Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 39
Filtrar
1.
Nature ; 2024 Mar 05.
Artículo en Inglés | MEDLINE | ID: mdl-38443667
3.
Heliyon ; 9(5): e16029, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-37206048

RESUMEN

The present study aims to elaborate a hydrogeological characterisation in the Water Sowing and Harvesting context. The study is focused on rural parishes in the Ecuadorian Andes that, despite their proximity to snow sources (Chimborazo glaciers), need more supply of this resource, to satisfy the demand of a population of 70,466 inhabitants. The study is based on hydrology and geomorphological analysis, a geophysical exploration, and a definition of water management strategies. The application of non-destructive geophysical methods and Geographic Information Systems support the hydrogeological study and the proposal of strategies for sustainable water management on the slopes of the Chimborazo volcano. An aquifer potential was identified (sand, gravel and fractured porphyritic andesites) with resistivity values between 51.3 and 157 Ω m at an approximate depth of 30 m from the geophysical characterisation addressed. This potential saturated zone is on the southern slope of the Chimborazo volcano within the hydrographic watershed, with favourable drainage networks for water accumulation. The aquifer shows a high-water saturation level but uncontrolled losses. As a consequence of these characteristics, alternatives for managing water resources are proposed, such as wells construction, using Water Sowing and Harvesting system methods ("camellones") based on Nature-Based Solutions, dam construction and environmental education. The different proposals are associated with the four sustainability axes of Brundtland (economic, social, environmental and cultural axis) and contribute to the sixth objective of the Sustainable Development Goal 2030 Agenda.

4.
Sci Total Environ ; 881: 163372, 2023 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-37054791

RESUMEN

Peru is the eighth largest producer of cacao beans globally, but high cadmium contents are constraining access to international markets which have set upper thresholds for permitted concentrations in chocolate and derivatives. Preliminary data have suggested that high cadmium concentrations in cacao beans are restricted to specific regions in the country, but to date no reliable maps exist of expected cadmium concentrations in soils and cacao beans. Drawing on >2000 representative samples of cacao beans and soils we developed multiple national and regional random forest models to develop predictive maps of cadmium in soil and cacao beans across the area suitable for cacao cultivation. Our model projections show that elevated concentrations of cadmium in cacao soils and beans are largely restricted to the northern parts of the country in the departments of Tumbes, Piura, Amazonas and Loreto, as well as some very localized pockets in the central departments of Huánuco and San Martin. Unsurprisingly, soil cadmium was the by far most important predictor of bean cadmium. Aside from the south-eastern to north-western spatial trend of increasing cadmium values in soils and beans, the most important predictors of both variables in nation-wide models were geology, rainfall seasonality, soil pH and rainfall. At regional level, alluvial deposits and mining operations were also associated with higher cadmium levels in cacao beans. Based on our predictive map of cadmium in cacao beans we estimate that while at a national level <20 % of cacao farming households might be impacted by the cadmium regulations, in the most affected department of Piura this could be as high as 89 %.


Asunto(s)
Cacao , Contaminantes del Suelo , Cadmio/análisis , Suelo/química , Perú , Cacao/química , Contaminantes del Suelo/análisis
5.
MethodsX ; 10: 101982, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36593760

RESUMEN

Remotely Piloted Aircrafts (RPAs) are commonly used as a platform for collecting images which can be processed with Structure from Motion-Multi View Stereo (SfM-MVS) to generate 3D models. However, mobile applications for mapping planning are not designed for image acquisition of vertical surfaces, such as quarry walls or large cliffs, leaving the user to a manual flight operation, which does not ensure optimal overlap between images. Here we describe a workflow, based on the Litchi App, for automated RPA missions designed to acquire images of vertical surfaces or structures.•An easy-to-follow 8 steps method to survey vertical surfaces using a Remotely Piloted Aircraft.•It can be applied to outcrops, quarry walls, high cliffs and virtually any other type of vertical surface.•The workflow is flexible and can be adapted to a variety of target configurations and user-defined parameters.

6.
Hist Sci ; 61(3): 383-408, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-35509140

RESUMEN

Spatial and temporal scales are essential components of geological sciences; both are almost always imbricated in complex ways, challenging geoscientific knowledge among nonspecialists and students. The present paper focuses on the efforts made by the French naturalist Simon-Suzanne Nérée Boubée (1806-62) regarding popular education on geology. Though Boubée is poorly known nowadays, he experienced some prestige during his lifetime. He worked as an independent teacher, offering private as well as free public courses. Boubée, as a nineteenth-century science popularizer, repeatedly insisted on his disposition for "spreading science for all." He extensively published books and journals on geology, all aimed at popularizing geological scientific knowledge, considered to be of paramount relevance. This paper analyzes three visual examples extracted from his works: the Tableau Mnémonique des Terrains Primitifs, destiné au géologue voyageur, avec son explication (1831), the Tableau de l'État du Globe à ses différents âges (1832), and the Tableau figuratif de la structure minérale du globe, ou résumé synoptique du Cours de géognosie de M. N. Boubée (1839), supplemented with images from the travel guide Deux Promenades au Mont Doré (1834). Our goal is to understand Boubée's efforts to synthesize information, scaling down geologic time and space into foldable materials that made geological knowledge cognitively and materially accessible to laypeople.


Asunto(s)
Planeta Tierra , Geología , Geología/educación
7.
Evolution (N Y) ; 15(1): 20, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36567680

RESUMEN

Scientist-teacher partnerships are highly beneficial to K-12 STEM education. While much is known about the benefits for teachers in these partnerships, the corresponding benefits for scientists are less well known. With emphasis on the scientists' perspective, here we describe our NSF RET (Research Experiences for Teachers) project consisting of five successive cohorts from 2012 to 2016. Coincident with a "once-in-a-century" expansion of the Panama Canal, the science research focused on the paleontology, evolutionary biology, and geology of this region to better understand the ancient Neotropical biota related to the Great American Biotic Interchange (GABI). In the field, scientists and teachers worked together collecting fossils and geological samples. Back in the K-12 classrooms, lesson plans related to their experiences were implemented and the teachers hosted scientist role-model visits. More than 30 scientists and 44 teachers participated in this Panama "GABI RET" project. Using a new validated survey developed during this project and focus groups, we explored the impact of this project, and in particular the perceived benefits accrued by the scientists. Our study confirmed that scientists felt they improved their communication skills, had a better appreciation for the K-12 teaching professions, greatly enjoyed working with the teachers, considered them colleagues, and many wanted to continue K-12 outreach as part of their careers. Overall, scientists perceived that they greatly benefited from these partnerships. In addition to describing their activities, they had numerous recommendations for similar partnerships in the future. For example, these include: (1) having more teachers participate in multiple cohorts, (2) continued opportunities for teachers to be involved in professional meetings, (3) ongoing webinars and face-to-face engagement, and (4) more diversity of racial and ethnic backgrounds, subjects taught, and regions represented. Although this case study was focused on the GABI RET, our results also potentially inform other projects that involve scientists' education and outreach activities. Supplementary Information: The online version contains supplementary material available at 10.1186/s12052-022-00177-z.

8.
J Forensic Sci ; 67(5): 2020-2031, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35821593

RESUMEN

Soils have distinctive chemical, physical, mineralogical and biological properties, which make it possible to differentiate them in different environments and also to test for an association of a particular questioned item with a crime scene. Mineral compositions and structures in the soil clay fraction can reflect a distinct characteristic when analyzed by powerful techniques. In this way, the aim of this study was to compare the discriminative power of Fe-oxides concentrated clay samples from the same soil class with and without differences in parent material when analyzed using the Rietveld method and two sources of X-ray diffraction: conventional and high-resolution synchrotron radiations. Clay samples were Fe concentrated (kaolinite and gibbsite removal) to clarify mineralogical composition of 12 samples from three simulated crime scenes, developed under claystone and granite. By Rietveld refinement, detailed crystallographic data were obtained to discriminate samples according their provenance. By synchrotron radiation, mineral data demonstrated the power of quantitative (crystallite size and minerals contents) and qualitative (identification of majoritarian and accessory minerals) analysis by Rietveld refinement, which provides well-resolved data able to discriminate samples from different and same geology. The techniques can be applied in other criminal investigations given their potential of discrimination.


Asunto(s)
Óxidos , Sincrotrones , Arcilla , Análisis de los Mínimos Cuadrados , Minerales/análisis , Óxidos/análisis , Suelo/química , Difracción de Rayos X
9.
F1000Res ; 11: 1239, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-37614309

RESUMEN

The Chalan ravine is a deep bed creek that runs through Licto (Ecuador). It has been known since the 19th century for the abundance of paleontological remains of Pleiostocene fauna and megafauna in its profiles, where entire remains of mastodons were recovered. The abundance of these remains made one of the high areas, where marmites exist in different forms, was traditionally considered as mastodon footprints. Archaeological prospecting, geographic information system (GIS) technology, unmanned aerial vehicle (UAV), photogrammetry, and the geological study of the place, allowed us to determine that the mythical traces of mastodon were marmites made by the water erosion produced in the same ravine over time.


Asunto(s)
Mastodontes , Animales , Ecuador , Ambiente , Tecnología , Agua
10.
Forensic Sci Int ; 330: 111109, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34839156

RESUMEN

In this study, we present a correlation between δ18OC values of carbonate in tooth enamel samples from the modern Brazilian population and the available δ18ODW data for the meteoric water from the Global Network of Isotopes in Precipitation (GNIP). Tooth enamel from 119 Brazilian individuals from five different regions of the country were analyzed. The δ18OC isoscape obtained is in good agreement with the isoscape based on regional meteoric and drinking water. The regression matrix obtained for the δ18O values of the carbonate tooth enamel and meteoric water was used to build an isoscape using the regression-kriging approach. Our data show that Brazil can be divided in two main regions with respect to the δ18O values of the carbonate tooth enamel: (1) the most easterly part of the northeast region, which is characterized by a warm and dry climate and (2) the remainder of the country, stretching from the Amazon rain forest to the more southernly regions. The data herein reported can be used for forensic purposes related to human identification.


Asunto(s)
Carbonatos , Esmalte Dental , Agua Potable , Brasil , Esmalte Dental/química , Odontología Forense , Humanos , Isótopos de Oxígeno/análisis
11.
Rev. bioét. (Impr.) ; 29(4): 734-742, out.-dez. 2021.
Artículo en Portugués | LILACS | ID: biblio-1365506

RESUMEN

Resumo O artigo discute os conceitos de Antropoceno e de Gaia, apontados por Bruno Latour como categorias para entender o regime climático que estamos vivendo e servir de base teórica para buscar respostas apropriadas para a crise do clima. Os conceitos buscam superar dois pressupostos da racionalidade moderna: a oposição entre natureza e cultura - questionando o princípio de que os humanos são os únicos atores da realidade e introduzindo todos os seres vivos como agentes conformadores do ambiente - e a visão globalizante do planeta Terra, que impede de ver a terra como solo localizado onde acontecem os ciclos biogeoquímicos de transformação da energia que possibilitam a vida. Conclui-se que a reflexão de Latour fornece bases ontológicas para a discussão sobre a mudança climática e pressupostos para a bioética ambiental.


Abstract This article discusses the concepts of Anthropocene and Gaia, raised by Bruno Latour, as categories to understand the climate regime we are experiencing and serve as a theoretical basis to seek appropriate responses to the climate crisis. These concepts seek to overcome two assumptions of modern rationality: the opposition between nature and culture - questioning the principle that humans are the only actors in reality and introducing all living beings as agents shaping the environment - and the globalizing vision of planet Earth that prevents us from seeing it as localized soil where biogeochemical cycles of energy transformation that make life possible take place. It is concluded that Latour's reflection provides ontological bases for the discussion on climate change and assumptions for environmental bioethics.


Resumen Este artículo discute los conceptos de Antropoceno y Gaia, señalados por Bruno Latour como categorías para entender el régimen climático que estamos viviendo y para servir de base teórica para buscar respuestas adecuadas a la crisis climática. Los conceptos buscan superar dos supuestos de la racionalidad moderna: la oposición entre naturaleza y cultura -cuestionando el principio de que los humanos son los únicos actores de la realidad e introduciendo a todos los seres vivos como agentes conformadores del medio ambiente- y la visión globalizante del planeta Tierra, que impide ver la tierra como un suelo localizado en el que tienen lugar los ciclos biogeoquímicos de transformación de la energía que hacen posible la vida. Se concluye que la reflexión de Latour proporciona bases ontológicas para la discusión sobre el cambio climático y supuestos para la bioética ambiental.


Asunto(s)
Cambio Climático , Bioética , Ecosistema , Ecología , Biosfera , Geología
12.
Sci Total Environ ; 800: 149514, 2021 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-34391151

RESUMEN

In this research, emphasis is placed on the information and diagnostic phase of the physical environment for land-use planning (LUP). Our work is mainly focused on a land-planning case study of a tectonic depression, the Tulum Valley, which extends into the Pampean flat-slab segment. We propose the use of tectonic structures to define Environment Units (EUs) as necessary boundaries for the LUP. For this purpose, we have studied tectonic structures using geophysical methods and, subsequently, subjected multiple dimensions of the physical environment in the territory to an exhaustive analysis. Moreover, we have examined the influence of structural geology on water, soils, processes, materials and forms in the landscape. The study revealed the close and significant relationship between the different elements of the physical environment observable on the surface (shape, distribution, appearance, degree of development) and the tectonic structures, which supported the use of this criterion to define EUs. In order to test it, we applied the same methodology in another area of South America, the city of Bucaramanga, where it was possible to define EUs based on tectonics and to also establish comparisons. The methodology proposed for the diagnostic phase based mainly on the tectonic factor represents a challenge as regards its application in other active tectonic zones. Some limitations could arise such as fragmented environmental information from different institutions or the small to non-existent number of tectonic studies available. As a strong point, we find that the method allows achieving a comprehensive study of the environmental setting and thus to propose activities and land uses in each EU according to the real reception capacity of the land. This exhaustive analysis of the physical environment will also help decision-makers to understand and manage the socio-natural risks of the territory where communities develop.


Asunto(s)
Ambiente , Geología , Ciudades , América del Sur
14.
E-Cienc. inf ; 11(1)jun. 2021.
Artículo en Español | LILACS, SaludCR | ID: biblio-1384749

RESUMEN

RESUMEN El objetivo de la investigación fue describir la producción científica de la Facultad de Geología y Minas del Instituto Superior Minero Metalúrgico de Moa (Cuba), en revistas científicas durante el período 2003-2015. El estudio se desarrolló a través de una estrategia de investigación que combina técnicas exploratorias de búsqueda de información y análisis cuantitativos, mediante el análisis documental y la estadística descriptiva. En este sentido, se analizó la producción científica por años, departamentos docentes, autores y en revistas. Se consultó un total de 224 publicaciones, de ellas 80 en revistas científicas, a partir de la identificación de los focos temáticos de investigación, la información contenida en los curriculum vitae y la consulta a las bases de datos. Los resultados muestran la evolución e impacto de la producción científica en los doce años del período en estudio. Se concluye que, a pesar de que el número de publicaciones registradas en revistas científicas es pequeño, existe una correspondencia entre la producción científica y las líneas de investigación establecidas por la institución. Estos resultados son un reflejo de los intereses y áreas activas de esta Facultad, por lo que los resultados pueden constituir un indicador de su evolución en la institución.


Abstract The purpose of the research was to describe the scientific production of the Geology and Mining School of the Higher Institute of Mining and Metallurgy of Moa (Cuba), in scientific journals during 2003-2015 period. The study is developed by means of a research strategy that combines exploratory techniques of information search and quantitative analyses, through the documentary analysis and descriptive statistics. In this sense analyzed the scientific production for years, teaching departments, authors, and journals. A total of 224 publications were surveyed, of those 80 in scientific journals, through of the identification of the thematic focuses of research, the information given in the curriculum vitae and the databases queries. The results show the evolution and impact of the scientific production in the twelve years of the period under study. It concluded that, despite the number of registered publications in scientific journals is small, there is a matching between the scientific production and the established lines of investigation by the institution. These results reflect the interests and active areas of this Faculty, so the results can be an indicator of his evolution in the institution.


Asunto(s)
Publicaciones Periódicas como Asunto , Universidades , Bibliometría , Actividades Científicas y Tecnológicas , Geología/educación , Cuba , Minería/educación
15.
Heliyon ; 6(11): e05320, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-33225085

RESUMEN

This study presents a correct time and depth correlations with enhanced velocity analysis, based on two reservoir horizons mapped across two wells (Osl-1 and Osl-2). It involves the use of high-resolution images to delineate the complex geological structures associated with Reservoir A-horizon (R-Ah) and Reservoir B-horizon (R-Bh) based on 3-D seismic sections and wireline logs. It focuses on showcasing magnified images of the well to seismic tie (W-ST), to enhance appropriate times and depths posting to aid correct determination of the pay thicknesses (Pt), drainage areas (Ad) and the mapping of other probable areas within the hydrocarbon field. The idea is to magnify the points of interested at very close intervals (≤2 feet) to enable the mapping of the actual positions and times of events within the reservoirs. The aim is to enhance better results and confidence in the interpretation, as such, reduce the uncertainty regarding hydrocarbon viability and volume estimation. R-Ah is tracking below 9550 feet and 2.460 s in Osl-1. It is below 9510 feet at 2.450 s in Osl-2. Similarly, R-Bh is tracking below 10550 feet at 2.655 s in Osl-1 and below 10520 feet at 2.650 s in Osl-2. R-Ah is about 70 feet (21.34 m) thick across Ols-1 and Osl-2 while R-Bh is 70 feet (21.34 m) thick and 100 feet (30.48 m) in Osl-1 and Osl-2 respectively. In total, Ad is 172 acres (69.6 × 104 m2) for R-Ah and 206 acres (83.4 × 104 m2) for R-Bh while the Pt is 140 feet (42.67 m) for R-Ah and 170 feet (51.82 m) for R-Bh. Possible wellbore positions to aid future developmental activities could be within the south-east, south-west and north-west directions of Osl-1 and Osl-2. The field is viable with regards to hydrocarbon availability, and the use of high-resolution images has aided accurate evaluation of Pt and Ad, hence, increased the confidence in the results of the interpretation.

16.
Expo Health ; 12(4): 555-560, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33210017

RESUMEN

The World Health Organization (WHO) estimates that around ~150 million people in 70 different countries have been consuming water with arsenic levels higher than the recommended limit of 10 µg/L. Here we describe the concentrations of inorganic arsenic in drinking water in homes of pregnant women living in the province of Tacna, near the southern border of Peru. 161 pregnant women were enrolled in their second trimester of pregnancy. A total of 100mL drinking water was collected in each household from the source of most common use. Inorganic arsenic was categorized into 3 levels with a commercial kit. Thirty percent of women had drinking water ≤10 µg/L (the WHO recommended level), 35% had 25 µg/L, and 35% had greater than 50 µg/L. Low arsenic levels were found in the southernmost homes, supplied by groundwater, while high levels were found in the northern and metropolitan homes supplied by river water.

17.
J Forensic Sci ; 65(6): 1921-1934, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-32579744

RESUMEN

Soil trace evidence can be useful in criminal investigations. A homicide which had occurred in South Brazil been concluded through the courts with a guilty conviction. A spade with soil traces adhering to it was seized from the confessed killer's house, it having been established that it had been used to bury parts of the victim's body. In the context of this confession, it provided an opportunity to test a protocol of analysis and verify the potential of discriminate soil sample analysis in such case works. This allowed us to test the practice of sequential analysis which had been developed for forensic case works in Brazil, with three sequential extractions: (i) 0.2 mol/L pH 3.0 ammonium oxalate; (ii) dithionite-citrate-bicarbonate; and (iii) 0.5 mol/L NaOH. It was possible to predict the sequence of events related to the homicide by using the sequential extraction technique and to conclude that: (i) the A horizon soil from the burial location of the torso was found to be very similar to the soil samples which had been recovered from the spade, which was able to be established despite there only being a small amount of soil adhering to the spade; (ii) the location where the legs were buried contributed a low amount of soil adhering to the spade. Therefore, it is suggested that, where possible, sequential extractions should be prioritized from a questioned sample to best provide information about the likely sequence of contact places and this test likely scenarios and criminal events.

18.
Sci Total Environ ; 721: 137787, 2020 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-32179354

RESUMEN

The aim of this work was to perform a groundwater quality monitoring in Uruguay, from the Medical Geology perspective, focusing attention on arsenic levels and its correlations with other relevant inorganic parameters. For this purpose, a total of 46 groundwater samples from private wells, out of the scope of the state-run water utility company, were analyzed. The accuracy of the analytical methods was ensured by using certified reference materials. Arsenic concentration range was 1.72-120.5 µg L-1, half of the samples being above the limit of 10 µg L-1 recommended by WHO for drinking water, with the corresponding risks for human health. Pearson correlations were performed, resulting in strong positive correlations for the pairs As/Cl-, As/F-, As/Na and As/V. These relationships between arsenic and other inorganic parameters in groundwater should be deeply studied, to prevent long-term health effects.

19.
Heliyon ; 6(3): e03584, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-32215328

RESUMEN

The morphological evolution of the basins in the Sierra Madre del Sur (SMS), southern México is poorly understood. This work explains for the first time the geomorphological development of the tectonic, fluvially-interconnected SMS basins named San Juan Raya (SJRb) and Zapotitlán (ZAPb). The evolution of the SJRb and ZAPb are analysed within the context of the transformations of the well-studied Tehuacán basin (TEHb). A new interpretation of a series of tectonic features of the TEHb valley area is also presented. Published geological data and extensive field work provided the basis for our geomorphological and evolutionary interpretation of basin evolution of this part of Mesoamerica during the late Cenozoic. Stratigraphic and sedimentary records suggest that after the late Cretaceous-early Cenozoic orogeny the TEHb and ZAPb were closed basins, and that the TEHb graben system was activated during the Paleogene as a response to the dominant regional NW-SE trending faults. We propose that the ZAPb and SJRb formed sequentially during the Neogene as a result of new E-W, N-S and NE-SW faults. The continuation of the TEHb extension during the Oligocene widened its lowland area and allowed the formation of an extensive lake. No alluvial or fluvial records of this interval are found in the ZAPb and SJRb. No sedimentation rather than formation and subsequent erosion of such sediments is supported by the basin morphology and by the absence of re-worked alluvial deposits at the outlet area where both connect to the TEHb. By middle to late Miocene the TEHb lost its endorheic configuration, ending the lake-type deposition while new faults initiated the opening of the ZAPb. Intensive tectonics, alluvial deposition and the confinement of the Tehuacán lake to the north sector of this basin characterised the Pliocene. During the late Pliocene to the early Pleistocene the formation of the SJRb was initiated. Quaternary faulting related to basin extension along the north watershed of the SJRb and ZAPb is supported by independent data on the biogeography of the cactus Mammillaria pectinifera. We introduce the idea that the departure from the regional NW-SE fault alignment that formed the major Miocene basins to a more local E-W trend that formed Neogene-Quaternary basins was probably a response to the latest post-orogenic relaxation of the crust in the Mixteca terrane.

20.
Sci Total Environ ; 695: 133673, 2019 Dec 10.
Artículo en Inglés | MEDLINE | ID: mdl-31425994

RESUMEN

Occurrences of high arsenic (As) in sediments and groundwaters were investigated in the Claromecó fluvial basin, southern Pampean plain, Argentina. This investigation includes sedimentology, mineralogy, and hydrogeochemistry of the Neogene and Quaternary aquifers to determine possible sources and transport mechanisms for As in the Claromecó basin. Characterization of the sediments revealed homogeneous mineralogy in both Neogene highlands and Quaternary floodplains with abundant plagioclase, volcanic glass shards (VGS), K-feldspar, quartz, clay minerals and minor concentrations of clinopyroxenes, orthopyroxenes, hornblende, epidote, Fe-(oxy)hydroxides and fluorapatite. The sedimentary As concentrations ranged between 2.8 and 31 mg kg-1 in both aquifers. The average total dissolved As (dissolved AsT) concentrations was 47.2 ±â€¯30.8 µg L-1 (15.3-110 µg L-1) in groundwater in Neogene aquifer (GW1), while it was 97.1 ±â€¯30.6 µg L-1 (45-144 µg L-1) in Quaternary floodplain aquifer (GW2), with all samples exceeding WHO's guideline for dissolved AsT in safe drinking water of 10 µg L-1. Some GW1 (33%) and all GW2 samples contained high levels of fluoride (F-) ranging from 0.6 to 2.6 mg L-1 (1.37 ±â€¯0.59 mg L-1) in GW1 and 2 to 5 mg L-1 (3.2 ±â€¯0.9 mg L-1) in GW2 which also exceeded WHO's guideline for F- in safe drinking water of 1.5 mg L-1. Elevated concentrations of Na+, Cl- and SO42- in the Quaternary flood plain groundwater (GW2) could indicated some degree of sea water mixing as well as some contribution from inland processes (e.g. high evapotranspiration rates, long residence time and soil-water interactions). Dissolution of As bearing VGS or Fe-(oxy)hydroxides, alkaline desorption or competitive desorption with HCO3- from Fe-(oxy)hydroxides appear to be dominating processes of As mobilization, while desorption from fluorapatite elevate dissolved F- levels. This study provides valuable insights on As mobilization processes in Neogene and near coast Quaternary floodplain aquifer.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA