Distribution of rare earth elements in sediments of the marine lake Mir (Dugi otok, Croatia)

The Lake Mir represents a small, isolated and shallow marine lake situated in the south- eastern part of the Dugi Otok Island, in a karstic landscape of the eastern Adriatic coast. The surrounding karstic background, with occasional occurrences of red soil, characterizes the sediments in the lake as coarse grained and carbonate rich. Previous studies suggested the influence of the lake bathymetry and the overall biological production on the element composition of the lake sediments. To confirm previous assumptions and obtain a better understanding of the factors influencing sediment composition of this marine lake, the distribution of rare earth elements in sediments of the Mir Lake and the nearby Telašćica Bay as well as surrounding soils was investigated. In the lake sediments REY ranged from 10.6 mg kg-1 to 25.3 mg kg-1 ; in the Telašćica Bay sediments REY were higher compared to the lake and ranged from 56.4 mg kg-1 to 85.2 mg kg-1, while the highest REY, from 83.3 mg kg- 1 to 227 mg kg-1 were observed in soils surrounding the lake. Despite the difference in the levels of the rare earth elements, the REE normalized patterns and associated fractionation parameters (LREE/ HREE, (La/Yb)N and (Nd/Yb)N) showed similarities between the lake sediments and the surrounding soils, confirming a significant influence of local lithology on the lake composition. Results of the statistical analysis, on the other hand, suggest the contribution of both the carbonate and non- carbonate minerals, i.e. alumosilicates and Al- Fe-hydroxides, on the total REY content in the lake sediments