Urânio em solos, águas e plantas da antiga mina de Sevilha, Tábua, Centro de Portugal Uranium in soils, waters and plants of the old mine of Sevilha, Tábua, Central Portugal

Samples of soil, water and plants (terrestrial and aquatics) were collected in the vicinities of the old uranium (U) mine of Sevilha (Tabua, Central Portugal). Fluorometry was the methodology that was adopted for the determination of the U content in samples. Current U soil contamination on the Sevilha mine ranges from 8 to 560 mg kg -1 . In the most abundant families of terrestrial plants, the results show that the Asteraceae and Ericaceae families have the highest concentrations. For the Asteraceae, an average of 4.91 mg kg - 1 and a maximum of 13.12 mg kg -1 was found in Helichrysum stoechas and an average of 4.07 mg kg -1 and a maximum of 10.52 mg kg -1 was recorded in Hypochaeris radicata. In Erica umbellata an average of 1.70 mg kg -1 and a maximum of 7.50 mg kg -1 were obtained. Even though the concentrations obtained in this later species are not high it is particularly interesting because it has a high bio-productivity. Although the U concentrations in waters did not surpass 13 µg L -1 we have verified that in the vicinities of the mine drainage area, the U concentrations in aquatic plants are higher than in the surrounding water bodies. For these species proved to be uranium accumulators with maximum concentrations: Callitriche stagnallis (55.53 mg kg -1 ), Lemna minor (52.98 mg kg -1 ), Riccia fluitans (50.59 mg kg -1 ) and Lythrum portula (32.93 mg kg -1 ).