Global sourcing of low-inorganic arsenic rice grain

Artículo escrito por un elevado número de autores, solo se referencia el que aparece en primer lugar, el nombre del grupo de colaboración, si lo hubiere, y los autores pertenecientes a la UAMArsenic in rice grain is dominated by two species: the carcinogen inorganic arsenic (the sum of arsenate and arsenite) and dimethylarsinic acid (DMA). Rice is the dominant source of inorganic arsenic into the human diet. As such, there is a need to identify sources of low-inorganic arsenic rice globally. Here we surveyed polished (white) rice across representative regions of rice production globally for arsenic speciation. In total 1180 samples were analysed from 29 distinct sampling zones, across 6 continents. For inorganic arsenic the global x~ was 66 μg/kg, and for DMA this figure was 21 μg/kg. DMA was more variable, ranging from < 2 to 690 μg/kg, while inorganic arsenic ranged from < 2 to 399 μg/kg. It was found that inorganic arsenic dominated when grain sum of species was < 100 μg/kg, with DMA dominating at higher concentrations. There was considerable regional variance in grain arsenic speciation, particularly in DMA where temperate production regions had higher concentrations. Inorganic arsenic concentrations were relatively consistent across temperate, subtropical and northern hemisphere tropical regions. It was only in southern hemisphere tropical regions, in the eastern hemisphere that low-grain inorganic arsenic is found, namely East Africa (x~ < 10 μg/kg) and the Southern Indonesian islands (x~ < 20 μg/kg). Southern hemisphere South American rice was universally high in inorganic arsenic, the reason for which needs further exploratio

Soil contamination in nearby natural areas mirrors that in urban greenspaces worldwide

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAMSoil contamination is one of the main threats to ecosystem health and sustainability. Yet little is known about the extent to which soil contaminants differ between urban greenspaces and natural ecosystems. Here we show that urban greenspaces and adjacent natural areas (i.e., natural/semi-natural ecosystems) shared similar levels of multiple soil contaminants (metal(loid)s, pesticides, microplastics, and antibiotic resistance genes) across the globe. We reveal that human influence explained many forms of soil contamination worldwide. Socio-economic factors were integral to explaining the occurrence of soil contaminants worldwide. We further show that increased levels of multiple soil contaminants were linked with changes in microbial traits including genes associated with environmental stress resistance, nutrient cycling, and pathogenesis. Taken together, our work demonstrates that human-driven soil contamination in nearby natural areas mirrors that in urban greenspaces globally, and highlights that soil contaminants have the potential to cause dire consequences for ecosystem sustainability and human wellbein

Plant-based methods for remediating arsenic-polluted mine soils in Spain = Recuperación de suelos mineros contaminados con arsénico mediante fitotecnologías

Tesis doctoral inédita. Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Agrícola. Fecha de lectura: 23-04-201

CO-PrOx over nano-Au/TiO2: Monolithic catalyst performance and empirical kinetic model fitting

In this work, the performance of ceramic monoliths washcoated with Au/TiO2 is studied on CO preferential oxidation (CO-PrOx) reaction in H2-rich environments under a wide range of operating conditions of practical interest. The parameter estimation of a nonlinear kinetic empirical model representing this system is made via genetic algorithms by fitting the model predictions against our laboratory observations. Parameter uncertainty leading to inaccurate predictions is often present when kinetic models with nonlinear rate equations are considered. Here, after the fitting was concluded, a statistical study was conducted to determine the accuracy of the parameter estimation. Activation energies of ca. 30 kJ/mol and 55 kJ/mol were adjusted for CO and H2 oxidations, respectively. The catalyst showed appropriate activity and selectivity values on the CO oxidation on a H2-rich environment. After ca. 45 h on stream the catalyst showed no deactivation. Results show that the model is suitable for reproducing the behavior of the CO-PrOx reactions and it can be used in the design of reactors for hydrogen purification.Peer ReviewedPostprint (author's final draft

The fate of arsenic in soil-plant systems

The final publication is available at Springer via http://dx.doi.org/10.1007/978-1-4614-1463-6_1Arsenic (As) is an element belonging to the group V-A, and it demonstrates characteristics of a metalloid. Because arsenic more easily forms anions, its non-metal properties dominate. When arsenic is in an oxidation state of +5, it acts similar to phosphorus, a fact that has many implications for the way in which it reacts in soil, as well as its potential toxicity in plants. The most common oxidation states of As are -3, 0, +3, and +5. Arsines and metal arsines are those in which As has an oxidation state of -3, and these forms are very unstable under oxidizing conditions. Under aerobic conditions, the oxidation state of As tends to be +5, and when this occurs at a pH between 2 and 3, arsenic acid (H3AsO4) is formed. When the pH rises to values between 3 and 11, this compound disassociates to H2AsO4 - and HAsO4 2- (Smedley and Kinninburgh 2002). Under anaerobic conditions, the predominant As species is H3AsO3This study was supported by the Spanish Ministry of Education and Science, project CTM 2010-21922-CO2-02, and by Comunidad de Madrid, project S2009/AMB- 147

Rice grain cadmium concentrations in the global supply-chain

Artículo escrito por un elevado número de autores, solo se referencia el que aparece en primer lugar, el nombre del grupo de colaboración, si lo hubiere, y los autores pertenecientes a la UAMOne of cadmium’s major exposure routes to humans is through rice consumption. The concentrations of cadmium in the global polished (white), market rice supply-chain were assessed in 2270 samples, purchased from retailers across 32 countries, encompassing 6 continents. It was found on a global basis that East Africa had the lowest cadmium with a median for both Malawi and Tanzania at 4.9 μg/kg, an order of magnitude lower than the highest country, China with a median at 69.3 μg/kg. The Americas were typically low in cadmium, but the Indian sub-continent was universally elevated. In particular certain regions of Bangladesh had high cadmium, that when combined with the high daily consumption rate of rice of that country, leads to high cadmium exposures. Concentrations of cadmium were compared to the European Standard for polished rice of 200 μg/kg and 5% of the global supply-chain exceeded this threshold. For the stricter standard of 40 μg/kg for processed infant foods, for which rice can comprise up to 100% by composition (such as rice porridges, puffed rice cereal and cakes), 25% of rice would not be suitable for making pure rice baby foods. Given that rice is also elevated in inorganic arsenic, the only region of the world where both inorganic arsenic and cadmium were low in grain was East Afric

La alfabetización en Educación Infantil como práctica social en zonas en riesgo de exclusión social

La alfabetización en espacios urbanos en los que concurren situaciones estructurales de pobreza y marginación social requiere de un conocimiento profundo de las prácticas y eventos que tienen lugar en dichos espacios. Esta investigación describe los eventos alfabetizadores y su valor social en los dominios hogar, escuela, barrio y otras comunidades. Se ha desarrollado según un enfoque etnográfico colaborativo con un diseño de estudio de casos múltiples, representados por tres centros de Educación Infantil de la provincia de Sevilla. La recogida de información se ha realizado mediante entrevistas, observación participante, documentos, fotografías y vídeos, y ha concluido con la construcción de mapping. El análisis crítico del discurso y la perspectiva aportada por los Nuevos Estudios de Literacidad (NEL) han servido de referente para el análisis de la información recogida. Los resultados muestran que el desarrollo de la alfabetización puede ser explicado a partir del modo en que se interiorizan los valores sociales de la lectura y la escritura. El valor concedido a la alfabetización en diferentes dominios se convertirá en un factor clave de la escolarización y en un referente del contenido del discurso y de los modos y medios elegidos para comunicarlo.Literacy in urban spaces where there are structural and social risks requires a thorough knowledge of the practices and events that take place in these spaces. The research carried out aims to describe the literacy events and its social value in home domain, school, neighbourhood and other communities. The research has been developed according to a collaborative ethnographic approach with a multiple case study design. The cases are represented by three Pre-school schools of the province of Seville. The collection of information has been done through interviews, participant observation, written documents, photographs, and videos, and has concluded with the construction of mapping. The critical analysis of the discourse and the theoretical perspective provided by the New Literacy Studies (NLS) have been used to analyse the information collected. The results of this study show that the development of literacy can be explained by the way in which each of the children interferes with the social values of reading and writing. The value accorded to literacy at home, in school, in the neighbourhood and in other communities becomes a key factor in their schooling and, in the medium term, in a reference of the content of their discourse and the ways and means chose to communicate it

Evidence of a new Hg-tolerant ecotype of Rumex induratus from Almadén (Ciudad Real, Spain)

This is an Accepted Manuscript of an article published by Taylor & Francis Group in Plant Biosystems on 01/01/2014, available online: http://www.tandfonline.com/10.1080/11263504.2012.758188Mercury tolerance in wild vascular plants has hardly been studied and a tolerant ecotype is not known. In order to confirm the tolerance to Hg of Rumex induratus naturally growing in the biggest Hg mine in the world (Almadén population), the population was compared in a hydroponic experiment with another population from a non-Hg-contaminated area (Colmenar). The plants were exposed to different doses of Hg and a dose of As to establish whether the tolerance to Hg coincides with tolerance to other trace elements. Plants from Colmenar reached up to 1322 μg Hg g-1 in roots and 65 μg Hg g-1 in shoots and showed a significant decrease in biomass due to Hg exposure, whilst Almadén accumulated only 812 μg Hg g-1 and 56 μg Hg g-1 in roots and shoots, respectively. The Almadén population showed a higher tolerance to intense exposure to Hg, but not to As. Plants from Almadén exposed to Hg showed higher capacity to synthesise thiols in the root and to control oxidative stress and Zn starvation. Our findings suggest that R. induratus could be used to enhance understanding of the mechanisms of Hg tolerance in plantsThis study was supported by Spanish Ministry of Education and Science, Project CGL 2009-13171-C03-02 and by Comunidad de Madrid, Project EIADES (S2009 AMB-1474