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Sedimentation rate using 137Cs and mineralogy of the Middle and South Adriatic Sea

Sediment accumulation rate was conducted using radiometric measurements of cesium, 137Cs. The aim of this study was better understanding transport and sedimentation processes of the middle and south Adriatic Sea, especially because it is a marine area that is not influenced by the delivery of suspended matter. Mineralogical and grain size analysis has also been used to evaluate this results, with the special interest in K- and Cs-bearing minerals (K-feldspars and clay minerals). Samples were taken on characteristic areas of the middle and south Adriatic Sea that were investigated for the project “Marine Environmental Assessment of the Mediterranean Region”. Sediments are mainly composed of carbonate and clay minerals, represented by calcite and smectite, following quartz, muscovite/illite, chlorite, K-feldspars, plagioclase and kaolinite. Grain size analysis showed no changes in vertical distribution through depth and these results indicate uniform sedimentation as it is expected in deeper marine environments. Distribution of the 137Cs is similar on the different locations, as are also granulometric parameters in which are dominant silts (~60%) and clay sized fraction (~30%). Almost all cesium is contained by the sediments in the upper part. The distribution of 137Cs provides information on the process of sediment accumulation. Highest accumulation rates are found in Albanija (~4 mm/year) and Jabuka (3, 1 mm/year), while in South Adriatic pit (SA PIT 1 and 2) and Palagruza the sedimentation rate is 1, 8 mm/year. We can conclude that the sediment accumulation rate in middle and south Adriatic Sea is very low.

137Cs; sedimentation rate; mineralogy; Adriatic Sea

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