Sediment accumulation rates based on 210Pb dating in the Coreaú River Estuary, northeastern Brazil

The analysis of sediment accumulation rates from cores collected from marine environments has enabled the reconstruction of depositional records spanning the past century using radionuclides such as ²¹⁰ Pb. ²¹⁰ Pb is a member of the ²³⁸ U decay series and is commonly used to investigate recent processes owing to its half-life of 22.3 years. This radionuclide enters the marine environment through dry and wet conditions and from the decay of its parent isotopes. ²¹⁰ Pb is particularly effective in determining the accumulation rates within the sediment layers formed from 5 to 100 years. This study focused on the Coreaú River Estuary, located in Camocim on the Ceará coast of Brazil. Nine sediment cores collected throughout the estuary revealed steady-state sediment accumulation rates in some of the cores. In the other cores, the ²¹⁰ Pb profiles were inconclusive. These cores exhibited substantial bioturbated mud in the upper 10–30 cm, below which the radioactivity decreased abruptly. These findings provide insights into sediment accumulation across the estuary, particularly near its mouth. Our findings indicate sediment accumulation was more rapid on the eastern bank and near the estuary mouth and was likely influenced by estuarine hydrodynamics and the influx of organic material from human activities into the secondary channels of the river. These findings highlight the importance of monitoring sediment dynamics in estuarine systems impacted by human activities and provide a foundation for future coastal management and conservation efforts. Further research incorporating additional dating methods and hydrodynamic modeling is recommended to refine sedimentation trends and their long-term implications