In situ characterization using natural radio-tracers in a submarine freshwater spring, Kiveri, Greece.

A medium resolution underwater gamma ray spectrometer was deployed in the submarine groundwater spring of Anavalos and was combined with conductivity and temperature sensors for continuous measurements of natural radioactivity, salinity and water temperature, respectively. The activity concentrations of radon progenies varied from (5-40) kBq m-3, exhibited reverse dependence with salinity and were found above the guideline proposed by Environmental Protection Agency (11 kBq m-3). Their ratio was above unity indicating radon gas escape to the atmosphere. Time-series of the activity concentration together with their ratios were provided enabling the system configuration for long term monitoring applications. The in-situ method proved to be an effective tool to study the radioactivity levels of the spring and the groundwater - seawater interaction process. Furthermore, the proposed tool provides cost-effective measurements in terms of real-time and long-term requirements and, it is characterized by flexibility in terms of sensor integration in different platforms to perform submarine groundwater studies in a temporal and spatial manner.

Trace metal variability, background levels and pollution status assessment in line with the water framework and Marine Strategy Framework EU Directives in the waters of a heavily impacted Mediterranean Gulf.

The aim of this work is to assess trace metal pollution status (Cd, Cu, Ni, Pb, Zn) in the waters of Saronikos Gulf, Greece, in line with the WFD and MSFD European Directives, based on data collected over a decade (2000-2010). Dissolved metal background levels are estimated for the first time for Greek marine waters and the upper limits are: Cd: 0.574 nmol L(-1); Cu: 8.26 nmol L(-1); Ni: 7.94 nmol L(-1); Pb: 2.60 nmol L(-1); Zn: 115 nmol L(-1). The variability of dissolved and particulate metals reflected the presence of several point sources and revealed the importance of natural mechanisms acting as non-point sources. The status of Saronikos Gulf is classified as 'High' for most metals studied. An exception to this is the enclosed Elefsis Bay where Cu, Ni and Zn concentrations are found above background. Our work will assist the implementation of WFD and MSFD directives in Greece.