Using radium isotopes to characterize water ages and coastal mixing rates: A sensitivity analysis

摘要: Numerous studies have used naturally occurring Ra isotopes (223Ra, 224Ra, 226Ra, and 228Ra, with half-lives of 11.4 d, 3.7 1600 y, 5.8 respectively) to quantify water mass ages, coastal ocean mixing rates, submarine groundwater discharge (SGD). Using Monte Carlo models, this study investigated how uncertainties in isotope activities the derived activity ratios (AR) arising from analytical uncertainty natural variability affect associated Ra-derived ages eddy diffusion coefficients, both which can be calculate SGD. Analytical 228Ra were reported most published less than 10% sample activity; those for 223Ra ranged 7% 40%. Relative related — estimated 224Ra replicate field samples 15% 50% was similar activity, 224Ra/223Ra AR. Our analysis revealed that AR-based shorter 3–5 d often relative greater 100%, potentially limiting their utility. Uncertainties coefficients based on cross-shore gradients short-lived when fewer points determine linear trend, coefficient determination (R2) low, rather 223Ra, used. By exploring will enable researchers apply these methods more effectively reduce uncertainty.