**Author details**

this variation could be related to the apparent solubility and stability of the iron oxy-hydrox‐ ides precipitated at different values of pH [44, 45], but more detailed studies are carrying out

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8

**Pbw (mg kg-1)**

Figure 4. Soluble Pb content (Pbw) in the two Group of soils (A: acid, B: basic). (boxes show the confidence interval at 95% for the mean; vertical lines mark the mean values).

**Figure 4.** Soluble Pb content (Pbw) in the two Group of soils (A: acid, B: basic). (boxes show the confidence interval at

The mobility and solubility of Pb in the contaminated soils of this study is mainly controlled by the soil properties and ageing (oxidation) of the pyrite tailings. Regardless of the soil type, the Pb accumulates mainly in the top of the soils without contaminating the subsoil or

groundwater. The climatic conditions (semi-arid Mediterranean climate) produce the upwardmovement of the soil solutions, which cause the formation of surface crusts but only in acidic

soils (where the iron and contaminants remain soluble in higher proportion). The main Pbbearing mineral in acid soils should be Pb-sulphates, and in basic ones should be iron hydrox‐ ysulphates (mainly plumbojarosite). The amounts of Pb retained by iron oxyhydroxides are very little in all soil types. The soluble Pb is significantly higher in basic soils than in acid ones, which contradict the normal behaviour of this contaminant in soils. According to the obtained results, more detailed studies in relation to the solubility and stability of the different phases precipitated at the early stages of the contamination are required, to improve the applications

in the future of adequate remediation measurements in similar affected areas.

 The mobility and solubility of Pb in the contaminated soils of this study is mainly controlled by the soil properties and ageing (oxidation) of the pyrite tailings. Regardless of the soil type, the Pb accumulates mainly in the top of the soils without contaminating the subsoil or groundwater. The climatic conditions (semi-arid Mediterranean climate) produce the upward movement of the soil solutions, which cause the formation of surface crusts but only in acidic soils (where the iron and contaminants remain soluble in higher proportion). The main Pb-bearing mineral in acid soils should be Pb-sulphates, and in basic ones should be iron hydroxysulphates (mainly plumbojarosite). The amounts of Pb retained by iron oxyhydroxides are very little in all soil types. The soluble Pb is significantly higher in basic soils than in acid ones, which contradict the normal behaviour of this contaminant in soils. According to the obtained results, more detailed studies in relation to the solubility and stability of the different phases precipitated at the early stages of the contamination are required, to improve the applications in the future of adequate remediation measurements in

to verify this point.

794 Environmental Risk Assessment of Soil Contamination

**CONCLUSIONS**

95% for the mean; vertical lines mark the mean values).

**4. Conclusions**

Group A soils

Group B soils

similar affected areas.

F. Martín1 , M. Simón2 , I. García2 , A. Romero1 and V. González2

1 Departamento de Edafología y Química Agrícola, Facultad de Ciencias, Universidad de Granada, Granada, Spain

2 Departamento de Agronomía, Área de Edafología y Química Agrícola, Universidad de Al‐ mería, Almería, Spain
