Using Stable Carbon Isotopes to Quantify Radiocarbon Reservoir Age Offsets in the Coastal Black Sea

Abstract

Constraining radiocarbon (14C) reservoir age offsets is critical to deriving accurate calendar-age chronologies from 14C dating of materials which did not draw carbon directly from the atmosphere. The application of 14C dating to such materials is severely limited in hydrologically sensitive environments like the Black Sea because of the difficulty to quantify reservoir age offsets, which can vary quickly and significantly through time, due to the dynamics of the biogeochemical cycling of carbon. Here we reconstruct 14C reservoir age offsets (Rshell-atm) of Holocene bivalve shells from the coastal Black Sea relatively to their contemporaneous atmosphere. We show that the 14C reservoir age offset and the stable carbon isotope composition of bivalve shells are linearly correlated in this region. From a biogeochemical standpoint, this suggests that inorganic stable carbon isotope and 14C compositions of Black Sea coastal waters are controlled by the balance between autochthonous primary productivity and heterotrophic respiration of allochthonous pre-aged terrestrial organic matter supplied by rivers. This provided an important implication for Black Sea geochronology as the reservoir age offset of 14C-dated bivalve shell can be inferred from its stable carbon isotope composition. Our results provide a fundamental and inexpensive geochemical tool which will considerably improve the accuracy of Holocene calendar age chronologies in the Black Sea.

Geomicrobiology of the carbon, nitrogen and sulphur cycles in Powell Lake: a permanently stratified water column containing ancient seawater

“…The Black Sea, which is the Earth's largest contemporary meromictic water column, may be most similar to Powell Lake with respect to long-term stratification. It was established as a marine basin by connection to the Mediterranean Sea at approximately the same time as Powell Lake was disconnected from the ocean (Yanko-Hombach et al, 2014), but the 'age' of Black Sea deep waters is estimated to be <1000 years (Fontugne et al, 2009;Soulet et al, 2019).…”

Reconstruction of Climate Changes Based δ18Ocarb on the Northeastern Tibetan Plateau: A 16.1-cal kyr BP Record From Hurleg Lake

“…However, owing to the spatiotemporal variability of the carbon reservoir, the carbon reservoir could differ between the sediment cores from the same area (Reimer and Reimer, 2006;Mischke et al, 2013;An et al, 2012;Zhou et al, 2014). Moreover, the carbon reservoirs within the same core are not always constant (Schneider et al, 2019;Soulet et al, 2019), and the commonly used method of subtracting the carbon reservoir ages from the whole section may be unreasonable. Nevertheless, the occurrence of a linear relationship or a quadratic regression suggests that the carbon reservoirs are constant because the hydrochemical conditions in the lake are generally stable (Xiao et al, 2004;Herzschuh et al, 2006;An et al, 2012;Zhang et al, 2016).…”

A Multi-Proxy Approach to Reconstruct Hypoxia on the NW Black Sea Shelf over the Holocene

“…The obtained Local ∆R corrections were 126 ± 40 years for GC7 and 57 ± 85 years for GC15. The second one was based on a new method developed by Soulet et al [34] to estimate the total reservoir ages of the Black Sea bivalve shells. This method uses the δ 13 C determined by isotope ratio mass spectrometer (IRMS).…”

“…This method uses the δ 13 C determined by isotope ratio mass spectrometer (IRMS). The difference between the shell age and the atmospheric organism's age (R shell−atm , i.e., ∆R) was estimated following the formula of Soulet et al [34]:…”

“…a Estimated from the Marine Reservoir Correction Database (http://calib.org/marine/, accessed on October 24, 2019), based on Siani et al[32] and Jones and Gagnon[33]. b Estimated from δ 13 C measurements on bivalve shells from GC15, based on the method of Soulet et al[34].…”