Occurrence and Distribution of Technology-Critical Elements in Recent Freshwater and Marine Pristine Lake Sediments in Croatia: A Case Study

The occurrence and vertical distribution of ten technology critical elements (TCEs) (Li, Nb, Sc, Ga, Y, La, Sb, Ge, Te, and W) were studied in sediment cores collected from remote freshwater and marine lakes (Plitvice, Visovac and Mir Lakes) in three protected areas of Croatia. These environmental archives were used to assess natural TCE levels in lake sediments and temporal trends in historical anthropogenic atmospheric deposition. TCE was determined after complete sediment digestion using high-resolution inductively coupled plasma mass spectrometry (HR ICP-MS). The measured TCE concentrations spanned a wide range, which can be attributed to the varying input of terrigenous material into the studied lake systems. All obtained TCE concentrations were close to natural conditions and therefore could be used as a reference for other equivalent sediment systems in the coming years. The evaluation of anthropogenic influence on TCE concentrations showed a slight anthropogenic enrichment with Sb and Te in the upper sediment layers of some lakes (Plitvice and Mir Lakes), indicating a widespread atmospheric deposition, which, however, cannot be related to the recent increase in the use of TCE in modern technology.