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doi:10.1016/j.jenvrad.2006.03.008 
Copyright © 2006 Elsevier Ltd All rights reserved.
Characterisation of submarine groundwater discharge offshore south-eastern Sicily
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P.P. Povineca, 
, 
, P.K. Aggarwalb, A. Aurelic, W.C. Burnettd, E.A. Kontare, K.M. Kulkarnib, W.S. Mooref, R. Rajarg, M. Taniguchih, J.-F. Comanduccia, G. Cusimanoi, H. Dulaiovad, L. Gattoi, M. Groeningb, S. Hauserj, I. Levy-Palomoa, B. Oregionia, Y.R. Ozorovichk, A.M.G. Priviterac and M.A. Schiavoi
Received 27 July 2005;
Abstract
A complex approach in characterisation of submarine groundwater discharge (SGD) off south-eastern Sicily comprising applications of radioactive and non-radioactive tracers, direct seepage measurements, geophysical surveys and a numerical modelling is presented. SGD fluxes in the Donnalucata boat basin were estimated by direct seepage measurements to be from 4 to 12 L s−1, which are comparable with the total SGD flux in the basin of 17 L s−1 obtained from radon measurements. The integrated SGD flux over the Donnalucata coast estimated on the basis of Ra isotopes was around 60 m3 s−1 per km of the coast. Spatial variations of SGD were observed in the Donnalucata boat basin, the average 222Rn activity concentration in seawater varied from 
0.1 kBq m−3 to 3.7 kBq m−3 showing an inverse relationship with salinity. The continuous monitoring carried out at the site closest to the coast has revealed an inverse relationship of 222Rn activity concentration on the tide. The 222Rn concentrations in seawater varied from 2.3 kBq m−3 during high tides to 4.8 kBq m−3 during low tides, thus confirming an influence of the tide on submarine groundwater discharge. Stable isotopes (δ2H and δ18O) showed that SGD samples consist up to 50% of groundwater. Geo-electrical measurements showed a spatial variability of the salt/fresh water interface and its complex transformation in the coastal zone. The presented results imply that in the studied Donnalucata site there are at least two different sources of SGD, one superficial, represented by mixed fresh water and seawater, and the second one which originates in a deeper limestone aquifer.
Keywords: Submarine groundwater discharge; Groundwater; Seawater; Radioactive and stable isotopes; Seepage measurement; Geophysical survey; Numerical modelling; Mediterranean Sea
Article Outline
- 1. Introduction
- 2. Hydrogeological background
- 3. Materials and methods
- 3.1. Samples
- 3.2. Methods
- 3.2.1. Chemical and isotopic analyses
- 3.2.2. Seepage measurements
- 3.2.3. Radon measurements
- 3.2.4. Underwater gamma-ray spectrometry
- 3.2.5. Radium isotope measurements
- 3.2.6. Geophysical survey
- 3.2.7. Computer modelling
- 4. Results and discussion
- 4.1. Hydrogeochemistry of the Ragusa area
- 4.2. Stable isotopes and tritium
- 4.3. Seepage measurements at the Donnalucata area
- 4.4. Radon measurements in the Donnalucata area
- 4.5. Underwater gamma-ray spectrometry of radon decay products in the Donnalucata area
- 4.6. Radium isotope studies in the Donnalucata area
- 4.7. Geophysical survey of salt-fresh water interface at the Donnalucata coast
- 4.8. Modelling of the SGD phenomena in the Donnalucata boat basin
- 5. Conclusions
- Acknowledgements
- References
