Age dating of sediment cores in Sorsogon Bay, Philippines, using ²¹⁰Pb method: A revisit

The ²¹⁰Pb dating technique is widely applied for reconstructing sediment accumulation in aquatic environments. However, its reliability depends strongly on appropriate age model and independent validation. In this study, previously reported sedimentation rates for the highly dynamic coastal environment of Sorsogon Bay, Philippines, derived using the Constant Initial Concentration (CIC) model, were reassessed to validate and improve chronological robustness. Guided by statistical and physical assumptions, and supported by the results of CF:CS and CRS age model, the evaluation of regression intervals of excess ²¹⁰Pb activity concentration profiles, the average sedimentation rates of the three sediment cores SO-01 (CAS), SO-03 (CAD), and SO-07 (SAM) were determined to be the best fit. Results of Mann-Whitney U test revealed the influence of natural disturbances, such as eruptions of Mt. Bulusan and major typhoon events that hit the Bicol Region, to sediment characteristics particularly dry bulk density (DBD) and calculated mass accumulation rate (MAR). This further strengthen the qualitative analysis of peak association of DBD and MAR to the documented natural disturbances. This study demonstrates the importance of multi-proxy validation and Mann-Whitney U test in strengthening ²¹⁰Pb-derived chronologies, which are critical for a more robust foundation for investigating land-use change, coastal evolution, pollution histories, climate variability, and other natural and anthropogenic drivers of sediment dynamics over the past century.