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137Caesium distribution in the eastern Mediterranean Sea: Recent changes and future trends

Title137Caesium distribution in the eastern Mediterranean Sea: Recent changes and future trends
Publication TypeArticolo su Rivista peer-reviewed
Year of Publication1999
AuthorsPapucci, C., and Delfanti Roberta
JournalScience of the Total Environment
Volume237-238
Pagination67-75
ISSN00489697
KeywordsAccidents, article, cesium, cesium 137, Cesium Radioisotopes, chemistry, Chernobyl accident, conference paper, Geographic distribution, Marine pollution, Mediterranean Sea, pollution transport, priority journal, Radiation, radiation accident, radiation monitoring, Radioactive, radioactive contamination, Radioactive Fallout, radioactive pollution, radioactive waste, sea pollution, sea water, Seawater, Sodium chloride, statistics, Time, Time Factors, Ukraine, water pollutant, Water Pollutants, Water pollution, water sampling
Abstract

A series of sampling campaigns were carried out in the eastern Mediterranean in the period 1995-1997, to examine the relationship between the distribution of 137Cs in the water column and water mass circulation. 137Cs concentration in the surface water ranges between 3.3 and 4.0 mBq/l all over the area, indicating that the input due to the Chernobyl accident has been transferred to deep water layers by convection processes. In fact, in the vertical profiles, relative maxima are observed in the intermediate (4 mBq/l) and deep waters (≃2.5 mBq/l) formed after the Chernobyl accident. A clear Chernobyl signal also traces the new deep waters formed in the Aegean Sea that, exiting from the Cretan Arc Straits, since 1991 are spreading in the bottom layer of the eastern Mediterranean. The changes in 137Cs vertical profiles related to the new thermohaline circulation of the intermediate and deep waters of the eastern Mediterranean are being monitored at a deep station in the western Ionian Sea. The 1997 profile shows a decrease in 137Cs concentration both in the Levantine intermediate water and in the eastern Mediterranean deep water with respect to 1996. The decrease in Levantine intermediate water is likely due to seasonal/interannual variability, while the changes in the deep layer are related to the spreading westward into the Ionian of the new Aegean dense water. Along the path towards the western Mediterranean, 137Cs content in the Levantine intermediate water decreases from ≃4 mBq/l in the W-Ionian Sea to ≃2 mBq/l at the western sill of the Sicily Straits, due to mixing with underlying water, with lower caesium content, near the Malta Sill. Time- series measurements at the western sill of the Sicily Straits show that, while 137Cs concentration in the surface water entering the eastern Mediterranean remained constant (≃3.5 mBq/l) in the period 1993-1997, its level in the Levantine intermediate water leaving the basin decreased from 3.5 to 2.0 mBq/l.

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URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-0032589860&doi=10.1016%2fS0048-9697%2899%2900125-4&partnerID=40&md5=23cfb23242fc76ba2407cd6cca049680
DOI10.1016/S0048-9697(99)00125-4
Citation KeyPapucci199967