Guillermo Chalar - Academia.edu (original) (raw)

Papers by Guillermo Chalar

Zenodo (CERN European Organization for Nuclear Research), Jun 9, 2022

Zenodo (CERN European Organization for Nuclear Research), Jun 10, 2022

INNOTEC

Experiencia de aplicación de microorganismos efectivos nativos (MEN) para el tratamiento de aguas... more Experiencia de aplicación de microorganismos efectivos nativos (MEN) para el tratamiento de aguas residuales Application of effective microorganisms from native origin (MEN) for wastewater treatment Ensaio de aplicação de microorganismos efetivos nativos (MEN) para o tratamento de águas residuais Gimena echeverriborda (1) Federico mesa (1) Guillermo chalar (2) carla KruK (2) (3) claudia Piccini (4) (1) Cooperativa Entrebichitos, Canelones, Uruguay.

Natura neotropicalis, Apr 8, 2005

Limnologica, Sep 1, 2009

Many biotic and abiotic processes contribute to variability in phytoplankton diversity in aquatic... more Many biotic and abiotic processes contribute to variability in phytoplankton diversity in aquatic ecosystems. Depending on their intensity and on their frequency, these may drive non-equilibrium dynamics and enhance the species diversity. Different studies propose that biodiversity buffers ecosystem functioning against environmental fluctuations leading to more predictable aggregate community or ecosystem properties. Salto Grande reservoir is polymictic and eutrophic with recurrent summer cyanobacterial blooms. The aim of this study was to determine the key variable(s) related with phytoplankton diversity in order to predict the possible occurrence of an algal bloom at the ecosystem. A preliminary analysis of the data matrix suggested non-linear relationships between diversity and the selected variables: phytoplankton abundance and the vertical attenuation coefficient (Kd). The best function fitting of the scatter plot of phytoplankton diversity versus phytoplankton abundance was a rational function. The inflection point of phytoplankton diversity estimated by the second derivate of this function was 2.7 bit cell À1 which corresponded to an abundance of 3000 cells ml À1. The relationship of phytoplankton diversity and vertical attenuation coefficient values also show a humped distribution pattern (Gauss function). The inflection point of this function corresponded to a diversity value of 1.9 bit cell À1 and 2.5 m À1 for Kd. These inflection points were, respectively, related with the resource competition among the present species and the light limitation conditions. The showed patterns of diversity and the estimated threshold values could be integrated to construct a predictive model for the reservoir based on phytoplankton diversity and the probable ambient conditions of the reservoir.

Revista Chilena de Historia Natural, 1994

Bulletin of Environmental Contamination and Toxicology, Aug 20, 2017

and management changes in the reservoir basins could be successful long-term measures.

International Journal of Environmental Science and Technology, Mar 13, 2019

Constructed wetlands are suitable for treating industrial effluents due to their low cost and eff... more Constructed wetlands are suitable for treating industrial effluents due to their low cost and effectiveness, thus preventing the deterioration of waterways witnessed in recent decades at global level. Advances in the study of wetland design are necessary for the development of constructed wetlands. An artificial wetland model with subsurface flow (three replications), Typha domingensis, and hydraulic retention time of 5 days was used. It was designed for the post-treatment of the effluent from a fish processing plant. All samples were taken at the model system inlet and outlet every 21 days for 1 year. Significant removal of nitrogen and organic matter (biochemical oxygen demand and the chemical oxygen demand) was achieved, but phosphorus removal was less than expected. Wetland performance was not affected by seasonal variations in ambient temperature. The increase in the C/N ratio was related with a higher wetland efficiency of organic matter removal. Overall performance for the wetland model under in situ environmental conditions was determined by the intrinsic reaction rate of the system.

Science of The Total Environment, 2021

A recent paper by Beretta-Blanco and Carrasco-Letelier (2021) claims that agricultural eutrophica... more A recent paper by Beretta-Blanco and Carrasco-Letelier (2021) claims that agricultural eutrophication is not one of the main causes for cyanobacterial blooms in rivers and artificial reservoirs. By combining rivers of markedly different hydrological characteristics e.g., presence/absence and number of dams, river discharge and geological setting, the study speculates about the role of nutrients for modulating phytoplankton chlorophyll-a. Here, we identified serious flaws, from erratic and inaccurate data manipulation. The study did not define how erroneous original dataset values were treated, or how the variables below the detection/quantification limit were numerically introduced, lack of mandatory variables for river studies such as flow and rainfall, arbitrary removal of pH > 7.5 values (which were not outliers), and how extreme values of other environmental variables were included. In addition, we identified conceptual and procedural mistakes such as biased construction/evaluation of model prediction capability. The study trained the model using pooled data from a short restricted lotic section of the (large) Uruguay River and from both lotic and reservoir domains of the Negro River, but then tested predictability within the (small) Cuareim River. Besides these methodological considerations, the article shows misinterpretations of the statistical correlation of cause and effect neglecting basic limnological knowledge of the ecology of harmful algal blooms (HABs) and international research on land use effects on freshwater quality. The argument that pH is a predictor variable for HABs neglects overwhelming basic paradigms of carbon fluxes and change in pH as a result of primary productivity. As a result, the article introduce the notion that HABs formation are not related to agricultural land use and water residence time and generate a great risk for the management of surface waterbodies. This reply also emphasizes the need for good practices of open data management, especially for public databases in view of external reproducibility.

Nature sustainability, Feb 13, 2023

From 1985 onwards, South America has undergone a major expansion of agriculture at the expense of... more From 1985 onwards, South America has undergone a major expansion of agriculture at the expense of native vegetation (e.g. native Pampa grassland). As an emblematic crop, the surface area cultivated with soybeans has increased by 1000% between 1990 and 2020 in Uruguay. The environmental consequences of this massive land use conversion on soil degradation remain poorly documented although the agriculture expansion is projected to continue to increase in the coming years in South America. In this study, sediment cores were collected in reservoirs located downstream of two contrasted agricultural catchments draining the Rio Negro River (Uruguay) for reconstructing the sediment dynamics and the sources of erosion associated with this expansion. Results demonstrated the occurrence of two periods of acceleration of sediment delivery since the 1980s. The first period of acceleration was recorded in the mid-1990s and was related to afforestation programs. The second and larger acceleration phase was recorded after 2000 during the soybean crop expansion. This period has been marked by a greater supply of sediment from the native grassland source highlighting the impact of agriculture expansion at the expense of native vegetation. Conservation measures should therefore be urgently taken to preserve biodiversity and soil functions in this region.

Environmental Monitoring and Assessment

Science of The Total Environment

Los macroinvertebrados acuáticos responden a las características de su ambiente reflejando las al... more Los macroinvertebrados acuáticos responden a las características de su ambiente reflejando las alteraciones en el mismo. Por ello, son frecuentemente utilizados como indicadores biológicos en estudios de calidad de agua y monitoreo ambiental. El índice de estado trófico TSI-BI creado para la cuenca del río Santa Lucía, que incluye la cuenca de estudio, permite conocer el estado trófico de los arroyos mediante su composición de macroinvertebrados acuáticos. El objetivo de este trabajo es evaluar el estado trófico de los arroyos de la cuenca del embalse Paso Severino a través de la comunidad de macroinvertebrados mediante el índice TSI-BI. El embalse es utilizado como fuente de agua potable para la zona sur densamente poblada del país. La zona ha tenido un importante desarrollo de la actividad lechera en las últimas décadas. Se seleccionaron 10 subcuencas pertenecientes a arroyos de órdenes 2-4 tomándose muestras estacionales (2009-2010) de macroinvertebrados con red de mano de 500 μm...

INNOTEC

Cianobacterias y cianotoxinas en ecosistemas límnicos de Uruguay Cyanobacteria and cyanotoxins in... more Cianobacterias y cianotoxinas en ecosistemas límnicos de Uruguay Cyanobacteria and cyanotoxins in freshwaters of Uruguay Bonilla, Sylvia (1)(2) , Haakonsson, Signe (1)(2) , Somma, Andrea (1)(2) , Gravier, Ana (3) , Britos, Anamar (3) , Vidal, Leticia (1)(3) , De León, Lizet (1)(4) , Brena, Beatriz, M. (1)(6)(7) , Pírez, Macarena (8) , Piccini, Claudia (1)(5) , Martínez de la Escalera, Gabriela (5) , Chalar, Guillermo (2) , González-Piana, Mauricio (2) , Martigani, Fátima (1)(2) , Aubriot, Luis (1)(2)

<p>Recent agriculture expansion and land cover conversion (post-198... more <p>Recent agriculture expansion and land cover conversion (post-1985) induced major deleterious environmental effects in South-America in general and in Uruguay in particular, affecting locally the sustainability of soil and water resources. Whilst the environmental consequences of agriculture’s development were largely studied (e.g. monitoring, modeling) in Europe or North America, much less attention was devoted to the intensity of land degradation in South-America and more specifically, on the Pampa Biome. In this study, sediment cores collected in two reservoirs installed along the Rio Negro river (catchments of 23.000 and 39.000 km²) and draining agricultural catchments were used for reconstructing the evolution of sediment dynamics and source contributions in this region during the last several decades. Various chemical and physical analyses were performed for characterizing this accumulated sediment (e.g. fallout radionuclides, organic matter properties (TOC, δ<sup>15</sup>N, δ<sup>13</sup>C, C:N), X-ray fluorescence). Results indicate the significant acceleration of sediment accumulation rates (e.g. by 67% on average in the Rincon del Bonete dam between 2003 and 2019) associated with major phases of agricultural expansion (e.g. expansion of soybean and afforestation). Sediment properties show an increase of native vegetation source contributions associated with the conversion of native grassland into cropland. Understanding the causes of past and present acceleration of sediment delivery are of prime importance in order to protect the soil and water resources with the design of adapted management schemes at the catchment scale.</p>

Innotec, 2015

Cyanobacterial blooms are a worldwide environmental problem. This phenomenon is typically associa... more Cyanobacterial blooms are a worldwide environmental problem. This phenomenon is typically associated with eutrophication (nutrient enrichment) and changes in hydrology. In this study we analysed the distribution of planktonic cyanobacteria in Uruguay and their toxins (microcystin, saxitoxin and cylindrospermopsin), working with an interagency team (OSE, DINAMA, IM, University of the Republic and IIBCE). An historical data base (n = 3061 for 64 ecosystems, years 1980-2014) was generated. Differences between lotic and lentic ecosystems were found in terms of chlorophyll a and nutrient concentrations, usually indicating eutrophication. Two geo-referenced maps for the country were generated with cyanobacteria biomass indicators and the most relevant toxin (microcystin), according to risk levels suggested by the World Health Organization for recreational waters. The areas of greatest risk of exposure were the reservoirs of large rivers (Uruguay and Río Negro) and Río de la Plata beaches....

Boletín de la Sociedad Zoológica del Uruguay, 2020

Los sistemas fluviales están sometidos a una fuerte presión antropogénica que afecta su calidad d... more Los sistemas fluviales están sometidos a una fuerte presión antropogénica que afecta su calidad de agua y biodiversidad. En Uruguay, el Río Negro es el mayor río interior y lo atraviesa de Este a Oeste luego de nacer en Brasil. Recibe los efluentes de algunas ciudades como Paso de los Toros y drena una cuenca con usos agrícola, ganadero y forestal. La Dirección Nacional de Medio Ambiente realiza un monitoreo de la calidad de agua del Río Negro desde el año 2009 con resultados que indican una calidad aceptable en todo el curso (excepto por el fósforo). Sin embargo, el río recibe de sus tributarios de menor orden principalmente materia orgánica, y efluentes domésticos de las ciudades ubicadas sobre los cursos principales. El presente estudio busca evaluar el impacto urbano y la capacidad de autodepuración del río comparando la comunidad de macroinvertebrados bentónicos entre zonas aguas arriba (control) y abajo de la ciudad de Paso de los Toros (contaminación y autodepuración).

Zenodo (CERN European Organization for Nuclear Research), Jun 9, 2022

Zenodo (CERN European Organization for Nuclear Research), Jun 10, 2022

INNOTEC

Experiencia de aplicación de microorganismos efectivos nativos (MEN) para el tratamiento de aguas... more Experiencia de aplicación de microorganismos efectivos nativos (MEN) para el tratamiento de aguas residuales Application of effective microorganisms from native origin (MEN) for wastewater treatment Ensaio de aplicação de microorganismos efetivos nativos (MEN) para o tratamento de águas residuais Gimena echeverriborda (1) Federico mesa (1) Guillermo chalar (2) carla KruK (2) (3) claudia Piccini (4) (1) Cooperativa Entrebichitos, Canelones, Uruguay.

Natura neotropicalis, Apr 8, 2005

Limnologica, Sep 1, 2009

Many biotic and abiotic processes contribute to variability in phytoplankton diversity in aquatic... more Many biotic and abiotic processes contribute to variability in phytoplankton diversity in aquatic ecosystems. Depending on their intensity and on their frequency, these may drive non-equilibrium dynamics and enhance the species diversity. Different studies propose that biodiversity buffers ecosystem functioning against environmental fluctuations leading to more predictable aggregate community or ecosystem properties. Salto Grande reservoir is polymictic and eutrophic with recurrent summer cyanobacterial blooms. The aim of this study was to determine the key variable(s) related with phytoplankton diversity in order to predict the possible occurrence of an algal bloom at the ecosystem. A preliminary analysis of the data matrix suggested non-linear relationships between diversity and the selected variables: phytoplankton abundance and the vertical attenuation coefficient (Kd). The best function fitting of the scatter plot of phytoplankton diversity versus phytoplankton abundance was a rational function. The inflection point of phytoplankton diversity estimated by the second derivate of this function was 2.7 bit cell À1 which corresponded to an abundance of 3000 cells ml À1. The relationship of phytoplankton diversity and vertical attenuation coefficient values also show a humped distribution pattern (Gauss function). The inflection point of this function corresponded to a diversity value of 1.9 bit cell À1 and 2.5 m À1 for Kd. These inflection points were, respectively, related with the resource competition among the present species and the light limitation conditions. The showed patterns of diversity and the estimated threshold values could be integrated to construct a predictive model for the reservoir based on phytoplankton diversity and the probable ambient conditions of the reservoir.

Revista Chilena de Historia Natural, 1994

Bulletin of Environmental Contamination and Toxicology, Aug 20, 2017

and management changes in the reservoir basins could be successful long-term measures.

International Journal of Environmental Science and Technology, Mar 13, 2019

Constructed wetlands are suitable for treating industrial effluents due to their low cost and eff... more Constructed wetlands are suitable for treating industrial effluents due to their low cost and effectiveness, thus preventing the deterioration of waterways witnessed in recent decades at global level. Advances in the study of wetland design are necessary for the development of constructed wetlands. An artificial wetland model with subsurface flow (three replications), Typha domingensis, and hydraulic retention time of 5 days was used. It was designed for the post-treatment of the effluent from a fish processing plant. All samples were taken at the model system inlet and outlet every 21 days for 1 year. Significant removal of nitrogen and organic matter (biochemical oxygen demand and the chemical oxygen demand) was achieved, but phosphorus removal was less than expected. Wetland performance was not affected by seasonal variations in ambient temperature. The increase in the C/N ratio was related with a higher wetland efficiency of organic matter removal. Overall performance for the wetland model under in situ environmental conditions was determined by the intrinsic reaction rate of the system.

Science of The Total Environment, 2021

A recent paper by Beretta-Blanco and Carrasco-Letelier (2021) claims that agricultural eutrophica... more A recent paper by Beretta-Blanco and Carrasco-Letelier (2021) claims that agricultural eutrophication is not one of the main causes for cyanobacterial blooms in rivers and artificial reservoirs. By combining rivers of markedly different hydrological characteristics e.g., presence/absence and number of dams, river discharge and geological setting, the study speculates about the role of nutrients for modulating phytoplankton chlorophyll-a. Here, we identified serious flaws, from erratic and inaccurate data manipulation. The study did not define how erroneous original dataset values were treated, or how the variables below the detection/quantification limit were numerically introduced, lack of mandatory variables for river studies such as flow and rainfall, arbitrary removal of pH > 7.5 values (which were not outliers), and how extreme values of other environmental variables were included. In addition, we identified conceptual and procedural mistakes such as biased construction/evaluation of model prediction capability. The study trained the model using pooled data from a short restricted lotic section of the (large) Uruguay River and from both lotic and reservoir domains of the Negro River, but then tested predictability within the (small) Cuareim River. Besides these methodological considerations, the article shows misinterpretations of the statistical correlation of cause and effect neglecting basic limnological knowledge of the ecology of harmful algal blooms (HABs) and international research on land use effects on freshwater quality. The argument that pH is a predictor variable for HABs neglects overwhelming basic paradigms of carbon fluxes and change in pH as a result of primary productivity. As a result, the article introduce the notion that HABs formation are not related to agricultural land use and water residence time and generate a great risk for the management of surface waterbodies. This reply also emphasizes the need for good practices of open data management, especially for public databases in view of external reproducibility.

Nature sustainability, Feb 13, 2023

From 1985 onwards, South America has undergone a major expansion of agriculture at the expense of... more From 1985 onwards, South America has undergone a major expansion of agriculture at the expense of native vegetation (e.g. native Pampa grassland). As an emblematic crop, the surface area cultivated with soybeans has increased by 1000% between 1990 and 2020 in Uruguay. The environmental consequences of this massive land use conversion on soil degradation remain poorly documented although the agriculture expansion is projected to continue to increase in the coming years in South America. In this study, sediment cores were collected in reservoirs located downstream of two contrasted agricultural catchments draining the Rio Negro River (Uruguay) for reconstructing the sediment dynamics and the sources of erosion associated with this expansion. Results demonstrated the occurrence of two periods of acceleration of sediment delivery since the 1980s. The first period of acceleration was recorded in the mid-1990s and was related to afforestation programs. The second and larger acceleration phase was recorded after 2000 during the soybean crop expansion. This period has been marked by a greater supply of sediment from the native grassland source highlighting the impact of agriculture expansion at the expense of native vegetation. Conservation measures should therefore be urgently taken to preserve biodiversity and soil functions in this region.

Environmental Monitoring and Assessment

Science of The Total Environment

Los macroinvertebrados acuáticos responden a las características de su ambiente reflejando las al... more Los macroinvertebrados acuáticos responden a las características de su ambiente reflejando las alteraciones en el mismo. Por ello, son frecuentemente utilizados como indicadores biológicos en estudios de calidad de agua y monitoreo ambiental. El índice de estado trófico TSI-BI creado para la cuenca del río Santa Lucía, que incluye la cuenca de estudio, permite conocer el estado trófico de los arroyos mediante su composición de macroinvertebrados acuáticos. El objetivo de este trabajo es evaluar el estado trófico de los arroyos de la cuenca del embalse Paso Severino a través de la comunidad de macroinvertebrados mediante el índice TSI-BI. El embalse es utilizado como fuente de agua potable para la zona sur densamente poblada del país. La zona ha tenido un importante desarrollo de la actividad lechera en las últimas décadas. Se seleccionaron 10 subcuencas pertenecientes a arroyos de órdenes 2-4 tomándose muestras estacionales (2009-2010) de macroinvertebrados con red de mano de 500 μm...

INNOTEC

Cianobacterias y cianotoxinas en ecosistemas límnicos de Uruguay Cyanobacteria and cyanotoxins in... more Cianobacterias y cianotoxinas en ecosistemas límnicos de Uruguay Cyanobacteria and cyanotoxins in freshwaters of Uruguay Bonilla, Sylvia (1)(2) , Haakonsson, Signe (1)(2) , Somma, Andrea (1)(2) , Gravier, Ana (3) , Britos, Anamar (3) , Vidal, Leticia (1)(3) , De León, Lizet (1)(4) , Brena, Beatriz, M. (1)(6)(7) , Pírez, Macarena (8) , Piccini, Claudia (1)(5) , Martínez de la Escalera, Gabriela (5) , Chalar, Guillermo (2) , González-Piana, Mauricio (2) , Martigani, Fátima (1)(2) , Aubriot, Luis (1)(2)

<p>Recent agriculture expansion and land cover conversion (post-198... more <p>Recent agriculture expansion and land cover conversion (post-1985) induced major deleterious environmental effects in South-America in general and in Uruguay in particular, affecting locally the sustainability of soil and water resources. Whilst the environmental consequences of agriculture’s development were largely studied (e.g. monitoring, modeling) in Europe or North America, much less attention was devoted to the intensity of land degradation in South-America and more specifically, on the Pampa Biome. In this study, sediment cores collected in two reservoirs installed along the Rio Negro river (catchments of 23.000 and 39.000 km²) and draining agricultural catchments were used for reconstructing the evolution of sediment dynamics and source contributions in this region during the last several decades. Various chemical and physical analyses were performed for characterizing this accumulated sediment (e.g. fallout radionuclides, organic matter properties (TOC, δ<sup>15</sup>N, δ<sup>13</sup>C, C:N), X-ray fluorescence). Results indicate the significant acceleration of sediment accumulation rates (e.g. by 67% on average in the Rincon del Bonete dam between 2003 and 2019) associated with major phases of agricultural expansion (e.g. expansion of soybean and afforestation). Sediment properties show an increase of native vegetation source contributions associated with the conversion of native grassland into cropland. Understanding the causes of past and present acceleration of sediment delivery are of prime importance in order to protect the soil and water resources with the design of adapted management schemes at the catchment scale.</p>

Innotec, 2015

Cyanobacterial blooms are a worldwide environmental problem. This phenomenon is typically associa... more Cyanobacterial blooms are a worldwide environmental problem. This phenomenon is typically associated with eutrophication (nutrient enrichment) and changes in hydrology. In this study we analysed the distribution of planktonic cyanobacteria in Uruguay and their toxins (microcystin, saxitoxin and cylindrospermopsin), working with an interagency team (OSE, DINAMA, IM, University of the Republic and IIBCE). An historical data base (n = 3061 for 64 ecosystems, years 1980-2014) was generated. Differences between lotic and lentic ecosystems were found in terms of chlorophyll a and nutrient concentrations, usually indicating eutrophication. Two geo-referenced maps for the country were generated with cyanobacteria biomass indicators and the most relevant toxin (microcystin), according to risk levels suggested by the World Health Organization for recreational waters. The areas of greatest risk of exposure were the reservoirs of large rivers (Uruguay and Río Negro) and Río de la Plata beaches....

Boletín de la Sociedad Zoológica del Uruguay, 2020

Los sistemas fluviales están sometidos a una fuerte presión antropogénica que afecta su calidad d... more Los sistemas fluviales están sometidos a una fuerte presión antropogénica que afecta su calidad de agua y biodiversidad. En Uruguay, el Río Negro es el mayor río interior y lo atraviesa de Este a Oeste luego de nacer en Brasil. Recibe los efluentes de algunas ciudades como Paso de los Toros y drena una cuenca con usos agrícola, ganadero y forestal. La Dirección Nacional de Medio Ambiente realiza un monitoreo de la calidad de agua del Río Negro desde el año 2009 con resultados que indican una calidad aceptable en todo el curso (excepto por el fósforo). Sin embargo, el río recibe de sus tributarios de menor orden principalmente materia orgánica, y efluentes domésticos de las ciudades ubicadas sobre los cursos principales. El presente estudio busca evaluar el impacto urbano y la capacidad de autodepuración del río comparando la comunidad de macroinvertebrados bentónicos entre zonas aguas arriba (control) y abajo de la ciudad de Paso de los Toros (contaminación y autodepuración).