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While determining the uranium concentration in the rock (background level) and soils on the Iberian Massif of western Spain, several geochemical anomalies were observed. The uranium concentration was much higher than the geochemical levels at these locations, and several uranium minerals were detected. The proposed uranium background levels for natural soils in the west of Salamanca Province (Spain) are 29.8 mg kg−1 in granitic rock and 71.2 mg kg−1 in slate. However, the soil near the tailings of abandoned mines exhibited much higher concentrations, between 207.2 and 542.4 mg kg−1. The calculation of different pollution indexes (Pollution Factor and Geo-accumulation Index), which reveal the conditions in the superficial horizons of the natural soils, indicated that a good percentage of the studied samples (16.7–56.5%) are moderately contaminated. The spatial distribution of the uranium content in natural soils was analysed by applying the inverse distance weighted method. The distribution of uranium through the horizons of the soils shows a tendency to accumulate in the horizons with the highest clay content. The leaching of uranium from the upper horizons and accumulation in the lower horizons of the soil could be considered a process for natural attenuation of the surface impacts of this radiogenic element in the environment. Environmental restoration is proposed in the areas close to the abandoned mining facilities of this region, given the high concentration of uranium. First, all the tailings and other mining waste would be covered with a layer of impermeable material to prevent leaching by runoff. Then, a layer of topsoil with organic amendments would be added, followed by revegetation with herbaceous plants to prevent surface erosion.

20 páginas, 6 figuras y 9 tablas, The environmental quality of soil in the central part of the Northern Plateau of Spain has been analyzed by studying the heavy metal content of 166 samples belonging to the horizons A, B and C of 89 soil profiles. The analysis to assess the environmental risk of heavy metals in the soil was carried out by means of the spatial distribution of nine heavy metals and the use of several pollution indices. The results showed that the concentration values of heavy metals (x ± S) in the superficial soil horizons were the following: With a total of 6.71 ± 3.51 mg kg −1, the contents of Cd is 0.08 ± 0.06 mg kg−1, Co is 6.49 ± 3.21 mg kg−1, Cu is 17.19 ± 10.69 mg kg−1, Cr is 18.68 ± 12.28 mg kg−1, Hg is 0.083 ± 0.063 mg kg−1, Ni is 12.05 ± 6.76 mg kg−1, Pb is 14.10 ± 11.32 mg kg−1 and Zn is 35.31 ± 14.63 mg kg−1. These nine metals exceed the values of the natural geological background level of Tertiary period sediments and rocks that form part of the Northern Plateau in Spain. Nemerow and Potential Ecological Risk indices were calculated, with the “improved” Nemerow index allowing pollution within the soil superficial horizons to be determined. The data obtained indicated that the majority of the soil (54.61%) showed low to moderate contamination, 22.31% showed moderate contamination and 21.54% of the samples were not contaminated. If we consider the Potential of Ecological Risk Index (RI), the largest percentage of soil samples showed low (70.79%) to moderate (25.38%) ecological risk of potential contamination, where the rest of the soil presented a considerable risk of contamination. The nine trace elements were divided into three principal components: PC1 (Cu, Cr, Ni, Co and Zn), PC2 (As and Hg) and PC3 (Cd). All metals accumulated in the soil came from parent rock, agricultural practices and the run-off of residual waters towards rivers and streams caused by industrial development and an increase in population density. Finally, cartography of the spatial distribution of the heavy metal contents in the soil of the Northern Plateau of Spain was generated using Kriging interpolation methods. Furthermore, the total heavy metal contents in three soil orders present in the area, namely Entisols, Inceptisols, and Alfisols, were analyzed. Other soil parameters, such as the organic matter content, pH, clay content and cation exchange capacity, was measured to determine their influence on and correlation with the heavy metal contents., This work has been supported by the USAL research projects CGL2012-37281-C02.01, CGL2015-67169-P and CGL2015-69919-R (MINECO-FEDER)., We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).

A study has been made of 10 endemic communities from south-western Europe (Iberian Peninsula) described in the literature in which the taxa Echinospartum ibericum Rivas-Martinez, Sanchez-Mata and Sancho and Echinospartum barnadesii (Graells) Roth participate and which are integrated within the Cytisetea scopario-striati and Junipero-Pinetea ibericae phytosociological classes. A categorical principal components analysis was used for the multivariate study of a total of 148 releves in which the abundance of the different species present in the Iberian communities described and studied is reported. From this analysis, it seems possible to conclude that only seven communities actually exist in the west of the Iberian Peninsula, the other three being aspects or variants of those described previously.