In Situ Radioactivity Measurements and Water Flow Characteristics of a Thermal Spring in Gera Gulf, Lesvos Island, Greece

Abstract

In this study, a thermal spring located in the Gulf of Gera (Lesvos Island) is investigated in terms of radiotracers, water flow velocities and acoustic back-scattering properties by in situ observations. Water flow characteristics were deduced using in situ deployments of three marine sensors: an Acoustic Doppler Velocimeter (ADV), a High-Frequency Acoustic Doppler Current Profiler (ADCP), and a medium-resolution underwater gamma-ray detection system. The flow velocity combined with the activity concentration of natural radionuclides in the thermal spring provided information on the characteristics of the thermal spring in the specific gulf. The proposed methodology estimated the water supply, the residence time in the effective area of the in situ systems, and the residence time in the gulf. Eventually, the estimation of the characteristics of the discharged water source resulted from the synthetic evaluation of oceanographic measurements alongside appropriate models.

Keywords

• thermal spring
• in situ instrumentation
• natural radionuclides
• water flow
• residence time models