BACKGROUND CONTENTS OF THE POTENTIALLY HAZARDOUS ELEMENTS IN SOILS OF THE CZECH-REPUBLIC (TOTAL CONTENTS)

There are two reasons for the estimation of background concentrations of hazardous substances in soils and their variability: the necessity of the identification of soils contamination (exceeding of the upper background limit of their variability); the correlation of the lowest limits of ecotoxicologically relevant concentrations. The total contents of potentially hazardous elements serve as comparable links among some levels of critical contents of trace elements in soils and as the basis of their mobility assessments. In the set of 1 280 samples taken both in the immission-free and immission impact regions the total contents of As, Be, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, V and Zn in Ap horizons were determined. The total set was subdivided into 13 soil-lithological groupings in accordance with the previous analysis of the trace elements distribution in the soil profiles due to lithology of the profiles (Tab. I). Tabs II to IV comprise the geometric means and their variance of the mentioned subsets after eliminating the outliers. The data in Tab. II reflect the increasing contents of Co, Cr, Cu, Mn, Ni and V in the sequence of soils from the transported weathered products of acid granites, micaceous gneisses and mafic - ultramafic rocks with the maximum values of Be in gneisses. The last mentioned soils represent the most widespread geogenic anomaly in the Czech Republic; high profile trace elements concentrations of As occur in some acid rocks and of Cd (and mostly the same elements like in mafic rocks) in weathered products of limestones and some shales (Tab. V). Tab. III gives the significantly lowest contents of the most elements in soils derived from sands and low contents of them in soils from most sandstones and loamy albic luvisols and stagnosols (due to argilluviation). The increasing contents of trace elements in loamy and clayey soils do not correspond to the extent proposed for soils in the Netherlands. The fluvisols especially from recently flooded alluvial sediments downstream the industrial cities are contaminated or even intoxicated (Cd, Hg, Pb, Zn, Cu, Cr, Mn). The contents of Cd, Hg, As and Be are more influenced (except the mentioned anomalies) by the anthropogenic inputs by parent materials. Combined sets of data are presented in Tab. IV.