Assessing the Radioactivity Level of Seawater and Sand Samples from the Baltic Sea Region

Abstract

Current work reports on a novel method for determining radionuclide concentration and radioactivity in seawater by comparing the gamma-ray spectra of water-free samples of seawater and foreshore sand flooded by waves. By applying the proposed method, it is possible to save time and effort that are used to monitor the quality of seawater in the Baltic Sea with its characteristic sandy shores. Foreshore sand filters seawater trapping insoluble sediments together with radionuclides brought by waves. Radiation spectra of natural and artificial radionuclides in samples of seawater, foreshore sand, and sand taken on top of the dune (reference sample) in the Juodkrante area in Lithuania, were recorded by a gamma-ray spectrometer utilizing a NaI detector. The analysis of radiation spectra in the energy range of 30–1670 keV and the identification of radionuclides were performed using computer software. The richest collection and the highest concentration of radionuclides, including Na-22, Ar-41, Sc-46, Fe-59, Y-91, Zr-97, Nb-94, and Te-132, found in the foreshore sand confirm that the sand traps them from seawater carried by waves. Simultaneous analysis of both seawater and foreshore sand spectra is a way of accurate estimation of the radionuclide concentration at the time of seawater sampling and prior to that. Using a reference sample, the NaI detector, operating at room temperature, can be exploited to make a qualitative determination of the concentration and radioactivity of radionuclides in water-free samples.