La Angostura Research Articles

Historical fluxes of metal and metalloids in an aquatic ecosystem affected by land-use change and mining activities in northwestern Mexico

Freshwater reservoirs are essential owing because of their ecological, economic, and social importance. They are particularly vulnerable to contamination, as of metal and metalloids, derived from anthropogenic activities like mining. The temporal variations in trace element concentrations (arsenic (As), mercury (Hg), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn)), enrichment, fluxes, and possible sources were evaluated by studying two sediment cores from the La Angostura (ANG) Reservoir (northwest Mexico), using 210Pb geochronology. The enrichment factors showed from null to minor enrichment for most elements, but moderate to severe enrichment of mercury (Hg). Most trace element concentrations had a detrital origin, and notable Hg concentration increases since the past decade were associated with severe drought periods, likely resulting from wildfires. The observed sediment concentrations of As and Hg can cause adverse effects on biota in the ecosystem since they are above the probable effect level (PEL). Development of strategies for metal attenuation in this reservoir is recommended and metals should be controlled until specific ecotoxicological studies are performed.

Tendencia del NDVI en el Área de Conservación Regional Angostura Faical de Tumbes, Perú, 1999-2019

The Angostura Faical Regional Conservation Area is a protected area of the Equatorial Dry Forest, which seeks to guarantee the appropriate use of fauna and flora resources under sustainable practices by local populations, in addition to reducing the effects of climate change. Therefore, the trend of the Normalized Difference Vegetation Index (NDVI) in the Angostura Faical Regional Conservation Area was determined and the areas were quantified based on their trend over time. Geographic information systems, remote sensing and platforms such as Google Earth Engine made it possible to obtain data from Landsat 5-7-8 satellite images, and the R programming language was also used in the RStudio integrated development environment for statistical analysis with the Mann Kendall test which is qualitative in nature. It was found that in the time series the neutral trend predominates with a normal behavior in an area of 7,304,568 hectares, in a favorable case in the vegetation, 1,489,457 hectares were found with a positive trend and with a negative trend in the vegetation one surface of 0, 458 hectares located near the La Angostura creek where runoff is captured in rainy weather. It should be considered that the monitoring of the environment is of vital importance for the conservation of natural areas and of the utmost importance for those that provide an environmental service. For this reason, the behavior of our protected areas must be known in order to make decisions with foundations and taking hold of technology.

Bridging Parliamentary Cultures in the Americas – Enhancing Parliamentary Dialogue in the World

Abstract After much anticipation, the International Workshop of Scholars and Parliamentarians took place in Villa La Angostura, Argentina, from 7–8 April 2022. This report will first outline the general framework of the workshop’s organisation and implementation. It then describes the main areas of scientific debate, with a particular focus on the digital transformation of parliamentary institutions. Finally, the report outlines the main outcomes that, notably, seek to enhance parliamentarism through the development of an international culture of dialogue.

Micro-Raman spectroscopy and complementary techniques applied for the analysis of rock art paintings at the archaeological locality La Angostura, lower valley of Chubut River (Patagonia, Argentina)

In this paper, we characterized for the first time the painting materials in rock art panels of the Patagonian archaeological locality La Angostura using a methodological approach that combined micro-Raman spectroscopy, attenuated total reflection Fourier Transform infrared spectroscopy, and X-ray fluorescence spectroscopy. In this way, we obtained detailed information on the red, green, and black pigments as well as on accessory minerals present in the paints. Hematite was the chromophore in the red paintings while celadonite and glauconite were identified in the green motifs. A manganese oxide, presumably pyrolusite, was characterized as the black pigment. The pigment compositions were also compared to those of natural sediments collected along the valley of the Chubut River, but the components of the red and green sediment samples differed from those present in the rock art paints. In the red motifs of two of the rock art panels, a relevant finding was the presence of gypsum and anhydrite as a priming layer of the corrugated rock support onto which the red paints were applied. This revealed a different painting technique in comparison to that at the other analyzed panels of La Angostura where paints were applied as thin layers on a smooth surface of the rock support. As far as we know, this is the first report on the identification of gypsum and anhydrite as components of a preparation layer in Patagonian rock art. This result contributes to the open discussion on the origin and function of calcium sulfate in rock art.

Modelación hidrológica para medir el impacto del cambio climático en la cuenca del río Yaqui

Objective: To model and analyze the behavior of surface runoff in the Yaqui river basin under climate change scenarios. Methodology: Representative concentration pathways (RCP) of three sub-basins (La Angostura, El Novillo and El Oviachic) were shown using hydrologic modeling with SWAT, where the simulated variable was surface runoff. Results: A change in water availability of -67 % is expected in La Angostura for the period 2021-2040 (RCP2.6) and an increase of 60 % from 2041-2060 (RCP8.5), in El Novillo a decrease of 65 % is predicted for the period 2061-2080 (RCP4. 5) and a 42 % increase from 2061-2080 (RCP2.6), and in El Oviachic a 63 % decrease is predicted for the period 2041-2060 (RCP2.6 and 4.5) and a 47 % increase from 2041-2060 (RCP4.5). Limitations: Veracity and impact of basins studies depend on quality hydro-climatic information of unrestricted availability. Originality: The impact of climate change on the availability of water for agricultural use in the Yaqui River basin was projected. In addition, there is a technological platform for planning processes. Conclusions: The data collected can be used to generate adaptation and mitigation strategies for efficient water use in the basin and to propose long-term sustainable management alternatives.

Comparative Assessment of Metal Bioaccumulation in Tilapia and Largemouth Bass from Three Dams of the Yaqui River

In the present paper, we investigated the accumulation of six metals in tilapia (Oreochromis nilocticus) and largemouth bass (Micropterus salmoides) as indicators of the environmental pollution present at three constructed dams in the Yaqui River basin in Sonora, Mexico. The La Angostura (ANG), El Cajon de Onapa (ECO), and El Oviachic (OVI) dams are ecosystems under different degrees of anthropogenic stress. The collected fishes were dissected to obtain liver, gonad, stomach, gill, and muscle samples to determine the metal concentrations of Fe, Mn, Ni, Cu, Zn, and Cr. The results of a PERMANOVA showed that the concentrations of Fe, Cu, and Zn were significantly higher in tilapia liver, stomach, and gill tissues compared with those of the largemouth bass. Also, differences were detected between seasons, with the metal concentrations during the dry season being significantly higher than those of the rainy season (p < 0.001). The results of a principal component analysis showed an association between metals, tissues, and dams with significantly higher (p < 0.001) concentrations in tilapia from the ECO dam compared with those from the ANG and OVI dams. The general distribution of metals in the tissues was as follows: liver > stomach-gills > gonads > muscle. Variations in metal concentrations may be indicative of the different sources of anthropogenic stress in each ecosystem.

Remagnetized limestones and dolostones from the Upper Cambrian La Flecha Formation, La Rioja province, Argentine Precordillera

Representative rock-magnetic experiments and petrographic studies on remagnetized limestones and dolostones from the Upper Cambrian La Flecha Formation (Quebrada La Angostura, Precordillera of La Rioja, Argentina) carrying a pre-tectonic Permo-Triassic secondary magnetization are reported in order to improve the understanding of the pervasive Sanrafaelic overprint that reset the palaeomagnetic record of most of the Early Cambrian to Mid-Ordovician units of the Argentine Precordillera and the San Rafael Block. The main carrier of the remagnetization is determined as fine-grained magnetite of chemical origin, though three additional ferromagnetic phases were identified (pyrrhotite, hematite and goethite). A power-law model fitted to hysteresis ratio data (Mrs/Msvs. Bcr/Bc) defined an almost identical trend as that of the limestones from the Middle-Ordovician Ponón Trehué Formation (San Rafael Block, Mendoza province, Argentina) which were affected by the same regional event. Magnetic fabrics revealed by anisotropy of magnetic susceptibility and of anhysteretic remanence show mostly a pre-tectonic origin and, in some cases, a secondary overprint probably related to recent formation of magnetic minerals.

Herramientas de una aplicación móvil de mensajería instantánea para el fortalecimiento del proceso enseñanza – aprendizaje del Inglés.

El presente estudio busca optimizar el uso de los dispositivos móviles en el ambiente de aprendizaje (aula de clase), utilizando para ello una aplicación móvil de mensajería instantánea de uso masivo, aprovechando el envío de información en formato audio, vídeo, imágenes y texto, con el fin de fortalecer el aprendizaje del inglés en los aprendices de un programa de formación, en el Centro de Formación Agroindustrial “La Angostura”, del Servicio Nacional de Aprendizaje SENA (Colombia). El enfoque de esta investigación es de carácter mixto secuencial, con énfasis en lo cualitativo, por cuanto se describen las actividades realizadas con la aplicación móvil en cuatro fases. La aplicación a través del dispositivo móvil se evalúa a través del modelo FRAME de Koole y las capacidades de dispositivos o 4 C de Quinn. Se observan como resultados que se puede fortalecer el aprendizaje del inglés, motiva el trabajo autónomo, fomenta el trabajo colaborativo y mejora en la competencia digital. Finalmente, el aprendizaje móvil se caracteriza porque “el estudiante desarrollará sus capacidades cognitivas mediante la interacción, al tener como soporte la tecnología y las herramientas que proporciona” (Gómez, 2016).

First record of a fossil procyonid (Cyonasua cf. C. pascuali), Mammalia, Procyonidae) in Bolivia, Tariquía Fm., Late Miocene

We present the first record of an extinct procyonid for Bolivia (Tariquía Formation, La Angostura, Santa Cruz de La Sierra; Late Miocene). It corresponds to Cyonasua, the first Carnivore taxon to enter South America from North America before the Paniamian Isthmus raised and as a part of the “proto Great American Biotic Interchange” (GABI). Cyonasua fossil record, comprises the temporal lapse late Miocene to early Pleistocene in several localities of Argentina, Venezuela and Uruguay. This genus encompasses ten formally named species: C. argentina, C. brevirostris, C. longirostris, C. pascuali, C. groeberi, C. lutaria, C. clausa, C. robusta, C. argentines, and C. meranii. The mandible and teeth preserved of the new specimen, YPFBLIT-PAL-020, allows us to assign it to Cyonasua cf. C. pascuali. This record reinforces the paleoenvironment with warm climates and humid environments with abundant water bodies, vegetation and trees proposed previously for Tariquia Fm. Also, the proposed Huayquerian Age for this Formation is supported by this record.

La Gran Hidráulica en los ríos Yaqui y Mayo, Sonora, 1936-1957

En el trabajo se aborda el papel de la Comisión Nacional de Irrigación y de la Secretaria de Recursos Hidráulicos como constructora la primera y después, como contratistas y supervisoras en la construcción de las grandes presas de almacenamiento sobre el río Yaqui, La Angostura y Álvaro Obregón (Oviáchic) y el río Mayo, Adolfo Ruiz Cortines (Mocúzari), en el estado de Sonora, México, para uso agrícola en los valles del Yaqui y Mayo. También se estudia su incidencia en la modificación del medioambiente.

Modelling of erosion processes associated with rainfall-triggered lahars following the 2011 Cordon Caulle eruption (Chile)

In this work we investigate the sheet and rill erosion process as a possible lahar initiation mechanism in two catchments located in Villa la Angostura, Argentina (Southern Andes), in association with the 2011 eruption of Cordón Caulle (Chile). A few days after the climactic phase of the eruption, several lahar events occurred in Villa la Angostura where 15 cm of tephra mantled the slopes. The physically based model LISEM (openLISEM, 2013a, b) was applied to two small catchments where sheet and rill erosion of tephra deposits was observed. Model input parameters related to vegetation, soil surface and infiltration were obtained from field measurements, geotechnical tests and the literature. A total of 20 scenarios were simulated using a range of values of rainfall intensity and duration and hydraulic conductivity; only 16 of these scenarios resulted in erosion. Results show that hydraulic conductivity (Ks) and rainfall intensity significantly affect the runoff volume, with the smallest Ks (i.e. the tephra deposits associated with the largest fraction of fine ash) being associated with the largest eroded volumes and the largest discharges of water and sediment. The scenarios with the highest hydraulic conductivity did not show erosion for any modelled rainfall intensity. Nonetheless, we conclude that sheet and rill erosion were not the principal mechanism for rain-triggered lahars associated with the Cordón Caulle eruption, but mostly shallow landslide and similar erosion mechanisms contributed to lahars in Villa La Angostura. In fact, the eroded volumes calculated with LISEM are significantly smaller than the volume calculated with shallow landslide models for the same catchments (TRIGRS).

Tephra clean-up after the 2015 eruption of Calbuco volcano, Chile: a quantitative geospatial assessment in four communities

Reliable methods for volcanic impact and risk assessments are essential. They provide constructive information to emergency and disaster managers, critical infrastructure providers, the insurance industry, and wider society. Post-eruption clean-up of tephra deposits is a prevalent and expensive (time and resource) activity which is often not planned for. Here, we present an overview of the clean-up efforts undertaken in four communities after the VEI 4 eruption of Calbuco volcano in 2015. We narratively reconstruct clean-up efforts in Ensenada (Chile), Junín de los Andes (Argentina), San Martín de los Andes (Argentina), and Villa La Angostura (Argentina) using semi-structured interviews, syn- and post-deposition photographs, pre- and post-event visual spectrum satellite imagery, and media reports. We compare these reconstructions with estimates based on a geospatial modelling approach adapted from Hayes et al. (Journal of Applied Volcanology 6:1; 2017). Specifically, we compare reported and geospatially derived estimates for volume of tephra removed, and clean-up operation duration. Our modelling approach performed well for Junín de los Andes but did not adequately capture volume and clean-up operation duration for the three remaining case study locations. We discuss several sources of uncertainty (including observational errors and natural variance of tephra deposit thickness), reported tephra removal volume estimates, clean-up methods, land use, and temporal evolution of clean-up operation demand. Our work demonstrates the utility of using simple geospatial data to develop assessments for tephra clean-up for use in response and recovery planning, and quantitative volcanic impact and risk assessments.

Remobilized Cordón Caulle 2011 tephra deposits in north-Patagonian watersheds: Resedimentation at deltaic environments and its implications

The Argentinean side of the Andean North Patagonia is drained by several fluvio-lacustrine systems flowing eastwards from their headwaters at the Andes mountains towards large glacial lakes. These watersheds are recurrently affected by the deposition of tephra erupted from the many active Andean volcanos located in the Southern Volcanic Zone. This research focusses on two fluvial systems (Pireco and Totoral, PT) located in Nahuel Huapi National Park, which were severely impacted by the Cordón Caulle 2011 eruption (CC2011). We investigate particularly the resedimentation of pyroclastic materials on their lacustrine deltas and its potential implications considering 1) the deltas morphology and 2) mass-wasting processes developing at the delta fronts. Original tephra fall deposits were registered at Nahuel Huapi National Park in 2011. Based on the isopach map, we performed a GIS-based volume estimation of the deposit for the studied watersheds. Delta plain progradation from 2011 to 2017 was analyzed from satellite images. We studied the temporal evolution of the subaqueous morphology and mass-wasting processes at the delta fronts using high resolution bathymetric grids registered in 2011, 2014 and 2017. During June 2011 the studied watersheds received a tephra input of ~72 x 106m3. The significant progradation experienced by both deltas especially during the first month of the eruption was favored by 1) abundant precipitation at the watersheds concomitant to heavy tephra deposition and 2) the pre-existing subaqueous morphology characterized by a wide, shallow “terrace” bordering PT delta plains. About six years after the beginning of CC2011, 6% of the tephra fallen over the entire basins had been resedimented at the delta environments (terrace and delta front), totalizing ~3 x 106t. Evidence of pre-eruption and/or co-eruptive mass-wasting processes occurring at PT delta fronts was found on November 2011. Up to 30-m thick pyroclastic deposits were accumulated at PT delta fronts since November 2011, burying mass-wasting features at the upper delta fronts. A suspended-sediment collector installed at the prodelta in 2012 detected hyperpycnal currents transporting pyroclastic materials. These currents probably explain the development of mass-movements at high depths, such as the one that displaced and filled up the bottom sediment trap. This frontally-confined landslide initiated at a depth of >60 m and involved tephra and organic materials deposited at the lower part of Totoral delta front. Because of their recent deposition and loose consolidation, we propose that fresh tephra deposits at PT delta fronts could become particularly unstable and represent a potential hazard to failure, especially if a strong earthquake affects the study area in the next years. A landslide-induced tsunami wave generated at these deltas would impact rural settlements located along the coasts of Brazo Rincón and probably reach the coastal city of Villa La Angostura.

Impacts to agriculture and critical infrastructure in Argentina after ashfall from the 2011 eruption of the Cordón Caulle volcanic complex: an assessment of published damage and function thresholds

The 2011 Cordon Caulle (Chile) was a large silicic eruption that dispersed ashfall over 75,000 km2 of land in Central Argentina, affecting large parts of the Neuquen, Rio Negro, and Chubut provinces, including the urban areas of Villa la Angostura, Bariloche and Jacobacci. These regions all received damage and disruption to critical infrastructure and agriculture due to the ashfall. We describe these impacts and classify them according to published damage/disruption states (DDS). DDS for infrastructure and agriculture were also assigned to each area using the tephra thickness thresholds suggested by previous studies reported in the volcanological literature. The objective of this study was to evaluate whether the impacts were as expected based on the DDS suggested thresholds, and to determine whether other factors, apart from ashfall thickness, played a part. DDS thresholds based on tephra thickness were a good predictor of the impacts that occurred in the semi-arid steppe area around Jacobacci. This was unexpected as the more severe impacts were related to the challenging environmental conditions (low precipitation levels, high levels of wind erosion) and the daily wind remobilisation of ash that occurred, rather than the ashfall thicknesses received. The temperate region, including Villa la Angostura and Bariloche, performed better than the DDS assigned by ashfall thickness suggested. Despite deposits as thick as 300 mm, full recovery occurred within months of the ashfall event. The DDS scales need to incorporate a wider range of system characteristics, and environmental and vulnerability factors, as we propose here.

Past vegetation influence on the hydrological cycle in the Chihuahuan Desert, North Mexico as indicated by data of four pollen sites

Pollen studies of four sites in the Laguna Mayran region of North Central Mexico, along with sedimentary data reconstruct changes of vegetation and hydrology of both upland and lowland zones in the southern Chihuahuan Desert region of the past 13,000 years. Dual palynology–sedimentology data sets presented here are indicative of major vegetation influence on the hydrological cycle that represents a factor in the interpretation of climate changes. Most significant reconstructions include the development Ulmus–Quercus woodland along edges of the Laguna Mayran and increased evapo-transpiration. In contrast, Late Holocene environments contain opportunistic wetland plants in a desert setting. This suggests that higher lake levels may result at least from lower transpiration and that major precipitation events as such are episodic in the Late Holocene. Ponding also occurs at higher elevation, with lower transpiration according to a prominence of cool steppe plants at the site of La Angostura in the Late Pleistocene, when evaporation levels are also lower. Carbon isotope data at examined sites is also suggestive of an importance of local factors in the prominence of C3 versus C4 plants.

Secondary lahar hazard assessment for Villa la Angostura, Argentina, using Two-Phase-Titan modelling code during 2011 Cordón Caulle eruption

Abstract. This paper presents the results of lahar modelling in the town of Villa La Angostura (Neuquén-Argentina) based on the Two-Phase-Titan modelling computer code. The purpose of this exercise is to provide decision makers with a useful tool to assess lahar hazard during the 2011 Puyehue-Cordón Caulle Volcanic Complex eruption. The possible occurrence of lahars mobilized from recent ash falls that could reach the city was analysed. The performance of the Two-Phase-Titan model using 15 m resolution digital elevation models (DEMs) developed from optical satellite images and from radar satellite images was evaluated. The output of these modellings showed inconsistencies that, based on field observations, were attributed to bad adjustment of the DEMs to real topography. Further testing of results using more accurate radar-based 10 m DEM, provided more realistic predictions. This procedure allowed us to simulate the path of flows from Florencia, Las Piedritas and Colorado creeks, which are the most hazardous streams for debris flows in Villa La Angostura. The output of the modelling is a valuable tool for city planning and risk management especially considering the glacial geomorphic features of the region, the strong urban development growth and the land occupation that has occurred in the last decade in Villa La Angostura and its surroundings.

Palaeoenvironmental implications of the giant crocodylian Mourasuchus (Alligatoridae, Caimaninae) in the Yecua Formation (late Miocene) of Bolivia

Tineo, D.E., Bona, P., Pérez, L.M., Vergani, G.D., González, G., Poiré, D.G., Gasparini, Z.N. & Legarreta, P., 1.10.2014. Palaeoenvironmental implications of the giant crocodylian Mourasuchus (Alligatoridae, Caimaninae) in the Yecua Formation (late Miocene) of Bolivia. Alcheringa 39, xxx–xxx. ISSN 0311-5518Outcrops of the Yecua Formation (late Miocene) are exposed for approximately 230 m along the La Angostura section of the Piraí River (50 km southwest of Santa Cruz de la Sierra). These reveal massive (argillic palaeosols) and laminated (quiet-water lacustrine and marsh settings) mudstones interbedded with thin sandstones containing microfossils, molluscs and vertebrate remains. Significantly, the succession hosts a giant crocodylian, Mourasuchus (Alligatoridae, Caimaninae), which is represented by both skull and postcranial fragments found in association with freshwater turtles and fishes. Mourasuchus was distributed widely from the middle Miocene of Colombia to upper Miocene of Venezuela, Brazil and Argentina, suggesting connections between major fluvial systems and an active mechanism for dispersal of South American freshwater vertebrates during the Miocene.David Eric Tineo [tineo.d.e@gmail.com] and Daniel Gustavo Poiré [dgpoire@yahoo.com.ar], CONICET—Centro de Investigaciones Geológicas, Universidad Nacional de La Plata. Calle 1 (644), B1900FWA, La Plata, Argentina; Paula Bona [paulabona26@gmail.com] and Zulma Gasparini [zgaspari@fcnym.unlp.edu.ar], CONICET—División Paleontología Vertebrados, Museo de La Plata. Paseo del Bosque s/n, B1900FWA, La Plata, Argentina; Leandro Martín Pérez [pilosaperez@gmail.com] CONICET—División Paleozoología Invertebrados, Museo de La Plata. Paseo del Bosque s/n, B1900FWA, La Plata, Argentina; Gustavo Dardo Vergani [gvergani@pluspetrol.net]—Pluspetrol S.A. Lima (339), C1073AAG, Ciudad Autónoma de Buenos Aires, Argentina; Gloria González Rigas [ggonzalez@pluspetrol.net]—Pluspetrol Bolivia Corporation SA, Av. Grigotá esq. Las Palmas, Santa Cruz de la Sierra, Bolivia; Pablo Legarreta [plegarreta@pluspetrol.net]—Pluspetrol S.A. Lima (339), C1073AAG, Ciudad Autónoma de Buenos Aires, Argentina.

Plantas utilizadas en cercos vivos de ciudades patagónicas: aportes de la etnobotánica para la conservación

Plants used for hedging in Patagonian cities: an ethnobotanical contribution to conservation: Hedges constitute a significant part of Patagonian city landscapes, and can be very important not only as reservoirs of biodiversity, but also as possible sources of invasion. In this work, carried out in eight Patagonian tourist cities, species richness was estimated and the botanical families and biogeographical origin of the plants chosen for hedges were recorded. Considering the influence of European colonists on cultural and landscaping development in the region, one would expect a high proportion of resources to be of Holarctic origin. Species were identified in 100 homes chosen at random in each locality (San Martin de los Andes, Villa la Angostura, Dina Huapi, El Bolson, Lago Puelo, Esquel and Trevelin) and in 300 homes in Bariloche, due to its greater size. Total plant richness was 137 species, the most common being Cytisus scoparius (L.) Link (9%), Rosa sp. (8%), Pseudotsuga menziesii (Mirb.) Franco (7%), Cupressus macrocarpa Hartw. ex Gordon (5%) and Ligustrum sinense Lour. (3%). Of the 48 botanical families represented, the most frequent were Rosaceae, Fabaceae, Cupressaceae and Pinaceae (67% of the total registered). Species come from the following regions: Holarctic (72%), Antarctic (23%), Paleotropical (19%), Neotropical (5%) and Australian (2%). We conclude that the hedges studied, in terms of species richness, display similarities with the main ornamental species at a global level. However, the presence of Antarctic elements (32 species) indicates the incorporation of species native to Andean-Patagonian forests, and therefore an important role is being played here in terms of conservation. In addition, our survey shows that certain species may present a risk of biological invasion (e.g., Sorbus aucuparia L., Crataegus monogyna Jacq., Ulex europaeus L.) and we therefore propose that the population should be warned about the negative effects of these species.

Spectroscopic and Microscopic Characterization of Volcanic Ash from Puyehue-(Chile) Eruption: Preliminary Approach for the Application in the Arsenic Removal

Volcanic ash from Puyehue Cordon Caulle Volcanic Complex (Chile), emitted on June 4, 2011, and deposited in Villa La Angostura at ~40 km of the source, was collected and analyzed by Raman spectroscopy, optical and scanning electron microscopy (SEM-EDS), X-ray diffraction (XRD), surface area (BET), and chemical analysis (ICP-AES-MS technique). The mineralogical and physicochemical study revealed that the pyroclastic mixture contains iron oxides in the form of magnetite and hematite as well as pyroxene and plagioclase mineral species and amorphous pumiceous shards. Carbonaceous material was also identified. Physicochemical techniques allow us to select two representative samples (average composition and Fe-rich materials) which were used to analyze their performances in the adsorption process to remove arsenic from water. Additional iron activation by means of ferric salts was performed under original sample. Results showed that the low-cost feedstock exhibited a good adsorption capacity to remove the contaminant, depending on the iron content and the water pH.

A recently established Kelp Gull colony in a freshwater environment supported by an inland refuse dump in Patagonia

Populations of several species of gull are increasing worldwide as a result of a plentiful supply of anthropogenic food in urbanised environments. In light of this, we decided to examine the importance of anthropogenic food in the diet of a recently established colony of Kelp Gulls (Larus dominicanus). We collected 241 regurgitated pellets of the Kelp Gull during the 2008–09 breeding season at the colony in the De La Guardia Islands, Nahuel Huapi Lake, Argentina. In terms of percentage frequency of occurrence in pellets, human refuse (65.6%) was the most frequently recorded item, followed by insects (42.3%; mostly coleopterans) and fish (21.2%). In terms of the percentage number of total prey items, insects (62.1%) and human refuse (21.3%) were the most abundant items. The consumption of insects decreased and that of human refuse increased during chick-rearing. Human refuse was recorded in samples from most nests (97.3%). We compare our results with those obtained for other localities and discuss the consequences of the management of urban refuse. Our results suggest that the Kelp Gull breeding colony in the De La Guardia Islands is sustained by the availability of food from the rubbish tip of Villa la Angostura. This is the first dietary study of the Kelp Gull in a continental freshwater ecosystem and one more example of a gull colony supported by anthropogenic sources of food.