GEOCHEMISTRY ACROSS LAND USES IN THE LAKE ȚAGA MARE CATCHMENT, TRANSYLVANIA: INSIGHTS FOR FUTURE SEDIMENT SOURCE TRACKING USING LAKE SEDIMENTS

This study investigates geochemical variability in the Lake Țaga Mare catchment located in central Transylvania, Romania, to separate sediment sources contributing to the lake sediment archive. Geochemical analyses of parent material, soils and subaerial sediments were conducted across diverse land-use types. A Principal Component Analysis (PCA) was employed to differentiate sediment sources. Results indicate that parent material is characterized by high concentrations of carbonate-related elements (Ca > 1 wt.%, Mg > 0.65 wt.%, Sr > 100 mg·kg-1), while agricultural soils exhibit elevated Si (> 23 wt.%) and Ti (> 0.45 wt.%) and lower Zr (< 180 mg·kg-1). Baseline geochemical ranges for other natural elements such as Pb (15 - 25 mg·kg-1), S (maximum catchment values of 380 mg·kg-1), P (300 - 600 mg·kg-1), Mn (400 - 1000 mg·kg-1) and Fe (2.5 - 4.5 wt.%) further allow identification of deviations linked to historical and modern anthropogenic pollution or lacustrine redox processes. The principal components effectively differentiate between carbonate-rich parent material, weathered soils, and surface vs. subsurface erosion sources. This novel approach, the first such attempt at a national level, provides a geochemical framework for historical sediment source tracking and palaeoenvironmental interpretation of Lake Țaga Mare sediment archive. Specifically, it enables the identification of natural erosion phases, anthropogenic disturbances associated with historical land use changes, and abrupt events such as floods, landslides or other forms of deeper soil disturbance. Finally, results could inform locally-adapted strategies to mitigate long-term soil degradation and guide sustainable land-use planning.