<sup>13</sup>C of plants and topsoils from semi-arid Mongolia

Leaf wax <i>n</i>-alkane pattern and compound-specific δ<sup>13</sup>C of plants and topsoils from semi-arid Mongolia