El objetivo del trabajo fue realizar un análisis de estudios cuantitativos de riesgo a la salud asociados a sustancias presentes en el agua, con relación a su representación espacial, integración de distintos escenarios de exposición y estimaciones de riesgos a la salud en áreas ambientales críticas. Se analizaron diferentes aplicaciones de la metodología de evaluación de riesgos a la salud de USEPA, implementadas en la provincia de Buenos Aires, Argentina. A partir de la realización del estudio se observó que estas herramientas presentan importantes potencialidades, más allá de ciertas limitaciones. Las evaluaciones de riesgo espacializadas, al estimar el riesgo basándose en información de exposición distribuida en el espacio, permiten ofrecer un panorama más completo y realista. Además, la combinación de diferentes escenarios de exposición, como los residenciales y escolares, brinda una visión más integral de los riesgos para la salud. En el caso de la cuenca del río Matanza-Riachuelo, se han evaluado riesgos asociados a contaminantes como cromo y nitrato, lo que facilita la priorización de riesgos en contextos críticos y contribuye a la toma de decisiones informadas.

Un análisis de riesgo (AR) evalúa la gravedad de amenazas en una matriz ambiental. Si se aplica por sustancias peligrosas, busca determinar posibles efectos tóxicos. Un AR a la salud humana (ARS) tiene en cuenta el contaminante y su concentración en el medio, las rutas de exposición —ingestión, inhalación, absorción dérmica—, los escenarios de exposición —recreativo, residencial, ocupacional, entre otros— y la duración de la exposición —aguda o crónica— para un tipo de individuo expuesto –niño o adulto. Se revisan los ARS frente a otra metodología (Niveles Máximos Permitidos establecidos en normativas —NMP) como herramientas para evaluar la calidad del agua (como bebida, para baño recreativo, etc.). Se analizan sus ventajas y desventajas usando ARS por contaminantes en aguas subterráneas y superficiales desarrollados en la cuenca del Arroyo Azul (centro de la Provincia de Buenos Aires). Los ARS evalúan la calidad del agua en escenarios de exposición concretos para poblaciones específicas, lo que los hace herramientas versátiles. Además, permiten considerar múltiples contaminantes por diferentes vías de exposición simultáneamente, ganando realismo en la evaluación. Son herramientas más potentes porque sirven para identificar, analizar y priorizar los riesgos más significativos en contextos específicos. Además, pueden operar sobre contaminantes sin NMPs. Pero tienen desventajas: como escasez de información sobre variables del modelo, tener sustancias sin referenciales toxicológicos, lidiar con las interacciones toxicológicas en los ARS acumulativos, complejidades metodológicas con las técnicas probabilísticas y la dependencia de software específicos. Se discuten las ventajas y se presentan alternativas metodológicas para afrontar las desventajas.

Low-gradient, prairie streams from the Pampa Plain, Argentina, constitute the southernmost geographic occurrence for many Neotropical fish species. Fish assemblages in Neotropical streams have shown drastic responses to the modification of habitat and water quality. Under this scenario it could be hypothesized that the water quality will be influenced by the anthropic activities and the natural conditions and that the ichthyofauna will be responsive. Therefore, understanding the functioning of these ecosystems is crucial for their conservation in a world with ever-growing anthropic pressures. In order to explore patterns in fish assemblage and water quality under urbanization pressure, the Del Azul stream (Buenos Aires, Argentina) was sampled. The objectives of the study were: (1) to explore trends in water quality and fish assemblage structure along the stream, (2) to study the relationship between fish assemblage structure and water quality, and (3) to pinpoint individual species with potential for biomonitoring. Seven sites were selected along the stream, and they were sampled twice during each of five consecutive summer periods. Through the use of multivariate analysis, we revealed trends in water quality and fish assemblage structure where water quality characteristics were more distinctive of a basin sector than the fish species abundances. Irrespective of that, the Indicator Species Analysis evidenced some key species indicative of given groups of sites sharing similar water quality characteristics. Namely, Cnesterodon decemmaculatus was associated to polluted reaches downstream from the point-source urban effluent, and Cheirodon interruptus, Pimelodella laticeps and Oligosarcus jenynsii to lower salinities and less polluted reaches upstream from the point-source urban effluent. All these species could be useful for biomonitoring temperate Neotropical streams.

Se evaluó la calidad de agua en tres arroyos pampeanos bonaerenses, dos urbanos (Arroyo del Azul y Arroyo Langueyú) y uno rural (el Arroyo de los Huesos), comparando como ésta se ve afectada por la urbanización dentro de tramos del mismo arroyo y entre distintos arroyos, y comparando con el arroyo rural. A través del análisis de variables fisicoquímicas, niveles guía, índice de calidad de agua de la National Sanitation Foundation e indicador 6.3.2 de los Objetivos de Desarrollo Sostenible se determinó que los dos arroyos urbanos se encontrarían mayormente impactados en sus tramos posturbanos, producto de los vuelcos que reciben. Por otra parte, se observó una mayor recuperación aguas abajo de estos vuelcos en el Arroyo del Azul que en el Langueyú; en el primer caso, el mayor caudal y menor población permitiría una mayor recuperación. En el sector preurbano de estas cuencas, al igual que en el Arroyo de los Huesos (rural) se detectaron niveles elevados de nitrato y fósforo que podrían ser de origen natural, aunque posiblemente influenciados por la agricultura. Este estudio contribuye a conocer el estado de conservación de arroyos pampeanos, el efecto de la urbanización y a detectar indicios de contaminación.

Abstract: Aim Freshwater communities respond to abiotic and biotic changes in the environment, and are widely used as indicators of environmental integrity. Fish have been one of the most used biological groups for this purpose. The Del Azul stream located in the pampean region of Argentina has been monitored using a physicochemical approach with this monitoring being sporadic due to economic and operational constraints associated with the chemical analyses. In this paper we developed an Index of Biotic Integrity for the Del Azul stream (IBIA) based on Karr´s Index of Biotic Integrity as an alternative. Methods We computed two existent physicochemical indexes for comparison, one of them is the NSF-WQI and the other one is a local index referred to as Water Quality Index for Del Azul Stream and based on the former. Results The three indexes followed similar trends along the examined reaches, showing good conditions in the upper basin, poor conditions just downstream of the urban area and a recovery state further downstream in the basin. Conclusions Since the IBIA followed the same patterns as the physicochemical indexes, has a lower implementation cost and it is simpler to apply, we promote it as an alternative to the traditional physicochemical water quality monitoring for pampean streams.

Water movement modeling in plain areas requires digital elevation models (DEMs) adequately representing the morphological and geomorphological land patterns including the presence of civil structures that could affect water flow patterns. This has a direct effect on water accumulation and water flow direction. The objectives of this work were to analyze, compare and improve DEMs so surface water movement in plain areas could be predicted. In order to do that, we evaluated the accuracy of a digital elevation data set consisting in 4064 points measured with a differential global positioning system (GPS) in a plain area of central Buenos Aires province. Three DEMs were analyzed: (1) the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), (2) the Shuttle Radar Topography Mission (SRTM) and (3) the Advanced Land Observing Satellite with the Phased Array Type L-Band Synthetic Aperture Radar (ALOS PALSAR). Several topographic attributes (i.e., height, surface area, land slope, delimitation of geomorphological units, civil structures, basin boundaries and streams network) and different interpolation methods were analyzed. The results showed that both the SRTM and the ALOS PALSAR DEMs had a +/- 4.4 m root mean square error (RMSE) in contrast to the ASTER DEM which had a +/- 9 m RMSE. Our analysis proved that the best DEM representing the study area is the SRTM. The most suitable interpolation methods applied to the SRTM were the inverse distance weighting and the ANUDEM, whereas the spline method displayed the lowest vertical accuracy. With the proposed method we obtained a DEM for the study area with a +/- 3.2 m RMSE, a 33% error reduction compared to the raw DEM.

Due to the socioeconomical impact of water extremes in plain areas, there is a considerable demand for suitable strategies aiding in the management of water resources and rainfed crops. Numerical models allow for the modelling of water extremes and their consequences in order to decide on management strategies. Moreover, the integration of hydrologic models with hydraulic models under continuous or event-based approaches would synergistically contribute to better forecasting of water extreme consequences under different scenarios. This study conducted at the Santa Catalina stream basin (Buenos Aires province, Argentina) focuses on the integration of numerical models to analyze the hydrological response of plain areas to water extremes under different scenarios involving the implementation of an eco-efficient infrastructure (i.e., the integration of a green infrastructure and hydraulic structures). The two models used for the integration were: the Soil and Water Assessment Tool (SWAT) and the CELDAS8 (CTSS8) hydrologic-hydraulic model. The former accounts for the processes related to the water balance (e.g., evapotranspiration, soil moisture, percolation, groundwater discharge and surface runoff), allowing for the analysis of water extremes for either dry or wet conditions. Complementarily, CTSS8 models the response of a basin to a rainfall event (e.g., runoff volume, peak flow and time to peak flow, flooded surface area). A 10-year data record (2003–2012) was analyzed to test different green infrastructure scenarios. SWAT was able to reproduce the waterflow in the basin with Nash Sutcliffe (NS) efficiency coefficients of 0.66 and 0.74 for the calibration and validation periods, respectively. The application of CTSS8 for a flood event with a return period of 10 years showed that the combination of a green infrastructure and hydraulic structures decreased the surface runoff by 28%, increased the soil moisture by 10% on an average daily scale, and reduced the impact of floods by 21% during rainfall events. The integration of continuous and event-based models for studying the impact of water extremes under different hypothetical scenarios represents a novel approach for evaluating potential basin management strategies aimed at improving the agricultural production in plain areas.

Se evaluo la importancia del consumo diario de agua por ingesta en la evaluacion de riesgo a la salud humana (ERS) de contaminantes presentes en agua subterranea de pozos domiciliarios en la ciudad de Azul, Argentina. El riesgo probabilistico acumulativo se calculo en base al modelo de la Agencia de Proteccion Ambiental de Estados Unidos (USEPA) para cuatro grupos de edad (5, 10, 15 anos y adultos). Los resultados fueron comparados mediante la aplicacion de un consumo diario de agua por ingesta estimado utilizado con frecuencia en la literatura frente a una cantidad ingerida local. De las seis variables usadas (Concentracion de la sustancia peligrosa en el agua; Ingesta diaria de agua (I); Frecuencia de exposicion; Duracion de la exposicion; Peso corporal del individuo expuesto; Factor de correccion para el tiempo promedio de exposicion cronica), la Ifue la variable mas influyente en el va­lor del riesgo presentando diferencias significativas entre los resultados derivados de ambos tipos de I. La diferencia mas alta fue en los 5 anos de edad, grupo que presento un riesgo acumulado asociado con I local 98% mas bajo respecto del riesgo calculado utilizando I basada en la literatura. La seleccion de la I tuvo un impacto significativo en los resultados del riesgo, lo que sugiere una cuidadosa eleccion de las variables de entrada al modelo de la evaluacion del riesgo para evitar subestimaciones o sobreestimaciones

We evaluated the influence of the direct water intake rate ( IR ) on health risk assessment (HRA) for humans exposed to pollutants in residential well water in Azul, Argentina. The probabilistic cumulative risk was calculated considering four age groups (5, 10, 15 years old and adults). We compared the risk results for two different IRs : one frequently used in literature and the other one based on local survey results. From the six variables used in the HRA, IR was the most influential one. There were significant differences in risk values between the two considered IRs . The largest difference was found in the 5-years-old group in which the cumulative risk associated with the local IR was 98% lower than the literature based IR . We concluded that the IR has such a significant influence on the risk results that its value must be carefully determined before performing HRA to avoid misleading results.

Using the USEPA methodology we estimated the probabilistic chronic risks for calves and adult cows due to pesticide exposure through oral intake of contaminated surface and ground waters in Tres Arroyos County (Argentina). Because published data on pesticide toxicity endpoints for cows are scarce, we used threshold levels based on interspecies extrapolation methods. The studied waters showed acceptable quality for cattle production since none of the pesticides were present at high-enough concentrations to potentially affect cow health. Moreover, ground waters had better quality than surface waters, with dieldrin and deltamethrin being the pesticides associated with the highest risk values in the former and the latter water compartments, respectively. Our study presents a novel use of the USEPA risk methodology proving it is useful for water quality evaluation in terms of pesticide toxicity for cattle production. This approach represents an alternative tool for water quality management in the absence of specific cattle pesticide regulatory limits.

The aim of this study was to assess the risk associated with recreational bathing at Del Azul stream, Argentina, a water course naturally containing Arsenic. It represents a case study on the carcinogenic risk for bathers and on how the risk varies among age groups and genders, analyzing the uncertainties of the model input variables and the risk quantification technique. The risk was probabilistically estimated with the 2D Monte Carlo method considering four age groups (5, 10, 15, and 20years old) and separate exposure routes: accidental water intake, skin contact, and the two combined. Although in all the studied groups the risk levels were within safety limits, differences in risk values were observed among age groups and genders. Accidental water intake during bathing was the most risky exposure route. The risk decreased with age and it was higher in males than in females, with larger differences between the two older age groups. This could be attributed to the difference in the accidental water intake rate associated with the daily duration of the bathing event, which varied according to age and gender.