A re-evaluation of the average chain length of lacustrine sedimentary n-alkanes as a paleoproxy on the Qinghai-Tibet Plateau

Abstract

Long-chain n-alkanes are one of the most common organic compounds in terrestrial plants and they are well-preserved in various geological archives. n-alkanes are relatively resistant to degradation and thus they can provide high-fidelity records of past vegetation and climate changes. Nevertheless, previous studies have shown that the interpretation of n-alkane proxies, such as the average chain length (ACL), is often ambiguous since this proxy depends on more than one variable. Both vegetation and climate could exert controls on the n-alkane ACL, and hence its interpretation requires careful consideration, especially in regions like the Qinghai-Tibet Plateau (QTP) where topography, biome type and moisture source are highly variable. To further evaluate the influences of vegetation and climate on the ACL in high-elevation lakes, we examined the n-alkane distributions of the surface sediments of 55 lakes across the QTP. Our results show that the ACL across a climatic gradient is significantly affected by precipitation, rather than by temperature. The positive correlation between ACL and precipitation may be because of the effect of microbial degradation during deposition. Finally, we suggest that more caution is needed in the interpretation of ACL data in different regions.

Graphical abstract

Keywords

ACL / average chain length / n-alkanes / leaf wax / lake sediments / Qinghai-Tibet Plateau

References

[1] Aichner B, Herzschuh U, Wilkes H (2010). Influence of aquatic macrophytes on the stable carbon isotopic signatures of sedimentary organic matter in lakes on the Tibetan Plateau.Org Geochem, 41(7): 706–718

[2] Badewien T, Vogts A, Rullkötter J (2015). n-Alkane distribution and carbon stable isotope composition in leaf waxes of C₃ and C₄ plants from Angola. Org Geochem, 89–90: 71–79

[3] Bai Y, Azamdzhon M, Wang S, Fang X, Guo H, Zhou P, Chen C, Liu X, Jia S, Wang Q (2019). An evaluation of biological and climatic effects on plant n-alkane distributions and δ²H_alk in a field experiment conducted in central Tibet.Org Geochem, 135: 53–63

[4] Bai Y, Fang X, Nie J, Wang Y, Wu F (2009). A preliminary reconstruction of the paleoecological and paleoclimatic history of the Chinese Loess Plateau from the application of biomarkers.Palaeogeogr Palaeoclimatol Palaeoecol, 271(1–2): 161–169

[5] Bird B W, Polisar P J, Lei Y, Thompson L G, Yao T, Finney B P, Bain D J, Pompeani D P, Steinman B A (2014). A Tibetan lake sediment record of Holocene Indian summer monsoon variability.Earth Planet Sci Lett, 399: 92–102

[6] Bliedtner M, Schäfer I K, Zech R, von Suchodoletz H (2018). Leaf wax n-alkanes in modern plants and topsoils from eastern Georgia (Caucasus)–implications for reconstructing regional paleovegetation.Biogeosciences, 15(12): 3927–3936

[7] Bondada B R, Oosterhuis D M, Murphy J B, Kim K S (1996). Effect of water stress on the epicuticular wax composition and ultrastructure of cotton (Gossypium hirsutum L.) leaf, bract, and boll.Environ Exp Bot, 36(1): 61–69

[8] Brincat D, Yamada K, Ishiwatari R, Uemura H, Naraoka H (2000). Molecular-isotopic stratigraphy of long-chain n-alkanes in Lake Baikal Holocene and glacial age sediments.Org Geochem, 31(4): 287–294

[9] Bush R T, McInerney F A (2013). Leaf wax n-alkane distributions in and across modern plants: implications for paleoecology and chemotaxonomy.Geochim Cosmochim Acta, 117: 161–179

[10] Bush R T, McInerney F A (2015). Influence of temperature and C₄ abundance on n-alkane chain length distributions across the central USA.Org Geochem, 79: 65–73

[11] Callegaro A, Battistel D, Kehrwald N M, Matsubara Pereira F, Kirchgeorg T, Villoslada Hidalgo M D C, Bird B W, Barbante C (2018). Fire, vegetation, and Holocene climate in a southeastern Tibetan lake: a multi-biomarker reconstruction from Paru Co.Clim Past, 14(10): 1543–1563

[12] Carr A S, Boom A, Grimes H L, Chase B M, Meadows M E, Harris A (2014). Leaf wax n-alkane distributions in arid zone South African flora: environmental controls, chemotaxonomy and palaeoecological implications.Org Geochem, 67: 72–84

[13] Castañeda I S, Caley T, Dupont L, Kim J H, Malaizé B, Schouten S (2016). Middle to Late Pleistocene vegetation and climate change in subtropical southern East Africa.Earth Planet Sci Lett, 450: 306–316

[14] Castañeda I S, Mulitza S, Schefuss E, Lopes dos Santos R A, Sinninghe Damsté J S, Schouten S (2009a). Wet phases in the Sahara/Sahel region and human migration patterns in North Africa.Proc Natl Acad Sci USA, 106(48): 20159–20163

[15] Castañeda I S, Werne J P, Johnson T C, Filley T R (2009b). Late Quaternary vegetation history of southeast Africa: the molecular isotopic record from Lake Malawi.Palaeogeogr Palaeoclimatol Palaeoecol, 275(1–4): 100–112

[16] Chen L, Zhou W, Zhang Y, Zheng Y, Huang X (2020). Postglacial floral and climate changes in southeastern China recorded by distributions of n-alkan-2-ones in the Dahu sediment-peat sequence.Palaeogeogr Palaeoclimatol Palaeoecol, 538: 109448

[17] Chen Y, Cao J, Zhao J, Xu H, Arimoto R, Wang G, Han Y, Shen Z, Li G (2014). n-alkanes and polycyclic aromatic hydrocarbons in total suspended particulates from the southeastern Tibetan Plateau: concentrations, seasonal variations, and sources.Sci Total Environ, 470-471: 9–18

[18] Cooper J E, Bray E E (1963). A postulated role of fatty acids in petroleum formation.Geochim Cosmochim Acta, 27(11): 1113–1127

[19] Diefendorf A F, Freeman K H, Wing S L, Graham H V (2011). Production of n-alkyl lipids in living plants and implications for the geologic past.Geochim Cosmochim Acta, 75(23): 7472–7485

[20] Dodd R S, Afzal-Rafii Z (2000). Habitat-related adaptive properties of plant cuticular lipids.Evolution, 54(4): 1438–1444

[21] Dodd R S, Poveda M M (2003). Environmental gradients and population divergence contribute to variation in cuticular wax composition in Juniperus communis.Biochem Syst Ecol, 31(11): 1257–1270

[22] Doskey P V (2000). The air–water exchange of C₁₅–C₃₁ n-alkanes in a precipitation-dominated seepage lake.Atmos Environ, 34(23): 3981–3993

[23] Duan Y I, He J (2011). Distribution and isotopic composition of n-alkanes from grass, reed and tree leaves along a latitudinal gradient in China.Geochem J, 45(3): 199–207

[24] Eglinton G, Hamilton R J (1967). Leaf epicuticular waxes.Science, 156(3780): 1322–1335

[25] Eley Y L, Hren M T (2018). Reconstructing vapor pressure deficit from leaf wax lipid molecular distributions.Sci Rep, 8(1): 3967

[26] Feakins S J, deMenocal P B, Eglinton T I (2005). Biomarker records of late Neogene changes in northeast African vegetation.Geology, 33(12): 977–980

[27] Freeman K H, Pancost R D (2014). Biomarkers for terrestrial plants and climate. In: Holland HD, Turekian K K, eds. Treatise on Geochemistry. Oxford: Elsevier

[28] Gagosian R B, Peltzer E T (1986). The importance of atmospheric input of terrestrial organic material to deep sea sediments.Org Geochem, 10(4–6): 661–669

[29] Gaines S M, Eglinton G, Rullkötter J (2009). Echoes of life: what fossil molecules reveal about Earth history. Now York: Oxford University Press

[30] Garcin Y, Schefuß E, Schwab V F, Garreta V, Gleixner G, Vincens A, Todou G, Séné O, Onana J M, Achoundong G, Sachse D (2014). Reconstructing C₃ and C₄ vegetation cover using n-alkane carbon isotope ratios in recent lake sediments from Cameroon, Western Central Africa.Geochim Cosmochim Acta, 142: 482–500

[31] Gong P, Wang X, Yao T (2011). Ambient distribution of particulate- and gas-phase n-alkanes and polycyclic aromatic hydrocarbons in the Tibetan Plateau.Environ Earth Sci, 64(7): 1703–1711

[32] Günther F, Thiele A, Biskop S, Mäusbacher R, Haberzettl T, Yao T, Gleixner G (2016). Late quaternary hydrological changes at Tangra Yumco, Tibetan Plateau: a compound-specific isotope-based quantification of lake level changes.J Paleolimnol, 55(4): 369–382

[33] Guo Y, Guo N, He Y, Gao J (2015). Cuticular waxes in alpine meadow plants: climate effect inferred from latitude gradient in Qinghai-Tibetan Plateau.Ecol Evol, 5(18): 3954–3968

[34] Häggi C, Eglinton T I, Zech W, Sosin P, Zech R (2019). A 250 ka leaf-wax δD record from a loess section in Darai Kalon, Southern Tajikistan.Quat Sci Rev, 208: 118–128

[35] He J, Yang K, Tang W, Lu H, Qin J, Chen Y, Li X (2020). The first high-resolution meteorological forcing dataset for land process studies over China.Sci Data, 7(1): 25

[36] Hockun K, Mollenhauer G, Ho S L, Hefter J, Ohlendorf C, Zolitschka B, Mayr C, Lücke A, Schefuß E (2016). Using distributions and stable isotopes of n-alkanes to disentangle organic matter contributions to sediments of Laguna Potrok Aike, Argentina.Org Geochem, 102: 110–119

[37] Hoffmann B, Kahmen A, Cernusak L A, Arndt S K, Sachse D (2013). Abundance and distribution of leaf wax n-alkanes in leaves of Acacia and Eucalyptus trees along a strong humidity gradient in northern Australia.Org Geochem, 62: 62–67

[38] Hollister K V, Thomas E K, Raynolds M K, Bültmann H, Raberg J H, Miller G H, Sepúlveda J (2022). Aquatic and terrestrial plant contributions to sedimentary plant waxes in a modern Arctic lake setting.J Geophys Res: Biogeosci, 127: e2022JG006903

[39] Hou X (2001). Vegetation Atlas of China. Beijing: Science Press

[40] Howard S, McInerney F A, Caddy-Retalic S, Hall P A, Andrae J W (2018). Modelling leaf wax n-alkane inputs to soils along a latitudinal transect across Australia.Org Geochem, 121: 126–137

[41] Hu X, Zhu L, Wang Y, Wang J, Peng P, Ma Q, Hu J, Lin X (2014). Climatic significance of n-alkanes and their compound-specific δD values from lake surface sediments on the southwestern Tibetan Plateau.Chin Sci Bull, 59(24): 3022–3033

[42] Huang Y, Freeman K H, Eglinton T I, Alayne Street-Perrott F (1999a). δ¹³C analyses of individual lignin phenols in Quaternary lake sediments: a novel proxy for deciphering past terrestrial vegetation changes.Geology, 27(5): 471–474

[43] Huang Y, Street-Perrott F A, Perrott R A, Metzger P, Eglinton G (1999b). Glacial–interglacial environmental changes inferred from molecular and compound-specific δ¹³C analyses of sediments from Sacred Lake, Mt. Kenya.Geochim Cosmochim Acta, 63(9): 1383–1404

[44] Immerzeel W W, Lutz A F, Andrade M, Bahl A, Biemans H, Bolch T, Hyde S, Brumby S, Davies B J, Elmore A C, Emmer A, Feng M, Fernández A, Haritashya U, Kargel J S, Koppes M, Kraaijenbrink P D A, Kulkarni A V, Mayewski P A, Nepal S, Pacheco P, Painter T H, Pellicciotti F, Rajaram H, Rupper S, Sinisalo A, Shrestha A B, Viviroli D, Wada Y, Xiao C, Yao T, Baillie J E M (2020). Importance and vulnerability of the world’s water towers.Nature, 577(7790): 364–369

[45] Immerzeel W W, van Beek L P, Bierkens M F (2010). Climate change will affect the Asian water towers.Science, 328(5984): 1382–1385

[46] Jalali B, Sicre M A, Kallel N, Azuara J, Combourieu-Nebout N, Bassetti M A, Klein V (2017). High-resolution Holocene climate and hydrological variability from two major Mediterranean deltas (Nile and Rhone).Holocene, 27(8): 1158–1168

[47] Jia Q, Sun Q, Xie M, Shan Y, Ling Y, Zhu Q, Tian M (2016). Normal alkane distributions in soil samples along a Lhasa-Bharatpur Transect.Acta Geol Sin, 90: 738–748

[48] Jiang W, Wu H, Li Q, Lin Y, Yu Y (2019). Spatiotemporal changes in C₄ plant abundance in China since the Last Glacial Maximum and their driving factors.Palaeogeogr Palaeoclimatol Palaeoecol, 518: 10–21

[49] Jin C, Günther F, Li S, Jia G, Peng P, Gleixner G (2016). Reduced early Holocene moisture availability inferred from δD values of sedimentary n-alkanes in Zigetang Co, Central Tibetan Plateau.Holocene, 26(4): 556–566

[50] Ju J T, Zhu L P, Huang L, Yang R M, Ma Q F, Hu X, Wang Y J, Zhen X L (2015). Ranwu Lake, a proglacial lake with the potential to reflect glacial activity in SE Tibet. Chin Sci Bull, 60(1): 16–26 (in Chinese)

[51] Kawamura K, Ishimura Y, Yamazaki K (2003). Four years᾽ observations of terrestrial lipid class compounds in marine aerosols from the western North Pacific. Global Biogeochem Cycles, 17: 3–1-3–1

[52] Kuechler R R, Schefuß E, Beckmann B, Dupont L, Wefer G (2013). NW African hydrology and vegetation during the Last Glacial cycle reflected in plant-wax-specific hydrogen and carbon isotopes.Quat Sci Rev, 82: 56–67

[53] Kusch S, Rethemeyer J, Schefuß E, Mollenhauer G (2010). Controls on the age of vascular plant biomarkers in Black Sea sediments.Geochim Cosmochim Acta, 74(24): 7031–7047

[54] Leider A, Hinrichs K U, Schefuß E, Versteegh G J M (2013). Distribution and stable isotopes of plant wax derived n-alkanes in lacustrine, fluvial and marine surface sediments along an Eastern Italian transect and their potential to reconstruct the hydrological cycle.Geochim Cosmochim Acta, 117: 16–32

[55] Li L, Li Q, Li J, Wang H, Dong L, Huang Y, Wang P (2015). A hydroclimate regime shift around 270ka in the western tropical Pacific inferred from a late Quaternary n-alkane chain-length record.Palaeogeogr Palaeoclimatol Palaeoecol, 427: 79–88

[56] Li Q, Wu H, Yu Y, Sun A, Luo Y (2019). Large-scale vegetation history in China and its response to climate change since the Last Glacial Maximum.Quat Int, 500: 108–119

[57] Li R, Fan J, Xue J, Meyers P A (2017). Effects of early diagenesis on molecular distributions and carbon isotopic compositions of leaf wax long chain biomarker n-alkanes: comparison of two one-year-long burial experiments.Org Geochem, 104: 8–18

[58] Ling Y, Sun Q, Zheng M, Wang H, Luo Y, Dai X, Xie M, Zhu Q (2017a). Alkenone-based temperature and climate reconstruction during the last deglaciation at Lake Dangxiong Co, southwestern Tibetan Plateau.Quat Int, 443: 58–69

[59] Ling Y, Zheng M, Sun Q, Dai X (2017b). Last deglacial climatic variability in Tibetan Plateau as inferred from n-alkanes in a sediment core from Lake Zabuye.Quat Int, 454: 15–24

[60] Ling Y, Zheng M, Wang S, Sun Q, Xie B, Zhang C (2021). The impact of climatic and environmental factors on n-alkanes indices in southwestern Tibetan Plateau.Acta Geol Sin, 95: 648–658

[61] Liu H, Liu W (2016). n-Alkane distributions and concentrations in algae, submerged plants and terrestrial plants from the Qinghai-Tibetan Plateau.Org Geochem, 99: 10–22

[62] Liu J, Shen Z, Chen W, Chen J, Zhang X, Chen J, Chen F (2021). Dipolar mode of precipitation changes between north China and the Yangtze River Valley existed over the entire Holocene: evidence from the sediment record of Nanyi Lake.Int J Climatol, 41(3): 1667–1681

[63] Liu W, Liu Z, Wang H, He Y, Wang Z, Xu L (2011). Salinity control on long-chain alkenone distributions in lake surface waters and sediments of the northern Qinghai-Tibetan Plateau, China.Geochim Cosmochim Acta, 75(7): 1693–1703

[64] Liu W, Yang H, Wang H, An Z, Wang Z, Leng Q (2015). Carbon isotope composition of long chain leaf wax n-alkanes in lake sediments: a dual indicator of paleoenvironment in the Qinghai-Tibet Plateau. Org Geochem, 83–84: 190–201

[65] Liu X, Cheng Z, Yan L, Yin Z Y (2009). Elevation dependency of recent and future minimum surface air temperature trends in the Tibetan Plateau and its surroundings.Global Planet Change, 68(3): 164–174

[66] McDuffee K E, Eglinton T I, Sessions A L, Sylva S, Wagner T, Hayes J M (2004). Rapid analysis of ¹³C in plant-wax n-alkanes for reconstruction of terrestrial vegetation signals from aquatic sediments.Geochem Geophys Geosyst, 5(10): Q10004

[67] Meyers P A (1997). Organic geochemical proxies of paleoceanographic, paleolimnologic, and paleoclimatic processes.Org Geochem, 27(5–6): 213–250

[68] Meyers P A, Ishiwatari R (1995). Organic matter accumulation records in lake sediments. In: Lerman A, Imboden D M, Gat J R, eds. Physics and Chemistry of Lakes. Heidelberg: Springer Berlin

[69] Mountain Research Initiative EDW Working Group (2015). Elevation-dependent warming in mountain regions of the world.Nat Clim Chang, 5(5): 424–430

[70] Naafs B D A, Inglis G N, Blewett J, McClymont E L, Lauretano V, Xie S, Evershed R P, Pancost R D (2019). The potential of biomarker proxies to trace climate, vegetation, and biogeochemical processes in peat: a review.Global Planet Change, 179: 57–79

[71] Nelson D B, Ladd S N, Schubert C J, Kahmen A (2018). Rapid atmospheric transport and large-scale deposition of recently synthesized plant waxes.Geochim Cosmochim Acta, 222: 599–617

[72] Ni J, Cao X, Jeltsch F, Herzschuh U (2014). Biome distribution over the last 22,000yr in China.Palaeogeogr Palaeoclimatol Palaeoecol, 409: 33–47

[73] Nichols J E, Booth R K, Jackson S T, Pendall E G, Huang Y (2006). Paleohydrologic reconstruction based on n-alkane distributions in ombrotrophic peat.Org Geochem, 37(11): 1505–1513

[74] Norström E, Katrantsiotis C, Smittenberg R H, Kouli K (2017). Chemotaxonomy in some Mediterranean plants and implications for fossil biomarker records.Geochim Cosmochim Acta, 219: 96–110

[75] Norström E, Neumann F H, Scott L, Smittenberg R H, Holmstrand H, Lundqvist S, Snowball I, Sundqvist H S, Risberg J, Bamford M (2014). Late Quaternary vegetation dynamics and hydro-climate in the Drakensberg, South Africa.Quat Sci Rev, 105: 48–65

[76] Norström E, Norén G, Smittenberg R H, Massuanganhe E A, Ekblom A (2018). Leaf wax δD inferring variable medieval hydroclimate and early initiation of Little Ice Age (LIA) dryness in southern Mozambique.Global Planet Change, 170: 221–233

[77] Poynter J G, Farrimond P, Robinson N, Eglinton G (1989). Aeolian-derived higher plant lipids in the marine sedimentary record: links with palaeoclimate. In: Leinen M, Sarnthein M, eds. Paleoclimatology and Paleometeorology: Modern and Past Patterns of Global Atmospheric Transport. Dordrecht: Springer

[78] Poynter J, Eglinton G (1990). Molecular composition of three sediments from Hole 717 C: the Bengal fan. In: Proceedings of the Ocean Drilling Program, Scientific Results, 155–161

[79] Pu Y, Nace T, Meyers P A, Zhang H, Wang Y, Zhang C L, Shao X (2013). Paleoclimate changes of the last 1000 yr on the eastern Qinghai–Tibetan Plateau recorded by elemental, isotopic, and molecular organic matter proxies in sediment from glacial Lake Ximencuo. Palaeogeogr Palaeoclimatol Palaeoecol, 379–380: 39–53

[80] Qiao B, Zhu L, Yang R (2019). Temporal-spatial differences in lake water storage changes and their links to climate change throughout the Tibetan Plateau.Remote Sens Environ, 222: 232–243

[81] Qin F (2021). Modern pollen assemblages of the surface lake sediments from the steppe and desert zones of the Tibetan Plateau.Sci China Earth Sci, 64(3): 425–439

[82] Qin F, Zhao Y, Cao X (2022). Biome reconstruction on the Tibetan Plateau since the Last Glacial Maximum using a machine learning method.Sci China Earth Sci, 65(3): 518–535

[83] Rao Z, Jia G, Qiang M, Zhao Y (2014). Assessment of the difference between mid- and long chain compound specific δD-alkanes values in lacustrine sediments as a paleoclimatic indicator.Org Geochem, 76: 104–117

[84] Rao Z, Zhu Z, Jia G, Chen F, Barton L, Zhang J, Qiang M (2010). Relationship between climatic conditions and the relative abundance of modern C₃ and C₄ plants in three regions around the North Pacific.Chin Sci Bull, 55(18): 1931–1936

[85] Rojo F (2009). Degradation of alkanes by bacteria.Environ Microbiol, 11(10): 2477–2490

[86] Rommerskirchen F, Plader A, Eglinton G, Chikaraishi Y, Rullkötter J (2006). Chemotaxonomic significance of distribution and stable carbon isotopic composition of long-chain alkanes and alkan-1-ols in C₄ grass waxes.Org Geochem, 37(10): 1303–1332

[87] Sachse D, Billault I, Bowen G J, Chikaraishi Y, Dawson T E, Feakins S J, Freeman K H, Magill C R, McInerney F A, van der Meer M T J, Polissar P, Robins R J, Sachs J P, Schmidt H L, Sessions A L, White J W C, West J B, Kahmen A (2012). Molecular paleohydrology: interpreting the hydrogen-isotopic composition of lipid biomarkers from photosynthesizing organisms.Annu Rev Earth Planet Sci, 40(1): 221–249

[88] Saini J, Günther F, Aichner B, Mischke S, Herzschuh U, Zhang C, Mäusbacher R, Gleixner G (2017). Climate variability in the past ∼19,000 yr in NE Tibetan Plateau inferred from biomarker and stable isotope records of Lake Donggi Cona.Quat Sci Rev, 157: 129–140

[89] Sarkar S, Prasad S, Wilkes H, Riedel N, Stebich M, Basavaiah N, Sachse D (2015). Monsoon source shifts during the drying mid-Holocene: biomarker isotope based evidence from the core ‘monsoon zone’ (CMZ) of India.Quat Sci Rev, 123: 144–157

[90] Schefuß E, Ratmeyer V, Stuut J B W, Jansen J H F, Sinninghe Damsté J S (2003). Carbon isotope analyses of n-alkanes in dust from the lower atmosphere over the central eastern Atlantic.Geochim Cosmochim Acta, 67(10): 1757–1767

[91] Šepič E Leskovšek H, Trier C (1995). Aerobic bacterial degradation of selected polyaromatic compounds and n-alkanes found in petroleum.J Chromatogr A, 697(1–2): 515–523

[92] Shepherd T, Wynne Griffiths D (2006). The effects of stress on plant cuticular waxes.New Phytol, 171(3): 469–499

[93] Simoneit B R T, Chester R, Eglinton G (1977). Biogenic lipids in particulates from the lower atmosphere over the eastern Atlantic.Nature, 267(5613): 682–685

[94] Sinninghe Damsté J S, Verschuren D, Ossebaar J, Blokker J, van Houten R, van der Meer M T J, Plessen B, Schouten S (2011). A 25,000-year record of climate-induced changes in lowland vegetation of eastern equatorial Africa revealed by the stable carbon-isotopic composition of fossil plant leaf waxes.Earth Planet Sci Lett, 302(1–2): 236–246

[95] Still C J, Berry J A, Collatz G J, Defries R S (2009). ISLSCP, II: C₄ (Vegetation Percentage. In. ORNL Distributed Active Archive Center)

[96] Still C J, Berry J A, Collatz G J, DeFries R S (2003). Global distribution of C₃ and C₄ vegetation: carbon cycle implications. Global Biogeochemical Cycles, 17: 6–1-6–1

[97] Sun H, Bendle J, Seki O, Zhou A (2018). Mid- to- late Holocene hydroclimatic changes on the Chinese Loess Plateau: evidence from n-alkanes from the sediments of Tianchi Lake.J Paleolimnol, 60(4): 511–523

[98] Tian L, Wang M, Zhang X, Yang X, Zong Y, Jia G, Zheng Z, Man M (2019). Synchronous change of temperature and moisture over the past 50 ka in subtropical southwest China as indicated by biomarker records in a crater lake.Quat Sci Rev, 212: 121–134

[99] Tipple B J, Pagani M (2013). Environmental control on eastern broadleaf forest species’ leaf wax distributions and D/H ratios.Geochim Cosmochim Acta, 111: 64–77

[100] Toney J L, García-Alix A, Jiménez-Moreno G, Anderson R S, Moossen H, Seki O (2020). New insights into Holocene hydrology and temperature from lipid biomarkers in western Mediterranean alpine wetlands.Quat Sci Rev, 240: 106395

[101] Vogts A, Moossen H, Rommerskirchen F, Rullkötter J (2009). Distribution patterns and stable carbon isotopic composition of alkanes and alkan-1-ols from plant waxes of African rain forest and savanna C₃ species.Org Geochem, 40(10): 1037–1054

[102] Wakeham S G (1996). Aliphatic and polycyclic aromatic hydrocarbons in Black Sea sediments.Mar Chem, 53(3–4): 187–205

[103] Wan W, Long D, Hong Y, Ma Y, Yuan Y, Xiao P, Duan H, Han Z, Gu X (2016). A lake data set for the Tibetan Plateau from the 1960s, 2005, and 2014.Sci Data, 3(1): 1–13

[104] Wang B, Ma Y, Su Z, Wang Y, Ma W (2020). Quantifying the evaporation amounts of 75 high-elevation large dimictic lakes on the Tibetan Plateau.Sci Adv, 6(26): eaay8558

[105] Wang B, Yang J, Jiang H, Zhang G, Dong H (2019). Chemical composition of n-alkanes and microbially mediated n-alkane degradation potential differ in the sediments of Qinghai-Tibetan lakes with different salinity.Chem Geol, 524: 37–48

[106] Wang J, Axia E, Xu Y, Wang G, Zhou L, Jia Y, Chen Z, Li J (2018a). Temperature effect on abundance and distribution of leaf wax n-alkanes across a temperature gradient along the 400 mm isohyet in China.Org Geochem, 120: 31–41

[107] Wang J, Xu Y, Zhou L, Shi M, Axia E, Jia Y, Chen Z, Li J, Wang G (2018b). Disentangling temperature effects on leaf wax n-alkane traits and carbon isotopic composition from phylogeny and precipitation.Org Geochem, 126: 13–22

[108] Wang L, Lü H, Wu N, Chu D, Han J, Wu Y, Wu H, Gu Z (2004). Discovery of C₄ species at high altitude in Qinghai-Tibetan Plateau.Chin Sci Bull, 49(13): 1392–1396

[109] Wang M, Zhang W, Hou J (2015). Is average chain length of plant lipids a potential proxy for vegetation, environment and climate changes?.Biogeosciences Discuss, 12: 5477–5501

[110] Wang R Z (2003). C₄ plants in the vegetation of Tibet, China: their natural occurrence and altitude distribution pattern.Photosynthetica, 41(1): 21–26

[111] Wang S, Dou H (1998). Lakes in China. Beijing: Science Press

[112] Witt R, Günther F, Lauterbach S, Kasper T, Mäusbacher R, Yao T, Gleixner G (2016). Biogeochemical evidence for freshwater periods during the Last Glacial Maximum recorded in lake sediments from Nam Co, south-central Tibetan Plateau.J Paleolimnol, 55(1): 67–82

[113] Wu M S, West A J, Feakins S J (2019a). Tropical soil profiles reveal the fate of plant wax biomarkers during soil storage.Org Geochem, 128: 1–15

[114] Wu Y, Guo L, Zheng H, Zhang B, Li M (2019b). Hydroclimate assessment of gridded precipitation products for the Tibetan Plateau.Sci Total Environ, 660: 1555–1564

[115] Xie M, Sun Q, Dong H, Liu S, Shang W, Ling Y, Zhao J, Chu G (2020). n-Alkanes and compound carbon isotope records from Lake Yiheshariwusu in the Hulun Buir sandy land, northeastern China.Holocene, 30(10): 1451–1461

[116] Yan T, He J, Wang Z, Zhang C, Feng X, Sun X, Leng C, Zhao C (2020). Glacial fluctuations over the last 3500 years reconstructed from a lake sediment record in the northern Tibetan Plateau.Palaeogeogr Palaeoclimatol Palaeoecol, 544: 109597

[117] Yao T, Xue Y, Chen D, Chen F, Thompson L, Cui P, Koike T, Lau W K M, Lettenmaier D, Mosbrugger V, Zhang R, Xu B, Dozier J, Gillespie T, Gu Y, Kang S, Piao S, Sugimoto S, Ueno K, Wang L, Wang W, Zhang F, Sheng Y, Guo W, Ailikun , Yang X, Ma Y, Shen S S P, Su Z, Chen F, Liang S, Liu Y, Singh V P, Yang K, Yang D, Zhao X, Qian Y, Zhang Y, Li Q (2019). Recent Third Pole’s rapid warming accompanies cryospheric melt and water cycle intensification and interactions between monsoon and environment: multidisciplinary approach with observations, modeling, and analysis.Bull Am Meteorol Soc, 100(3): 423–444

[118] Yokoyama Y, Naruse T, Ogawa N O, Tada R, Kitazato H, Ohkouchi N (2006). Dust influx reconstruction during the last 26000 years inferred from a sedimentary leaf wax record from the Japan Sea.Global Planet Change, 54(3–4): 239–250

[119] Zech M, Pedentchouk N, Buggle B, Leiber K, Kalbitz K, Marković S B, Glaser B (2011). Effect of leaf litter degradation and seasonality on D/H isotope ratios of n-alkane biomarkers.Geochim Cosmochim Acta, 75(17): 4917–4928

[120] Zech R, Zech M, Marković S, Hambach U, Huang Y (2013). Humid glacials, arid interglacials? Critical thoughts on pedogenesis and paleoclimate based on multi-proxy analyses of the loess–paleosol sequence Crvenka, Northern Serbia.Palaeogeogr Palaeoclimatol Palaeoecol, 387: 165–175

[121] Zhang X, Xu B, Günther F, Witt R, Wang M, Xie Y, Zhao H, Li J, Gleixner G (2017). Rapid northward shift of the Indian Monsoon on the Tibetan Plateau at the end of the Little Ice Age.J Geophys Res Atmos, 122(17): 9262–9279

[122] Zhang Y, Liu X, Lin Q, Gao C, Wang J, Wang G (2014). Vegetation and climate change over the past 800 years in the monsoon margin of northeastern China reconstructed from n-alkanes from the Great Hinggan Mountain ombrotrophic peat bog.Org Geochem, 76: 128–135

[123] Zhang Z, Zhao M, Eglinton G, Lu H, Huang C (2006). Leaf wax lipids as paleovegetational and paleoenvironmental proxies for the Chinese Loess Plateau over the last 170 kyr.Quat Sci Rev, 25(5–6): 575–594

[124] Zhao J, Thomas E K, Yao Y, DeAraujo J, Huang Y (2018). Major increase in winter and spring precipitation during the Little Ice Age in the westerly dominated northern Qinghai-Tibetan Plateau.Quat Sci Rev, 199: 30–40

[125] Zhou B, Zheng H, Yang W, Taylor D, Lu Y, Wei G, Li L, Wang H (2012). Climate and vegetation variations since the LGM recorded by biomarkers from a sediment core in the northern South China Sea.J Quaternary Sci, 27(9): 948–955

[126] Zhou W, Xie S, Meyers P A, Zheng Y (2005). Reconstruction of late glacial and Holocene climate evolution in southern China from geolipids and pollen in the Dingnan peat sequence.Org Geochem, 36(9): 1272–1284

[127] Zhou W, Zheng Y, Meyers P A, Jull A J T, Xie S (2010). Postglacial climate-change record in biomarker lipid compositions of the Hani peat sequence, northeastern China.Earth Planet Sci Lett, 294(1–2): 37–46

[128] Zhu C S, Li L J, Huang H, Dai W T, Lei Y L, Qu Y, Huang R J, Wang Q Y, Shen Z X, Cao J J (2020). n-Alkanes and PAHs in the southeastern Tibetan Plateau: characteristics and correlations with brown carbon light absorption.J Geophys Res: Atmos, 125: e2020JD032666

Acknowledgments

We thank Mr. Mohammad Ali Salik from the Biomarkers for Environmental and Climate Science (BECS) research group at the University of Glasgow for assistance with laboratory techniques and equipment, Dr. Feng Qin for discussion of the vegetation information extraction, Dr. Yan Yan for discussion of n-alkanes, and Dr. Jan Bloemendal for English language improvement. We are especially grateful to Prof. Xianyu Huang and an anonymous reviewer for their helpful suggestions and advice for improving the manuscript. This work was financially supported by the National Natural Science Foundation of China (Grant No. 42171159) and the Second Tibetan Plateau Scientific Expedition and Research Program (STEP) (No. 2019QZKK0601). Financial support to Mingda Wang for a one-year visit to the University of Glasgow from the Chinese Academy of Sciences is also acknowledged.

Competing interests

The authors declare that they have no competing interests.

RIGHTS & PERMISSIONS

2023 Higher Education Press

审图号：GS京（2024）0126号