The paper presents the research results on the relation between the contents of total zinc and its bioavailable form (Zna) and physicochemical properties of soil carried out along three catenas in the postglacial valley of the middle Łyna River, in NE Poland. We focused on topographical factors to determine the amount of Zn in the soil in relation to specific geochemical landscape types. The analyzed soil showed a relatively low level of soil pollution with Zn and did not exceed the threshold values for soil contamination with Zn. The average Zn content amounted to 45.75 mg kg-1 d.m. and ranged from 8.80 to 176.26 mg kg-1 d.m. The heavy metal content in the soil was related to organic matter and clay fraction, while it was inversely proportional to the share of sandy fraction. Distribution of zinc showed variability due to factors derived from topography, soil heterogeneity in the river valley as well as fluvial processes taking place within the floodplain. Different geochemical landscapes showed depressive trends in both Zn and Zna contents along the catenas. It diminished from eluvial to transeluvial landscapes and increased again to superaqual landscape. Depressions after former river channel were favorable for the Zna accumulation. The most abundant in Zna were upper horizons of Fluvisols in superaqual landscape (45.12 mg kg–1) filling overgrown and terrestialized floodplain lakes. The share of Zna was the highest in organic horizons of Fluvisols and achieved 51.4% of total Zn. The nature and power of functional links between the heavy metal mobility and the soil properties were determined with multivariate statistics and GAM models. Applied ordination statistics confirmed its usefulness in soil factor analyses.

19.2.2014