Lipid distributions in loess-paleosol sequences from northwest China

Xie, Shucheng; Chen, Fahu; Wang, Zhiyuan; Wang, Hongmei; Gu, Yansheng; Huang, Yongsong

doi:10.1016/s0146-6380(03)00083-4

Cited by 68 publications

(52 citation statements)

References 32 publications

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“…The representative Quaternary loess from the Jiuzhoutai section at Lanzhou [Xie et al, 2003] is dominated by two peaks at n-C 18 and n-C 31 .…”

Section: Resultsmentioning

confidence: 99%

“…In reality, climate drying during Plio-Quaternary should produce more dried up lakebed upwind to the Loess Plateau area. However, many loess plateau sites (the Luochuan and Xunyi sections [Zhang et al, 2006], Chaona section [Bai et al, 2009], Jiuzhoutai section [Xie et al, 2003] and Tawan section [Zeng et al, 2011]) have relative low abundances of middle chain n-alkanes, which suggests that eolian contributions of middle-chain n-alkanes should be limited and abundant middle-chain n-alkanes observed from Tianshui are most likely autochthonous.…”

Section: Discussionmentioning

confidence: 99%

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Biomarkers challenge early Miocene loess and inferred Asian desertification

Peng¹,

Li²,

Song³

et al. 2012

Geophysical Research Letters

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[1] Fine-grained Miocene sediments from Tianshui Basin, northeastern Tibetan Plateau, have received intense attention recently because these sediments were identified as loess. The presence of early Miocene loess pushes the timing of initiation of inland Asian desertification from 8 Ma back to 22 Ma. However, mudflat/distal fan and shallow lake sediments of Miocene have also been reported in Tianshui Basin. Consequently, the origin of these fine-grained Miocene sediments in this area remains controversial. Here we investigate the n-alkane biomarker characteristics of Neogene sediments from a north-south transect of exposures within Tianshui Basin and compare these molecular distributions with those published Quaternary loess to help resolve the disputed origin. We found that n-C 23 and n-C 25 alkanes, sourced from either aquatic macrophytes or palustrine plants, are ubiquitous in the Miocene sediments from Tianshui Basin but are largely absent in Quaternary loess. This striking difference between n-alkane distributions in the Tianshui samples and the Quaternary loess casts doubt on an eolian origin for the Tianshui samples and challenges the hypothesis of an early Miocene onset of Asian interior desertification.

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“…The representative Quaternary loess from the Jiuzhoutai section at Lanzhou [Xie et al, 2003] is dominated by two peaks at n-C 18 and n-C 31 .…”

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Biomarkers challenge early Miocene loess and inferred Asian desertification

Peng¹,

Li²,

Song³

et al. 2012

Geophysical Research Letters

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“…Extracts from rye and maize roots as well as from farmyard manure (Halle, East-Germany) yielded high abundances of n-C 16 and/or n-C 18 , but in the soils under rye or maize cultivation these short-chain n-alkanes were hardly present (Jandl et al, 2007), and their findings were not supported by complementary studies on similar tissues (e.g., Wiesenberg et al, 2004b). Xie et al (2003) found maximum peaks at n-C 16 or n-C 18 in palaeosoils but with an odd-over-even predominance above n-C 22 . An even-over-odd predominance of nalkane compounds, including n-C 16-18 alkanes, was reported by Love et al (2005) for products derived from diverse marine and freshwater microalgae and bacteria species.…”

Section: N-alkanesmentioning

confidence: 94%

“…The distribution patterns of lipidic compounds like n-alkanes may therefore indicate the sources of biomass inputs in soils or sediments (Jambu et al, 1991;Amblè s et al, 1994;Marseille et al, 1999;Peters et al, 2005). Lipid analysis has been demonstrated to be a useful tool to detect vegetation or land use changes in soils after several thousands of years, e.g., to identify the use of grass turfs to build the Orkney plaggen soils (Bull et al, 1999a), or to follow the environmental history in lake sediments (Schwark et al, 2002;Fisher et al, 2003) and in a sequence of palaeosoils (Xie et al, 2003). During the recent past, a variety of lipid patterns and compounds have been described to be diagnostic for different organic materials.…”

Section: Introductionmentioning

confidence: 99%

Short-chain n-alkanes (C16–20) in ancient soil are useful molecular markers for prehistoric biomass burning

Eckmeier

Wiesenberg

2009

Journal of Archaeological Science

101

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The incorporation of plant biomass into soil usually leads to long-chain n-alkanes with a relative predominance of odd carbon numbered homologues. Contrastingly, an increase in short-chain even carbon numbered n-alkanes was found in charred biomass with progressing temperatures. We applied lipid analysis to buried ancient topsoils that contained charred organic matter and to corresponding control soils, which were characterized by a lighter color and lower contents of charred materials. Commonly, the proportion of lipid extracts was found to be lower in the ancient soil than in the control samples, which indicated an enhanced degradation of organic matter, e.g., by thermal degradation. All samples displayed a particular pattern of short-chain and even carbon numbered n-alkanes (maximum at n-C16 or n-C18). The ratios CPI (carbon preference index) and ACL (average chain length) for the investigated soil samples matched the ratios found for maize and rye straw charred at 400 °C or 500 °C, respectively. These molecular ratios indicate the presence of charred biomass. The predominance of short-chain and even carbon numbered n-alkanes was a result of thermal degradation of biomass. The degradation products were preserved in ancient soils and could be applied as molecular markers in archaeological or palaeoenvironmental research.Author's personal copy b s t r a c tThe incorporation of plant biomass into soil usually leads to long-chain n-alkanes with a relative predominance of odd carbon numbered homologues. Contrastingly, an increase in short-chain even carbon numbered n-alkanes was found in charred biomass with progressing temperatures. We applied lipid analysis to buried ancient topsoils that contained charred organic matter and to corresponding control soils, which were characterized by a lighter color and lower contents of charred materials. Commonly, the proportion of lipid extracts was found to be lower in the ancient soil than in the control samples, which indicated an enhanced degradation of organic matter, e.g., by thermal degradation. All samples displayed a particular pattern of short-chain and even carbon numbered n-alkanes (maximum at n-C 16 or n-C 18 ). The ratios CPI (carbon preference index) and ACL (average chain length) for the investigated soil samples matched the ratios found for maize and rye straw charred at 400 C or 500 C, respectively. These molecular ratios indicate the presence of charred biomass. The predominance of short-chain and even carbon numbered n-alkanes was a result of thermal degradation of biomass. The degradation products were preserved in ancient soils and could be applied as molecular markers in archaeological or palaeoenvironmental research.

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“…Thus, although n-alkan-2-ones have been addressed extensively in various kinds of sediments, most studies have focussed mainly on their distribution and origin, and assessments of their use as palaeoclimate proxies in sediments remain scarce (Xie et al, 2003(Xie et al, , 2008 in comparison with other n-alkyl lipids. Furthermore, only a few studies show the n-alkan-2-one distribution in modern plants, with C 17 to C 33 components being observed in cyanobacteria and aquatic macrophytes (Wenchuan et al, 1999), as well as seagrass (Hernández et al, 2001) and Sphagnum species (Baas et al, 2000;Nichols and Huang, 2007).…”

Section: Introductionmentioning

confidence: 99%

n-Alkan-2-ones in peat-forming plants from the Roñanzas ombrotrophic bog (Asturias, northern Spain)

Ortíz

Díaz-Bautista

Aldasoro

et al. 2011

Organic Geochemistry

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We determined the distribution of lipids (n-alkanes and n-alkan-2-ones) in present-day peat-forming plants in the Roñanzas Bog in northern Spain. Consistent with the observation of others, most Sphagnum (moss) species alkanes maximized at C 2 3, whereas the other plants maximized at higher molecular weight (C 2 7 to C 31 ). We show for the first time that plants other than seagrass and Sphagnum moss contain n-alkan-2-ones. Almost all the species analysed showed an n-alkan-2-one distribution between C 2 i and C 31 with an odd/even predominance, maximizing at C 2 7 or C 29 , except ferns, which maximized at lower molecular weight (C 21 -C 23 ). We also observed that microbial degradation can be a major contributor to the n-alkan-2-one distribution in sediments as opposed to a direct input of ketones from plants.

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Lipid distributions in loess-paleosol sequences from northwest China

Cited by 68 publications

References 32 publications

Biomarkers challenge early Miocene loess and inferred Asian desertification

Biomarkers challenge early Miocene loess and inferred Asian desertification

Short-chain n-alkanes (C16–20) in ancient soil are useful molecular markers for prehistoric biomass burning

n-Alkan-2-ones in peat-forming plants from the Roñanzas ombrotrophic bog (Asturias, northern Spain)

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