Figure 3: Radiocarbon age versus methane-derived carbon contribution to stonefly biomass in three of the wells.
From: Ancient and methane-derived carbon subsidizes contemporary food webs
Radiocarbon ages of stonefly tissue (each point is one individual) were strongly correlated with calculated levels of methane-derived carbon in biomass (R2=0.56, P=<0.0001, n=52), suggesting that (a) a broad range of methane ages was present in the aquifer, as shown by the variation in radiocarbon age even at levels of methane-derived carbon >60%; (b) non-methane-derived carbon was modern because low levels of methane-derived carbon in biomass approaching 0% corresponded with younger radiocarbon ages; and (c) the maximum methane age could be much older than 6900 years, because all stonefly tissue measured was a mixture of various organic carbon sources.
