Page 21 - RP90

Colaboraciones
pH
HCO3
SO
4 Cl
G1
7,40 ± 0,14
320 ± 72
291 ± 167
378 ± 189
G2
7,73 ± 0,04
680 ± 54
277 ± 12
105 ± 26
56 ± 17
G3
8,12 ± 0,1
361 ± 30
245 ± 13
23 ± 5
11 ± 4
Radionu- cleido
235U
234U
226Ra
Concentración (mBq L-1)
1,2
41
38
99,2
2,5
80
387
511,5
Coeficiente de dosis por ingestión (msV Bq-1)
4,7·10-5
4,9·10-5
2,8·10-4
Dosis efectiva comprometida (mSv a-1)
Eh
T
CE
413,5 ± 0,3
20 ± 3
2210 ± 147
462 ± 12
21,8 ± 1,1
489 ± 11
16,5 ± 0,7
238U
Media
19
Max
42
4,5·10-5
Media
6,5·10-4
4,3·10-5
1,5·10-3
8,1·10-3
Max
1,4·10-3
8,6·10-5
2,9·10-3
7,9·10-2
148 ± 26
70 ± 7
47 ± 4
Total
-
1,0·10-2
8,3·10-2
Ca
Mg
Na
K
SiO
2 PO
4 238U
235U
234U
226Ra
234U/238U
226Ra/234U
61 ± 7
214 ± 39
6± 4
10 ± 2
0,32 ± 0,13
29 ± 8
1,5 ± 0,3
66 ± 11
103 ± 6
2,4 ± 0,3
1,60 ± 0,17
40 ± 2
36 ± 10
1,6 ± 0,3
10,2 ± 0,6
0,188 ± 0,010
29 ± 2
1,64 ± 0,15
57 ± 4
28 ± 4
1,98 ± 0,11
0,51 ± 0,08
23,7 ± 0,9
8± 2
0,7 ± 0,3
6,4 ± 0,3
0,173 ± 0,009
8,4 ± 1,4
0,8 ± 0,2
21 ± 4
5,7 ± 1,8
2,51 ± 0,15
0,22 ± 0,04
Tabla III. Valores medios para las diferentes variables para los grupos ge- nerados por el análisis cluster. Unidades: pH (unidades estándar), Eh (mV), temperatura (oC), CE (μS cm-1), Concentración iónica (mg L-1), concentración radionucleidos (mBq L-1).
cambio catiónico, por tanto, una mayor fuerza iónica (mayor salinidad) generalmente significa una mayor competición por las posiciones de intercambio y una posible liberación de Ra2+ debido a su gran radio iónico. Este hecho ha sido observado en numerosos estudios que han mostrado una co- rrelación positiva entre el Ra y la salinidad \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\[13, 14\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\].
dosis efectiva comprometida
Tabla IV. Concentraciones y dosis efectivas comprometidas por isótopos de uranio y 226Ra.
que la dosis anual por ingestión de aguas de consumo de un determinado radionucleido es:
Di=gi(SvBq-1).ai(BqL-1).V(La-1) (1)
Donde gi es el factor de conversión a dosis y ai la concen- tración de actividad del radionucleido i, mientras que V es el volumen de referencia ingerido por una persona adulta durante un año, el cual es de 730 L.
En la Tabla IV se recogen las dosis efectivas comprometi- das obtenidas a partir de los valores medios y máximos para cada uno de los radionucleidos medidos en este estudio, así como la suma total de las dosis obtenidas a partir de estos valores.
Observando los valores obtenidos, y teniendo en cuenta que solo se han considerado los radionucleidos naturales medidos, se pone de manifiesto la ausencia de niveles con riesgo radiológico para la población que puedan inducir dosis efectivas superiores al límite legislado (0,1 mSv a-1), ya que en general todos los valores están considerablemente por debajo del mismo. En este sentido, se observa que la dosis efectiva comprometida obtenida a partir de los valores medios de concentración de actividad es un orden de magni- tud inferior al valor paramétrico legislado.
Únicamente las suma de valores máximos obtenido para los distintos puntos (0,083 mSv a-1) se acerca al límite pa- ramétrico, debido principalmente a la elevada concentración de 226Ra de la muestra S27. Por tanto, se espera que pueda superarse el valor paramétrico si se tienen en cuenta un ma- yor número de radionucleidos en el punto S27, pero debido a que es un punto termal no parece presentar riesgo puesto que no es un punto de abastecimiento de agua para consu- mo.
conclusiones
Se han determinado los niveles y estudiado el comportamien- to de los isótopos naturales de uranio y 226Ra en el sistema acuífero kárstico de la sierra de Gádor (Almería), el cual pre- senta una gran variabilidad y heterogeneidad hidroquímica.
La concentración de actividad de 238U osciló entre 2,8 y 42 mBq L-1 (media = 19 ± 2 mBq L-1). Se observa la exis-
Puesto que las aguas subterráneas de la Sierra de Gádor son utilizadas para abastecer de agua potable a la po- blación, resulta interesante conocer si existe riesgo desde el punto de vista radiológico debido a su consumo por el público general. Para ello, se ha utilizado el Real Decreto 140/2003 \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\[15\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\], modificado por Real Decreto 314/2016 \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\[16\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\], por el que se establecen los criterios sanitarios de la calidad del agua de consumo humano.
El RD 140/2003 establece la dosis indicativa (DI) en aguas de consumo humano de 0.1 mSv a-1, valor que sí se supera de- berían llevarse a cabo investigaciones radiológicas adicionales. Para un año, la DI se calculará como la suma de dosis (Di) procedentes de los radionucleidos ingeridos: DI = ∑Di, donde i = Radionucleido i. Los coeficientes de dosis por ingestión utilizados son los recomendados por el RD 783/2001 para adultos mayores de 17 años de edad. Por tanto tendremos
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J.L. Guerrero • RADIOPROTECCIÓN • No 90 • Diciembre 2017