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Abstract. In the area of Trujillo (Extremadura, Spain) we have found a variety of striking bluish and secondary yellow granites outcropping within the Plasenzuela pluton. They are all quarried under different names and are characterized by leucocratic minerals in which a bluish phosphate is dispersed throughout the rock. Their physical and mechanical properties make these granites a perfect option for most applications as ornamental rocks. Within the pluton the radiological background is fairly homogeneous, with no significant differences between the gamma ray fluxes of the different facies. U (6.4 ± 0.51 ppm), Th (2.9 ± 0.47 ppm) and K 2 O (4.32 ± 0.26 %) contents determined in the laboratory by gamma-ray spectrometry from representative samples are in good accordance with fast in situ measurements carried out with the same technique and also with conventional chemical analysis. Estimated activities for K-40, Ra-226 and Th-232 were, on average, 1022 ± 36 Bq kg −1 , 84 ± 9 Bq kg −1 and 6.8 ± 1.6 Bq kg −1 . On the basis of these results, the I index of EU technical document 112 was determined, with an average result of 0.66 ± 0.03. This suggests that the rock can be used with no restrictions for all types of construction purposes. Striking differences were observed between the blue facies and the yellow facies in radon exhalation tests from crushed material (0.03 Bq kg −1 vs. 0.20 Bq kg −1 ). Since both granites have similar uranium contents (6.3 ppm and 6.5 ppm, respectively), these results can probably be explained in terms of important differences in the mineralogical distribution of this chemical element, radon emanation being enhanced in the yellow facies. However, due to the ordinary use as ornamental stone, the yellow facies does not present a radiological risk in terms of excess effective dose due to internal exposure to radon.

Workers in the granite industry face an occupational hazard: silicosis due to the crystalline silica present in inhalable dust. As granite can also present a variable, and occasionally significant, content of naturally occurring radionuclides, they may also face a radiological hazard. In order to assess the risk, a granite industry with a quarry and processing factory was selected to assess the occupational exposure. Three main potential pathways were observed: external irradiation, inhalation of granite dust, and radon exposure. The external dose rate was similar to that in a nearby farming area. A slight increment (0.016-0.076 mSv yr) was observed in the quarry and stockpile, due to quarry faces and granite blocks. The effective dose due to granite dust inhalation was 0.182  ±  0.009 mSv yr in the worst case scenario (3 mg m dust load in air and no use of filter masks). Thus, the mean value of the effective dose from these two pathways was 0.26 mSv yr, lower than the reference level of 1 mSv yr for the general population. The annual mean value of radon concentration in the indoor air was 33 Bq m. However, during granite processing works the radon concentration can increase up to 216 Bq m, due to mechanical operations (sawing, polishing, sanding, etc). This radon concentration was below the 600 Bq m reference level for action in working places. Therefore, workers in this granite factory face no significant additional radiological exposure, and no-one needs to be designated as occupationally exposed and subject to individual dosimetry.

No abstract

Se analizan el l3e de la atmósfera, ríos y pozos del área de Madrid, al objeto de evaluar su distribución y origen, mediante adaptación y desarrollo de técnicas de muestreo y análisis. Las muestras atmosféricas presentan valores de 8 l3 e situados entre -9,81 y -14,64 %0, que se corresponden gradualmente con los puntos de menor a mayor grado de polución por aportes principalmente de e0 2 procedente de la quema de combustibles fósiles. Las aguas de los pozos analizados, pertenecientes al acuífero terciario del detríti-co, muestran un estrecho margen de variación, entre 8 l3 e -13,92 y -15,67 %0, relacionado con los procesos geoquímicos naturales. Las aguas de los ríos Jarama, Guadalix y Guadarrama, presentan una amplia variación en su composición isotópica (8 l3 e entre -7,07 y -11,85 %0) debido a la disolución de carbonatos a su paso por las formaciones de calizas del Mesozoico y, en menor medida, a los aportes de efluentes contaminados. The dissolution of carbonatic rocks and the biologic activity could be the origin of the wide variations 8 l3 e from -7.07 to -11.85 %0) found in the waters from rivers Jarama, Guadalix and Guadarrama.