ELECTRON MICROPROBE STUDIES ON SOIL SAMPL ES WITH VARYING HEAVY-METALCONTAMINATION .2. CONTENTS OF HEAVY-METALS AND OTHER ELEMENTS IN AGGREGATIONS OF HUMIC SUBSTANCES, LITTER RESIDUES AND CHARCOAL PARTICLES

EMA point analysis show that the organic matter constituents of heavy metal contaminated soils are highly enriched with heavy metals. The ma ximal trace element accumulation were for Cu up to 13,000 mg/kg, for Z n up to 48,000 mg/kg, for Cd up to 2,100 mg/kg and for Pb up to 193,00 0 mg/kg. The affinity for the accumulation of the different heavy meta ls in aggregations of humic substances can be described by the sequenc e Cu > Pb greater than or equal to Cd > Zn greater than or equal to Ni > Co. In very strongly acidified humic top soil horizons the Pb and C d accumulation in the organic matter constituents is in competition wi th the accumulation in Fe and Mn oxides. The heavy metal contents (esp ecially of Cu) of the organic matter are often correlated with the con tent of organically bound calcium. The EMA results also show that high heavy metal amounts occur in combination with Ca-accumulations in the epidermis and the outer bark parenchym of decayed roots. EMA point an alysis of the interior of fungus sclerotias show that sclerotias can c ontain high amounts of heavy metals, in particular lead (up to 49,700 mg Pb/kg). From statistical results of EMA point analysis follows that lead and other heavy metals attached to humic substances are not only bound as metal organic complexes but also as organic metal phosphate complexes. Also charcoal particles of polluted soils contain high amou nts of heavy metals. The accumulation affinity is quite similar to tha t of humic substances.