14c dating groundwater
In this aquifer system of low alkalinities and low p Hs, radiocarbon ages can be used without model correction.
The groundwaters studied ranged from 42.3% to 95.5% modern carbon and yielded uncorrected ages of 375–6790 yr.
Figure 1: This gif shows the comparison in radioactivity between a sample, or unknown (green area) , a modern standard (dark blue) and a background (small red peaks) derived from beta decay. A radiocarbon measurement, termed a conventional radiocarbon age (or CRA) is obtained using a set of parameters outlined by Stuiver and Polach (1977), in the journal Radiocarbon.The Oxalic acid standard was made from a crop of 1955 sugar beet. The isotopic ratio of HOx I is -19.3 per mille with respect to (wrt) the PBD standard belemnite (Mann, 1983). T designation SRM 4990 C) was made from a crop of 1977 French beet molasses.The Oxalic acid standard which was developed is no longer commercially available. In the early 1980's, a group of 12 laboratories measured the ratios of the two standards.All D14C values are normalized to the base value of -25.0 per mille with respect to the standard carbonate (VPDB).D14C is calculated using: Figure 1: Decay curve for C14 showing the activity at one half-life (t/2).