ABSTRACT
Management of water resources in hyper-arid areas faces vital challenges in a global climate change context. Consequently, understanding the effects on groundwater sources can help mitigating the problem of water scarcity and the negative impact of human intervention on the environment. A case study area in the hyper-arid climate of the United Arab Emirates, was tackled here with the focus on applying stable isotopes as tools for evaluating groundwater sources and quality assessment. The results of major ions indicate variable increase in groundwater salinity moving away from Al Hajar Mountains recharge areas to the discharge areas (Arabian Gulf coast). The data of stable isotopes (δ18OH2O, δ2HH2O, δ18ONO3, δ15NNO3, δ18OSO4, δ34SSO4, δ11B) suggest impact of paleo-groundwater in the abstractions of the wells nearest to the coast. Nitrate isotopes indicate farming activities sources that can be masked due to the contribution from the nitrate-poor paleo-groundwater. Nitrate reduction processes are expected near to the recharge front. Sulphate and boron isotopes further suggest that influence of ancient evaporite dissolution in salinization. Management efforts should be focused on the diffuse sources of quality mitigations that can be vital in fingerprinting local and regional (transboundary) effects.
Subject(s)
Groundwater , Water Pollutants, Chemical , Environmental Monitoring , Humans , Nitrates/analysis , Water , Water Pollutants, Chemical/analysis , Water WellsABSTRACT
A major quest in Mars' exploration has been the hunt for atmospheric gases, potentially unveiling ongoing activity of geophysical or biological origin. Here, we report the first detection of a halogen gas, HCl, which could, in theory, originate from contemporary volcanic degassing or chlorine released from gas-solid reactions. Our detections made at ~3.2 to 3.8 µm with the Atmospheric Chemistry Suite and confirmed with Nadir and Occultation for Mars Discovery instruments onboard the ExoMars Trace Gas Orbiter, reveal widely distributed HCl in the 1- to 4-ppbv range, 20 times greater than previously reported upper limits. HCl increased during the 2018 global dust storm and declined soon after its end, pointing to the exchange between the dust and the atmosphere. Understanding the origin and variability of HCl shall constitute a major advance in our appraisal of martian geo- and photochemistry.
ABSTRACT
The loss of water from Mars to space is thought to result from the transport of water to the upper atmosphere, where it is dissociated to hydrogen and escapes the planet. Recent observations have suggested large, rapid seasonal intrusions of water into the upper atmosphere, boosting the hydrogen abundance. We use the Atmospheric Chemistry Suite on the ExoMars Trace Gas Orbiter to characterize the water distribution by altitude. Water profiles during the 2018-2019 southern spring and summer stormy seasons show that high-altitude water is preferentially supplied close to perihelion, and supersaturation occurs even when clouds are present. This implies that the potential for water to escape from Mars is higher than previously thought.
ABSTRACT
The detection of methane on Mars has been interpreted as indicating that geochemical or biotic activities could persist on Mars today1. A number of different measurements of methane show evidence of transient, locally elevated methane concentrations and seasonal variations in background methane concentrations2-5. These measurements, however, are difficult to reconcile with our current understanding of the chemistry and physics of the Martian atmosphere6,7, which-given methane's lifetime of several centuries-predicts an even, well mixed distribution of methane1,6,8. Here we report highly sensitive measurements of the atmosphere of Mars in an attempt to detect methane, using the ACS and NOMAD instruments onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter from April to August 2018. We did not detect any methane over a range of latitudes in both hemispheres, obtaining an upper limit for methane of about 0.05 parts per billion by volume, which is 10 to 100 times lower than previously reported positive detections2,4. We suggest that reconciliation between the present findings and the background methane concentrations found in the Gale crater4 would require an unknown process that can rapidly remove or sequester methane from the lower atmosphere before it spreads globally.
ABSTRACT
Global dust storms on Mars are rare1,2 but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere3, primarily owing to solar heating of the dust3. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars4. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes5,6, as well as a decrease in the water column at low latitudes7,8. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H2O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H2O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals3. The observed changes in H2O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere.
ABSTRACT
The surname of author Cathy Quantin-Nataf was misspelled 'Quantin-Nata', authors Ehouarn Millour and Roland Young were missing from the ACS and NOMAD Science Teams list, and minor changes have been made to the author and affiliation lists; see accompanying Amendment. These errors have been corrected online.
ABSTRACT
The surname of author Cathy Quantin-Nataf was misspelled 'Quantin-Nata' , authors Ehouarn Millour and Roland Young were missing from the ACS Science Team list, and minor changes have been made to the author and affiliation lists; see accompanying Amendment. These errors have been corrected online.
ABSTRACT
The change from a traditional agricultural model to a modern, more productive one, coupled with population growth, has entailed an increased consumption of water, fertilizers and pesticides. This transformation has led to a greater risk of groundwater contamination. This study has analysed for this purpose a total of 314 samples (period 2010-2013). In addition, 332 samples from the Mancha Oriental groundwater body (period 2001-2003) were also examined in order to gain a better perspective on the temporal evolution of pesticides in groundwater bodies. Using this database, this study aims to characterize pesticide pollution and to examine possible processes. Triazine herbicides are the most common pesticides found and also appear in the highest concentrations, with terbuthylazine having a noteworthy concentration of 900 ng/L. The irrigated agriculture and the physicochemical properties of pesticides are the most important factors influencing the concentration and type of pesticides that can reach groundwater. The spatial distribution of nitrate and pesticides do not correspond as they would if the two behaved similarly. Pesticides can completely biodegrade before reaching the saturated zone, but it is also possible that their degradation products have not been analysed and, therefore, their concentrations are underestimated.
Subject(s)
Agricultural Irrigation , Environmental Monitoring , Groundwater/chemistry , Pesticides/analysis , Rivers , Water Pollutants, Chemical/analysis , Agriculture/methods , European Union , Fertilizers/analysis , Herbicides/analysis , Nitrates/analysis , Spain , Triazines/analysisABSTRACT
Objetivos: Conocer la variabilidad en las respuestas asistenciales que se ofrecen en la atención psiquiátrica ambulatoria a los menores de 18 años, medidas por el número de consultas y el tiempo de duración de los tratamientos. Método: Estudio observacional, analítico, prospectivo con datos históricos y longitudinal de seguimiento de 298 sujetos que consultan por primera vez en las unidades de atención ambulatoria de Leganés y Fuenlabrada (Madrid). Resultados: La mediana del número de consultas por paciente en Leganés fue de 6, mientras que en Fuenlabrada fue de 3 (p < 0,001). La mediana de la duración del tratamiento fue más del doble en Leganés (276 días) que Fuenlabrada (119 días) (p < 0,001). El análisis estratificado muestra que los tratamientos del distrito de Fuenlabrada suponen un menor número de consultas, ya sea el profesional responsable psiquiatra o psicólogo, se lleve a cabo psicoterapia individual, de otro tipo, o no se indique tratamiento de modo explícito, se realice alta concertada o ésta se produzca por abandono. Similares resultados se aprecian para la duración del tratamiento. Conclusiones: Las diferencias encontradas de estilos de práctica clínica ilustran las dificultades para desarrollar un sistema de ajustes de riesgos útil en salud mental, puesto que las diferencias en uso de recursos no son fácilmente atribuibles a variables relacionadas con el paciente, sino al tipo de intervención prestada, que depende de la discrecionalidad del facultativo
Objectives: To assess possible variability in the therapeutic approaches provided to patients aged less than 18 years old in community mental health centres (CMHC) in terms of the number of visits and length of treatment. Method: An observational, analytical, prospective, longitudinal study was performed in a clinical cohort of 298 subjects attending the CMHC of Leganés and Fuenlabrada (Madrid) for the first time. Results: The median number of visits per patient was six in Leganés and three in Fuenlabrada (p < 0.001). The mean length of treatment was more than twice as long in Leganés (276 days) than in Fuenlabrada (119 days) (p < 0.001). Stratified analysis showed that the treatments provided in Fuenlabrada involved fewer visits, irrespective of the health professional in charge (psychiatrist or psychologist), the treatment modality prescribed (individual psychotherapy, other psychotherapies or no explicit treatment prescribed), or whether the patient abandoned treatment or the discharge was agreed. Similar results were found for the length of treatment. Conclusions: The different clinical styles illustrate the difficulty of developing useful risk adjustment systems in mental health. The differences in resource consumption and costs cannot easily be attributed to patient-related variables, but are due rather to the intervention provided, which depends on the staff
Subject(s)
Male , Female , Child , Adolescent , Humans , Adolescent Health Services , Community Mental Health Centers , Child Health Services , Office Visits , Prospective Studies , SpainABSTRACT
OBJECTIVES: To assess possible variability in the therapeutic approaches provided to patients aged less than 18 years old in community mental health centres (CMHC) in terms of the number of visits and length of treatment. METHOD: An observational, analytical, prospective, longitudinal study was performed in a clinical cohort of 298 subjects attending the CMHC of Leganés and Fuenlabrada (Madrid) for the first time. RESULTS: The median number of visits per patient was six in Leganés and three in Fuenlabrada (p < 0.001). The mean length of treatment was more than twice as long in Leganés (276 days) than in Fuenlabrada (119 days) (p < 0.001). Stratified analysis showed that the treatments provided in Fuenlabrada involved fewer visits, irrespective of the health professional in charge (psychiatrist or psychologist), the treatment modality prescribed (individual psychotherapy, other psychotherapies or no explicit treatment prescribed), or whether the patient abandoned treatment or the discharge was agreed. Similar results were found for the length of treatment. CONCLUSIONS: The different clinical styles illustrate the difficulty of developing useful risk adjustment systems in mental health. The differences in resource consumption and costs cannot easily be attributed to patient-related variables, but are due rather to the intervention provided, which depends on the staff.
