The Holocene Isotopic Record of Aquatic Cellulose from Lake Äntu Sinijärv, Estonia: Influence of Changing Climate and Organic-Matter Sources

F. Alayne Street-Perrott,Jonathan A. Holmes, Lain Robertson,Katherine J. Ficken,Tiiu Koff,Neil J. Loader,Jim D. Marshall,Tonu Martma

Quaternary Science Reviews（2018）

Swansea Univ | UCL | Tallinn Univ | Univ Liverpool | Tallinn Univ Technol

Cited 16|Views38

Abstract

The well characterized oxygen-isotopic fractionation during cellulose biosynthesis has been utilised by numerous studies of stable isotopes in fine-grained aquatic cellulose. We measured the delta C-13(celluiose) and delta O-18(cellulose) values of bulk cellulose and moss fragments from similar to 11.4ka-long core obtained from a shallow, productive, spring-fed, hardwater lake, Antu Sinijarv, Estonia (593.8 ' N; 2614.5 ' E; 94.6 m a.s.l.; maximum depth 7.3 m), in order to reconstruct regional Holocene climate and lake-basin evolution. Isotopically, the modern waterbody is a well-behaved, open, hydrological system with negligible evaporative effects. Cellulose-isotope records were compared with down-core measurements of loss-on ignition (LOI), carbonate and mineral contents, total organic carbon (TOC), total nitrogen (TN), C/N ratio, delta C-13(roc), biomarker indices (P-aig and P-aq), published palaeoecological data and a delta O-18(carbonate) record from the same palaeolake. Green microalgae, freshwater macroalgae (Chara) and aquatic bryophytes were important sources of sedimentary cellulose during different phases in the environmental history of the lake. Although a strong palaeoclimatic imprint can be detected in the delta O-18(carbonate) record from Antu Sinijarv, notably the Preboreal oscillation, the 8.2ka event and an unnamed cold oscillation similar to 3.25ka BP, the isotopic signal of these events may have been amplified by increases in O-18-depleted spring snow melt. In contrast, delta C-13(cellulose) was tightly coupled to the Holocene evolution of terrestrial ecosystems and soils by significant inputs of biogenic carbon from the catchment and sublacustrine springs. During the early Holocene, similar to 11 - 9ka BP, the delta O-18(cellulose) and delta O-18(carbonate) records diverge markedly, which can be attributed to "no-analogue" seasonal, climatic, hydrological and isotopic conditions resulting from orbital forcing and residual ice-sheet impacts. (C) 2018 The Authors. Published by Elsevier Ltd.

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