**c. Salinity**

The results of these tests prompt the following conclusions. Cd and Zn showed highest percentages in the bioavailable fraction. In the case of Cd, this finding is of major concern given its high concentration in the soils examined and this situation has been also described by [19]. Arsenic shows the highest residual percentage and thus its available levels are low. The bioavailable fraction of Cu is fairly low, while remaining fractions vary according to the soils. The behavior of Pb was more irregular among the different soils. In general, the residual fraction was low. The organic matter fraction was variable being greatest at site 18. Its bioavailable fraction was very high at site 39, which is worrying given the high concentration

**Sample Zn Cu Pb Cd As** G-7 wetland 1425 102 278 3 16 G-18 slope 127529 1441 19500 364 32 G-23 platform 33446 2042 11057 106 10 G-39 slope 76120 1272 20032 223 14 G-46 platform 610 41 182 2 0

**Table 6.** Total concentration of trace elements (mg kg-1) in soils selected for conducting the sequential fractionation

Clearly the presence of very high concentrations of trace elements and heavy metals is a problem for the establishment of plant populations, worsened by the fact that the sites of

of this heavy metal at this site.

210 Environmental Risk Assessment of Soil Contamination

**Figure 4.** Percentage of metal content that is in each fraction

Salinity has been described as one of the main impacts on the plant populations and animals of the closed landfills of the Iberian Peninsula's central region [5, 12, 20, 21] as well as landfills in other environments [22-25]. This problem is therefore closely examined in the case of the Getafe landfill. Electrical conductivity was determined in all the soil samples collected, along with F- , Cl- , NO2 - , NO3 - , PO4 3 and SO4 2- anion concentrations by ion chromatography. These results may be found in Tables 7 and 8. As for the other chemical properties of the soil, points showing greatest salinity were unevenly distributed throughout the capping soil.

By comparing soils from the landfill and rubble tips by principal components analysis (PCA) (Statgraphics 15), we were able to observe that electrical conductivity was related to the Cland SO4 2- contents of the landfill cap and also to F- , Na, NO3 concentrations in the case of the rubble tips. The distribution of sites appearing on the new coordinate axes seems to indicate higher salinity in discharge areas. To confirm this observation, we conducted an analysis of variance (ANOVA) of the factors electrical conductivity and Cl- level in the different landfill areas. Our findings indicate that both variables were significantly higher in the soils of the wetlands where the landfill's runoff is deposited.
