Análisis de dos sistemas acuáticos : un enfoque ecohidrológico

Se aplicó el concepto de ecohidrología en dos cuencas: río Paraná Inferior y Arroyo Durazno con el objeto de estudiar las respuestas biogeoquímicas en ambos sistemas diferenciados por área de drenaje, magnitud de caudal y uso de la tierra. La primera presenta una amplia llanura aluvial (12.350 km2) vegetada por macrófitas. Durante las crecientes estivales, las condiciones favorecen la denitrificación en humedales y disminución de nitratos en cauce principal, siendo el intervalo de mayor frecuencia 25-108,3 μg N-NO3 -/l en aguas altas y 191,6-274,9 μg N-NO3 -/l en aguas bajas. Durante una creciente invernal (El Niño 1991-1992) se detectó correlación positiva significativa entre concentraciones de nitratos y amonio y altura hidrométrica. El arroyo Durazno (360 km2) no recibe aporte directo de contaminantes y presenta una rápida respuesta ante un evento de precipitación. En las primeras horas de la tormenta las concentraciones de nitratos y fósforo reactivo soluble (PRS) fueron mayores que al finalizar, debido al aporte por escorrentía. Los resultados revelan el efecto del valle aluvial sobre la hidroquímica de los cauces principales. El análisis muestra que cambios en componentes del ciclo hidrológico y/o en el uso de la tierra podrían alterar la calidad de aguas aun en cuencas de extensiones y caudales diferentes.The concept of ecohydrology was applied to the Lower Paraná river and the El Durazno stream catchments in order to study the biogeochemistry responses of the two systems, which differ in their drainage area, discharge and land use. The first catchment presents a vast floodplain dominated by macrophyte (12,350 km2). During summer rise, denitrification in wetlands is favoured, producing nitrate concentration reduction in the main channel. The nitrate range most frequently found in high water levels was 25-108,3 μg N-NO3 -/l and in low water levels was 191,6-274,9 μg N-NO3 -/l. During a winter rise (El Niño 1991-1992), a significant positive correlation was detected between nitrate and ammonia concentrations and hydrometric height. The El Durazno stream (360 km2) does not receive any direct polluted flow and responds rapidly to precipitation events. During the first hours of the studied storm and as consequence of runoff, nitrate and phosphorous concentrations were higher than at the beginning. The results here revealed the effect of the alluvial valley on the main river bed hydrochemistry. The analysis showed that changes in water cycle and/or in land use may alter water quality, even in catchments of different extension and river discharge.Fil: De Cabo, Laura.Fil: Seoane, Rafael. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de HidráulicaFil: Arreghini, Silvana. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y AmbienteFil: Callau, Ana. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Hidráulic

Interpreting Encoding and Decoding Models

Encoding and decoding models are widely used in systems, cognitive, and computational neuroscience to make sense of brain-activity data. However, the interpretation of their results requires care. Decoding models can help reveal whether particular information is present in a brain region in a format the decoder can exploit. Encoding models make comprehensive predictions about representational spaces. In the context of sensory systems, encoding models enable us to test and compare brain-computational models, and thus directly constrain computational theory. Encoding and decoding models typically include fitted linear-model components. Sometimes the weights of the fitted linear combinations are interpreted as reflecting, in an encoding model, the contribution of different sensory features to the representation or, in a decoding model, the contribution of different measured brain responses to a decoded feature. Such interpretations can be problematic when the predictor variables or their noise components are correlated and when priors (or penalties) are used to regularize the fit. Encoding and decoding models are evaluated in terms of their generalization performance. The correct interpretation depends on the level of generalization a model achieves (e.g. to new response measurements for the same stimuli, to new stimuli from the same population, or to stimuli from a different population). Significant decoding or encoding performance of a single model (at whatever level of generality) does not provide strong constraints for theory. Many models must be tested and inferentially compared for analyses to drive theoretical progress.Comment: 19 pages, 2 figures, author preprin

Evaluation of the effect of Zn salts on root anatomy of schoenoplectus californicus

El Zn es un micronutriente y también un importante contaminante en los ecosistemas acuáticos. El objetivo del ensayo fue evaluar los efectos de sales de Zn sobre el crecimiento radicular y la captación del metal por Schoenoplectus californicus, macrófita nativa frecuente en arroyos de la región. Se expusieron plantas a soluciones de sales de Zn en dos concentraciones (50ppm y 100ppm). Se evaluaron elongación radicular, captación de Zn y sorción sobre la superficie radicular. La tasa de elongación fue afectada por altas concentraciones de Zn y por el contraión de la sal utilizada. El agregado de Zn al sistema aumentó su concentración en raíces, aunque el factor de bioconcentración tendió a disminuir. La coprecipitación de Zn con óxidos de Fe sobre las raíces, inducidas por las condiciones óxicas asociadas a la pérdida radial de oxígeno y al desarrollo del aerénquima, constituirían la primer barrera para atenuar el ingreso de metales tóxicos.Centro de Investigaciones Geológica

Remediación de efluentes provenientes de feedlots mediante el uso de plantas acuáticas

Feedlots have increased in several regions of Argentina, particularly in the Pampas. The absence of adequate treatments of the effluents produced in these establishments creates serious problems to the society. Phytoremediation can be defined as inexpensive and environmentally sustainable strategy used to remove pollutants by plants. The aim of this study was to evaluate the remediation potential of two macrophyte species (Eichhornia crassipes and Hydrocotyle ranunculoides) on a feedlot effluent. This effluent was treated with these species for 31 days. Control and macrophyte treatments decreased dissolved inorganic nitrogen (DIN), Kjeldahl nitrogen (Kj N), biological oxygen demand (BOD), chemical oxygen demand (COD), total dissolved salts (TDS), total phosphorus (TP), Pb, Zn and Cr levels. At macrophyte treatments, relatively constant pH levels were kept and decreased EC and TDS values were obtained compared to control, mitigating the release of contaminants and potential greenhouse gases to the atmosphere. Moreover, significant increases in biomass were obtained, being higher in E. crassipes. The results allow concluding that the presence of aquatic plants increases the removal rates of nutrients, organic matter and heavy metals from wastewater in approximately 10-17 days for a feedlot effluent with high organic load.En diversas regiones de la Argentina, en particular en la región Pampeana, se han incrementado los sistemas de engorde a corral (feedlots). La ausencia de tratamientos adecuados de los efluentes producidos por estos establecimientos crea severos problemas para la sociedad. El uso de plantas nativas para la remediación de sistemas contaminados es una tecnología de muy bajo costo y ambientalmente sustentable. El objetivo de este estudio fue evaluar el potencial de remediación de dos especies de plantas acuáticas (Eichhornia crassipes e Hydrocotyle ranunculoides) sobre un efluente de feedlot. Este efluente fue tratado con estas especies durante 31 días. Tanto el tratamiento control como los tratamientos con macrófitas disminuyen los niveles de nitrógeno inorgánico disuelto, nitrógeno Kjeldahl, demanda bioquímica de oxígeno, demanda química de oxígeno, sales totales disueltas (STD), fósforo total, Pb, Zn y Cr. El uso de macrófitas mantuvo relativamente constante los niveles de pH, disminuyendo CE y STD respecto del control, pudiendo mitigar la liberación de contaminantes hacia la atmósfera. Además se alcanzaron incrementos significativos de biomasa, siendo mayores en E. crassipes. Los resultados permiten concluir que la presencia de plantas acuáticas incrementan las tasas de remoción de nutrientes, material orgánico y metales pesados en aproximadamente 10-17 días desde un efluente con alta carga orgánica.Fil: Rizzo, Pedro Federico. Instituto Nacional de Tecnología Agropecuaria (Argentina). Instituto de Microbiología y Zoología Agrícola. Laboratorio de Transformación de ResiduosFil: Arreghini, Silvana. Universidad de Buenos Aires. Facultad de AgronomíaFil: Serafini, Roberto José María. Universidad de Buenos Aires. Facultad de AgronomíaFil: Bres, Patricia Alina. Instituto Nacional de Tecnología Agropecuaria (Argentina). Instituto de Microbiología y Zoología Agrícola. Laboratorio de Transformación de ResiduosFil: Crespo, Diana Elvira. Instituto Nacional de Tecnología Agropecuaria (Argentina). Instituto de Microbiología y Zoología Agrícola. Laboratorio de Transformación de ResiduosFil: Fabrizio de Iorio, Alicia Rosa. Universidad de Buenos Aires. Facultad de Agronomí

Remediación de efluentes provenientes de feedlots mediante el uso de plantas acuáticas

Feedlots have increased in several regions of Argentina, particularly in the Pampas. The absence of adequate treatments of the effluents produced in these establishments creates serious problems to the society. Phytoremediation can be defined as inexpensive and environmentally sustainable strategy used to remove pollutants by plants. The aim of this study was to evaluate the remediation potential of two macrophyte species (Eichhornia crassipes and Hydrocotyle ranunculoides) on a feedlot effluent. This effluent was treated with these species for 31 days. Control and macrophyte treatments decreased dissolved inorganic nitrogen (DIN), Kjeldahl nitrogen (Kj N), biological oxygen demand (BOD), chemical oxygen demand (COD), total dissolved salts (TDS), total phosphorus (TP), Pb, Zn and Cr levels. At macrophyte treatments, relatively constant pH levels were kept and decreased EC and TDS values were obtained compared to control, mitigating the release of contaminants and potential greenhouse gases to the atmosphere. Moreover, significant increases in biomass were obtained, being higher in E. crassipes. The results allow concluding that the presence of aquatic plants increases the removal rates of nutrients, organic matter and heavy metals from wastewater in approximately 10-17 days for a feedlot effluent with high organic load.Feedlots have increased in several regions of Argentina, particularly in the Pampas. The absence of adequate treatments of the effluents produced in these establishments creates serious problems to the society. Phytoremediation can be defined as inexpensive and environmentally sustainable strategy used to remove pollutants by plants. The aim of this study was to evaluate the remediation potential of two macrophyte species (Eichhornia crassipes and Hydrocotyle ranunculoides) on a feedlot effluent. This effluent was treated with these species for 31 days. Control and macrophyte treatments decreased dissolved inorganic nitrogen (DIN), Kjeldahl nitrogen (Kj N), biological oxygen demand (BOD), chemical oxygen demand (COD), total dissolved salts (TDS), total phosphorus (TP), Pb, Zn and Cr levels. At macrophyte treatments, relatively constant pH levels were kept and decreased EC and TDS values were obtained compared to control, mitigating the release of contaminants and potential greenhouse gases to the atmosphere. Moreover, significant increases in biomass were obtained, being higher in E. crassipes. The results allow concluding that the presence of aquatic plants increases the removal rates of nutrients, organic matter and heavy metals from wastewater in approximately 10-17 days for a feedlot effluent with high organic load

Vías para la integración de tecnologías de tratamiento de residuos agropecuarios y producción de biocombustibles

La utilización de los desechos agropecuarios en la producción de biocombustibles podría reducir la dependencia de las fuentes convencionales de energía permitiendo además obtener beneficios económicos y ambientales. Los objetivos de este trabajo son: evaluar el efecto de diferentes sustratos sobre la producción de biogás, analizar la factibilidad de integrar tecnologías de producción de biocombustibles, y determinar la aptitud del efluente como biofertilizante. Se realizaron ensayos de producción de biogás utilizando diferentes sustratos (bosta fresca, silo de maíz y glicerina). Se midieron variables físico-químicas, producción diaria y total de biogás. La mayor producción se observó en el tratamiento con elevado porcentaje de silo de maíz (186 L/kgSV). En el tratamiento con glicerina la elevada producción inicial de biogás (2500ml/día) fue inhibida por la acidificación del medio (pH:5,5). Los valores de nutrientes y iones mayoritarios en el efluente sugieren que de corregirse la elevada conductividad eléctrica (>9,2dS/m) podría utilizarse como biofertilizante.Agricultural tailing might be used in biofuels production in order to reduce the dependence of conventional sources of energy, allowing to obtain in addition, economic and environmental benefits. The aims of this work are: to evaluate the effect of different substrates on the production of biogas, to analyze the feasibility of integrating technologies of biofuels production, and to determine the aptitude of the effluent as biofertilizer. Production tests of biogas with different substrates (fresh muck, corn silage and glycerine) were performed. Physico-chemical variables, daily and total biogas production were meassured. Major production of biogas was observed in treatment with high percentage of corn silage (186L/kgVS). In glycerine´s treatment, high initial production of biogas (2500ml/day) was inhibited due to acidification of the environment (pH:5,5). Nutrients and majority ions concentrations in the effluent suggest that if the high electrical conductivity is corrected (>9,2dS/m) it can be used as biofertilizer.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Vías para la integración de tecnologías de tratamiento de residuos agropecuarios y producción de biocombustibles

La utilización de los desechos agropecuarios en la producción de biocombustibles podría reducir la dependencia de las fuentes convencionales de energía permitiendo además obtener beneficios económicos y ambientales. Los objetivos de este trabajo son: evaluar el efecto de diferentes sustratos sobre la producción de biogás, analizar la factibilidad de integrar tecnologías de producción de biocombustibles, y determinar la aptitud del efluente como biofertilizante. Se realizaron ensayos de producción de biogás utilizando diferentes sustratos (bosta fresca, silo de maíz y glicerina). Se midieron variables físico-químicas, producción diaria y total de biogás. La mayor producción se observó en el tratamiento con elevado porcentaje de silo de maíz (186 L/kgSV). En el tratamiento con glicerina la elevada producción inicial de biogás (2500ml/día) fue inhibida por la acidificación del medio (pH:5,5). Los valores de nutrientes y iones mayoritarios en el efluente sugieren que de corregirse la elevada conductividad eléctrica (>9,2dS/m) podría utilizarse como biofertilizante.Agricultural tailing might be used in biofuels production in order to reduce the dependence of conventional sources of energy, allowing to obtain in addition, economic and environmental benefits. The aims of this work are: to evaluate the effect of different substrates on the production of biogas, to analyze the feasibility of integrating technologies of biofuels production, and to determine the aptitude of the effluent as biofertilizer. Production tests of biogas with different substrates (fresh muck, corn silage and glycerine) were performed. Physico-chemical variables, daily and total biogas production were meassured. Major production of biogas was observed in treatment with high percentage of corn silage (186L/kgVS). In glycerine´s treatment, high initial production of biogas (2500ml/day) was inhibited due to acidification of the environment (pH:5,5). Nutrients and majority ions concentrations in the effluent suggest that if the high electrical conductivity is corrected (>9,2dS/m) it can be used as biofertilizer.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Vías para la integración de tecnologías de tratamiento de residuos agropecuarios y producción de biocombustibles

La utilización de los desechos agropecuarios en la producción de biocombustibles podría reducir la dependencia de las fuentes convencionales de energía permitiendo además obtener beneficios económicos y ambientales. Los objetivos de este trabajo son: evaluar el efecto de diferentes sustratos sobre la producción de biogás, analizar la factibilidad de integrar tecnologías de producción de biocombustibles, y determinar la aptitud del efluente como biofertilizante. Se realizaron ensayos de producción de biogás utilizando diferentes sustratos (bosta fresca, silo de maíz y glicerina). Se midieron variables físico-químicas, producción diaria y total de biogás. La mayor producción se observó en el tratamiento con elevado porcentaje de silo de maíz (186 L/kgSV). En el tratamiento con glicerina la elevada producción inicial de biogás (2500ml/día) fue inhibida por la acidificación del medio (pH:5,5). Los valores de nutrientes y iones mayoritarios en el efluente sugieren que de corregirse la elevada conductividad eléctrica (>9,2dS/m) podría utilizarse como biofertilizante.Agricultural tailing might be used in biofuels production in order to reduce the dependence of conventional sources of energy, allowing to obtain in addition, economic and environmental benefits. The aims of this work are: to evaluate the effect of different substrates on the production of biogas, to analyze the feasibility of integrating technologies of biofuels production, and to determine the aptitude of the effluent as biofertilizer. Production tests of biogas with different substrates (fresh muck, corn silage and glycerine) were performed. Physico-chemical variables, daily and total biogas production were meassured. Major production of biogas was observed in treatment with high percentage of corn silage (186L/kgVS). In glycerine´s treatment, high initial production of biogas (2500ml/day) was inhibited due to acidification of the environment (pH:5,5). Nutrients and majority ions concentrations in the effluent suggest that if the high electrical conductivity is corrected (>9,2dS/m) it can be used as biofertilizer.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Assessment of heavy metal contamination and water quality in an urban river from Argentina

In aquatic ecosystems, the potential effects of toxic compounds are greatly determined by their physicochemical forms and bioavailability. The aim of this work was the assessment of metal toxicity to the green alga Pseudokirchneriella subcapitata in contaminated water samples of an urban river (Matanza-Riachuelo, Argentina). A total of 30 samples were analyzed. Physicochemical parameters and total and dissolved metal (Cd, Cu, Cr, Pb, Ni and Zn) concentrations were measured. Toxicity was related as a function of size fractionation and chemical speciation (using the program Mineql+) in the dissolved fraction (<1.2μm). Percentage inhibition of algal growth (%Iw) was estimated as the differences between cultures with and without EDTA additions in the filtered water samples. Concentrations of Cd (1-85μg.L-1), Cr (3-164μg.L-1), and Ni (10-99μg.L-1) in river waters were always lower than the respective EC50 for P. subcapitata, whereas concentrations of Cu (5-306μg.L-1), Pb (13-546μg.L-1), and Zn (4-380μg.L-1) in dissolved fractions resulted above the EC50 values in many samples. Only 10 samples showed algal growth inhibition (between 11.21% and 42.19%), which 8 of them also showed high concentrations of free ionic forms of Pd or Zn. Free ionic concentrations of Cu were always lower than the EC50 for the algae. Two samples resulted toxic to P. subcapitata in spite of the absence of toxic metal concentrations. Besides, 13 samples no inhibited the algal growth and high concentrations of Pd and Zn were obtained, producing expected %Iw values between 10.03% and 90.51%. The absence of toxicity in most samples with toxic metal concentrations could be related to the presence of organic ligands, colloidal organic matter, and antagonism effects among other metals, which reduce their bioavailability

Assessment of heavy metal contamination and water quality in an urban river from Argentina

In aquatic ecosystems, the potential effects of toxic compounds are greatly determined by their physicochemical forms and bioavailability. The aim of this work was the assessment of metal toxicity to the green alga Pseudokirchneriella subcapitata in contaminated water samples of an urban river (Matanza-Riachuelo, Argentina). A total of 30 samples were analyzed. Physicochemical parameters and total and dissolved metal (Cd, Cu, Cr, Pb, Ni and Zn) concentrations were measured. Toxicity was related as a function of size fractionation and chemical speciation (using the program Mineql+) in the dissolved fraction (&lt;1.2μm). Percentage inhibition of algal growth (%Iw) was estimated as the differences between cultures with and without EDTA additions in the filtered water samples. Concentrations of Cd (1-85μg.L-1), Cr (3-164μg.L-1), and Ni (10-99μg.L-1) in river waters were always lower than the respective EC50 for P. subcapitata, whereas concentrations of Cu (5-306μg.L-1), Pb (13-546μg.L-1), and Zn (4-380μg.L-1) in dissolved fractions resulted above the EC50 values in many samples. Only 10 samples showed algal growth inhibition (between 11.21% and 42.19%), which 8 of them also showed high concentrations of free ionic forms of Pd or Zn. Free ionic concentrations of Cu were always lower than the EC50 for the algae. Two samples resulted toxic to P. subcapitata in spite of the absence of toxic metal concentrations. Besides, 13 samples no inhibited the algal growth and high concentrations of Pd and Zn were obtained, producing expected %Iw values between 10.03% and 90.51%. The absence of toxicity in most samples with toxic metal concentrations could be related to the presence of organic ligands, colloidal organic matter, and antagonism effects among other metals, which reduce their bioavailability