Temporal investigation of radionuclides and heavy metals in a coastal mining area at Ierissos Gulf, Greece.

Vertical variations of radionuclides, trace metals, and major elements were determined in two sediment cores, which were collected in the marine environment of Ierissos Gulf near Stratoni's mining area. The enrichment factors (EFs) were also estimated and provided moderately severe to extremely severe enrichment for most trace elements and Mn, describing the anthropogenic influence in the gulf during the previous century. According to the applied dating models based on 210Pb and 137Cs, the effect in the marine sediment due to the exploitation of pyrite for the production of sulfuric acid during 1912-1920 was observed. Additionally, the decrease of mining activity during 1935-1945 due to the Second World War and the type of ore exploitation, the alteration of the exploited ores, and the construction and operation of Olympiada's floatation plant during 1950-1970 were identified. The end of tailing discharging into the marine environment during 1980-2010 was also noted.

Development and optimization of an underwater in-situ cerium bromide spectrometer for radioactivity measurements in the aquatic environment.

A new medium resolution gamma-ray spectrometer consisting of a cerium bromide (CeBr3) crystal (2˝ x 2˝), is developed and optimized for radioactivity measurements in aquatic environments. This apparatus named GeoMAREA (Gamma-ray spectrometer for in-situ Marine Environmental Applications) is designed to control and prevent radio-contaminants in aquatic environments as well as to estimate the variation of natural radionuclides in marine systems for studying oceanographic processes. The system offers activity concentrations in Bq/m3 for detected gamma-ray emitters in the energy range from 150 to 2600 keV, and can provide sequential continuous monitoring data in a stand-alone mode or it can be integrated in stationary/mobile platforms for (near) real-time applications. The photopeak efficiency values were estimated via the MCNPΧ code. Two experimental points were used to validate the theoretical estimations by deploying the system in a water tank with diluted reference sources such us Caesium-137 (137Cs) and Potassium-40 (40K). The system was subsequently deployed in the field along with a conductivity-temperature (CT) sensor, to measure 40K and radon daughters in a region where submarine groundwater discharges (Anavalos, Kiveri, Greece) are present. The experimental calibration data was utilized to provide a first estimation for the background contribution around the photopeak of 40K, attributed to the Cerium Bromide (CeBr3) intrinsic activity.

Integration of Underwater Radioactivity and Acoustic Sensors into an Open Sea Near Real-Time Multi-Parametric Observation System.

This work deals with the installation of two smart in-situ sensors (for underwater radioactivity and underwater sound monitoring) on the Western 1-Mediterranean Moored Multisensor Array (W1-M3A) ocean observing system that is equipped with all appropriate modules for continuous, long-term and real-time operation. All necessary tasks for their integration are described such as, the upgrade of the sensors for interoperable and power-efficient operation, the conversion of data in homogeneous and standard format, the automated pre-process of the raw data, the real-time integration of data and metadata (related to data processing and calibration procedure) into the controller of the observing system, the test and debugging of the developed algorithms in the laboratory, and the obtained quality-controlled data. The integration allowed the transmission of the acquired data in near-real time along with a complete set of typical ocean and atmospheric parameters. Preliminary analysis of the data is presented, providing qualitative information during rainfall periods, and combine gamma-ray detection rates with passive acoustic data. The analysis exhibits a satisfactory identification of rainfall events by both sensors according to the estimates obtained by the rain gauge operating on the observatory and the remote observations collected by meteorological radars.

Mobile underwater in situ gamma-ray spectroscopy to localize groundwater emanation from pockmarks in the Eckernförde bay, Germany.

Eckernförde Bay in the Baltic Sea is well-known for the pockmarks areas which are located in the centre and off the southern shore-line of the bay emanating groundwater in a non-continuous but episodic way. Mobile underwater in situ gamma-ray spectroscopy is exploited proving that both 214Bi and 40K are efficient radiotracers for localization of seepage areas whenever either sediment is in mixture with the emanating fluid or resuspension of surface sediment occurs as a side effect of the fluid emanation.

Historical trends and assessment of radionuclides and heavy metals in sediments near an abandoned mine, Lavrio, Greece.

Two sediment cores (coastal and offshore) and surface sediments were collected near an abandoned mine area in the marine environment of Oxygono Bay at Lavreotiki peninsula to investigate temporal and spatial variations among radionuclides and trace metals/major elements. Lavreotiki was and still is well known for the mining and metallurgical activities, which lasted from ancient times to nowadays (early 1980s). Gamma-ray and X-ray fluorescence measurements were held to determine the radionuclide and trace metal/major element concentrations, respectively. The sedimentation rate at Oxygono Bay coastal core was determined using the 210Pb and 137Cs tracers, while the enrichment factors were estimated to assess the anthropogenic influence due to metals in a spatial (surface sediments) and a temporal (coastal core sediments) basis. The mass flux at the coastal core was utilized to provide a baseline information at Lavreotiki peninsula. The trace metal/major element profiles were indeed associated with the mining activity in the area, revealing the mining history. The ERICA Tool was incorporated to estimate the dose rates due to natural and 137Cs radioactivity in the marine organisms and the values were found below the screening levels.

Chemical inputs from a karstic submarine groundwater discharge (SGD) into an oligotrophic Mediterranean coastal area.

The impacts of nutrient and other chemical inputs released by a submarine groundwater discharge (SGD) on the marine environment of an oligotrophic Mediterranean coastal area (Messiniakos Gulf, SE Ionian Sea) are investigated through a multidisciplinary approach. Nutrients and organic pollutants associated with the SGD are presented to study the chemical characteristics of the SGD and to investigate its effect on the marine ecosystem in comparison to freshwater discharges of the water bodies of Messinia Prefecture. Nutrient and organic pollutant fluxes were calculated from (214)Bi-based SGD estimates. An average of 22×10(3) mol of silicate per month and 8×10(3) mol of nitrate per month were released via the SGD. Nutrient concentrations at the mouth of the SGD were three times higher than in Messiniakos Gulf, and NO3(-) was the primary Dissolved Inorganic Nitrogen form discharged by SGD. Organic pollutant concentrations associated with agricultural activities were low at the SGD. The implementation of a Eutrophication Index (E.I.) showed that the water column at the SGD site corresponds to Moderate/Bad ecological quality, whereas the status switches rapidly to Good at a small distance from the SGD. Coastal areas influenced by river or sewage discharge correspond to a Moderate/Good ecological status. The BENTIX index used for the classification of the ecological quality status of the benthic macroinvertebrate communities showed that the SGD has a minor influence compared to the other freshwater discharges in Messiniakos Gulf. Though the SGD has a considerable outflow, morphology and hydrodynamics of the area favor the rapid dispersion of the upwelling water and degrades the SGD's effect even on a regional scale.

In-situ radionuclide characterization of a submarine groundwater discharge site at Kalogria Bay, Stoupa, Greece.

In-situ underwater gamma-ray spectrometer KATERINA was used for continuous measurements of radon progenies ((214)Pb, (214)Bi), thoron progeny ((208)Tl) and (40)K in submarine groundwater discharge (SGD) sites at Kalogria Bay, SW Peloponnesus (Greece). The spectrometer was deployed attached on measuring platform along with two conductivity - temperature data loggers while underwater battery packs supplied the system for acquisition periods up to 25 days. The radionuclide time series together with salinity data were obtained for spring (wet) and summer (dry) seasons. The (40)K activity concentrations correlated well with salinity of the emanating groundwater. Although the (214)Bi and (208)Tl activities showed usually similar trends anticorrelating with salinity, in some cases (208)Tl did not follow the (214)Bi record due to changes in the dynamics of the groundwater aquifer. As the half-life of (220)Rn is very short (55.6 s), its concentration in SGD may depend on the distance from its origin to the monitoring point. The observed temporal variations of (214)Bi and (208)Tl confirmed advantages of continuous in-situ monitoring of SGD in coastal areas.