Biogeochemical proxies of the sediment short core EN18232-1, Lake Khamra, Siberia

This data set is an extension to the previously published data in a bundled publication (Stieg et al., 2024a) from the Russian Lake Khamra (59.99°N, 112.98°E, 340 m a.s.l.), located in eastern Siberia in SW Yakutia. The short core (EN18232-1) was retrieved in summer 2018 and subsampled in 2021 in 39 continuous 1 cm increments covering the last 220 years (ca. 2015-1790 CE). Detailed information about the age-depth model of the short core EN18232-1 can be found in the research paper (Stieg et al., 2024b). The data contains total organic carbon (TOC) and total nitrogen (TN) content of all 39 samples from the short core EN18232-1. Freeze-dried aliquots were ground to obtain a homogeneous material. All measurements were carried out at the BioGeoChemistry Lab at AWI Potsdam. TOC was analysed by using an Elementar soli TOC cube, whereas TN was quantified by an Elementar rapid MAX N exceed. The measurement accuracy was 0.1 % for both devices. We computed the total carbon (TC) by the sum of TOC and the total inorganic carbon (TIC), available in a previous published data set (Stieg et al., 2024c (TIC)). Furthermore, we calculated the TOC/TN atomic ratio by multiplying its mass ratio by 1.167, which is the ratio of the atomic weights of nitrogen and carbon (Meyers and Teranes, 2001). Additionally, we calculated organic carbon accumulation rates (OCARs, g m-2 a-1) by dividing TOC by 100, multiplying it by the mass accumulation rate (MAR, available in Stieg et al., 2024d (Mercury)), and then converting it by further multiplication with a factor of 10,000 to g m-2 a-1 unit. Carbon and nitrogen isotopes (δ13C,δ15N) were determined using a ThermoFisher Scientific Delta‐V‐Advantage gas‐mass spectrometer equipped with a FLASH elemental analyser EA 2000 and a CONFLO IV gas‐mixing system and an MA200R autosampler system at ISOLAB of AWI Potsdam. We used freeze-dried and milled sample material and additionally removed inorganic carbon by a hydrochloric acid treatment (HCl, 1.3 mol L-1) for carbon isotopes. Isotope ratios are given relative to laboratory standards of known isotopic compositions relative to the Vienna Pee Dee Belemnite (VPDB) reference standard for carbon and to the standard atmospheric nitrogen ratio (air) for nitrogen. Results are given as delta notation (δ13C, δ15N) in per mill (‰), with 1σ standard error better than ± 0.15 ‰.