# Metal Mobility in Afforested Sites of an Abandoned Zn-Pb Ore Mining Area
## 3 Results
### Metal Speciation  
In the Lgota I profile (Figure 6a), three strata from different depths, characterised by their different mineralogical compositions, were selected for testing the chemical forms of Cd, Zn and Pb. The first is the organic stratum (3-7 cm), the second represents sands with dolomite debris (52-67 cm), whereas the third one is composed mainly of clays (144-149 cm). In each of them, the pH\({}_{\rm H_{2}O}\) is alkaline, while the pH\({}_{\rm KCl}\) only drops below 7 in the organic layer. Throughout the profile, cadmium occurs mainly in highly mobile forms (Figure 6). Acid-extractable and -reducible forms of this metal constitute about 90% of its total content. Mobile forms of Zn constitute a smaller portion of its load, decreasing with depth from about 65% to 20%. In general, the share of mobile forms of Pb increases with depth from about 15% to 80% however, reducible forms dominate the most mobile acid-extractable forms. Figure 4: Distribution of selected elements in the profiles at the Lgota heap (lines show former soil level). Samples selected for analysis in the Lgota II profile (Figure 6a), resemble those of the Lgota I profile and contain (1) organic (0-3 cm), (2) sands with dolomite debris (37-47 cm) and (3) loans (57-62 cm). The pH values are generally slightly lower than in the respective samples from the heaps of Lgota I. Again, cadmium is the most mobile element, with the portion of highly mobile forms reaching 70% in organic strata and 90% in sandy and clayey ones. The share of mobile forms of Zn and Pb is lower. Whereas Zn bonding is dominated by the most mobile forms, Pb is associated mainly with the less mobile, reducible forms of the element. In the shortest Lgota III profile (Figure 6a), only two strata were selected--organic (2-5 cm), with pH\({}_{\text{KCI}}\) = 4.6 and loam-dominated (20-27 cm) with pH\({}_{\text{KCI}}\) = 6.1. The portion of mobile forms of Cd and Zn is lower in loans than in organics whereas Pb occurs mainly in the reducible fraction, in similar amounts in both studied strata. At Paryz (Figure 6b), the selection of profiles was made on the same basis and characteristics as at Lgota. The first is the organic stratum (4-9 cm), characterised in the Paryz I profile by a pH\({}_{\text{KCI}}\) = 6.6, the second being sands with carbonate debris (67-74 cm) with a pH\({}_{\text{KCI}}\) = 7.7 whereas the third contains sandy-loams from a greater depth (246-256 cm) with a pH\({}_{\text{KCI}}\) = 6.3. In the first two strata, Cd occurs mainly in the acid-extractable fraction (61% and 65%, respectively) whereas, in the third one with the lowest total amount of Cd, this element is bound almost completely to the residual fraction. In all three samples, about 50% of the total amount of Zn is present in the stable fraction and only a few percent of the Zn is associated with the most mobile fraction; its amount grows with depth. The association with forms of Pb differs from that of Cd and Zn. In the organic layer, this element occurs mainly in the oxidizable fraction, in the lower layer in the acid-extractable fraction, and in the lowest layer in the reducible one. Figure 5: Distribution of selected elements in the profiles at the Paryz heap (lines show former soil level). In the Paryz II and Paryz III locations (Figure 6b), Cd occurs mainly in mobile fractions, whose share generally increases with depth. Zn occurs in various chemical forms depending on the profile location and soil depth, however, in most of the samples it is associated with residual fraction and its most mobile forms (acid-extractable and reducible) usually ranges between 20 and 40%. Lead is found in the largest quantities in reducible and oxidizable forms, varying predominantly from 40 to 80%.