Modern isotope hydrology and controls on δD of plant leaf waxes at Lake El'gygytgyn, NE Russia

Abstract

Abstract. Stable isotope data from lipid biomarkers and diatom silica recovered from lake sediment cores hold great promise for paleoclimate and paleohydrological reconstructions. However, these records rely on accurate calibration with modern precipitation and hydrologic processes and only limited data exist on the controls on the δD values for n-alkanoic acids from plant leaf waxes. Here we investigate the stable isotopic composition of modern precipitation, streams, lake water and ice cover, and use these data to constrain isotope systematics of the Lake El'gygytgyn Basin hydrology. Compound-specific hydrogen isotope ratios determined from n-alkanoic acids from modern vegetation are compared with modern precipitation and lake core top sediments. Multi-species net (apparent) fractionation values between source water (precipitation) and modern vegetation (e.g., ϵwax/precip mean value is −107 ± 12‰) agree with previous results and suggest a consistent offset between source waters and the δD values of alkanoic acids. We conclude that although there may be some bias towards a winter precipitation signal, overall δD values from leaf wax n-alkanoic acids record annual average precipitation within the El'gygytgyn Basin. A net fractionation calculated for 200-yr-integrated lake sediments yields ϵ30/precip = −96 ± 8‰ and can provide robust net "apparent" fractionation to be used in future paleohydrological reconstructions.

Preliminary estimation of Lake El'gygytgyn water balance and sediment income

“…In summer 2003 the active layer varied between 0.4 m in silty material and 0.8 m in sand and gravel (Schwamborn et al, 2012). The Crater region belongs to the hypoarctic tundra vegetation zone (Yurtsev, 1973) with discontinuous cover dominated by lichen and herbaceous taxa (Kohzevnikov, 1993;Minyuk, 2005;Lozhkin et al, 2006;Wilkie et al, 2013). …”

Neoglacial transition of atmospheric circulation patterns over Fennoscandia recorded in Holocene Lake Torneträsk sediments

“…In addition, the lower temperatures during evaporation and higher continentality of moisture originating from the Arctic Ocean and the Baltic Sea lead to further D-depletion of precipitation from these sources (Rosqvist et al 2007;Jonsson et al 2009). As previous results from Arctic environments have shown that the D/H isotopic composition of the C 26 fatty acid might be influenced by contributions of C 26 fatty acid from autochthonous production (Wilkie et al 2013), we only use the C 28 fatty acid for the palaeoclimatic reconstruction. The Tornetr€ ask compound-specific dD values of the C 28 and C 26 fatty acids (Fig.…”

Past freeze and thaw cycling in the margin of the El'gygytgyn crater deduced from a 141 m long permafrost record

“…to max. ranges; GMWL (global meteoric water line) after Craig (1961); * data from Wilkie et al (2013). 3.0 • C. Lake El'gygytgyn is similar to that: it has a measured temperature between 3 and 4 • at the bottom depending on the season (Cremer and Wagner, 2003). Time and depth dimensions of those two other sites are comparable with Lake El'gygytgyn when considering past talik growth at the lake edge.…”

“…Wilkie et al (2013) have specified an annual average partitioning of precipitation in El'gygytgyn crater into 60 % winter contribution and 40 % summer input (annual average δ 18 O = −19.3 ‰, δD = −152.9 ‰). Bearing in mind this estimate and also the error bars of minimum and maximum δ values in the sample sets (Table 1, Fig.…”