2024-03-29T04:42:18Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/395232022-05-26T10:49:45Zcom_10261_75com_10261_6col_10261_328
00925njm 22002777a 4500
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Navas Izquierdo, Ana
author
Valero-Garcés, Blas L.
author
Gaspar Ferrer, Leticia
author
Palazón Tabuenca, Leticia
author
2011-09
Purpose: The sediments accumulated in the Yesa Reservoir (Central Spanish Pyrenees) have greatly decreased
its water storage capacity and are a major threat to the sustainability of water resources in the region. The study
examines the contents of radionuclides and stable elements in the reservoir sediments and relates their variations
with the sediment composition and sedimentary dynamics, particularly flood frequency and intensity,
responsible for changes in the main supply and distribution of radionuclides in the basin.
Materials and methods:. The sedimentary sequence accumulated in the The Yesa Reservoir (471 Hm3) that
supplies water for 1,000,000 population and irrigation was examined in two 4 m long sediment cores (Y1, Y2)
and one profile (Y3) retrieved at its central part. In the sediments, radionuclide activities of 238U, 226Ra, 232Th,
40K, 210Pb, and 137Cs (Bq kg-1) were measured using a hyperpure Ge coaxial detector. The stable elements Mg,
Ca, Sr, Ba, Cr, Cu, Mn, Fe, Al, Zn, Ni, Co, Pb, Li, K and Na (mg kg-1) were analysed by ICP-OES.
Complementary analyses to characterize the sediments included: XRD in the profile, grain size distribution by
laser equipment and contents of organic matter, carbonates and the residual fraction by loss on ignition.
Results and discussion: Variation in radionuclide activities is associated with grain size and sediment
composition. The activity levels (Bq kg–1) ranged between 20–43 for 238U, 14–40 for 226Ra, 7–56 for 210Pb, 19–
46 for Th232, 1–48 for 137Cs and 185–610 for 40K. Enriched activity levels are associated with clayey and silty
layers, and depleted levels with sandy layers. The levels of radionuclides and trace elements were significantly
lower in the cores, than in the profile because of its higher silicate content and the influence of inflow of spring mineral rich waters. The correlations among radionuclides, sediment components and stable elements evidenced
stronger influence of the dynamic of sediment supplies by floods in the central areas closer to the main channel
(cores) than in the littoral areas (profile).
Conclusions: The radionuclide distributions were consistent with the history of the reservoir infilling and with
processes of transport and accumulation of sediments. Comparing with the natural radionuclides, the artificial
137Cs varied the most and showed distinctive patterns. The methods used allow identification of natural inputs
into the system and its differentiation from the fluvial transport and reservoir deposition. The results provide
insights into the pathways and processes involved in the mobilization of radionuclides in the environment.
Navas A, Valero Garcés B, Gaspar L, Palazón L. Radionuclides and stable elements in the sediments of the Yesa Reservoir, Central Spanish Pyrenees. Journal of soils and sediments 11 (6): 1082-1098 (2011)
1439-0108
http://hdl.handle.net/10261/39523
10.1007/s11368-011-0401-0
1614-7480
Gamma emitting
Natural and artificial radionuclides
Spanish Pyrenees
Stable elements
Sedimentary sequence
Siltation
Yesa Reservoir
Radionuclides and stable elements in the sediments of the Yesa Reservoir, Central Spanish Pyrenees