CONCENTRATION OF RARE EARTH ELEMENTS IN SURFACE WATER AND BOTTOM SEDIMENTS IN LAKE WADAG, POLAND

The paper presents the results of analyses of the content of rare earth elements (REEs) in surface water and bottom sediment in the river-lake system of Lake Wadag located in the Masuria Lakeland (Poland). The samples were collected in August 2015. The aim of the study was to describe the spatial variation of REEs concentration in the river-lake system, and to identify the hydro-geochemical factors that affect their distribution. Multivariate statistical methods of data analysis, i.e. cluster analysis (CA) and principal component analysis (PCA), were used to analyze similarities and differences in REEs content in water and bottom sediments of the lake-river system. In order to determine the enrichment of the river and lake water and bottom sediments with REEs, their concentrations were standardized in relation to the average concentrations in chondrite. Low concentrations of REEs in water and bottom sediments of the Wadag river-lake system indicate their geogenical origin. The REE concentrations in the inflows to the lake were higher and more variable than those found in the lake and its outflow. The similarity between the REE content in the water of the Wadqg River and Lake Wadqg results from the long exchange time of water in the lake. Eu anomalies in the river and lake water and Ce anomalies in the lake water were observed. Higher REE concentrations were detected in the bottom sediments of Lake Wadqg and at its outflow. The bottom sediments of the Wadqg river-lake system are characterized by higher enrichment with LREE in relation to HREE.