Performance of a hydrostatic sampler for collecting samples at the water-sediment interface in lakes

The water-sediment interface plays a significant role in the determination of the trophic degree of a waterbody. Numerous redox reactions take place there, resulting in the release of contaminants from the sediments to the water column. The aim of the present work was to develop an equipment for collecting samples from the water-sediment interface. Such equipment was to have a simple design, low construction cost, no depth limitations, and high levels of personal safety and to be reliable in the collection of samples. The performance of the hydrostatic sampler thus developed was tested against samples collected either remotely with a corer or directly with syringes by autonomous divers. The hydrostatic sampler permits access to depths where the costs of the traditional diving methodology are expensive, and where working conditions are dangerous for the diver. The hydrostatic sampler provides an additional means of collecting samples from the water-sediment interface, which together with pore-water samples, facilitates the investigation and understanding of chemical mechanisms in lakes, for instance, those that control the P release from sediment to the water column

May a natural lake behave as an efficient Fenton reactor under dark conditions

Phenol degradation experiments were performed to study the potential behavior of the acidic Lake Caviahue (LC) as a dark Fenton reactor under natural conditions and upon H₂O₂ addition at doses typically used for technological applications. In both cases, to assess the influence of dissolved organic matter present in the lake, control experiments were carried out under identical initial conditions (pH, concentrations of phenol, iron, and H₂O₂), but in the absence of organic matter. A first set of experiments was performed to test the feasibility of dark Fenton processes under environmental conditions. Lake water samples were used as reaction matrix and catalyst source, whereas phenol and H₂O₂ were added as model pollutant and oxidant, respectively. H₂O₂ concentrations used were similar to those reported for rainwater. Results show that phenol can be degraded under all conditions studied and that the amount of phenol consumed depends on both the H₂O₂ concentration added and the matrix composition LC A second set of experiments was designed to characterize the lake behavior as a natural Fenton reactor upon the addition of H₂O₂ concentrations typically used for technological applications. Although phenol concentration profiles obtained for LC and the artificial solution show the characteristic behavior of Fenton-like systems, the trends are rather different, since for LC, the lag phase is much longer than that for the artificial matrix. Overall, the results suggest that the Fe(III)-chelating effect of the organic matter present in LC slows down reaction rates, but it does not block phenol degradation through Fenton-like processes.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Water quality and guide levels for the protection of aquatic biodiversity: Interaction between science and management

La Argentina posee una gran diversidad de ambientes acuáticos asociada a la variedad de regiones climáticas que determinan características únicas de las cuencas hidrológicas. Esta diversidad está dada por condiciones morfológicas, por características físico-químicas y por la presencia de sustancias naturales y xenobióticas derivadas de la actividad antrópica. La toxicidad que pueden ejercer diferentes sustancias en la biota acuática genera modificaciones en la calidad de los sistemas acuáticos. Por ello, para mantener los bienes y servicios ecosistémicos que ofrecen los ambientes se necesita una gestión efectiva a largo plazo basada en su manejo integral. Las estrategias apropiadas de protección de la biodiversidad acuática demandan la definición de umbrales o niveles guía (NG) de calidad de agua. En línea con políticas hídricas y ambientales de la Argentina, quienes gestionan el recurso hídrico consideran a estos NG como un marco de referencia para definir su aptitud en relación con los usos asignados. Es incumbencia de la autoridad hídrica nacional definir NG, y para tal fin, el Ministerio de Ambiente y Desarrollo Sostenible de la Nación (MAyDS) se vinculó con el Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) para desarrollar y establecer NG para proteger la biodiversidad acuática (NG-PBA). Los objetivos del trabajo fueron obtener una metodología robusta que permita establecer NG-PBA, establecer criterios para seleccionar y priorizar sustancias a derivar y discutir la adaptación regional de dichos NG-PBA. La metodología consensuada se basó en la desarrollada previamente por la ex- Subsecretaría de Recursos Hídricos (SSRH), actualizada en términos de secuencia operativa, método estadístico y cantidad y priorización de especies. Generamos una lista preliminar de sustancias para las cuales establecer sus NG. Este estudio destaca los beneficios de la interacción de saberes científicos y de gestión de recursos naturales como herramienta sinérgica y mecanismo superador en la protección de la biodiversidad acuática.Argentina has a great diversity of aquatic environments associated with the variety of climatic regions that determine unique characteristics of hydrological basins. This diversity is given by morphological conditions, physicochemical characteristics and the presence of natural and xenobiotic substances derived from anthropic activity. The toxicity of different substances on aquatic biota produces modifications in the quality of the aquatic systems. To maintain the benefits and services that the ecosystems offer, a long time effective management based on its integral management is necessary. Strategies for protection of aquatic biodiversity demand definition of guide levels (NG) for water quality. According to the environmental policy of Argentina, those who manage the water resource consider the NG of water quality as a reference framework for the definition of its aptitude in relation to their uses. The definition of NG is among the incumbencies of the hydrological national authority. With this objective, the Ministry of Environment and Sustainable Development (MAyDS) was linked with the National Scientific and Technical Research Council - Argentina (CONICET) to work in the water quality and to establish NG for the protection of aquatic biodiversity (NG-PBA). Considering the demand from the government sector, the aims of this work were: to obtain a robust methodology that allows determining NG-PBA, to establish criteria for selection and prioritization of substances, and to discuss the regional adaptation of the NG-PBA. The agreed methodology was based on the NG-PBA previously developed by the ex- Secretary of Water Resources (SSRH), updated in terms of the operative sequences, statistic method, and amount and prioritization of species. A preliminary list of substances for which establishing the corresponding NG to derivate was determined. It was recognized the interaction between scientific knowledge and management of natural resources as a synergic tool, and as superlative mechanism for the protection of aquatic biodiversity.Fil: Menone, Mirta Lujan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Iturburu, Fernando Gastón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Demetrio, Pablo Martin. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigaciones del Medio Ambiente - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones del Medio Ambiente; ArgentinaFil: Venturino, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigaciones en Toxicología Ambiental y Agrobiotecnología del Comahue. Universidad Nacional del Comahue. Facultad de Ciencias Agrarias. Centro de Investigaciones en Toxicología Ambiental y Agrobiotecnología del Comahue; ArgentinaFil: Pedrozo, Fernando Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Temporetti, Pedro Felix. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Rodríguez, Alejandra. Ministerio del Interior, Obras Públicas y Vivienda. Secretaría de Obras Públicas. Subsecretaría de Recursos Hídricos. Instituto Nacional del Agua y del Ambiente (Ezeiza); ArgentinaFil: Amé, María Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; ArgentinaFil: Quaíni, Karina P.. Secretaría de Ambiente y Desarrallo Sustentable de la Nación; ArgentinaFil: Collins, Pablo Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentin