Search Results (25)

The Aconcagua River Basin is one of the most important basins in Chile, supporting a large percentage of economic activities such as intensive agriculture, mining, agroindustry, manufacturing, and hydropower generation. This basin is highly sensitive to climate change because it relies primarily on snowmelt and glacier contributions for water availability. In recent decades, a water deficit has been reported affecting water supply for the entire basin. This study focuses on changes in snow cover in the headwater catchment of the Aconcagua Basin and their relationship with meteorological conditions. The databases rely on satellite remote sensing and climate reanalysis data, using Landsat and MODIS collections for Snow Cover Area (SCA) data and ERA5 reanalysis for meteorological data, respectively. SCA, albedo, air temperature and relative humidity, in addition to snowfall, were assessed using Sen’s slope and Mann–Kendall non-parametric test to estimate trends and their significance. The results showed a decrease in SCA of about 99.1 and 138.2 km² per decade for MODIS and Landsat, respectively. Reanalysis datasets are related to the increase in warming trends, which accelerate the snow melting process and reduce water availability for the summer season. Hence, these results suggest the need to increase the ground-based snow monitoring stations to validate satellite data. Finally, the results can be used for new insights into water management at the basin scale in order to promote water use efficiency. Full article

The Juncal Norte Glacier (33°00′ S, 70°06′ W) is in the Dry Andes of central Chile within the Juncal Basin, a headwater watershed of the Aconcagua River, a semi-arid region experiencing an ongoing megadrought since 2010 and a 37% reduction in streamflow relative to pre-1990 baselines. This study provides the first glacier-specific annual melt and runoff estimate for Juncal Norte during mature megadrought conditions. Mass balance was estimated using a temperature index (positive degree day, PDD) model calibrated with automatic weather station (AWS) air temperature data and glacier hypsometry, assuming limited snow accumulation given that 2018–2019 precipitation and snow water equivalent (SWE) were extremely low relative to the long-term mean. Basin runoff was evaluated using a closure method comparing proglacial sub-basin-integrated discharge with modeled glacier melt volumes. Modeled glacier melt for 2018–2019 was equivalent to approximately 30% of observed annual discharge at the proglacial sub-basin, a disproportionate contribution given the glacier covers only 2.7% of the total basin area. The lower ablation zone (2900–4000 m), comprising 30% of glacier area, produced 90% of total melt volume. A + 1 °C temperature perturbation increased glacier-wide melt by 21.4%, confirming high climatic sensitivity. These results underscore the glacier’s critical but increasingly vulnerable buffering role for downstream water availability in the Dry Andes. Full article

This study evaluated the Snowmelt-Runoff Model (SRM) and the Génie Rural à X Paramètres Journalier (GRxJ) model family, analyzing the latter both independently and in combination with the CemaNeige snow module. SRM and GRxJ represent snowmelt-runoff and rainfall-runoff hydrological models, respectively. Accurate streamflow estimation in snow- and rain-dominated basins is crucial for water resource management, especially in the Andes where climate variability and glacier retreat threaten long-term water availability. The analysis was conducted in two Chilean watershed basins with contrasting regimes: the snow-dominated Aconcagua and the mixed rain–snow Duqueco basins. Daily data (2012–2020) of precipitation, temperature, evapotranspiration, snow cover (MODIS), and streamflow were used. Models were calibrated and validated with optimization algorithms and evaluated using $NSE$, $RMSE$, $R^2$, $PBIAS$, $KGE$, $MAE$, $logNSE$ and $APFB$. The results show that SRM effectively reproduces variability and, in the case of the rain–snow regime basin, extreme events, with $NSE$ ranging from $0.70$ to $0.78$ (Aconcagua) and $0.93$ to $0.94$ (Duqueco). Model selection should take into account the dominant hydrological processes. In this study, SRM showed the best performance in both analyzed catchments, although with limitations in reproducing extreme streamflow events. In contrast, the GRxJ models did not adequately capture the hydrological dynamics of the snow-dominated Aconcagua catchment. However, their performance improved considerably when applied to the mixed regime of the Duqueco River. These findings highlight the importance of adapting modeling strategies to local hydrological conditions and limited data availability, offering practical guidance for water management and climate change adaptation in Andean catchments. Full article

Background/Objectives: The maintenance of peri-implant soft tissue health is critical for the long-term success of implant therapy, particularly in edentulous patients rehabilitated with mandibular overdentures. Leukocyte- and platelet-rich fibrin (L-PRF) has been proposed as an autologous biomaterial to enhance peri-implant tissue quality. This randomized controlled clinical trial evaluated the effect of L-PRF on peri-implant mucosal thickness in edentulous patients treated with mandibular implant-retained overdentures. Methods: Edentulous patients received two interforaminal implants to retain a mandibular overdenture and were randomly assigned to a test group (L-PRF applied during surgery) or a control group (standard protocol without L-PRF). Clinical measurements of keratinized mucosal thickness and width were recorded at baseline, 12 weeks, and 24 weeks. Volumetric analyses of soft and hard tissue changes were performed using digital superimposition of STL models. The trial was conducted in accordance with the Declaration of Helsinki and approved by the Scientific Ethics Committee of the Aconcagua Health Service. All participants provided written informed consent. Results: A significant increase in keratinized mucosal thickness was observed in the L-PRF group at 12 and 24 weeks compared with baseline (p < 0.01). No significant differences were detected between the groups in soft tissue volume (p = 0.12) or bone volume (p = 0.45). Mucosal width remained stable in both groups throughout follow-up. Conclusions: The application of L-PRF at implant placement resulted in a significant gain in peri-implant mucosal thickness, suggesting a soft tissue modulating effect. Enhancing keratinized mucosal thickness during implant surgery may improve peri-implant tissue quality and support long-term stability of mandibular overdentures. Full article

This article examines the struggles for water justice led by women in the Aconcagua River Basin (Valparaíso, Chile) through a hydrofeminist perspective. Chile’s water crisis, rooted in a colonial extractivist model and exacerbated by neoliberal policies of water privatization, reflects a deeper crisis of socio-environmental injustice. Rather than understanding water merely as a resource, this research adopts a relational epistemology that conceives water as a living entity shaped by and shaping social, cultural, and ecological relations. Drawing on life-history interviews and the construction of a hydrofeminist cartography with women river defenders, this article explores how gendered and racialized bodies experience the crisis, resist extractive practices, and articulate alternative modes of co-existence with water. The hydrofeminist framework offers critical insights into the intersections of capitalism, colonialism, patriarchy, and environmental degradation, emphasizing how women’s embodied experiences are central to envisioning new water governance paradigms. This study reveals how women’s affective, spiritual, and territorial ties to water foster strategies of resilience, recovery, and re-existence that challenge the dominant extractivist logics. By centering these hydrofeminist life histories, this article contributes to broader debates on environmental justice, decolonial feminisms, and the urgent need to rethink human–water relationships within the current climate crisis. Full article

Background: Antimicrobial resistance (AMR) is a growing global health concern, driven in part by the environmental release of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs). Aquatic systems, particularly those exposed to urban, agricultural, and industrial activity, are recognized as hotspots for AMR evolution and transmission. In Chile, the Aconcagua River—subject to multiple anthropogenic pressures—offers a representative model for studying the environmental dimensions of AMR. Methods: Thirteen surface water samples were collected along the Aconcagua River basin in a single-day campaign to avoid temporal bias. Samples were filtered through 0.22 μm membranes and cultured on MacConkey agar, either unsupplemented or supplemented with ceftazidime (CAZ) or ciprofloxacin (CIP). Isolates were purified and identified using MALDI-TOF mass spectrometry. Antibiotic susceptibility was evaluated using the Kirby–Bauer disk diffusion method in accordance with CLSI guidelines. Carbapenemase activity was assessed using the Blue-Carba test, and PCR was employed for the detection of the bla_VIM, bla_KPC, bla_NDM, and bla_IMP genes. Results: A total of 104 bacterial morphotypes were isolated; 80 were identified at the species level, 5 were identified at the genus level, and 19 could not be taxonomically assigned using MALDI-TOF. Pseudomonas (40 isolates) and Aeromonas (25) were the predominant genera. No growth was observed on CIP plates, while 24 isolates were recovered from CAZ-supplemented media, 87.5% of which were resistant to aztreonam. Five isolates exhibited resistance to carbapenems; two tested positive for carbapenemase activity and carried the bla_VIM gene. Conclusions: Our results confirm the presence of clinically significant resistance mechanisms, including bla_VIM, in environmental Pseudomonas spp. from the Aconcagua River. These findings highlight the need for environmental AMR surveillance and reinforce the importance of adopting a One Health approach to antimicrobial stewardship and wastewater regulation. Full article

Snow cover is an important freshwater source in many mountain ranges around the world and is heavily affected by climate change, often leading to reduced overall snow cover availability and duration as well as shifts in seasonality. To monitor these changes and long-term trends, the analysis of remote sensing is a commonly used tool, as data are available consistently and for long time series. In this study we acquired and processed the whole archive of available Landsat data between 1985 and 2024 for two catchments in the Chilean Andes, Aconcagua and Río Maipo, located in the Valparaíso and Santiago de Chile metropolitan regions, respectively. We generated monthly Snow Line Elevation (SLE) time series from the entire archive for both catchments and performed trend analyses on these time series. Strong positive long-term SLE change rates of 11.25 m per year for the Aconcagua catchment and 9.85 m to 15.65 m per year for the Río Maipo catchment were detected, indicating a decrease in snow cover as well as available freshwater from snowmelt. The projection to the year 2050 revealed a potential loss of snow covered area of up to 42% during summer months, with the SLE receding up to 231 m. Full article

Land use and land cover (LULC) change is a dynamic process influenced by various factors, including agricultural expansion. In Chile’s Aconcagua Basin, avocado plantations are potentially driving territorial transformations. However, current land cover data lacks the resolution required to accurately assess this impact. Accordingly, our study used advanced geospatial analysis techniques to address this gap. Through a detailed analysis of the spatial and temporal changes, it was determined that the most significant expansion of avocado plantations occurred between 2003 and 2013, with an increase of 402%. This growth primarily took place at the expense of native vegetation, particularly sclerophyllous shrubland, as well as other agricultural lands, near agricultural and urban lands. By 2023, changes in avocado plantation were significantly slower, with minimal alterations in LULC (5%), suggesting a possible influence of drought on small-scale farmers. However, the small loss of avocado plantation was mainly replaced by fruit farm land. Moreover, our findings suggest that while avocado plantations have become larger, more dominant, and more isolated, native vegetation has become more fragmented and reduced in patch size. Based on these results, sustainable land management practices were proposed. These findings provide a crucial foundation for developing sustainable land management strategies that balance agricultural production with environmental sustainability, landscape transformation and the well-being of local communities. Full article

Chile is an important producer of copper, and it has serious soil contamination problems, mainly related to mining activities. A typical example is the Aconcagua River basin, which has been the scene of large-scale mining operations throughout history, making it critical to analyze due to the high concentrations of heavy metals in its soils. The objectives of this study are (1) to assess the level of As, Cu, Pb, and Zn contamination in the surface soil ecosystem based on different environmental indexes and (2) to determine the health risks of adults and children located in watersheds of the Aconcagua and Casablanca Rivers. A database of the Aconcagua River and Casablanca River basins is used to achieve the objectives. From the Aconcagua River basin, 20 topsoil samples from agricultural sectors without mining activity and 127 topsoil samples from sectors with mining activity were selected. On the other hand, thirty-five topsoil samples of the Casablanca River basin, without mining activity, were analyzed. The evaluation of soil contamination was done using environmental indexes. Finally, carcinogenic and noncarcinogenic risks to humans were calculated using the USEPA model. The mean concentration of chemical elements in the Aconcagua River basin for samples without mining presence was As 10.55 mg kg⁻¹, Cu 85.75 mg kg⁻¹, Pb 26.65 mg kg⁻¹, and Zn 139.5 mg kg⁻¹. The correlations show that the elements As, Cu, Pb, and Zn come from anthropogenic sources, which are also enhanced by the geogenic origin of Cu and Zn. The spatial distribution of the analyzed elements shows a spatial pattern that extends across industrial areas and emission sources, with higher concentrations of As, Cu, Pb, and Zn identified near mining areas of the Aconcagua River basin. The upper limit of the geogenic values determined by the MAD (median absolute deviation) method for the Aconcagua River basin without mining presence was 14.5 mg kg⁻¹ for As, 94 mg kg⁻¹ for Cu, 37.5 mg kg⁻¹ for Pb, and 194 mg kg⁻¹ for Zn. Finally, the geoaccumulation index, contamination factor, integrated contamination index, and potential ecological risk registered exceptionally high contamination in some soil samples, especially in areas with mining influence. It is essential to highlight that there are non-carcinogenic risks related to As, Cu, and Pb, a hazard quotient (HQ) higher than 1, and acceptable carcinogenic risks between 1.0 × 10⁻⁶ and 1.0 × 10⁻⁴ to As and Pb in children and adults in the Aconcagua River basin. Full article

Droughts and extreme rainfall events are two of the hazards that affect many people in the world and are frequent and complex hazards, the rate of occurrence and magnitude of which are expected to increase in a changing climate. In this context, understanding how different actors perceive changes in climate, drought, and extreme rainfall events and their impacts is relevant in contributing to successfully implementing adaptation strategies to reduce their impacts. This research seeks to explore the main changes the climate has undergone and the impacts of drought and precipitation events, as perceived at local levels by different stakeholders. A multi-method approach was applied, including qualitative methods such as observation, 51 semi-structured interviews, and document reviews in Chañaral and the Aconcagua Valley, Chile. This research shows what the perceived changes in climate are and that drought and extreme rainfall events have affected the well-being of the local people by severely impacting the economy, the environment, social interactions, quality of life, and human health. Additionally, the perception of climate change and its impacts vary depending on the type of hazard and the social, geographical, and environmental contexts in which communities live. This study is useful as it has generated knowledge relevant to inform policy decisions, practice, and theory. Full article

Asthma is a significant public health concern. This study identified the provinces with the highest morbidity and mortality rates due to asthma among the working-age population (15–69 years) in the Republic of Ecuador. The secondary objective was to explain the possible differences attributable to occupational exposure. This nationwide ecological study was conducted in 24 provinces between 2016 and 2019. Government databases were used as sources of information. Age-standardized rates were calculated for codes J45 and J46. The hospitalization morbidity rate for asthma decreased from 6.51 to 5.76 cases per 100,000 working-age population, and the mortality rate has consistently been low and stable from 0.14 to 0.15 deaths per 100,000 working-age population. Geographic differences between the provinces were evident. The risk of hospitalization and death due to asthma was higher in the Pacific coast (Manabí with 7.26 and 0.38, Esmeraldas with 6.24 and 0.43, Los Ríos with 4.16 and 0.40, El Oro with 7.98 and 0.21, Guayas with 4.42 and 0.17 and the Andean region (Azuay with 6.33 and 0.45, Cotopaxi (5.84 and 0.48)). The high rates observed in provinces with greater agricultural and industrial development could be national heterogeneity’s main determinants and act as occupational risk factors. The contribution of occupational hazards in each province should be examined in depth through ad hoc studies. The findings presented here provide valuable information that should prompt further detailed studies, which will assist in designing public policies aimed at promoting and safeguarding the respiratory health of the population, particularly that of workers. We believe that this study will inspire the creation of regional networks for the research and surveillance of occupational health. Full article

The mummy of a seven-year-old child that was discovered in 1985 in Cerro Aconcagua (Mendoza, Argentina) was likely part of an Inka sacrificial religious practice known as capacocha. Previous uniparental DNA marker studies conducted by some scholars have suggested that the mummified child may be related to the southern Andean population of Peru. However, autosome genome-wide analysis performed by others has indicated that the child was more closely related to the population along the northern Peruvian coast than to that of the southern Andes. In this study, we aimed to determine possible genealogical connections in the male lineage of the mummified child. To achieve this, we compared the genetic profile of the mummy with an extensive database of contemporary individuals from the northern Peruvian coastal and southern Andean regions. We used single nucleotide polymorphisms and short tandem repeats from the nonrecombining region of the Y-chromosome for our analysis. Our results confirmed that the Inka child mummy was closely related to individuals from the north coast of Peru. This suggests that the child was likely descended from the Muchik–Chimor-speaking people. Full article

Snow-covered regions are the main source of reflection of incident shortwave radiation on the Earth’s surface. The deposition of light-absorbing particles on these regions increases the capacity of snow to absorb radiation and decreases surface snow albedo, which intensifies the radiative forcing, leading to accelerated snowmelt and modifications of the hydrologic cycle. In this work, the changes in surface snow albedo and radiative forcing were investigated, induced by light-absorbing particles in the Upper Aconcagua River Basin (Chilean Central Andes) using remote sensing satellite data (MODIS), in situ spectral snow albedo measurements, and the incident shortwave radiation during the austral winter months (May to August) for the 2004–2016 period. To estimate the changes in snow albedo and radiative forcing, two spectral ranges were defined: (i) an enclosed range between 841 and 876 nm, which isolates the effects of black carbon, an important light-absorbing particle derived from anthropogenic activities, and (ii) a broadband range between 300 and 2500 nm. The results indicate that percent variations in snow albedo in the enclosed range are higher than in the broadband range, regardless of the total amount of radiation received, which may be attributed to the presence of light-absorbing particles, as these particles have a greater impact on surface snow albedo at wavelengths in the enclosed band than in the broadband band. Full article

Silicosis is one of the most important occupational respiratory diseases worldwide, hence the importance of making a correct diagnosis. Diagnosis is commonly based on radiological findings according to the ILO International Classification of Radiographs of Pneumoconioses and occupational exposure. High-resolution computed tomography is indicated for differential diagnosis. This article presents two cases with an initial diagnosis of silicosis that ended up being diagnosed as sarcoidosis and siderosis, respectively. The first case was a 42-year-old male who worked as a crushing operator in an underground copper and molybdenum mine for 22 years. He had a history of exposure to silicon dioxide and was asymptomatic. X-rays did not distinguish silicosis or siderosis, but histological findings (open lung biopsy) allowed for a diagnosis of sarcoidosis. The second case was a 50-year-old male who had worked as a welder in a molybdenum filter plant, an open pit mine since 2013; he spent the previous 20 years as a welder in an underground copper mine, with exposure to silicon dioxide and was symptomatic. The first radiograph showed opacities that were compatible with pulmonary silicosis. A subsequent high-resolution computed tomography and lung biopsy showed a pattern of pulmonary siderosis. Due to the similarities in the radiographs of these three diseases, greater emphasis must be placed on the differential diagnosis, for which a complete occupational and clinical history is important in order to provide clues for the performance of complementary tests to avoid misdiagnosing. Full article

This paper investigates exact solutions of cosmological interest in fractional cosmology. Given $\mu$, the order of Caputo’s fractional derivative, and w, the matter equation of state, we present specific exact power-law solutions. We discuss the exact general solution of the Riccati Equation, where the solution for the scale factor is a combination of power laws. Using cosmological data, we estimate the free parameters. An analysis of type Ia supernovae (SNe Ia) data and the observational Hubble parameter data (OHD), also known as cosmic chronometers, and a joint analysis with data from SNe Ia + OHD leads to best-fit values for the free parameters calculated at $1\sigma$, $2\sigma$ and $3\sigma$ confidence levels (CLs). On the other hand, these best-fit values are used to calculate the age of the Universe, the current deceleration parameter (both at $3\sigma$ CL) and the current matter density parameter at $1\sigma$ CL. Finding a Universe roughly twice as old as the one of $\Lambda$CDM is a distinction of fractional cosmology. Focusing our analysis on these results, we can conclude that the region in which $\mu >2$ is not ruled out by observations. This parameter region is relevant because fractional cosmology gives a power-law solution without matter, which is accelerated for $\mu >2$. We present a fractional origin model that leads to an accelerated state without appealing to $\Lambda$ or dark energy. Full article