COMPARISON OF ELEMENTAL CONTENTS IN O-HORIZON AND C-HORIZON SOILS FROM THE SURROUNDINGS OF NIKEL, KOLA-PENINSULA, USING DIFFERENT GRAIN-SIZE FRACTIONS AND EXTRACTIONS

Forty-five soil samples from the O- and C-horizons were taken in a 12, 000 km(2) area on the borders of Finland, Norway and Russia. The nicke l smelter at Nikel, the ore roasting plant at Zapoljarnij, both in Rus sia, and the iron ore mine acid processing plant at Kirkenes in Norway , are all situated within this area. Element levels and variation in b oth soil horizons (two different extractions of the O-horizon and two different grain size fractions of the C-horizon) are presented and dis cussed. No good correlation exists between element concentrations meas ured in the O-horizon and the parent C-horizon. Of the 30 analysed ele ments, 7 are clearly enriched (> 2 X) in the O-horizon, while 11 show higher concentrations (> 3 X)in the C-horizon, In Russia, near industr y, a number of heavy metals (Co, Cu, Ni) show extreme enrichments in t he O-horizon soils. All the anthropogenic contaminants show a marked d ecrease in element concentrations from the Russian nickel industry tow ards the west in the O-horizon samples. Chemistry of the C-horizon is very little affected by the emissions. For the O-horizon samples, a cl ose correlation was observed between 1 M ammonium acetate- and concent rated nitric-acid extractable element concentrations. Element availabi lity in 1 M ammonium acetate, however, differs widely from 65% (K) to less than 1% (Si, Ti). Of the heavy metals examined, Cd and Zn are mos t readily extractable. Copper is more strongly bound in the O-horizon than Ni or S. Interestingly, Na, K, Mg and P are less available at sit es affected by emissions from industry than in background areas. Eleme nt content and variation are generally higher in the < 0.063 mm than t he < 2 mm fraction of the C-horizon samples by a factor of 1.6 to 2.8. In addition, correlation between O-horizon and C-horizon chemistry is higher for the fine fraction of the C-horizon. The fine fraction of m ineral soils is thus considered more appropriate for the detection of element sources and for mapping regional differences than the < 2 mm f raction. Comparison of the results of the two extractions used for the O-horizon samples and the two fractions used to analyse the C-horizon samples helps to distinguish anthropogenic from geogenic element sour ces. (C) 1998 Elsevier Science B.V. All rights reserved.