Lead and zinc contaminated soils from a smelter area in the northern part o
f France have been studied by transmission electron microscopy (TEM). This
study was carried out with 4 different soils contaminated by Pb and Zn bur
with different chemical and physical characteristics. Two soils are tilled
and have a neutral or slightly basic pH, one is a wooded soil and the last
one is a meadow soil with acidic pH and high total organic content. TEM ima
ges of the soil samples have been coupled with focused energy dispersive X-
ray (EDX) analyses and chemical mapping on a few micron-sized windows. This
study demonstrates that TEM is a particularly efficient method to investig
ate metal speciation in the fine fractions of the contaminated soils. Zinc
could be detected locally in sulphide minerals probably coming from the sme
lter emissions, but the major phases retaining Zn are Fe-oxyhydroxides and
smectites. Lead could be detected in small aggregates which were characteri
zed by EDX and selected area electron diffraction. Their structural formula
e correspond to a pyromorphite-like mineral in which Pb is partly substitut
ed by Ca and Na. Pyromorphite is present only in the wooded and meadow soil
s where it forms partly from amorphous Si-rich phases (slags) coming from t
he smelter. These results are compared with data previously obtained by spe
ctroscopic methods on the same samples. (C) 2001 Elsevier Science Ltd. All
rights reserved.