Pergamon Applied Geochemistry, Vol. 11,pp. 35-42, 1996 Copyright fQ 1996 ElsevierScienceLtd Printed in Great Britain. All rights reserved 0883-2927/96 $15.00+0.00 088s2927(95)0006W Metal species distribution in top- and sub-soil in an area affected by copper smelter emissions Anna Karczewska Institute of Soil Science and Agricultural Environment Protection, Agricultural University of Wroclaw, ul. Grunwaldzka 53,50-357 Wroclaw, Poland Abstract-The major objective of this study was to investigate the chemical forms in which selected metals occur in soils polluted with metallurgical dusts as well as to estimate potential mobility and bioavailability of these metals. Six soil profiles situated at different distances from Cu smelters were chosen and soil samples were taken from top- and sub-surface layers. The soils differed in their textures but all of them showed high contents of sand fraction and were neutral or slightly alkaline in reaction, due to liming. Ale research involved the analysis of the total contents of 8 metals (Al, Fe, Mu, Zn, Cr, Ni, Cu and Pb) and their speciation according to the Zeien and Bruemmer method. Total concentrations of metals varied in the following ranges (mg/kg): Al, 1420-l 1,400; Fe, 1710-19,700; Mn, 55-470; Zn, 6.4153; Cr, 2.15-16.9; Ni, 1.18-13.8; Cu, 7.4-1710; Pb, 1l- 460. The metal fractions determined were: mobile, exchangeable, occluded in MnO,, organically bound, occluded in amorphous and crystalline FeO, and residual. The metals’ behaviour in soils depended both on the soil properties and the metals’ origin. Typically lithogenic metals (Al, Fe, Cr, Ni) occured in the soils predominantly in stable fractions (bound to FeO, and silicates), whereas metals of anthropogenic origin (Cu, Pb) showed considerably higher percentages of mobile and exchangeable fractions, which together made up 17.0-59.7% of Cu and 2.5-38.8% of Pb. The highest contributions of those fractions occured in the top layers of sandy soils. Therefore, it is concluded that anthropogenic metals are likely to be leached from the polluted soils, especially the sandy ones. Copyright 0 1996 Elsevier Science Ltd INTRODUCTION Since the 1980s there has been growing concern over environmental pollution in the areas affected by Cu metallurgy in the SW part of Poland (LGOM). Two Cu smelters “Legnica” and “Glogbw” have emitted into the atmospheare large amounts of metallurgical dusts containing heavy metals, in particular Cu and Pb. A yearly emission of these 2 metals in the early 1980s was as high as 2900 tons Cu and 3100 tons Pb (see Table 1). Dust precipitation has resulted in strong soil pollution in the vicinity of the smelters. Although the dust emissions from the smelters have been dramatically reduced in recent years. by over 10 times, the environmental problems arising from soil pollution are still of great importance. Total metal concentrations in the surface layers of the polluted soils have been measured and monitored for about 20 a (Kowaliriski et al., 1979; Szerszeti et al., 1991, Szersze6 et al., 1993), but there are still some unanswered questions concerning the processes of metal transformation, mobility and bioavailability as well as the long-term risk assessment. As it is the chemical forms of pollutants rather than their total concentrations in the soil that determines the potential risk of metal mobilization and transfer to other compartments of the environment (such as plants or underground water), the data on metal speciation would seem to be essential for any general conclusions. The main objective of this work was to investigate the chemical forms in which different metals, both of lithogenic and anthropogenic origin, occur in the polluted soils. Several sequential extrac- tion methods have recently been developed to estimate the “chemical forms” of heavy metals in soils and to assess the risk of metal mobilization. Although such procedures, being only operationally defined, appor- tion metals only to certain mineral phases without defining their chemical species, the term “ metal speciation” is generally used for this kind of assess- ment (Quevauviller et al., 1993) and is also used in this paper. None of the speciation methods has until now been commonly accepted as a standard procedure (Hirner, 1992; Quevauveller et al., 1993). In this work, a method developed by Zeien and Bruemmer (1989, 1991) was applied to determine the “forms” of metals in the surface and sub-surface layers of the polluted soils. Some conclusions obtained from this work are believed to be important for better understanding the mechanisms of metal transformations under real, non-artificial field circumstances. Furthermore, such conclusions should be helpful in predicting the fate of heavy metals in the examined soils. SAMPLING AREA Top- and sub-surface soil samples (depth: 5-15 cm and 30- 40 cm) were collected at 6 points situated in the area of the sanitary protection zone, at different distances from the Cu smelters “Legnica” and “Glogbw” (Fig. 1). The whole area around the smelters from where the soil samples were taken had been used as arable land until the late 1970s when the fields located close to the smelters were afforested. Conse- 35