BACKGROUND CONTENTS OF THE POTENTIALLY HA ZARDOUS ELEMENTS IN SOILS OF THE CZECH-REPUBLIC (CONTENTS IN THE 2M HNO3 EXTRACT)

The determination of the contents of potentially hazardous elements in the extract by 2M HNO3 (cold) has been introduced with the hope that the obtained data reflect their bioavailable fraction (which has not b een proved) and that this procedure is very expeditious. The method wa s used for soil testing purposes and in inventory studies in the Czech Republic. In the set of 1,280 samples taken from Ap-horizons of soils , the content of As, Be, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, V and Zn in t he extract of 2M HNO3 has been determined. In the Tabs I to III subdiv ided into subsets in the same manner as in the case of total contents, the similar gradation of trace elements concentrations has been found out. The first sequence (Tab. I) reflects the increasing of Co, Cr, C u, Mn, Ni, V and Zn and decreasing of Pb contents due to the mineralog ical properties of acid granites - gneisses - mafic - ultramafic paren t rocks. The next sequence (Tab. II) reflects the texture of soils fro m sedimentary parent materials and the anthropogenic enrichment of flu visols. The data obtained by this procedure have to be compared with t he total contents to correlate them with the internationally used crit eria and to verify their indicative role for assessing the anthropogen ic loads. Minimum values of solubility (Tab. IV) for Cr and V have bee n found in mafic and ultramafic rocks, for Mn and Ni in gneisses (mica ceous shists) and for Be in acid magmatic and metamorphic rocks. In th e sequence of soils from sedimentary rocks (Tab, V) only anthropogenic enrichment in fluvisols is accompanied by increased solubility Floode d fluvisols downstream the industrial cities are characterized by a ma rkedly increased solubility of Cu and Zn and an increase in solubility of As, Be, Ct, Mn, Mo, Ni, Pb and v. Element - specific solubility in the order Cd > Mn > Pb > Mo, Cu > Co > Zn > Be, Ni, V > As > Cr in no n contaminated and in slightly contaminated soils from immissions can serve for recalculations of total element contents. The changes in sol ubility caused by increased immission loads have to be assessed.