An industrial megasite in Italy interested by multi-compound pollution has been investigated by d... more An industrial megasite in Italy interested by multi-compound pollution has been investigated by different hydrodynamic, hydrochemical and isotopic techniques, with the aim of improving and validating a conceptual model of groundwater flow and contaminant transport and of providing a roughly evaluation of contaminant evolution with time in the context of a permanent remediation strategy
This paper presents a reconstruction of the Holocene palaeoenvironmental evolution in the central... more This paper presents a reconstruction of the Holocene palaeoenvironmental evolution in the central São Paulo State (Brazil) based on anthracological analyses, in association with soil isotopic composition (␦ 13 C) and radiocarbon dating from four sites. Anatomical identification of charcoal particles allows the reconstitution of past plant associations, and consequently of the vegetation and climate history. Rather precise interpretations may be achieved when associating anthracology and soil ␦ 13 C analysis. In the early Holocene, climate was dry and an open cerrado vegetation (savanna) covered most of this area. A cerradão (forested savanna) or a semideciduous forest existed in the more humid localities. After 3500/3000 14 C yr BP the climate was more humid, similar to the present, leading to the establishment of forested vegetation in all the studied sites. Comparison of these results with various palaeoenvironmental studies carried out in the Brazilian phytogeographical zone of c...
Closed basins are catchments whose drainage networks converge to lakes, salt flats or alluvial pl... more Closed basins are catchments whose drainage networks converge to lakes, salt flats or alluvial plains. Salt flats in the closed basins in arid northern Chile are extremely important ecological niches. The Salar del Huasco, one of these salt flats located in the high plateau (Altiplano), is a Ramsar site located in a national park and is composed of a wetland ecosystem rich in biodiversity. The proper management of the groundwater, which is essential for the wetland function, requires accurate estimates of recharge in the Salar del Huasco basin. This study quantifies the spatio-temporal distribution of the recharge, through combined use of isotopic characterization of the different components of the water cycle and a rainfall-runoff model. The use of both methodologies aids the understanding of hydrological behavior of the basin and enabled estimation of a long-term average recharge of 22 mm/yr (i.e., 15 % of the annual rainfall). Recharge has a high spatial variability, controlled by the geological and hydrometeorological characteristics of the basin, and a high interannual variability, with values ranging from 18 to 26 mm/yr. The isotopic approach allowed not only the definition of the conceptual model used in the hydrological model, but also eliminated the possibility of a hydrogeological connection between the aquifer of the Salar del Huasco basin and the aquifer that feeds the springs of the nearby town of Pica. This potential connection has been an issue of great interest to agriculture and tourism activities in the region.RésuméLes bassins fermés sont des bassins versants dont les réseaux de drainage convergent vers des lacs, des marais salants ou des plaines alluviales. Les marais salants des bassins fermés dans le nord aride du Chili constituent des niches écologiques très importantes. Le Salar del Huasco, l’une de ces salines situées sur les hauts plateaux (Altiplano) est un site Ramsar situé dans un parc national et composé d’un écosystème de zones humides riche en biodiversité. La bonne gestion des eaux souterraines, qui est essentielle pour la fonction des zones humides, nécessité une estimation précise de la recharge dans le bassin du Salar del Huasco. Cette étude quantifie la distribution spatio-temporelle de la recharge, en combinant l’utilisation de la caractérisation isotopique de différentes composantes du cycle de l’eau et d’un modèle pluie-ruissellement. L’utilisation des deux méthodologies contribue à la compréhension du comportement hydrologique du bassin et a permis l’estimation de la recharge moyenne sur le long terme, 22 mm/an (soit 15 % des précipitations annuelles). La recharge a une forte variabilité spatiale, contrôlée par les caractéristiques géologiques et hydrométéorologiques du bassin, et une forte variabilité interannuelle, avec des valeurs comprises entre 18 et 26 mm/an. L’approche isotopique a permis non seulement la définition d’un modèle conceptuel utilisé pour le modèle hydrologique, mais aussi d’éliminer la possibilité d’une connexion hydrogéologique entre l’aquifère du bassin du Salar del Huasco et l’aquifère qui alimente les sources situées à proximité de la ville de Pica. Cette connexion potentielle a été un sujet de grand intérêt pour les activités agricoles et du tourisme de la région.ResumenLas cuencas cerradas son cuencas cuyas redes de drenaje convergen hacia lagos, salares o llanuras aluviales. Las salinas en las cuencas cerradas del norte árido de Chile son extremadamente importantes como nichos ecológicos. El Salar del Huasco, una de estas salinas ubicado en una altiplanicie (Altiplano), es un sitio Ramsar que se encuentra en un parque nacional y se compone de un ecosistema de humedales ricos en biodiversidad. El manejo adecuado del agua subterránea en la cuenca del Salar del Huasco, lo cual es esencial para la función de los humedales, requiere estimaciones precisas de la recarga. Este estudio cuantifica la distribución espacio-temporal de la recarga, mediante el uso combinado de la caracterización isotópica de los distintos componentes del ciclo del agua y de un modelo lluvia-escorrentía. El uso de ambas metodologías ayuda a la comprensión del comportamiento hidrológico de la cuenca y permite la estimación de una recarga media a largo plazo, de 22 mm/año (es decir, el 15 % de la precipitación anual). La recarga tiene una alta variabilidad espacial, controlada por las características geológicas e hidrometeorológicas de la cuenca, y una alta variabilidad interanual, con valores que van del 18 al 26 mm/año. El enfoque isotópico permitió no sólo la definición del modelo conceptual utilizado en el modelo hidrológico, sino que también eliminó la posibilidad de una conexión hidrogeológica entre el acuífero de la cuenca del Salar del Huasco y el acuífero que alimenta a los manantiales de la localidad cercana de Pica. Esta conexión potencial ha sido un tema de gran interés para las actividades de la agricultura y del turismo en la…
Chlorinated volatile organic compounds were detected in an industrial facility (site) in the uppe... more Chlorinated volatile organic compounds were detected in an industrial facility (site) in the upper part of the underlying dolomite bedrock aquifer. The primary chlorinated solvent detected at the site is trichloroethene (TCE), and associated daughter products, such as cis-1,2- dichloroethene (cis-1,2-DCE) and vinyl chloride (VC), are also present. Several conventional monitoring wells installed at the site were recently sampled for
Historic practices at a wood-preserving facility along a major river in the lower main- land of B... more Historic practices at a wood-preserving facility along a major river in the lower main- land of British Columbia have contaminated the underlying tidally forced anaerobic aquifer. Creosote from the source zone, found mostly as an immobile separate phase, is dissolving and forming an aqueous-phase plume, which is discharging from the aquifer at the river bottom. Previous studies could only explain
The recharge processes in the overexploited aquifer of the Silao Romita basin, central Mexico, we... more The recharge processes in the overexploited aquifer of the Silao Romita basin, central Mexico, were investigated by means of gaseous tracers (chlorofluorocarbons, CFCs) and radioactive isotopes (C-14, tritium). CFC concentrations varied between 0.06 and 12 pmol/l (CFC-11), 0.03 and 1.7 pmol/l (CFC-12), and <0.01 and 0.23 pmol/l (CFC-113). CFC concentrations are controlled by irrigation return flow which became apparent by the comparison with tritium. Tritium activities ranged from 0 to 3.5 TU. The calculated mean residence times of 70 to more than 300 years are considerably lower than the ages estimated based on the CFCs data. These data showed that CFCs were not appropriate for groundwater dating in this particular area but the CFCs were suitable as a qualitative measure of the magnitude of irrigation return flow which proved to be a significant source of recharge in the irrigated areas. Radiocarbon activities were in the range of 6–109 pmC. Carbon-13 values varied between –11.9 and –7.2‰ VPDB. Modelling of carbon isotopes with NETPATH along a plausible flow path reveals considerable influences of exchange with soil CO2 and carbonate dissolution. Radiocarbon data indicate, at least in one case, the existence of groundwaters with residence times of more than 10,000 years. Los procesos de recarga en el acuífero sobre-explotado de la cuenca de Silao-Romita (centro de México) han sido investigados por medio de trazadores gaseosos (clorofluorocarbonados - CFCs) e isótopos radioactivos (C-14, tritio). Las concentraciones de CFCs variaron entre 0.06 y 12 pmol/l (CFC-11), 0.03 y 1.7 pmol/l (CFC-12), y <0.01 y 0.23 pmol/l (CFC-113). Las concentraciones de CFCs están controladas por aguas de retorno de riego, lo que se hace evidente por la comparación con datos de tritio. Las actividades de tritio variaron de 0 a 3.5 UT. Los tiempos medios de residencia calculados (70 a más de 300 años) son considerablemente menores que las edades estimadas en base a los datos de CFCs. Estos datos mostraron que los CFCs no son apropiados para la datación de aguas subterráneas en la zona de estudio, aunque los CFCs resultaron convenientes para estimar cuantitativamente la magnitud de los retornos de riego, los que son una fuente importante de recarga en los sectores regados. El rango de actividades del carbono radioactivo fue de 6 a 109 pmC. Los valores de Carbono-13 variaron entre -11.9 y -7.2 VPDB. La modelación de los isótopos de carbono a lo largo de caminos de flujo verosímiles revela considerable influencias de intercambio con CO2 del suelo y disolución de carbonatos. Al menos en un caso, los datos de carbono radoactico indican la existencia de aguas subterráneas con tiempos de residencia de más de 10,000 años. Les mécanismes de la recharge dans l’aquifère surexploité du bassin de Silao-Romita, Mexique central, ont été étudiés au moyen de traceurs gazeux (chlorofluocarbones - CFCs) et d’isotopes radioactifs (14 C, tritium. Les concentrations en CFC ont varié entre 0.06 et 12 pmol/l (CFC-11), 0.03 et 1.7 pmol/l (CFC-12), et <0.01 et 0.23 pmol/l (CFC-113). Les concentrations en CFC sont contrôlées par l’écoulement de restitution de l’irrigation ce qui est devenu évident par corrélation avec le tritium. Les activités tritium ont été de 0 à 3.5 UT. Les temps de résidence moyens calculés de 70 à plus de 300 années sont considérablement plus faibles que les ages estimés sur la base des données des CFCs. Ces données ont montré que les CFCs n’étaient pas adaptés à la datation de l’eau souterraine dans cette région en particulier mais les CFCs sont appropriés pour la mesure de l’ampleur de l’écoulement de restitution qui a démontré être une source de recharge dans les régions irriguées. Les activités radiocarbone ont été de 6 à 109 pmC. Les valeurs de carbone-13 ont varié entre -11.9 et -7.2 0/00 VPDB. La modélisation des isotopes du carbone avec NETPATH le long d’une ligne d’écoulement plausible révèle la grande influence des échanges avec le CO2 du sol et la dissolution des carbonates. Les données du radiocarbone indiquent, au moins dans un cas, l’existence d’eaux souterraines ayant des temps de résidence de plus de 10,000 années. Os processos de recarga no aquífero sobreexplorado da bacia de Silao Romita, México central, foram investigados utilizando traçadores gasosos (clorofluorcarbonos - CFCs) e isótopos radioactivos (C-14, trítio). As concentrações de CFC variaram entre 0.06 e 12 pmol/l (CFC-11), 0.03 e 1.7 pmol/l (CFC-12), e <0.01 e 0.23 pmol/l (CFC-113). As concentrações de CFC são controladas pelo retorno de água de rega, o que se torna evidente pela comparação com o trítio. As actividades do trítio variam entre 0 e 3.5 UT. Os tempos de residência médios, calculados entre 70 e mais de 300 anos, são consideravelmente mais baixos do que as idades estimadas baseadas nos dados de CFC. Nesta área em particular, estes dados mostraram que os CFC não foram apropriados para a datação de águas subterrâneas, mas foram…
This chapter presents carbon isotope data of soil organic matter (SOM), collected in natural fore... more This chapter presents carbon isotope data of soil organic matter (SOM), collected in natural forest ecosystems in different sites from Brazil. The studied areas are located in Londrina (Southern part of the country), Piracicaba (Southeast), Salitre (Central) and Altamira (Northern). This study is part of the research program on tropical and sub-tropical soils in Brazil, of which the main objective
Significant upward movement of mineralized water takes place in the Puebla aquifer system. Prefer... more Significant upward movement of mineralized water takes place in the Puebla aquifer system. Preferential groundwater flow paths related to the geological structure and the lowering of the potentiometric surface are suspected to be the prime factors for this intrusion. A combined approach of geochemical and isotope analyses was used to assess the sources of salinity and processes that are controlling
The impact of urbanization on groundwater quality is of special concern for water managers dealin... more The impact of urbanization on groundwater quality is of special concern for water managers dealing with the provision of drinking water to large urban centers. Nitrate is one of the most common contaminants found in urban aquifers. This paper presents a case study aiming at evaluating the distribution and sources of nitrate in an urban aquifer in the city of Mar del Plata, Argentina. Four study zones under different land uses, including a pristine, a semi-rural, an intermediate, and an urban area, were evaluated as a part of this study. The three latter zones are linked by the groundwater flow system. The average nitrate concentration in the pristine area is 6.7 mg/L as nitrate and is over the permissible level of 50 mg/L for drinking water in the other areas. In the semi-rural area it ranges from 39.2 to 107.1 mg/L with an average value of 38.2 mg/L and the nitrate concentration tends to decrease in the intermediate zone to an average value of 38.2 mg/L; however, values above 60 mg/L are also observed there. Then the nitrate concentration in the urban area water is higher than that in the intermediate zonewater ranging from 48.2 to 100.3 mg/L with an average value of 67.3 mg/L. Data on the stable isotopes 15N and 18O in nitrate show that the main sources of nitrate in the study area are manure associated to agriculture uses and cesspools in the semi-rural area, and leakage of the sewage distribution network in the urban area, respectively. This is supported by a previous study which found that 20 % of the water flooding many underground structures in the city came from leakage of the sewage network. No evidence of nitrate attenuation by denitrification was found in the groundwater. This study has shown that aquifers in urban areas can be affected by agricultural activity in the upstream areas and leakage of the sewage network in the urban area.
An industrial megasite in Italy interested by multi-compound pollution has been investigated by d... more An industrial megasite in Italy interested by multi-compound pollution has been investigated by different hydrodynamic, hydrochemical and isotopic techniques, with the aim of improving and validating a conceptual model of groundwater flow and contaminant transport and of providing a roughly evaluation of contaminant evolution with time in the context of a permanent remediation strategy
This paper presents a reconstruction of the Holocene palaeoenvironmental evolution in the central... more This paper presents a reconstruction of the Holocene palaeoenvironmental evolution in the central São Paulo State (Brazil) based on anthracological analyses, in association with soil isotopic composition (␦ 13 C) and radiocarbon dating from four sites. Anatomical identification of charcoal particles allows the reconstitution of past plant associations, and consequently of the vegetation and climate history. Rather precise interpretations may be achieved when associating anthracology and soil ␦ 13 C analysis. In the early Holocene, climate was dry and an open cerrado vegetation (savanna) covered most of this area. A cerradão (forested savanna) or a semideciduous forest existed in the more humid localities. After 3500/3000 14 C yr BP the climate was more humid, similar to the present, leading to the establishment of forested vegetation in all the studied sites. Comparison of these results with various palaeoenvironmental studies carried out in the Brazilian phytogeographical zone of c...
Closed basins are catchments whose drainage networks converge to lakes, salt flats or alluvial pl... more Closed basins are catchments whose drainage networks converge to lakes, salt flats or alluvial plains. Salt flats in the closed basins in arid northern Chile are extremely important ecological niches. The Salar del Huasco, one of these salt flats located in the high plateau (Altiplano), is a Ramsar site located in a national park and is composed of a wetland ecosystem rich in biodiversity. The proper management of the groundwater, which is essential for the wetland function, requires accurate estimates of recharge in the Salar del Huasco basin. This study quantifies the spatio-temporal distribution of the recharge, through combined use of isotopic characterization of the different components of the water cycle and a rainfall-runoff model. The use of both methodologies aids the understanding of hydrological behavior of the basin and enabled estimation of a long-term average recharge of 22 mm/yr (i.e., 15 % of the annual rainfall). Recharge has a high spatial variability, controlled by the geological and hydrometeorological characteristics of the basin, and a high interannual variability, with values ranging from 18 to 26 mm/yr. The isotopic approach allowed not only the definition of the conceptual model used in the hydrological model, but also eliminated the possibility of a hydrogeological connection between the aquifer of the Salar del Huasco basin and the aquifer that feeds the springs of the nearby town of Pica. This potential connection has been an issue of great interest to agriculture and tourism activities in the region.RésuméLes bassins fermés sont des bassins versants dont les réseaux de drainage convergent vers des lacs, des marais salants ou des plaines alluviales. Les marais salants des bassins fermés dans le nord aride du Chili constituent des niches écologiques très importantes. Le Salar del Huasco, l’une de ces salines situées sur les hauts plateaux (Altiplano) est un site Ramsar situé dans un parc national et composé d’un écosystème de zones humides riche en biodiversité. La bonne gestion des eaux souterraines, qui est essentielle pour la fonction des zones humides, nécessité une estimation précise de la recharge dans le bassin du Salar del Huasco. Cette étude quantifie la distribution spatio-temporelle de la recharge, en combinant l’utilisation de la caractérisation isotopique de différentes composantes du cycle de l’eau et d’un modèle pluie-ruissellement. L’utilisation des deux méthodologies contribue à la compréhension du comportement hydrologique du bassin et a permis l’estimation de la recharge moyenne sur le long terme, 22 mm/an (soit 15 % des précipitations annuelles). La recharge a une forte variabilité spatiale, contrôlée par les caractéristiques géologiques et hydrométéorologiques du bassin, et une forte variabilité interannuelle, avec des valeurs comprises entre 18 et 26 mm/an. L’approche isotopique a permis non seulement la définition d’un modèle conceptuel utilisé pour le modèle hydrologique, mais aussi d’éliminer la possibilité d’une connexion hydrogéologique entre l’aquifère du bassin du Salar del Huasco et l’aquifère qui alimente les sources situées à proximité de la ville de Pica. Cette connexion potentielle a été un sujet de grand intérêt pour les activités agricoles et du tourisme de la région.ResumenLas cuencas cerradas son cuencas cuyas redes de drenaje convergen hacia lagos, salares o llanuras aluviales. Las salinas en las cuencas cerradas del norte árido de Chile son extremadamente importantes como nichos ecológicos. El Salar del Huasco, una de estas salinas ubicado en una altiplanicie (Altiplano), es un sitio Ramsar que se encuentra en un parque nacional y se compone de un ecosistema de humedales ricos en biodiversidad. El manejo adecuado del agua subterránea en la cuenca del Salar del Huasco, lo cual es esencial para la función de los humedales, requiere estimaciones precisas de la recarga. Este estudio cuantifica la distribución espacio-temporal de la recarga, mediante el uso combinado de la caracterización isotópica de los distintos componentes del ciclo del agua y de un modelo lluvia-escorrentía. El uso de ambas metodologías ayuda a la comprensión del comportamiento hidrológico de la cuenca y permite la estimación de una recarga media a largo plazo, de 22 mm/año (es decir, el 15 % de la precipitación anual). La recarga tiene una alta variabilidad espacial, controlada por las características geológicas e hidrometeorológicas de la cuenca, y una alta variabilidad interanual, con valores que van del 18 al 26 mm/año. El enfoque isotópico permitió no sólo la definición del modelo conceptual utilizado en el modelo hidrológico, sino que también eliminó la posibilidad de una conexión hidrogeológica entre el acuífero de la cuenca del Salar del Huasco y el acuífero que alimenta a los manantiales de la localidad cercana de Pica. Esta conexión potencial ha sido un tema de gran interés para las actividades de la agricultura y del turismo en la…
Chlorinated volatile organic compounds were detected in an industrial facility (site) in the uppe... more Chlorinated volatile organic compounds were detected in an industrial facility (site) in the upper part of the underlying dolomite bedrock aquifer. The primary chlorinated solvent detected at the site is trichloroethene (TCE), and associated daughter products, such as cis-1,2- dichloroethene (cis-1,2-DCE) and vinyl chloride (VC), are also present. Several conventional monitoring wells installed at the site were recently sampled for
Historic practices at a wood-preserving facility along a major river in the lower main- land of B... more Historic practices at a wood-preserving facility along a major river in the lower main- land of British Columbia have contaminated the underlying tidally forced anaerobic aquifer. Creosote from the source zone, found mostly as an immobile separate phase, is dissolving and forming an aqueous-phase plume, which is discharging from the aquifer at the river bottom. Previous studies could only explain
The recharge processes in the overexploited aquifer of the Silao Romita basin, central Mexico, we... more The recharge processes in the overexploited aquifer of the Silao Romita basin, central Mexico, were investigated by means of gaseous tracers (chlorofluorocarbons, CFCs) and radioactive isotopes (C-14, tritium). CFC concentrations varied between 0.06 and 12 pmol/l (CFC-11), 0.03 and 1.7 pmol/l (CFC-12), and <0.01 and 0.23 pmol/l (CFC-113). CFC concentrations are controlled by irrigation return flow which became apparent by the comparison with tritium. Tritium activities ranged from 0 to 3.5 TU. The calculated mean residence times of 70 to more than 300 years are considerably lower than the ages estimated based on the CFCs data. These data showed that CFCs were not appropriate for groundwater dating in this particular area but the CFCs were suitable as a qualitative measure of the magnitude of irrigation return flow which proved to be a significant source of recharge in the irrigated areas. Radiocarbon activities were in the range of 6–109 pmC. Carbon-13 values varied between –11.9 and –7.2‰ VPDB. Modelling of carbon isotopes with NETPATH along a plausible flow path reveals considerable influences of exchange with soil CO2 and carbonate dissolution. Radiocarbon data indicate, at least in one case, the existence of groundwaters with residence times of more than 10,000 years. Los procesos de recarga en el acuífero sobre-explotado de la cuenca de Silao-Romita (centro de México) han sido investigados por medio de trazadores gaseosos (clorofluorocarbonados - CFCs) e isótopos radioactivos (C-14, tritio). Las concentraciones de CFCs variaron entre 0.06 y 12 pmol/l (CFC-11), 0.03 y 1.7 pmol/l (CFC-12), y <0.01 y 0.23 pmol/l (CFC-113). Las concentraciones de CFCs están controladas por aguas de retorno de riego, lo que se hace evidente por la comparación con datos de tritio. Las actividades de tritio variaron de 0 a 3.5 UT. Los tiempos medios de residencia calculados (70 a más de 300 años) son considerablemente menores que las edades estimadas en base a los datos de CFCs. Estos datos mostraron que los CFCs no son apropiados para la datación de aguas subterráneas en la zona de estudio, aunque los CFCs resultaron convenientes para estimar cuantitativamente la magnitud de los retornos de riego, los que son una fuente importante de recarga en los sectores regados. El rango de actividades del carbono radioactivo fue de 6 a 109 pmC. Los valores de Carbono-13 variaron entre -11.9 y -7.2 VPDB. La modelación de los isótopos de carbono a lo largo de caminos de flujo verosímiles revela considerable influencias de intercambio con CO2 del suelo y disolución de carbonatos. Al menos en un caso, los datos de carbono radoactico indican la existencia de aguas subterráneas con tiempos de residencia de más de 10,000 años. Les mécanismes de la recharge dans l’aquifère surexploité du bassin de Silao-Romita, Mexique central, ont été étudiés au moyen de traceurs gazeux (chlorofluocarbones - CFCs) et d’isotopes radioactifs (14 C, tritium. Les concentrations en CFC ont varié entre 0.06 et 12 pmol/l (CFC-11), 0.03 et 1.7 pmol/l (CFC-12), et <0.01 et 0.23 pmol/l (CFC-113). Les concentrations en CFC sont contrôlées par l’écoulement de restitution de l’irrigation ce qui est devenu évident par corrélation avec le tritium. Les activités tritium ont été de 0 à 3.5 UT. Les temps de résidence moyens calculés de 70 à plus de 300 années sont considérablement plus faibles que les ages estimés sur la base des données des CFCs. Ces données ont montré que les CFCs n’étaient pas adaptés à la datation de l’eau souterraine dans cette région en particulier mais les CFCs sont appropriés pour la mesure de l’ampleur de l’écoulement de restitution qui a démontré être une source de recharge dans les régions irriguées. Les activités radiocarbone ont été de 6 à 109 pmC. Les valeurs de carbone-13 ont varié entre -11.9 et -7.2 0/00 VPDB. La modélisation des isotopes du carbone avec NETPATH le long d’une ligne d’écoulement plausible révèle la grande influence des échanges avec le CO2 du sol et la dissolution des carbonates. Les données du radiocarbone indiquent, au moins dans un cas, l’existence d’eaux souterraines ayant des temps de résidence de plus de 10,000 années. Os processos de recarga no aquífero sobreexplorado da bacia de Silao Romita, México central, foram investigados utilizando traçadores gasosos (clorofluorcarbonos - CFCs) e isótopos radioactivos (C-14, trítio). As concentrações de CFC variaram entre 0.06 e 12 pmol/l (CFC-11), 0.03 e 1.7 pmol/l (CFC-12), e <0.01 e 0.23 pmol/l (CFC-113). As concentrações de CFC são controladas pelo retorno de água de rega, o que se torna evidente pela comparação com o trítio. As actividades do trítio variam entre 0 e 3.5 UT. Os tempos de residência médios, calculados entre 70 e mais de 300 anos, são consideravelmente mais baixos do que as idades estimadas baseadas nos dados de CFC. Nesta área em particular, estes dados mostraram que os CFC não foram apropriados para a datação de águas subterrâneas, mas foram…
This chapter presents carbon isotope data of soil organic matter (SOM), collected in natural fore... more This chapter presents carbon isotope data of soil organic matter (SOM), collected in natural forest ecosystems in different sites from Brazil. The studied areas are located in Londrina (Southern part of the country), Piracicaba (Southeast), Salitre (Central) and Altamira (Northern). This study is part of the research program on tropical and sub-tropical soils in Brazil, of which the main objective
Significant upward movement of mineralized water takes place in the Puebla aquifer system. Prefer... more Significant upward movement of mineralized water takes place in the Puebla aquifer system. Preferential groundwater flow paths related to the geological structure and the lowering of the potentiometric surface are suspected to be the prime factors for this intrusion. A combined approach of geochemical and isotope analyses was used to assess the sources of salinity and processes that are controlling
The impact of urbanization on groundwater quality is of special concern for water managers dealin... more The impact of urbanization on groundwater quality is of special concern for water managers dealing with the provision of drinking water to large urban centers. Nitrate is one of the most common contaminants found in urban aquifers. This paper presents a case study aiming at evaluating the distribution and sources of nitrate in an urban aquifer in the city of Mar del Plata, Argentina. Four study zones under different land uses, including a pristine, a semi-rural, an intermediate, and an urban area, were evaluated as a part of this study. The three latter zones are linked by the groundwater flow system. The average nitrate concentration in the pristine area is 6.7 mg/L as nitrate and is over the permissible level of 50 mg/L for drinking water in the other areas. In the semi-rural area it ranges from 39.2 to 107.1 mg/L with an average value of 38.2 mg/L and the nitrate concentration tends to decrease in the intermediate zone to an average value of 38.2 mg/L; however, values above 60 mg/L are also observed there. Then the nitrate concentration in the urban area water is higher than that in the intermediate zonewater ranging from 48.2 to 100.3 mg/L with an average value of 67.3 mg/L. Data on the stable isotopes 15N and 18O in nitrate show that the main sources of nitrate in the study area are manure associated to agriculture uses and cesspools in the semi-rural area, and leakage of the sewage distribution network in the urban area, respectively. This is supported by a previous study which found that 20 % of the water flooding many underground structures in the city came from leakage of the sewage network. No evidence of nitrate attenuation by denitrification was found in the groundwater. This study has shown that aquifers in urban areas can be affected by agricultural activity in the upstream areas and leakage of the sewage network in the urban area.
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Papers by Ramón Aravena