In the SW of Spain, just in the confluence of the mouths of the Tinto and Odiel River and in the ... more In the SW of Spain, just in the confluence of the mouths of the Tinto and Odiel River and in the vicinity of Huelva town, there is a big industrial complex which includes between others an industry devoted during more than 40 years to the production of phosphoric acid, by treating sedimentary phosphate rock by the so-called "wet acid method". As a by-product of the mentioned process it have been produced historically huge amounts of a compound called phosphogypsum, which composition is mostly di-hydrate calcium sulphate containing some of the impurities of heavy metals and natural radionuclides originally present in the raw material. Due to the lack of market for this by-product, it has been mostly piled over some salt-marshes located in the vicinity of the industry, on the bank of the Tinto River. About 100 million tons of phosphogypsum have been piled in an area covering more than 1000 hectares, constituting a clear environmental and radiological anomaly in the zone. The...
ABSTRACT Liquid scintillation counting (LSC) is an easy and straightforward technique, and combin... more ABSTRACT Liquid scintillation counting (LSC) is an easy and straightforward technique, and combined with its low limit of detection, makes it a powerful tool for both routine and low level measurements that can be applied to 210Pb low level counting in environmental samples. 210Pb can be easily measured following a sulphate co-precipitation method; the addition of a carrier and the weighing of the recovered amount is a widespread technique to evaluate radiochemical yield, however, this evaluation of the recovery is sometimes questioned. The samples employed in this work were recollected in 1999 and 2005 from the estuary of the Odiel and Tinto rivers (SW of Spain), which were affected by phosphogypsum (pg.) discharges until 1998. Phosphogypsum contains most of the 210Pb from the treated raw material, for that reason analysed riverbed sediments have enhanced 210Pb activity concentrations and hence, enhanced activity concentration of its daughter 210Po, both in secular equilibrium after two years.
A big fertilizer industrial complex and a vast extension of phosphogypsum piles (12 km2), sited i... more A big fertilizer industrial complex and a vast extension of phosphogypsum piles (12 km2), sited in the estuary formed by the Odiel and Tinto river mouths (southwest of Spain), are producing an unambiguous radioactive impact in their surrounding aquatic environment through radionuclides from the U-series. The levels and distribution of radionuclides in sediments from this estuarine system have been determined. The analyses of radionuclide concentrations and activity ratios have provided us with an interesting information to evaluate the extension, degree and routes of the radioactive impact, as well as for the knowledge of the different pathways followed for the radioactive contamination to disturb this natural system. The obtained results indicate that the main pathway of radioactive contamination of the estuary is through the dissolution in its waters of the radionuclides released by the industrial activities and their later fixation on the particulate materials. Tidal activity also plays an important role in the transport and homogenization along the estuary of the radioactivity released from the fertilizer plants.
En el Capitulo 2 se hace una revision de los trabajos previos relacionados con nuestra investigac... more En el Capitulo 2 se hace una revision de los trabajos previos relacionados con nuestra investigacion. Pretendemos justificar el interes del problema que abordamos. ... : 12pt">En el Capitulo 3 se revisan los metodos radioquimicos empleados habitualmente para el analisis de 90Sr en distintos tipos de muestras ambientales. A continuacion se describe el metodo radioquimico utilizado por nosotros, los trabajos realizados para su desarrollo y puesta a punto y, por ultimo, los resultados (rendimiento quimico) obtenidos en las muestras analizadas.En el Capitulo 4 se describe el sistema detector, Quantulus 1220, utilizado para la determinacion de las concentraciones de 90Sr en las muestras analizadas. Se describen los trabajos de seleccion de los diversos parametros que inciden en la calidad de la medida o en su evaluacion. Un aspecto que se estudio en profundidad, y que se describe en este Capitulo, es la dependencia de la eficiencia de deteccion con el grado de color de la muestra. Tambien en el Capitulo 4 aparece una breve referencia al sistema de deteccion, y metodo de analisis, utilizado en la medida de 137Cs, y otros radionuclidos naturales, por espectrometria gamma.En el Capitulo 5 se describe la investigacion desarrollada en la plantacion de eucaliptos. Se distingue entres dos tipos de muestras: El suelo forestal y la vegetacion. En los dos casos se comienza describiendo la seleccion y recogida de muestras, su pretratamiento y los resultados de las medidas de las concentraciones de 137Cs y 90Sr. A continuacion se realizan diversos estudios comparativos entre los resultados obtenidos y diversos parametros fisicos y quimicos. Al final de este capitulo se expone la metodologia utilizada, para la evaluacion y los resultados obtenidos de los coeficientes de transferencia y flujos, correspondientes a los diversos compartimentos que hemos distinguido en la plantacion.La complejidad de la descripcion del funcionamiento de la fabrica de produccion de pasta de celulosa, y la consecuente interpretacion de los resultados obtenidos, nos ha llevado a optar por exponer en dos Capitulos independientes las investigaciones desarrolladas en la fabrica.En el Capitulo 6 se describe el proceso industrial y el funcionamiento de la fabrica de produccion de pasta de papel y se detallan las muestras recogidas, asi como su pretratamiento, para su estudio. En el Capitulo 7 se presentan los resultados obtenidos acerca de las concentraciones de radionuclidos en las muestras que consideramos representativas de los diferentes procesos que hemos distinguido en la fabrica. A continuacion se hace una evaluacion del flujo anual medio de 90Sr y 137Cs en la fabrica, comparandolo con elementos quimicos mayoritarios en los diferentes procesos y con radionuclidos naturales (fundamentalmente 40K) que se pueden considerar quimicamente semejantes. Finalmente se realiza una estimacion de los flujos de radionuclidos asociados a los vertidos generados en el proceso de produccion.Finalmente, en el Capitulo 8, se presentan las conclusiones mas importantes de esta memoria de Tesis.
Estuaries are sinks of materials and substances which are released directly into them or transpor... more Estuaries are sinks of materials and substances which are released directly into them or transported from rivers that drain the basin. It is usual to find high organic matter loads and fine particles in the sediments. We analyzed radionuclide concentrations ((210)Po, (230)Th, (232)Th, (234)U, (238)U, (226)Ra, (228)Th, (228)Ra, (40)K) in sediments and three different organs (roots, stems and leaves) of three species of halophytes plants (Spartina maritima, Spartina densiflora and Sarcocornia perennis). The study was carried out in two tidal salt marshes, one polluted by U-series radionuclides and another nearby that was unpolluted and was used as a control (or reference) area. The Tinto River salt marsh shows high levels of U-series radionuclides coming from mining and industrial discharges. On the contrary, the unperturbed Piedras River salt marsh is located about 25 km from the Tinto marsh, and shows little presence of contaminants and radionuclides. The results of this work have shown that natural radionuclide concentrations (specially the U-isotopes) in the Tinto salt marsh sediments are one order of magnitude higher than those in the Piedras marsh. These radionuclide enhancements are reflected in the different organs of the plants, which have similar concentration increases as the sediments where they have grown. Finally, the transfer factor (TF) of the most polluted radionuclides (U-isotopes and (210)Po) in the Tinto area are one order of magnitude higher than in the Piedras area, indicating that the fraction of each radionuclide in the sediment originating from the pollution is more available for the plants than the indigenous fraction. This means that the plants of the salt marshes are unhelpful as bioindicators or for the phytoremediation of radionuclides.
In this paper, (238)U-series radionuclides have been analysed in particulate matter samples colle... more In this paper, (238)U-series radionuclides have been analysed in particulate matter samples collected at a phosphogypsum stack system located near the city of Huelva (SW Spain) during the course of 1 year. The results have been compared to those collected at a reference (background) site located a few km away, in order to establish if the stack system provokes an increase in radionuclide exposure due to inhalation with particulate matter. The (222)Rn progeny, which is considered a very important contributor to the internal dose rate received by the population, was collected for 6 months. The results indicate that for several types of radionuclides there is a significant increase in the radioactivity adsorbed by the aerosol particles collected at phosphogypsum stacks. The isotope analysis indicates that this increment could be affected by the water vapour emissions from the factory, which contain high concentrations of these radionuclides. However, the majority of these radionuclides...
The obtaining of phosphate fertilizers results in large amounts of residues that are frequently a... more The obtaining of phosphate fertilizers results in large amounts of residues that are frequently accumulated in deposits or pools occupying a wide area. These residues are acidic, and contain variable amounts of trace elements and radionuclides. The potentially polluting agents can be leached by rainwater, and so transferred to the surface waters and then to the groundwater after soil infiltration. Since the distribution and thickness of the residue deposits are variable, the contaminants cannot be easily traced back to a single, well defined source, and so a diffuse contamination (nonpoint source pollution) of the surrounding soils and waters occurs. This communication reports the results obtained in the study of soils close to the phosphogypsum deposits placed near Rio Tinto (Huelva, Spain). The zone is affected not only by the mentioned residues but also by the tides due to the vicinity of the sea. The samples studied had a low organic content and a low acidity with average values...
This paper presents a method for the determining 90Sr via its β-emitting daughter, 90Y, in enviro... more This paper presents a method for the determining 90Sr via its β-emitting daughter, 90Y, in environmental sam- ples by Cerenkov counting. The method is based on the isolation of 90Y by solvent extraction, using HDEHP as an extractor. The liquid scintillation (LS) analyzer Tri-Carb 3170 TR/SL has been employed. After radiochemical treatment, environmen- tal samples might be colored, and this
ABSTRACT Tropospheric ozone is considered one of the most significant air pollutants due to its n... more ABSTRACT Tropospheric ozone is considered one of the most significant air pollutants due to its negative effects on human health, agricultural crops, ecosystems and climate. The features of the southwest of the Iberian Peninsula (high temperatures and high solar radiation, the presence of the Guadalquivir basin and sources of precursors) favour the occurrence of episodes of high concentrations that cause exceedances of legal thresholds with relative frequency. Despite this, no study examining regional ozone episodes has been carried out in this region until now. In the present work a surface hourly ozone dataset (2003–2006) measured at 11 representative stations located in the southwest of the Iberian Peninsula (western Andalusia) was analysed in order to identify and characterise, for the first time, the regional ozone episodes that occur in this area. Using a statistical criterion, eight regional episodes were identified and analysed. The analysis of synoptic weather patterns revealed that these episodes occur in conjunction with two different synoptic conditions (high surface pressure either close to the British Isles or over the Atlantic Ocean). Both conditions generate weak isobaric surface pressure over the Iberian Peninsula, favouring the establishment of easterly winds at 500 m and the development of winds with two main prevailing directions (southwest-northwest, following the Guadalquivir basin) in the study area. During episodic days ozone follows a similar daily cycle to that observed on non-episode summer days, although the levels reached during the former are higher. In both cases, a direct relationship between the daily ozone cycle and the local wind regimen was not observed. This therefore seems to indicate that the daily cycle followed by ozone is mainly regulated by the precursor emissions produced in the environment, by the temperature changes taking place during the day and by the influence of the lower troposphere during anticyclonic weather conditions.
ABSTRACT The estuary formed by the confluence of Tinto and Odiel river‐mouths is located in the S... more ABSTRACT The estuary formed by the confluence of Tinto and Odiel river‐mouths is located in the South of Spain, close to Huelva town. This estuary has been deeply studied through the years because it has a double particularity. On one hand, since the beginning of the 1960s, the estuary has been affected by direct and indirect phosphogypsum (pg.) releases from two phosphoric acid and fertilizers factories that are working in the area. On the other hand, the pyrite mining operations upstream the Odiel and Tinto rivers has caused historically the formation of H2SO4, through oxidation of the natural sulphur deposits, the acidification of the waters and the consequent mobilisation of heavy metals from the mining area to the Huelva estuary. As a consequence, enhancement contamination levels in natural emitters from the 238U series were found in the surroundings of the factories in the previous years to 1998. However, in 1998 the management policy of waste releases drastically changed in the area, and direct discharges to Tinto and Odiel River had to be ceased.
In the SW of Spain, just in the confluence of the mouths of the Tinto and Odiel River and in the ... more In the SW of Spain, just in the confluence of the mouths of the Tinto and Odiel River and in the vicinity of Huelva town, there is a big industrial complex which includes between others an industry devoted during more than 40 years to the production of phosphoric acid, by treating sedimentary phosphate rock by the so-called "wet acid method". As a by-product of the mentioned process it have been produced historically huge amounts of a compound called phosphogypsum, which composition is mostly di-hydrate calcium sulphate containing some of the impurities of heavy metals and natural radionuclides originally present in the raw material. Due to the lack of market for this by-product, it has been mostly piled over some salt-marshes located in the vicinity of the industry, on the bank of the Tinto River. About 100 million tons of phosphogypsum have been piled in an area covering more than 1000 hectares, constituting a clear environmental and radiological anomaly in the zone. The...
ABSTRACT Liquid scintillation counting (LSC) is an easy and straightforward technique, and combin... more ABSTRACT Liquid scintillation counting (LSC) is an easy and straightforward technique, and combined with its low limit of detection, makes it a powerful tool for both routine and low level measurements that can be applied to 210Pb low level counting in environmental samples. 210Pb can be easily measured following a sulphate co-precipitation method; the addition of a carrier and the weighing of the recovered amount is a widespread technique to evaluate radiochemical yield, however, this evaluation of the recovery is sometimes questioned. The samples employed in this work were recollected in 1999 and 2005 from the estuary of the Odiel and Tinto rivers (SW of Spain), which were affected by phosphogypsum (pg.) discharges until 1998. Phosphogypsum contains most of the 210Pb from the treated raw material, for that reason analysed riverbed sediments have enhanced 210Pb activity concentrations and hence, enhanced activity concentration of its daughter 210Po, both in secular equilibrium after two years.
A big fertilizer industrial complex and a vast extension of phosphogypsum piles (12 km2), sited i... more A big fertilizer industrial complex and a vast extension of phosphogypsum piles (12 km2), sited in the estuary formed by the Odiel and Tinto river mouths (southwest of Spain), are producing an unambiguous radioactive impact in their surrounding aquatic environment through radionuclides from the U-series. The levels and distribution of radionuclides in sediments from this estuarine system have been determined. The analyses of radionuclide concentrations and activity ratios have provided us with an interesting information to evaluate the extension, degree and routes of the radioactive impact, as well as for the knowledge of the different pathways followed for the radioactive contamination to disturb this natural system. The obtained results indicate that the main pathway of radioactive contamination of the estuary is through the dissolution in its waters of the radionuclides released by the industrial activities and their later fixation on the particulate materials. Tidal activity also plays an important role in the transport and homogenization along the estuary of the radioactivity released from the fertilizer plants.
En el Capitulo 2 se hace una revision de los trabajos previos relacionados con nuestra investigac... more En el Capitulo 2 se hace una revision de los trabajos previos relacionados con nuestra investigacion. Pretendemos justificar el interes del problema que abordamos. ... : 12pt">En el Capitulo 3 se revisan los metodos radioquimicos empleados habitualmente para el analisis de 90Sr en distintos tipos de muestras ambientales. A continuacion se describe el metodo radioquimico utilizado por nosotros, los trabajos realizados para su desarrollo y puesta a punto y, por ultimo, los resultados (rendimiento quimico) obtenidos en las muestras analizadas.En el Capitulo 4 se describe el sistema detector, Quantulus 1220, utilizado para la determinacion de las concentraciones de 90Sr en las muestras analizadas. Se describen los trabajos de seleccion de los diversos parametros que inciden en la calidad de la medida o en su evaluacion. Un aspecto que se estudio en profundidad, y que se describe en este Capitulo, es la dependencia de la eficiencia de deteccion con el grado de color de la muestra. Tambien en el Capitulo 4 aparece una breve referencia al sistema de deteccion, y metodo de analisis, utilizado en la medida de 137Cs, y otros radionuclidos naturales, por espectrometria gamma.En el Capitulo 5 se describe la investigacion desarrollada en la plantacion de eucaliptos. Se distingue entres dos tipos de muestras: El suelo forestal y la vegetacion. En los dos casos se comienza describiendo la seleccion y recogida de muestras, su pretratamiento y los resultados de las medidas de las concentraciones de 137Cs y 90Sr. A continuacion se realizan diversos estudios comparativos entre los resultados obtenidos y diversos parametros fisicos y quimicos. Al final de este capitulo se expone la metodologia utilizada, para la evaluacion y los resultados obtenidos de los coeficientes de transferencia y flujos, correspondientes a los diversos compartimentos que hemos distinguido en la plantacion.La complejidad de la descripcion del funcionamiento de la fabrica de produccion de pasta de celulosa, y la consecuente interpretacion de los resultados obtenidos, nos ha llevado a optar por exponer en dos Capitulos independientes las investigaciones desarrolladas en la fabrica.En el Capitulo 6 se describe el proceso industrial y el funcionamiento de la fabrica de produccion de pasta de papel y se detallan las muestras recogidas, asi como su pretratamiento, para su estudio. En el Capitulo 7 se presentan los resultados obtenidos acerca de las concentraciones de radionuclidos en las muestras que consideramos representativas de los diferentes procesos que hemos distinguido en la fabrica. A continuacion se hace una evaluacion del flujo anual medio de 90Sr y 137Cs en la fabrica, comparandolo con elementos quimicos mayoritarios en los diferentes procesos y con radionuclidos naturales (fundamentalmente 40K) que se pueden considerar quimicamente semejantes. Finalmente se realiza una estimacion de los flujos de radionuclidos asociados a los vertidos generados en el proceso de produccion.Finalmente, en el Capitulo 8, se presentan las conclusiones mas importantes de esta memoria de Tesis.
Estuaries are sinks of materials and substances which are released directly into them or transpor... more Estuaries are sinks of materials and substances which are released directly into them or transported from rivers that drain the basin. It is usual to find high organic matter loads and fine particles in the sediments. We analyzed radionuclide concentrations ((210)Po, (230)Th, (232)Th, (234)U, (238)U, (226)Ra, (228)Th, (228)Ra, (40)K) in sediments and three different organs (roots, stems and leaves) of three species of halophytes plants (Spartina maritima, Spartina densiflora and Sarcocornia perennis). The study was carried out in two tidal salt marshes, one polluted by U-series radionuclides and another nearby that was unpolluted and was used as a control (or reference) area. The Tinto River salt marsh shows high levels of U-series radionuclides coming from mining and industrial discharges. On the contrary, the unperturbed Piedras River salt marsh is located about 25 km from the Tinto marsh, and shows little presence of contaminants and radionuclides. The results of this work have shown that natural radionuclide concentrations (specially the U-isotopes) in the Tinto salt marsh sediments are one order of magnitude higher than those in the Piedras marsh. These radionuclide enhancements are reflected in the different organs of the plants, which have similar concentration increases as the sediments where they have grown. Finally, the transfer factor (TF) of the most polluted radionuclides (U-isotopes and (210)Po) in the Tinto area are one order of magnitude higher than in the Piedras area, indicating that the fraction of each radionuclide in the sediment originating from the pollution is more available for the plants than the indigenous fraction. This means that the plants of the salt marshes are unhelpful as bioindicators or for the phytoremediation of radionuclides.
In this paper, (238)U-series radionuclides have been analysed in particulate matter samples colle... more In this paper, (238)U-series radionuclides have been analysed in particulate matter samples collected at a phosphogypsum stack system located near the city of Huelva (SW Spain) during the course of 1 year. The results have been compared to those collected at a reference (background) site located a few km away, in order to establish if the stack system provokes an increase in radionuclide exposure due to inhalation with particulate matter. The (222)Rn progeny, which is considered a very important contributor to the internal dose rate received by the population, was collected for 6 months. The results indicate that for several types of radionuclides there is a significant increase in the radioactivity adsorbed by the aerosol particles collected at phosphogypsum stacks. The isotope analysis indicates that this increment could be affected by the water vapour emissions from the factory, which contain high concentrations of these radionuclides. However, the majority of these radionuclides...
The obtaining of phosphate fertilizers results in large amounts of residues that are frequently a... more The obtaining of phosphate fertilizers results in large amounts of residues that are frequently accumulated in deposits or pools occupying a wide area. These residues are acidic, and contain variable amounts of trace elements and radionuclides. The potentially polluting agents can be leached by rainwater, and so transferred to the surface waters and then to the groundwater after soil infiltration. Since the distribution and thickness of the residue deposits are variable, the contaminants cannot be easily traced back to a single, well defined source, and so a diffuse contamination (nonpoint source pollution) of the surrounding soils and waters occurs. This communication reports the results obtained in the study of soils close to the phosphogypsum deposits placed near Rio Tinto (Huelva, Spain). The zone is affected not only by the mentioned residues but also by the tides due to the vicinity of the sea. The samples studied had a low organic content and a low acidity with average values...
This paper presents a method for the determining 90Sr via its β-emitting daughter, 90Y, in enviro... more This paper presents a method for the determining 90Sr via its β-emitting daughter, 90Y, in environmental sam- ples by Cerenkov counting. The method is based on the isolation of 90Y by solvent extraction, using HDEHP as an extractor. The liquid scintillation (LS) analyzer Tri-Carb 3170 TR/SL has been employed. After radiochemical treatment, environmen- tal samples might be colored, and this
ABSTRACT Tropospheric ozone is considered one of the most significant air pollutants due to its n... more ABSTRACT Tropospheric ozone is considered one of the most significant air pollutants due to its negative effects on human health, agricultural crops, ecosystems and climate. The features of the southwest of the Iberian Peninsula (high temperatures and high solar radiation, the presence of the Guadalquivir basin and sources of precursors) favour the occurrence of episodes of high concentrations that cause exceedances of legal thresholds with relative frequency. Despite this, no study examining regional ozone episodes has been carried out in this region until now. In the present work a surface hourly ozone dataset (2003–2006) measured at 11 representative stations located in the southwest of the Iberian Peninsula (western Andalusia) was analysed in order to identify and characterise, for the first time, the regional ozone episodes that occur in this area. Using a statistical criterion, eight regional episodes were identified and analysed. The analysis of synoptic weather patterns revealed that these episodes occur in conjunction with two different synoptic conditions (high surface pressure either close to the British Isles or over the Atlantic Ocean). Both conditions generate weak isobaric surface pressure over the Iberian Peninsula, favouring the establishment of easterly winds at 500 m and the development of winds with two main prevailing directions (southwest-northwest, following the Guadalquivir basin) in the study area. During episodic days ozone follows a similar daily cycle to that observed on non-episode summer days, although the levels reached during the former are higher. In both cases, a direct relationship between the daily ozone cycle and the local wind regimen was not observed. This therefore seems to indicate that the daily cycle followed by ozone is mainly regulated by the precursor emissions produced in the environment, by the temperature changes taking place during the day and by the influence of the lower troposphere during anticyclonic weather conditions.
ABSTRACT The estuary formed by the confluence of Tinto and Odiel river‐mouths is located in the S... more ABSTRACT The estuary formed by the confluence of Tinto and Odiel river‐mouths is located in the South of Spain, close to Huelva town. This estuary has been deeply studied through the years because it has a double particularity. On one hand, since the beginning of the 1960s, the estuary has been affected by direct and indirect phosphogypsum (pg.) releases from two phosphoric acid and fertilizers factories that are working in the area. On the other hand, the pyrite mining operations upstream the Odiel and Tinto rivers has caused historically the formation of H2SO4, through oxidation of the natural sulphur deposits, the acidification of the waters and the consequent mobilisation of heavy metals from the mining area to the Huelva estuary. As a consequence, enhancement contamination levels in natural emitters from the 238U series were found in the surroundings of the factories in the previous years to 1998. However, in 1998 the management policy of waste releases drastically changed in the area, and direct discharges to Tinto and Odiel River had to be ceased.
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