Datación de sedimentos y evaluación de tasas de sedimentación mediante el análisis de isótopos radiactivos de origen natural y artificial usados como trazadores

Abstract

The study of the sedimentation rates and dating of sediments has been carried out for years using the disintegration of natural and artificial radioactive isotopes present in the environment. In periods of time corresponding to the last decades, those are with major anthropogenic influence, the used methods are those based ones on the isotope 210Pb of natural origin and 137Cs of artificial origin, both are used in this study. The possibility of relating the concentration of the activity 210Pb present in a sedimentary sample with the depth allows dating the difeerent caps of the cores by the applying mathematical models based in this radioisotope. The establishment of a chronology in the accumulation of sediments will allow in turn, to study the temporary evolution of the sedimentation rate during the last 125 years in San Simón's Inlet, a place in the Vigo's Ria. In this job we describe the models CIC (Constant Initial Concentration) and CRS (Constant Rate of Supply). We consider the conditions of their application to sediments placed in marshes and estuaries. The measurement of the concentrations of interest has carried out using gamma spectrometry, with the corresponding study, calibration in energy and efficiency, and adjustment of the hyper pure germanium detector HPGe.