The Worldwide Marine Radiocarbon Reservoir Effect: Definitions, Mechanisms, and Prospects

Abstract

When a carbon reservoir has a lower radiocarbon content than the atmosphere, this is referred to as a reservoir effect. This is expressed as an offset between the radiocarbon ages of samples from the two reservoirs at a single point in time. The marine reservoir effect (MRE) has been a major concern in the radiocarbon community, as it introduces an additional source of error that is often difficult to accurately quantify. For this reason, researchers are often reluctant to date marine material where they have another option. The influence of this phenomenon makes the study of the MRE important for a broad range of applications. The advent of Accelerator Mass Spectrometry (AMS) has reduced sample size requirements and increased measurement precision, in turn increasing the number of studies seeking to measure marine samples. These studies rely on overcoming the influence of the MRE on marine radiocarbon dates through the worldwide quantification of the local parameter ΔR, that is, the local variation from the global average MRE. Furthermore, the strong dependence on ocean dynamics makes the MRE a useful indicator for changes in oceanic circulation, carbon exchange between reservoirs, and the fate of atmospheric CO2, all of which impact Earth's climate. This article explores data from the http://calib.qub.ac.uk/marine/ and reviews the place of natural radiocarbon in oceanic records, focusing on key questions (e.g., changes in ocean dynamics) that have been answered by MRE studies and on their application to different subjects.

A genomic dating tool resolves the origins of ancient Eurasian genomes

“…The imprecise dating of nearly half of the ancient individuals and the absence of an independent dating method to radiocarbon dating are the most daunting problems in Paleogenomics. Radiocarbon dating (6,41) is the acceptable dating approach, however its reliance on a large 10 amount of organic material renders many samples undatable.…”

“…Constructing the temporal components. To identify the temporal components, we randomly selected 300 samples from that were merged with 250 individuals ( ) selected evenly 10 from five present-day populations (Chinese CHB, Yoruba YRI, Finnish FIN, British GBR, and Tuscan TSI) from the 1000 Genomes database (42), and filtered them for the same 147,229 SNPs. We applied unsupervised ADMIXTURE (24) for K's ranging from 4 to 12.…”

“…3A). To gauge the reliability 10 of TPS predictions, we defined the accuracy per individual as the absolute difference between TPS result and radiocarbon date. The average accuracy for this testing procedure was 417 years and 68% of the individuals were assigned a TPS date within 500 years from their radiocarbon date.…”

“…A total of 10 samples were excavated from Pannonia at Szólád, a site considered to be of a Longobard type in terms of grave goods, location, and burial practices (36). Amorim et 10 al. (36) suggested that the graves of nine of the samples (SZ2-SZ5, SZ11, SZ15, SZ36, SZ43, SZ45) are from the mid-sixth century after radiocarbon-dated one individual (SZ43: 1,475-1,355 BP).…”

“…We termed these markers Time Informative Markers (TIMs). Conceptually, TIMs are reminiscent of ancient Ancestry Informative Markers (aAIMs) 10 (23), except that they operate along the time axis. Random time-dependent events create unique allele frequencies in the TIMs that are characteristic of the historical period in which individuals lived, which we termed temporal components.…”