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Publications (4)4.24 Total impact

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    ABSTRACT: Within an extensive multinational and multidisciplinary project carried out in Doñana National Park (Spain) to investigate its preservation and regeneration, the filling velocity of the salt marshes has been evaluated through the calculation of their average sediment accumulation rates. (239+240)Pu and (137)Cs from weapons testing fallout and total (210)Pb distribution profiles and inventories have been determined in some of the most characteristic zones of the park, namely, the ponds (or "lucios") and the waterjets (or "caños"). Plutonium inventories range from 16 to 101 Bq m(-2), (137)Cs values fluctuate between 514 and 3,758 Bq m(-2) and unsupported (210)Pb values comprise between 124 and 9398 Bq m(-2). Average sedimentation rates range from 3 to 5 mm y(-1) (1952-2002). These data are higher than those obtained by carbon dating for the period 6,500 AD-present, estimated as 1.5-2 mm y(-1), suggesting an increase in the accumulation of sediments and the alteration of the park's hydrodynamics caused by the re-channeling of the major rivers feeding the salt marshes.
    Journal of Environmental Radioactivity 02/2006; 89(2):159-71. · 2.12 Impact Factor
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    ABSTRACT: Continental margins are important areas to be considered when studying the distributions and depositions of pollutants, both conventional and radioactive. Coastal sediments accumulate most of those contaminants which can be introduced following atmospheric and/or fluvial pathways. Moreover, their residence times within the water column are usually shortened due to their affinity to associate with the downward falling particulate matter, more abundant at shallower depths. In this paper the distribution profiles and inventories of plutonium, americium and cesium are detailed, providing useful information about recent sedimentation phenomena such as sediment mixing, slumping processes and bioturbation. Unsupported 210Pb data are used as reliable indicators of enhanced/reduced deposition events. Also, the calculated inventories have enabled the estimation of the radiological contribution of the Spanish Mediterranean margin to the total radioactivity deposited onto the Mediterranean sea floor.
    Journal of Environmental Radioactivity 02/2002; 59(1):75-89. · 2.12 Impact Factor
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    ABSTRACT: The distribution and behaviour of the radionuclides 210Pb,210Po and 226Ra in the Odiel and Tinto river estuaries, southwest Spain, have been studied. This system receives large quantities of solid and liquid effluents in the form of phosphogypsum waste from the phosphate industry containing natural radionuclides. Ranges of activities from 20 to 5000 Bq kg−1(d.w.) in riverine sediments were observed. The ratios of radionuclides were also determined (uncertainties quoted to 2 σ), showing clear disequilibria in the effluents from the factories (210Pb/210Po = 2.7±0.6, 210Pb/226Ra = 0.6±0.1, 210Po/226Ra = 0.24±.03) and from the phosphogypsum piles (210Pb/210Po = 2.1±0.6, 210Pb/226Ra = 1.5±0.6, 210Po/226Ra = 0.7±0.2). However, the sampling sites on the rivers affected directly by the discharges exhibit activity ratios other than those found in the effluents, manifesting their different behaviour in the estuarine environment. The estimated inventory in sediments for these radionuclides was 0.92±0.20 TBq (1993) which can be compared with the annual release of 0.52±.04 TBq (1993) from the phosphogypsum piles and factories. Preferential deposition of 210Po and 210Pb rather than 226Ra onto the river bed was observed. The proportion of total sediment 210Pb activity associated with particles less than 2 μm in diameter, which is one of the most resuspendable and transportable sizes, is 5%-15%.
    Studies in Environmental Science 01/1997; 68:267-279.
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    ABSTRACT: The analytical problems while performing the sequential determination of some artificial and natural radionuclides in air filters are described. The anthropogenic radionuclides from fallout of the 60's are extracted quantitatively from the filters in 8M HNO 3 medium whilst the natural radionuclides need a stronger acid leaching (HF/HCl/HNO 3). The influence of the 210 Pb in the analysis of americium due to the 210 Po ingrowth in the 243 Am tracer is determined and evaluated (decontamination factors are ranged from 7·10 4 to 5·10 5). The Uranium analysis is carried out with two procedures (chemical and isotopic) in two filter aliquots (residue and leached sample). Both techniques have proven to be useful in determining natural uranium from the uranium mine tailings. The uranium percentage that remains in the residue can be considered as a constant (20 ± 5%) being possible to correct the quantity of the dissolved uranium by this fixed percentage and its associated uncertainty. The concentration of 210 Po in the filters is given as an approximate result as the existing compound in the filter (likely polonium oxide -500ºC melting temperature-) can be partially evaporated during ashing (450ºC) and can ingrow again from its progenitor (210 Pb) during its analysis. The 209 Po tracer loss -added before or after ashing-has been also determined in different media (HCl-HNO 3). The decision thresholds and detection limits have been assessed to decide in which air samples the radionuclides are present.