Heavy metal sorption in postglacial soils: Linking cadmium and lead retention to landscape geomorphology

Postglacial landscapes across the northern hemisphere exhibit distinct geomorphological features that influence soil interactions with heavy metals. This study examined how landform characteristics control the sorption capacity of sediments for cadmium (Cd(II)) and lead (Pb(II)) across five landforms - morainic uplands, ablation covers, kame terraces, ice-dammed basins, and side valleys - in three areas of Poland, formed during different Pleistocene glaciations (two phases MIS 6 - Bielsk Plain, Nidzica Upland and MIS 2-5 - Masurian Lakeland). Sorption was characterized using Langmuir and Freundlich isotherms, alongside physicochemical analyses (organic matter, clay, authigenic iron, CaCO3, CEC). Both models described sorption well, though Langmuir fits were superior for Cd(II). Spatial variability in sorption capacities was directly linked to landform origin and sediment properties. The highest metal retention occurred in melt-out depressions rich in organic matter (mean AmPb = 0.24 mmol g-1, AmCd = 0.05 mmol g-1) and in clay-rich sediments from morainic uplands (AmPb = 0.11 mmol g-1, AmCd = 0.02 mmol g-1), the lowest on sandy kame terraces (mean values AmPb = 0.01 mmol g-1, AmCd = 0.01 mmol g-1). Strong positive correlations (p < 0.05) were found between metal sorption and organic matter, clay fraction, authigenic iron, and CEC. Although the proportions of these components - and thus their sorption influence - vary across the studied areas, their combined effect is consistent for respective landform types, indicating complementary interactions. Geomorphological structure therefore exerts primary control over landscape-scale heavy metal retention and should be considered in geochemical, soil, and environmental assessments. These results provide a framework for pollution risk evaluation, remediation planning, and land-use management in postglacial regions, enabling prediction of metal mobility from landform characteristics.