Page 19 - RP90
P. 19
Colaboraciones
Muestra
238U
226Ra
234U/238U 226Ra/234U
235U
234U
(mBq L-1)
M1 5,8 ± 0,3 0,37 ± 0,05 12,8 ± 0,5 0,91 ± 0,09 2,19 ± 0,13 0,071 ± 0,007
M2 4,3 ± 0,2 2,49 ± 0,14 10,7 ± 0,4 1,26 ± 0,09 2,49 ± 0,16 0,117 ± 0,009
M3 3,3 ± 0,3 0,41 ± 0,08 7,3 ± 0,5 1,65 ± 0,13 2,2 ± 0,2 0,22 ± 0,02
M4 3,2 ± 0,2 0,23 ± 0,05 5,9 ± 0,3 0,76 ± 0,08 1,82 ± 0,17 0,130 ± 0,016
M5 10,3 ± 0,4 0,66 ± 0,06 38,8 ± 1,3 23,4 ± 1,4 3,77 ± 0,19 0,60 ± 0,04
S6 18,9 ± 0,7 1,19 ± 0,08 52,9 ± 1,8 95 ± 31 2,79 ± 0,13 1,82 ± 0,6
S7 25,5 ± 1,0 2,29 ± 0,15 59 ± 2 41 ± 2 2,32 ± 0,13 0,69 ± 0,04
M8 7,6 ± 0,5 0,37 ± 0,07 18,2 ± 0,9 6,9 ± 0,3 2,41 ± 0,19 0,38 ± 0,02
S9 24,7 ± 1,0 1,54 ± 0,12 39,4 ± 1,5 16,8 ± 0,9 1,60 ± 0,09 0,425 ± 0,03
S10 28,9 ± 1,1 1,16,10 77 ± 3 14,8 ± 0,6 2,65 ± 0,14 0,19 ± 0,011
S11 29,7 ± 1,4 1,40 ± 0,14 64 ± 3 43 ± 2 2,15 ± 0,14 0,67 ± 0,04
S12 15,1 ± 0,7 0,79 ± 0,09 33,3 ± 1,4 33,6 ± 1,3 2,21 ± 0,13 1,01 ± 0,06
S13 23,0 ± 0,9 1,12 ± 0,10 48,8 ± 1,8 42 ± 3 2,12 ± 0,11 0,87 ± 0,06
M14 15,8 ± 0,6 0,97 ± 0,08 37,8 ± 1,4 8,6 ± 0,7 2,40 ± 0,13 0,23 ± 0,02
M15 18,2 ± 0,7 0,99 ± 0,08 42,8 ± 1,5 9,8 ± 0,4 2,35 ± 0,12 0,228 ± 0,013
S16 32,1 ± 1,5 1,49 ± 0,15 70 ± 3 28,4 ± 1,2 2,17 ± 0,14 0,41 ± 0,02
M17 28,3 ± 1,0 2,50 ± 0,15 54 ± 1,9 11,2 ± 1,3 1,91 ± 0,10 0,21 ± 0,03
M18 33,1 ± 1,2 1,93 ± 0,13 61 ± 2 31 ± 1,4 1,84 ± 0,10 0,51 ± 0,03
M19 33,3 ± 1,2 1,61 ± 0,11 61 ± 2 34,8 ± 1,8 1,82 ± 0,09 0,57 ± 0,04
M20 37 ± 1,2 2,21 ± 0,12 42,4 ± 1,4 4,5 ± 0,2 1,15 ± 0,05 0,105 ± 0,007
M21 2,8 ± 0,3 1,31 ± 0,19 9 ± 0,7 N.M. 3,2 ± 0,4 N.M.
M22 6,2 ± 0,3 0,38 ± 0,05 12,3 ± 0,5 2,4 ± 0,2 1,99 ± 0,12 0,196 ± 0,015
M23 5,7 ± 0,3 0,39 ± 0,05 17,7 ± 0,7 N.M. 3,1 ± 0,2 N.M.
M24 13,3 ± 0,6 0,69 ± 0,07 30,8 ± 1,2 4,5 ± 0,4 2,32 ± 0,13 0,147 ± 0,013
S25 41,6 ± 1,5 1,68 ± 0,11 78 ± 3 31 ± 4 1,87 ± 0,09 0,40 ± 0,05
M26 12,2 ± 0,6 0,71 ± 0,10 28,6 ± 1,3 3,0 ± 0,2 2,34 ± 0,16 0,106 ± 0,009
S27 18,7 ± 0,9 1,25 ± 0,13 61 ± 3 387 ± 20 3,3 ± 0,2 6,3 ± 0,4
S28 39,4 ± 1,8 1,83 ± 0,17 80 ± 4 111 ± 10 2,02 ± 0,13 1,39 ± 0,14
Media 19 1,2 41 38 2,3 0,7
Mediana 18 1,8 41 16 2,2 0,4
Mínimo 2,8 ± 0,3 0,23 ± 0,05 5,9 ± 0,3 0,76 ± 0,08 1,15 ± 0,05 0,071 ± 0,007
Máximo 41,6 ± 1,5 2,50 ± 0,15 80 ± 4 387 ± 20 3,77 ± 0,19 6,3 ± 0,4
SD 12 0,68 23 76 0,55 1,2
Tabla II. Concentración de actividad de los isótopos naturales de U y 226Ra, y principales co- cientes de actividad. N.M.: No medido.
de las especies de uranio disueltas y los índices de saturación (IS) de las principales fases minerales con el código PHREEQC. El IS es una magnitud logarítmica donde los va- lores positivos identifican minerales potencialmente saturados pudién- dose producir la precipitación de los mismos, mientras que los valores negativos identifican minerales po- tencialmente subsaturados en las aguas.
El potencial redox ejerce un papel esencial controlando la movilidad del U en las aguas subterráneas, ya que bajo condiciones reductoras el uranio aparece predominantemen- te en su estado tetravalente U(IV) y tiende a precipitar formando mi- nerales insolubles, mientras que en condiciones oxidantes aparece co- mo U(VI) en forma de iones uranilo (UO22+) muy solubles \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\[10\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\].
La modelización de las especies de uranio disueltas confirma que todo el uranio se encuentra en el estado hexavalente U(VI), como era esperado debido a los altos po- tenciales redox de las aguas. Los complejos de carbonato de uranilo \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\[UO2(CO3)2\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\]2 y \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\[UO2(CO3)3\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\]4 son las especies dominantes de uranio disueltas en las aguas (Figura 2), con un valor medio del 25 y 63%, respectivamente en relación al total de especies disueltas. El complejo de fosfato de uranilo \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\[UO2(HPO4)2\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\]2
presenta un valor medio del 12% en relación al total de especies disueltas, llegando a ser la especie dominante en las muestras S6 y M24 (Figura 2).
Todas las muestras están claramente subsatu- radas respecto a las principales fases minerales de uranio, hecho que se ratifica analizando los valores obtenidos para los índices de saturación (IS) de las diferentes especies de U en las mues- tras (Figura 3).
Así, los rangos obtenidos para el IS fue- ron: USiO4 (IS: -23 a -16), UO2 (amorfo) (IS: -26 a -20), UO2 (cristalino) (IS: -22 a -15), U(HPO4)2·4H2O (IS: -43 a -31), U(OH)2SO4 (IS:
J.L. Guerrero • RADIOPROTECCIÓN • No 90 • Diciembre 2017
Figura 2. Especies de uranio disueltas. 20
