PROCEEDINGS OF THE XVI MEXICAN SYMPOSIUM ON MEDICAL PHYSICS
The activity concentration of polonium-210 in the soft tissue of several species of mollusks of c... more The activity concentration of polonium-210 in the soft tissue of several species of mollusks of coastal areas from Tabasco, Mexico, has been determined. Polonium-210 is a natural radionuclide that may be bioaccumulated by flora and fauna, particularly by mollusks. Radioecological evaluation of polonium-210 in mollusks is of particular interest for environmental radioactivity surveillance and to understand the mechanisms of migration of this radionuclide from the environment to humans. In this work, an analysis of the levels of polonium-210 in mollusks from Mexico is presented. Methods include the use of alpha-particle spectrometry to measure polonium-210 in the soft tissue of the studied mollusks. Results show an average value of 158 Bq/kg in mollusks from Tabasco, Mexico. Mollusks from the taxonomic class Bivalvia bioaccumulate more polonium-210 than Gastropods. The activity concentration values of polonium-210 in mollusks from Mexico are of the same order as those reported internationally. A further work on the mechanisms of migration and bioaccumulation of polonium in these organisms is necessary.
... Vioque Département de Física Aplicada II, Escuela Técnica Superior de Arquitectura de Sevilla... more ... Vioque Département de Física Aplicada II, Escuela Técnica Superior de Arquitectura de Sevilla Universidad de Sevilla Abdelghani Adib Idrissi Unit of ... Specific activity and isotopes ratios: 234U/238U, 230Th,232Th/238U were determined at 20 sediments sam-ples collected at ...
Trabajo presentado a la II International Conference on Radioecological Concentration Processes (5... more Trabajo presentado a la II International Conference on Radioecological Concentration Processes (50 years later), celebrada en Sevilla (Espana) del 6 al 9 de noviembre de 2016.
Trabajo presentado en el 18th Radiochemical Conference, celebrado en Marianske Lazně (Republica C... more Trabajo presentado en el 18th Radiochemical Conference, celebrado en Marianske Lazně (Republica Checa), del 13 al 18 de mayo de 2018
ABSTRACT. Using liquid scintillation counting (LSC), 241Pu is usually measured after isolating th... more ABSTRACT. Using liquid scintillation counting (LSC), 241Pu is usually measured after isolating the Pu isotopes and then electroplating onto planchets via supported-disc LSC (SD-LSC) to minimize quenching problems that might have appeared when dissolving the precipitate deposited on the disc. However, if those quenching problems are carefully controlled or cor-rected, the measurement of 241Pu activity, once dissolved from the disc, could well be valid. In this paper, we approached the problem of measuring 241Pu directly from the disc in 2 ways: a procedure of Pu dissolution from the planchet is developed in parallel with a study of the chemical quenching in these kinds of environmental samples to obtain the counting efficiency of the measurement of 241Pu by LSC. In relation to the SD-LSC method, an increase in counting efficiency was observed using our radiochemical procedure. Finally, we propose a validation of the LS technique by measuring the 241Pu in electroplated lacustrine sedi...
Trabajo presentado a la II International Conference on Radioecological Concentration Processes (5... more Trabajo presentado a la II International Conference on Radioecological Concentration Processes (50 years later), celebrada en Sevilla (Espana) del 6 al 9 de noviembre de 2016.
Trabajo presentado a la II International Conference on Radioecological Concentration Processes (5... more Trabajo presentado a la II International Conference on Radioecological Concentration Processes (50 years later), celebrada en Sevilla (Espana) del 6 al 9 de noviembre de 2016.
Trabajo presentado a la 4th International Conference on Environmental Radioactivity: Radionuclide... more Trabajo presentado a la 4th International Conference on Environmental Radioactivity: Radionuclides as Tracers of Environmental Processes, celebrada en Vilnius (Lithuania) del 29 de mayo al 2 de junio de 2017.
Abstract. In general, the validation of any method for Pu-isotopes determination in environmental... more Abstract. In general, the validation of any method for Pu-isotopes determination in environmental samples by alpha-spectrometry is performed through the analysis of reference materials or participating in intercomparison exercises. However, in most cases only 239 + 240 Pu activities are considered, and no information is given concerning to 238 Pu. A complete validation of the method requires additional tests in order to be also confident for 238 Pu. In this sense, if the origin of the plutonium in an environmental sample is known, 238 Pu/ 239 + 240 Pu activity ratios can be used as the demanded additional quality assurance test. The value of this ratio is usually known in any ecosystem where the origin of Pu is well determined. We have participated in several 239 + 240 Pu intercomparison exercises and, additionally, we have analysed some samples, which are contaminated by a well-defined source of plutonium, for the complete validation of the method used in our laboratory for Pu-isot...
This study was undertaken to investigate the natural materials before and after appropriate physi... more This study was undertaken to investigate the natural materials before and after appropriate physicochemical treatments. The samples were collected at different depths from the outcrop Lamsied located in the Tarfaya-Boujdour basin. This work concerns a mineralogical and geochemical characterization of local black shale. For instance, mineralogical and granulometric analysis showed that the local black shale is composed essentially of calcite, and the texture does not depend neither on the depth nor on the lithology. The distribution of stable elements such as rare earth elements (RRE) and other trace and major elements was determined. Different techniques of analysis were used for the characterization of the samples. Enrichment or depletion of major elements was observed. NASC-normalized REE patterns revealed a heavy REE (HREE) enrichment, a light REE (LREE) depletion, a positive Eu anomaly and a negative Ce anomaly. The result indicates reduction conditions. Results of correlation a...
Natural radioactivity in the environment is a field gaining more attention in last decades. This ... more Natural radioactivity in the environment is a field gaining more attention in last decades. This work is focused on the study of natural radioactivity complemented with elementary characterization at former non-uraniferous mining areas in Sweden. This aim is addressed through the study of mining lakes, called pit lakes, which are water bodies generated after opencast mining. Environmental matrices (water, sediments and rocks) from 32 Swedish pit lakes, commonly used for recreational purposes were radiometrically characterized via alpha (238U, 234U, 232Th, 230Th, 210Po isotopes) and gamma spectrometry (238U and 232Th series radionuclides). Additionally, ambient dose rate equivalent in the immediate surrounding of each pit lake was quantified. Physico-chemical parameters (pH, specific conductivity, dissolved oxygen, oxidation–reduction potential) and elemental composition (major and trace elements by ICP-MS) were analysed in water samples and elementary composition of sediments/rocks ...
Journal of Radiation and Nuclear Applications, 2018
Incandescent gas mantles are used for illumination by nocturnal food stalls, camping and other ac... more Incandescent gas mantles are used for illumination by nocturnal food stalls, camping and other activities. In some countries, thorium-containing gas mantles are available without any indication of the possible radioactive content, resulting in a potential increase of exposure to consumers. In this work, the radioactive content of gas mantles of several brands from Mexico and Spain is studied. Scanning electron microscopy, gamma-ray and alpha-particle spectrometry were used for morphological and radio metrical characterization of gas mantles. The results indicate that some of the analyzed gas mantles contain 232 Th and their descendants, with values ranging from detection limits up to 683, 345 and 277 Bq/g for 232 Th, 228 Ra and 228 Th, respectively. The levels of activity concentration of radio nuclides in thorium-containing gas mantles exceed the limits set by International Basic Safety Standards, but still, gas mantles with radioactive content are available in some countries to consumers without any radiological control.
A pit lake arises as a consequence of anthropogenic activities in opencast mining areas. These wa... more A pit lake arises as a consequence of anthropogenic activities in opencast mining areas. These water bodies may be enriched in hazardous stable contaminants and/or in naturally occurring radionuclides depending on the local geological conditions. Mining legacy in Sweden produced hundreds of these pit lakes and most of them are used for recreational purposes in the southern part of the country. In this paper, one pit lake was selected for having enhanced levels of natural radionuclides. Physico-chemical parameters (temperature, pH, oxidation-reduction potential, dissolved oxygen and depth), elemental composition (via Inductive Coupled Plasma Mass Spectrometry) and radiometric characterization (via alpha spectrometry of 226 Ra, 210 Po and 210 Pb) were carried along the depth of a 60 m depth pit lake, with the main aim to describe how natural radionuclides and elements behaves with depth in a non-uraniferous pit lake. Based on observed changes in physico-chemical parameters, a thermocline and a chemocline region were identified at around 10 and 30 m depth respectively. Concerning radionuclides, 226 Ra ranged from 75 ± 3 up to 360 ± 12 mBq/kg while 210 Po ranged from 11 ± 1 up to 71 ± 3 mBq/kg. 210 Pb distribution with depth was also determined via secular equilibrium with 210 Po after 2 years and also stable Pb was measured. Disequilibrium 226 Ra-210 Pb was found and the residence time of 210 Pb in the water column was assessed. Additionally, different vertical distributions between 210 Pb and Pb were found which points out different sources for different lead isotopes in the water body.
A radiological evaluation associated to the future mining of grey monazite nodules enriched in li... more A radiological evaluation associated to the future mining of grey monazite nodules enriched in light rare-earths, from a modest superficial deposit located in the centre of Spain, has been performed at pre-operational level, and the main results are shown in this paper. Although the monazite nodules in the deposit are clearly enriched in radionuclides from the uranium and thorium series with activity concentrations higher than 1 Bq/g, the size of these nodules (in the 0.5 mm-2 mm grain size interval), its refractory behaviour that prevents the leaching or dissemination of natural radionuclides to waters or other ecosystem compartments and consequently the impact in the food chain, and its presence quite diluted in the deposit at concentrations of 2.5-3 kg/m3, conducted to conclude that pre-operationally the area to be mined for the extraction of the monazite is generating a negligible radiological impact in the public and the nearby environment. Additionally, the extraction of the raw material and the restoration of the area after mining (i.e. the mining activities which will be done in-situ, in the mining area) will be exempted of any radiological regulation attending to the European Union legislation being expected that will not generate a radiological impact.
In this work, the reactivity of the surface of bituminous schists has been studied using a cation... more In this work, the reactivity of the surface of bituminous schists has been studied using a cation adsorbent, so-called Methylene Blue (MB). This bituminous schist is a calcareous clay rock that contains some amounts of organic matter. The samples were collected from an outcrop of Lamsied (Laâyoune), zone around Tarfaya-Boujdour. Once the granulometry of samples was well determined, the rocks were characterized by X-ray diffraction and they were analysed by X-ray fluorescence. Some parameters were considered relevant on the adsorption of MB by surface rock and they have been studied. One of these parameters is the adsorbed molecules-adsorbent contact time. This is the contact between a starting concentration of MB and a certain mass of gross rock. The analysis of results has shown that adsorption of MB can be well modelled by the Langmuir isotherm and also that a rapid kinetic (<100 min for L-type) can be fitted by a second-order equation model. The gross rock takes 84 % of the am...
The main aim of this work was to determine the levels of multiple natural radionuclides in an aqu... more The main aim of this work was to determine the levels of multiple natural radionuclides in an aquatic system (Moulouya river, Morocco) impacted by multiple abandoned Zinc and Lead mines. 238 U, 234 U, 232 Th, 230 Th and 210 Po were determined by alpha-particle spectrometry in water and sediment samples collected along the river and in samples from three pit lakes of abandoned mines, located in the Upper Moulouya catchment area. The results enabled the analysis of the different levels of impact of former mining activities, depending on the natural radionuclides. While the activity concentration of U-isotopes in Moulouya river water was slightly elevated in the vicinity of abandoned mine wastes, other natural radionuclides (Th-isotopes and 210 Po) levels were typical of a natural environment. This fact is clearly reflected in the magnitude and range observed in the distribution coefficients for the different radionuclides analyzed.
The mining activities performed in the Iberian Pyrite Belt (south of Spain) have generated since ... more The mining activities performed in the Iberian Pyrite Belt (south of Spain) have generated since long-time acid mining drainage (AMD) inputs to the Odiel River and its tributaries. These inputs are continuing nowadays, with origin mostly in the abandoned mines that cover the area, provoking a steady-state situation where the river waters present very low pH and very high concentrations of different heavy metals. In this work, the behavior of several natural radionuclides (210Po, Th- and U-isotopes) in water and sediment samples collected in the Odiel River and its tributaries have been analyzed and their levels determined looking for assessing the radiological environmental impact of the AMD.
PROCEEDINGS OF THE XVI MEXICAN SYMPOSIUM ON MEDICAL PHYSICS
The activity concentration of polonium-210 in the soft tissue of several species of mollusks of c... more The activity concentration of polonium-210 in the soft tissue of several species of mollusks of coastal areas from Tabasco, Mexico, has been determined. Polonium-210 is a natural radionuclide that may be bioaccumulated by flora and fauna, particularly by mollusks. Radioecological evaluation of polonium-210 in mollusks is of particular interest for environmental radioactivity surveillance and to understand the mechanisms of migration of this radionuclide from the environment to humans. In this work, an analysis of the levels of polonium-210 in mollusks from Mexico is presented. Methods include the use of alpha-particle spectrometry to measure polonium-210 in the soft tissue of the studied mollusks. Results show an average value of 158 Bq/kg in mollusks from Tabasco, Mexico. Mollusks from the taxonomic class Bivalvia bioaccumulate more polonium-210 than Gastropods. The activity concentration values of polonium-210 in mollusks from Mexico are of the same order as those reported internationally. A further work on the mechanisms of migration and bioaccumulation of polonium in these organisms is necessary.
... Vioque Département de Física Aplicada II, Escuela Técnica Superior de Arquitectura de Sevilla... more ... Vioque Département de Física Aplicada II, Escuela Técnica Superior de Arquitectura de Sevilla Universidad de Sevilla Abdelghani Adib Idrissi Unit of ... Specific activity and isotopes ratios: 234U/238U, 230Th,232Th/238U were determined at 20 sediments sam-ples collected at ...
Trabajo presentado a la II International Conference on Radioecological Concentration Processes (5... more Trabajo presentado a la II International Conference on Radioecological Concentration Processes (50 years later), celebrada en Sevilla (Espana) del 6 al 9 de noviembre de 2016.
Trabajo presentado en el 18th Radiochemical Conference, celebrado en Marianske Lazně (Republica C... more Trabajo presentado en el 18th Radiochemical Conference, celebrado en Marianske Lazně (Republica Checa), del 13 al 18 de mayo de 2018
ABSTRACT. Using liquid scintillation counting (LSC), 241Pu is usually measured after isolating th... more ABSTRACT. Using liquid scintillation counting (LSC), 241Pu is usually measured after isolating the Pu isotopes and then electroplating onto planchets via supported-disc LSC (SD-LSC) to minimize quenching problems that might have appeared when dissolving the precipitate deposited on the disc. However, if those quenching problems are carefully controlled or cor-rected, the measurement of 241Pu activity, once dissolved from the disc, could well be valid. In this paper, we approached the problem of measuring 241Pu directly from the disc in 2 ways: a procedure of Pu dissolution from the planchet is developed in parallel with a study of the chemical quenching in these kinds of environmental samples to obtain the counting efficiency of the measurement of 241Pu by LSC. In relation to the SD-LSC method, an increase in counting efficiency was observed using our radiochemical procedure. Finally, we propose a validation of the LS technique by measuring the 241Pu in electroplated lacustrine sedi...
Trabajo presentado a la II International Conference on Radioecological Concentration Processes (5... more Trabajo presentado a la II International Conference on Radioecological Concentration Processes (50 years later), celebrada en Sevilla (Espana) del 6 al 9 de noviembre de 2016.
Trabajo presentado a la II International Conference on Radioecological Concentration Processes (5... more Trabajo presentado a la II International Conference on Radioecological Concentration Processes (50 years later), celebrada en Sevilla (Espana) del 6 al 9 de noviembre de 2016.
Trabajo presentado a la 4th International Conference on Environmental Radioactivity: Radionuclide... more Trabajo presentado a la 4th International Conference on Environmental Radioactivity: Radionuclides as Tracers of Environmental Processes, celebrada en Vilnius (Lithuania) del 29 de mayo al 2 de junio de 2017.
Abstract. In general, the validation of any method for Pu-isotopes determination in environmental... more Abstract. In general, the validation of any method for Pu-isotopes determination in environmental samples by alpha-spectrometry is performed through the analysis of reference materials or participating in intercomparison exercises. However, in most cases only 239 + 240 Pu activities are considered, and no information is given concerning to 238 Pu. A complete validation of the method requires additional tests in order to be also confident for 238 Pu. In this sense, if the origin of the plutonium in an environmental sample is known, 238 Pu/ 239 + 240 Pu activity ratios can be used as the demanded additional quality assurance test. The value of this ratio is usually known in any ecosystem where the origin of Pu is well determined. We have participated in several 239 + 240 Pu intercomparison exercises and, additionally, we have analysed some samples, which are contaminated by a well-defined source of plutonium, for the complete validation of the method used in our laboratory for Pu-isot...
This study was undertaken to investigate the natural materials before and after appropriate physi... more This study was undertaken to investigate the natural materials before and after appropriate physicochemical treatments. The samples were collected at different depths from the outcrop Lamsied located in the Tarfaya-Boujdour basin. This work concerns a mineralogical and geochemical characterization of local black shale. For instance, mineralogical and granulometric analysis showed that the local black shale is composed essentially of calcite, and the texture does not depend neither on the depth nor on the lithology. The distribution of stable elements such as rare earth elements (RRE) and other trace and major elements was determined. Different techniques of analysis were used for the characterization of the samples. Enrichment or depletion of major elements was observed. NASC-normalized REE patterns revealed a heavy REE (HREE) enrichment, a light REE (LREE) depletion, a positive Eu anomaly and a negative Ce anomaly. The result indicates reduction conditions. Results of correlation a...
Natural radioactivity in the environment is a field gaining more attention in last decades. This ... more Natural radioactivity in the environment is a field gaining more attention in last decades. This work is focused on the study of natural radioactivity complemented with elementary characterization at former non-uraniferous mining areas in Sweden. This aim is addressed through the study of mining lakes, called pit lakes, which are water bodies generated after opencast mining. Environmental matrices (water, sediments and rocks) from 32 Swedish pit lakes, commonly used for recreational purposes were radiometrically characterized via alpha (238U, 234U, 232Th, 230Th, 210Po isotopes) and gamma spectrometry (238U and 232Th series radionuclides). Additionally, ambient dose rate equivalent in the immediate surrounding of each pit lake was quantified. Physico-chemical parameters (pH, specific conductivity, dissolved oxygen, oxidation–reduction potential) and elemental composition (major and trace elements by ICP-MS) were analysed in water samples and elementary composition of sediments/rocks ...
Journal of Radiation and Nuclear Applications, 2018
Incandescent gas mantles are used for illumination by nocturnal food stalls, camping and other ac... more Incandescent gas mantles are used for illumination by nocturnal food stalls, camping and other activities. In some countries, thorium-containing gas mantles are available without any indication of the possible radioactive content, resulting in a potential increase of exposure to consumers. In this work, the radioactive content of gas mantles of several brands from Mexico and Spain is studied. Scanning electron microscopy, gamma-ray and alpha-particle spectrometry were used for morphological and radio metrical characterization of gas mantles. The results indicate that some of the analyzed gas mantles contain 232 Th and their descendants, with values ranging from detection limits up to 683, 345 and 277 Bq/g for 232 Th, 228 Ra and 228 Th, respectively. The levels of activity concentration of radio nuclides in thorium-containing gas mantles exceed the limits set by International Basic Safety Standards, but still, gas mantles with radioactive content are available in some countries to consumers without any radiological control.
A pit lake arises as a consequence of anthropogenic activities in opencast mining areas. These wa... more A pit lake arises as a consequence of anthropogenic activities in opencast mining areas. These water bodies may be enriched in hazardous stable contaminants and/or in naturally occurring radionuclides depending on the local geological conditions. Mining legacy in Sweden produced hundreds of these pit lakes and most of them are used for recreational purposes in the southern part of the country. In this paper, one pit lake was selected for having enhanced levels of natural radionuclides. Physico-chemical parameters (temperature, pH, oxidation-reduction potential, dissolved oxygen and depth), elemental composition (via Inductive Coupled Plasma Mass Spectrometry) and radiometric characterization (via alpha spectrometry of 226 Ra, 210 Po and 210 Pb) were carried along the depth of a 60 m depth pit lake, with the main aim to describe how natural radionuclides and elements behaves with depth in a non-uraniferous pit lake. Based on observed changes in physico-chemical parameters, a thermocline and a chemocline region were identified at around 10 and 30 m depth respectively. Concerning radionuclides, 226 Ra ranged from 75 ± 3 up to 360 ± 12 mBq/kg while 210 Po ranged from 11 ± 1 up to 71 ± 3 mBq/kg. 210 Pb distribution with depth was also determined via secular equilibrium with 210 Po after 2 years and also stable Pb was measured. Disequilibrium 226 Ra-210 Pb was found and the residence time of 210 Pb in the water column was assessed. Additionally, different vertical distributions between 210 Pb and Pb were found which points out different sources for different lead isotopes in the water body.
A radiological evaluation associated to the future mining of grey monazite nodules enriched in li... more A radiological evaluation associated to the future mining of grey monazite nodules enriched in light rare-earths, from a modest superficial deposit located in the centre of Spain, has been performed at pre-operational level, and the main results are shown in this paper. Although the monazite nodules in the deposit are clearly enriched in radionuclides from the uranium and thorium series with activity concentrations higher than 1 Bq/g, the size of these nodules (in the 0.5 mm-2 mm grain size interval), its refractory behaviour that prevents the leaching or dissemination of natural radionuclides to waters or other ecosystem compartments and consequently the impact in the food chain, and its presence quite diluted in the deposit at concentrations of 2.5-3 kg/m3, conducted to conclude that pre-operationally the area to be mined for the extraction of the monazite is generating a negligible radiological impact in the public and the nearby environment. Additionally, the extraction of the raw material and the restoration of the area after mining (i.e. the mining activities which will be done in-situ, in the mining area) will be exempted of any radiological regulation attending to the European Union legislation being expected that will not generate a radiological impact.
In this work, the reactivity of the surface of bituminous schists has been studied using a cation... more In this work, the reactivity of the surface of bituminous schists has been studied using a cation adsorbent, so-called Methylene Blue (MB). This bituminous schist is a calcareous clay rock that contains some amounts of organic matter. The samples were collected from an outcrop of Lamsied (Laâyoune), zone around Tarfaya-Boujdour. Once the granulometry of samples was well determined, the rocks were characterized by X-ray diffraction and they were analysed by X-ray fluorescence. Some parameters were considered relevant on the adsorption of MB by surface rock and they have been studied. One of these parameters is the adsorbed molecules-adsorbent contact time. This is the contact between a starting concentration of MB and a certain mass of gross rock. The analysis of results has shown that adsorption of MB can be well modelled by the Langmuir isotherm and also that a rapid kinetic (<100 min for L-type) can be fitted by a second-order equation model. The gross rock takes 84 % of the am...
The main aim of this work was to determine the levels of multiple natural radionuclides in an aqu... more The main aim of this work was to determine the levels of multiple natural radionuclides in an aquatic system (Moulouya river, Morocco) impacted by multiple abandoned Zinc and Lead mines. 238 U, 234 U, 232 Th, 230 Th and 210 Po were determined by alpha-particle spectrometry in water and sediment samples collected along the river and in samples from three pit lakes of abandoned mines, located in the Upper Moulouya catchment area. The results enabled the analysis of the different levels of impact of former mining activities, depending on the natural radionuclides. While the activity concentration of U-isotopes in Moulouya river water was slightly elevated in the vicinity of abandoned mine wastes, other natural radionuclides (Th-isotopes and 210 Po) levels were typical of a natural environment. This fact is clearly reflected in the magnitude and range observed in the distribution coefficients for the different radionuclides analyzed.
The mining activities performed in the Iberian Pyrite Belt (south of Spain) have generated since ... more The mining activities performed in the Iberian Pyrite Belt (south of Spain) have generated since long-time acid mining drainage (AMD) inputs to the Odiel River and its tributaries. These inputs are continuing nowadays, with origin mostly in the abandoned mines that cover the area, provoking a steady-state situation where the river waters present very low pH and very high concentrations of different heavy metals. In this work, the behavior of several natural radionuclides (210Po, Th- and U-isotopes) in water and sediment samples collected in the Odiel River and its tributaries have been analyzed and their levels determined looking for assessing the radiological environmental impact of the AMD.
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