An open source Python library for environmental isotopic modelling

Altres ajuts: from the Balearic Island Government through the Margalida Comas postdoctoral fellowship programme (PD/036/2020).Isotopic composition modelling is a key aspect in many environmental studies. This work presents Isocompy, an open source Python library that estimates isotopic compositions through machine learning algorithms with user-defined variables. Isocompy includes dataset preprocessing, outlier detection, statistical analysis, feature selection, model validation and calibration and postprocessing. This tool has the flexibility to operate with discontinuous inputs in time and space. The automatic decision-making procedures are knitted in different stages of the algorithm, although it is possible to manually complete each step. The extensive output reports, figures and maps generated by Isocompy facilitate the comprehension of stable water isotope studies. The functionality of Isocompy is demonstrated with an application example involving the meteorological features and isotopic composition of precipitation in N Chile, which are compared with the results produced in previous studies. In essence, Isocompy offers an open source foundation for isotopic studies that ensures reproducible research in environmental fields

Insights on the hydrological cycle and its interaction with anthropic pressures: the Katari basin and minor Titicaca lake

The hydrologic cycle behaviour in the Bolivian Altiplano and how it interacts with human activity are still not fully understood. The hydraulic cycle is examined in a novel way in this work by considering extended time series of associated hydrologic and climatic data. Results show that human exploitation and losses from the sewage and water supply networks in the urban areas might cause an hydraulic imbalance in the region. These anthropogenic incomes, at the same time, increase concentrations of different pollutants. Water isotopic analysis reinforces the conceptual model showing that the groundwater sampled are mainly from precipitation. Workshops with local municipalities supported and defined the most relevant anthropic pressures in the basin. This information supports a vulnerability analysis in collaboration among them. The decision-making process for government entities might be strengthened by this study, which would help to develop long-term strategies to prevent and mitigate the issues found in the evaluation of water vulnerability in the region.</p

Brain Functional Connectivity Is Modified By A Hypocaloric Mediterranean Diet And Physical Activity In Obese Women

Functional magnetic resonance imaging (fMRI) in the resting state has shown altered brain connectivity networks in obese individuals. However, the impact of a Mediterranean diet on cerebral connectivity in obese patients when losing weight has not been previously explored. The aim of this study was to examine the connectivity between brain structures before and six months after following a hypocaloric Mediterranean diet and physical activity program in a group of sixteen obese women aged 46.31 +/- 4.07 years. Before and after the intervention program, the body mass index (BMI) (kg/m(2)) was 38.15 +/- 4.7 vs. 34.18 +/- 4.5 (p < 0.02), and body weight (kg) was 98.5 +/- 13.1 vs. 88.28 +/- 12.2 (p < 0.03). All subjects underwent a pre- and post-intervention fMRI under fasting conditions. Functional connectivity was assessed using seed-based correlations. After the intervention, we found decreased connectivity between the left inferior parietal cortex and the right temporal cortex (p < 0.001), left posterior cingulate (p < 0.001), and right posterior cingulate (p < 0.03); decreased connectivity between the left superior frontal gyrus and the right temporal cortex (p < 0.01); decreased connectivity between the prefrontal cortex and the somatosensory cortex (p < 0.025); and decreased connectivity between the left and right posterior cingulate (p < 0.04). Results were considered significant at a voxel-wise threshold of p <= 0.05, and a cluster-level family-wise error correction for multiple comparisons of p <= 0.05. In conclusion, functional connectivity between brain structures involved in the pathophysiology of obesity ( the inferior parietal lobe, posterior cingulate, temporo-insular cortex, prefrontal cortex) may be modified by a weight loss program including a Mediterranean diet and physical exercise

Isotopic characterization of precipitation and its relationship with groundwater in the Central Andes

[eng] The availability of water resources is increasingly limited worldwide. Therefore, optimal and sustainable management is necessary to ensure a balance between ecosystems and human rights and activities. In the arid Central Andes, there is a great demand for water for different uses, including domestic consumption, intensive mining and, in some areas, livestock and emerging ecotourism. These human activities must respect and conserve the lagoon systems of the salt flats, on which the fauna depend. Understanding the hydrological and hydrogeological functioning of basins is essential for the optimal and sustainable management of water resources. To address this issue, the objective of this thesis is to advance the knowledge on the isotopic composition of precipitation and its relationship with groundwater in the Central Andes, particularly in the Salar de Atacama basin (Chile). This thesis contributes to the (1) understanding of the origin of precipitation in the Central Andes and reviews how it varies isotopically (δ18O and δ2H) throughout the Amazon basin and in the Central Andes between 14°S and 28°S, (2) identification of the factors that control the isotopic composition of precipitation in areas with scarce isotopic and meteorological data and estimation of the meteorological and isotopic variables of precipitation, (3) characterisation of precipitation and identification of the recharge zone of the Salar de Atacama basin using stable isotopes, and (4) quantification of the contribution of snowmelt to the recharge of the aquifer of the basin. Through an exhaustive review of the literature, precipitation in the Central Andes has been characterised. Precipitation occurs mainly during the austral summer. The masses of humidity have different origin: (1) from the North Atlantic Ocean through the Amazon basin, (2) from the South Atlantic Ocean through the Plate River basin and the Gran Chaco in summer, and (3) the Pacific Ocean in winter. The processes involved in the isotopic evolution of summer convective precipitation in the Eastern Cordillera are known. However, there is no consensus on the factors that control the isotopic variation in the Western Cordillera. To identify the processes that determine the precipitation isotopy in the Cordillera Occidental, a statistical analysis is carried out between geospatial, meteorological and isotopic variables. The result indicates that temperature is controlled by altitude and latitude, while relative humidity is controlled by latitude, and summer precipitation is controlled by altitude and latitude. The stable isotopes of precipitation are controlled by temperature, altitude, latitude, longitude, and precipitation. Finally, based on these relationships, these variables are estimated by independent models throughout the study area and three isotopic models (summer, winter and annual). The isotopic compositions of the surface water and groundwater indicate the presence of evaporation and that they are similar to each other in each subbasin, both in the Salar de Atacama and in the Altiplano-Puna. Finally, the meteoric source of the waters of the Altiplano-Puna basins is more depleted of heavy isotopes than are the waters of the peripheral subbasins of the salar. Therefore, these results show that there is no hydraulic connection between basins and that there is no significant transfer of water from the Altiplano-Puna to the peripheral aquifer of the Salar de Atacama. This thesis presents a first view of the behavior of snow in the Toconao subbasin (subbasin east of the Salar de Atacama) through physical models. The total average precipitation was 139 mm/year in 2017, of which a third was in the form of snow. In summer the snow was above 4500 m asl and it melted in 10 days. In winter, when the temperature is lower, the snow cover covered much of the basin and slowly melted for a month.[spa] La disponibilidad de los recursos hídricos cada vez es más limitada en el mundo. Por ello, es necesaria su gestión óptima y sustentable, asegurando el equilibrio entre los ecosistemas y la actividad humana. En los Andes centrales existe una gran demanda de agua para diferentes usos, el consumo doméstico, la explotación intensiva de la minería y, a nivel local, la ganadería y el turismo de naturaleza emergente. Estas actividades antrópicas deben de respetar y conservar los sistemas lagunares de lo s salares, de los cuales depende la fauna. Comprender el funcionamiento hidrológico e hidrogeológico de las cuencas es fundamental para una gestión óptima y sustentable de los recursos hídricos. Para solucionar esta situación, el objetivo de esta tesis ha sido avanzar en el conocimiento de la composición isotópica de la precipitación y su relación con las aguas subterráneas en los Andes Centrales, particularmente en la cuenca del Salar de Atacama (Chile). Esta tesis contribuye a (1) comprender el origen de la precipitación en los Andes Centrales y revisar cómo varía isotópicamente (δ18O y δ2H) a lo largo de la cuenca del Amazonas y en los Andes Centrales entre 14°S y 28°S, (2) a la identificación de los factores que controlan la composición isotópica de la precipitación en áreas con escasos datos isotópicos y meteorológicos y a la estimación de las variables meteorológicas e isotópicas de la precipitación, (3) a la caracterización de la precipitación e identificación de la zona de recarga mediante isótopos estables en la cuenca del Salar de Atacama y (4) a cuantificar el aporte del deshielo en la recarga del acuífero de la cuenca. En esta tesis se concluye que (i) la incertidumbre que existía en la literatura sobre los procesos involucrados en los isótopos estables de la precipitación en la Cordillera Occidental se ha resuelto, que (ii) lo descrito en la literatura a gran escala (Andes Centrales) es coherente con los resultados de las muestras recolectadas y analizadas en la cuenca del Salar de Atacama y (iii) que la nieve es una componente importante en el ciclo hidrológico del Salar de Atacama

Origin and variability of oxygen and hydrogen isotopic composition of precipitation in the Central Andes: A review

This review concerns the knowledge of the isotopic composition of current precipitation and its association with climate, geography and orography, in the Central Andes (14–28°S and 75–63°W). This knowledge is required for the evaluation of other hydrological values, especially aquifer recharge and water resources, in environments varying from rainy to hyper-arid. Since the 1960s, oxygen (δ18O) and deuterium (δ2H) isotope composition of natural water have been used as tracers of the global hydrological cycle. In the present article, the goal is to identify the origin and trajectory of air masses that produce rainfall in the Central Andes and the isotopic composition of the precipitation, as a first step to evaluate recharge and groundwater resources. The isotopic composition of rainfall varies spatially and temporarily, depending on the climatic phenomena that originate the movement of air masses, their moisture content and the isotope fractionation processes that occur until precipitation falls. Most of the significant and recent literature on the mechanisms of δ18O and δ2H transport and fractionation in precipitation along the Central Andes has been collected and summarized in this review. Precipitation in the eastern and central Andes comes mainly from the humidity generated in the Atlantic Ocean. Although the processes involved in isotope content variability of precipitation are well known, the processes involved in isotopic variability in the Western Cordillera remain poorly understood. This is mostly due to mixing of different moisture sources: from the Atlantic Ocean in summer and from the Pacific Ocean in winter. In general, winter rainfall is more enriched in δ18O and δ2H than summer rainfall. Looking at existing data, their distribution is far from being homogeneous and well-distributed, so spatial accuracy is poor in some areas, especially in the Altiplano. Hydrological and hydrogeological research and water resources evaluation in the Central Andes would greatly benefit from initiatives to obtain broader spatial coverage of rainfall collection to get isotope data for more accurate and continuous assessment of the local weather patterns. Groundwater isotope composition is a future tool to help in increasing the coverage in data scarce areas.The authors acknowledge SQM (Chile) for their support and for sharing isotopes data of the Salar de Atacama, as well as Southern Copper (Peru) for providing isotopic information. We thank two anonymous reviewers for their valuable comments. Further to this, numerous researchers, professors and practitioners from Argentina and Chile (Daniel E. Martinez, Cristina Dapeña and Christian Herrera) have contributed published and unpublished information and their personal experience.Peer reviewe

Environmental isotope concepts of precipitation and surface water and groundwater in the central andes: A review

Se muestra la revisión de la información existente sobre la composición isotópica del oxígeno (δ18O) y del hidrógeno (δ2H) de la molécula del agua en el sector Norte de los Andes chilenos, entre 17°30´y 25°30´ de latitud sur. Durante el verano austral, los vientos del este favorecen la entrada de humedad atlántica, predominantemente a través de la cuenca del Amazonas, que originan más del 80% de la precipitación anual que se produce en los Andes Centrales. La cordillera de los Andes Centrales actúa como una barrera geográfica respecto a la humedad del Atlántico, siendo uno de los factores que produce en la costa norte chilena el área climática más seca de la Tierra. Se revisan brevemente los antecedentes sobre la hidrología isotópica, los que han permitido dar respuesta a cuestiones tales como el origen de las precipitaciones que recargan los acuíferos, la localización de las zonas de recarga, las posibles conexiones entre cuencas, y la identificación de los procesos que modifican la isotopía de las aguas, como la evaporación o los efectos geotérmicos. Se ha observado en las aguas superficiales, subterráneas y precipitaciones del norte de Chile, que existe un enriquecimiento en isótopos pesados en sentido norte sur, desde la región de Arica y Parinacota a la región de Antofagasta. La investigación de la isotopía de las precipitaciones y de las aguas superficiales y subterráneas es necesaria para un manejo sustentable de los recursos hídricos y para comprender el actual clima y las variaciones climáticas pasadas y futuras.Peer reviewe

Characterization of precipitation and recharge in the peripheral aquifer of the Salar de Atacama

To reduce uncertainty in the identification of the recharge areas in the Peripheral Aquifer of the Salar de Atacama (SdA), a few studies have investigated the isotopic characteristics and moisture sources of precipitation in the SdA basin. In the present study, the seasonal cycle of meteorological parameters and the relationships of this cycle with sea surface temperature anomalies are shown, the sources of humidity are identified, and the types of clouds producing precipitation are defined. Finally, the isotopic compositions of precipitation, surface water and groundwater in the SdA basin and the Altiplano-Puna Plateau basins are analysed to identify the area recharging the northern, eastern and southern subbasins of the SdA. In summer, when the highest temperature, relative humidity and precipitation values of the year are recorded, the precipitation is due to deep convection. The trajectories of the arriving air masses can be classified into three groups: from the North Atlantic Ocean across the Amazon basin, from the South Atlantic Ocean across the La Plata River basin and the Gran Chaco, and from the Pacific Ocean. In winter, when the temperature, relative humidity and precipitation are lower, the moisture masses come from the Pacific Ocean. Winter precipitation is more depleted in heavy isotopes than summer precipitation. The isotopic analysis of precipitation, surface water and groundwater shows that recharge of the eastern subbasins of the SdA occurs by diffuse infiltration of precipitation and concentrated infiltration of surface water, both within the hydrographic basin of the SdA. The meteoric source of the waters in the Altiplano-Puna Plateau basins is isotopically lighter than the waters found in the side basins of the SdA, so there is no significant water quantity transfer to the peripheral aquifers of the SdA from outside the hydrographic basin.The authors thank SQM (Chile) for their support and cooperation, Atacama Large Millimeter/submillimeter Array (ALMA), to the staff of the Paso Jama border crossing and indigenous communities of Atacameñas de Caspana and Toconce responsible for the Geysers of El Tatio, for their support in the obtaining the isotope data. Thanks to Xavier Querol and Cristina Carnerero for their help and with model HYSPLIT, and to Dr. Rotman Criollo for his help. Sonia Valdivielso and Enric Vázquez-Suñé would like to thanks Spanish Ministry of Science and Innovation (Project CEX2018-000794-S) IDAEA-CSIC, Centre of Excellence Severo Ochoa. The authors are thankful to Dr. Carlos Ayora for his critical and constructive comments on the manuscript of this paper.Peer reviewe