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Estimation of sedimentation rate and sediment origin by natural radionuclides and 137Cs in the Vrana Lake, Croatia (CROSBI ID 588970)

Prilog sa skupa u zborniku | sažetak izlaganja sa skupa | međunarodna recenzija

Fajković, Hana ; Lovrenčić Mikelić, Ivanka ; Prohić, Esad Estimation of sedimentation rate and sediment origin by natural radionuclides and 137Cs in the Vrana Lake, Croatia // 9th ISEG - International Symposium on Environmental Geochemistry / Eduardo Ferreira da Silva ; Amelia Paula Reis ; Carla Patinha et al. (ur.). Aveiro: PLM-Plural, S.A., 2012. str. 198-199

Podaci o odgovornosti

Fajković, Hana ; Lovrenčić Mikelić, Ivanka ; Prohić, Esad

engleski

Estimation of sedimentation rate and sediment origin by natural radionuclides and 137Cs in the Vrana Lake, Croatia

The objective of the study was to investigate the Vrana lake sediments and to provide information about their mineralogical composition and sedimentation rate. Additional objectives were to determine whether the sedimentation rates are uniform in the whole Lake and to establish the relationship between the materials deposited in the Lake and the surrounding carbonate and flysch rocks. To carry out this study, we retrieved three 30-cm long sediment cores from the Vrana Lake, the largest natural lake in Croatia. The cores were cut into smaller sub-samples of 2 cm in thickness, and prepare for further analyses. The following parameters were measured: 137Cs, 40K and 232Th activities, carbonate content and mineralogy. The surroundings of the lake are made of limestone (Cretaceous and Eocene) and Eocene flysch, while the lake bottom and karst poljes are filled with Quaternary deposits. Sedimentation rate were estimated by 137Cs measurements and calculation. Sedimentation rates are not uniform in the whole lake. In the NW part of the lake, sedimentation rates of 10mm.y-1, 4.1mm.y-1 and 5.0mm.y-1 were estimated for 1954– 1964, 1964–1986 and 1986–2010 time periods, respectively. In the SE part, sedimentation rates for the same three periods were as follows: 8.0mm.y-1, 2.3mm.y-1 and 2.5mm.y- 1. Average sedimentation rates were 6.4mm.y-1 for the NW part of the lake, and 4.2mm.y-1 for the SE part. Massic activities of 40K and 232Th were used as sediment source tracers. 40K massic activities ranged around 31–166Bq.kg-1, 232Th ranged around 3.1–18Bq.kg-1 and 137Cs ranged around 0.3–68Bq.kg- 1. Correlations between radionuclides massic activities are positive. All three radionuclides are indicators of the silicate material influence. Carbonate component predominates in the sediment composition, where CaCO3 mass fractions range between 72 and 94% and with mean values around 82– 88%. All analysed sediment samples (23) were classified as sandy silt, with a mean grain size of 20-56µm. Such classification can indicate a uniform sedimentation. The phase analysis showed the presence of the calcite, quartz, micas and pyrite. CaCO3 mass fractions and the radionuclides massic activities are negatively correlated, indicating that all studied radionuclides are transported into the lake mainly in particulate form, connected with the silicate material influence.

Sedimentation rate; Vransko Lake; Radionuclide; 137Cs; 232Th; 40K; Gamma-spectrometry;

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Podaci o prilogu

198-199.

2012.

objavljeno

Podaci o matičnoj publikaciji

9th ISEG - International Symposium on Environmental Geochemistry

Eduardo Ferreira da Silva ; Amelia Paula Reis ; Carla Patinha ; Eduarda Pereira ; Sonia Rodriguez

Aveiro: PLM-Plural, S.A.

978-972-789-365-2

Podaci o skupu

9th ISEG - International Symposium on Environmental Geochemistry

poster

15.07.2012-22.07.2012

Aveiro, Portugal

Povezanost rada

Geologija