Distribution of lipids in modern soils from various regions with continuous climate (moisture-heat) change in China and their climate significance

Abstract

Total 26 modern soil samples were collected from various regions under different climate conditions from tropical to arid temperate in China and systematically analyzed for their organic matters by GC/MSin order to evaluate climatic impacts on soil organic components. Abundant lipids molecules were recognized, including n-alkanes, n-alkenones, and long-chain branched alkanes. We find the predominance of main peaks of long-chain n-alkanes (nC 29 , nC 31 , nC 33 ) and short-chain ones (nC 16 , nC 17 , nC 18 ) records information of soil generation in warm-humid and cold-dry regions. The proportion of n-alkanes (nC 16 +nC 17 +nC 18 ) to (nC 29 +nC 31 +nC 33 ) varies in good agreement with moisture-heat conditions and thus probably can serve as a new index for climate change. The ratios of C 21 − /nC 22 + , nC 17 /nC 31 and (nC 15 +nC 17 +nC 19 ) / ( nC 27 +nC 29 +nC 31 ) of n-alkanes, indicating respectively input ratios of lower bacterial alga, aquatic organisms, and higher plants and terraneous organisms, co-vary well in different climate regions from forest to grassland and desert, suggesting that they have also reflected the difference of climates between monsoon region and inland one. The C 21 − /C 22 + ratio of n-alkan-2-one records largely the discrepancy of temperature from north to south of China bordered by the Qinling Mountains, but less humidity. The C 21 − /C 22 + ratio of n-alkan-3-ones changes well with climatic factors, such as temperature and humidity. The biogenic source of series A-D long-chain branched alkanes may be derived from some kinds of special epiphyte that most likely live in weak oxic-anoxic and moisture-heat environments, suggesting their distribution record as well some information on climatic change. All these researches demonstrate that the distributions of lipids molecules in modern soils in China record well signals of climates from quite different climatic regions, and can serve as important climatic proxies to reveal climatic change over China.lipids molecule, modern soil, climate (moisture-heat) continuously changing regions, climate index, ChinaAt present, the use of molecular fossils to reconstract paleoclimate and ancient human activities has become an important part of molecular stratigraphy [1][2][3][4][5][6] . Molecular fossils have the characteristics of stable compounds, long-time preservation and wide distribution, being good indication of climate and environmental change and providing great information on provenience of parent materials, redox degree of organic matters, development status of bacteria and microorganisms in

Is the maximum carbon number of long-chain n-alkanes an indicator of grassland or forest? Evidence from surface soils and modern plants

“…Of the 62 samples, most (57) were dominated by n-C 29 or n-C 31 (only 5 were dominated by n-C 27 ), regardless of the type of overlying vegetation. This is consistent with the findings of other surface soil studies [13][14][15][16]. More importantly, the patterns of n-alkane distribution in more than 100 surface soils are consistent with those reported for more than 300 modern plant species [2,5,, because most modern plants, whether they are trees, grasses, or shrubs, are also dominated by n-C 29 and n-C 31 .…”

“…This trend has also been reported in other studies. In a similar smaller study of 26 surface soil samples from China and Mongolia, most samples were dominated by n-C 29 and n-C 31 with n-C 31 as the most frequent MCN, and only few samples were dominated by n-C 27 [13]. In another study, n-alkanes of 10 surface soil samples from different climatic and vegetation zones were analyzed.…”

Latitudinal Distribution of Ammonia-Oxidizing Bacteria and Archaea in the Agricultural Soils of Eastern China

“…1). Due to variations in rainfall, solar irradiance, and the mineralogical composition of parent rocks, different types of soils are formed under these climatic conditions (1). The arable lands in eastern China are responsible for Ͼ70% of gross grain yield within China (2).…”

Organic carbon isotope and molecular fossil records of vegetation evolution in central Loess Plateau since 450 kyr

“…In recent years, molecular fossils such as n-alkanes (also called lipids, compound leaf waxes) have become a proxy with great potential in the study of vegetation evolution in loess strata (Xie et al, 2002;Liu et al, 2005;Zhang et al, 2006;Wang et al, 2007;Zhang et al, 2004;Liu et al, 2008;Bai et al, 2009;Long et al, 2011). Long-chain n-alkanes (hereinafter referred to as n-alkanes), mostly produced by terrestrial higher plants, are more stable in the sediment after being buried or stored, and thus can provide a proxy record of original biological and climate information (Eglinton and Hamilton, 1967).…”