Nanoscale Zero-Valent Iron Has Minimum Toxicological Risk on the Germination and Early Growth of Two Grass Species with Potential for Phytostabilization

Two Poaceae species, Agrostis capillaris and Festuca rubra, were selected for their potential as phytostabilizing plants in multicontaminated soils. These species are resistant to contamination and maintain high concentrations of contaminants at the root level. Nanoscale zero-valent iron (nZVI) is an engineered nanomaterial with the ability to stabilize metal(loid)s in soils; its potential toxicological effects in the selected species were studied in a germination test using: (i) control variant without soil; (ii) soil contaminated with Pb and Zn; and (iii) contaminated soil amended with 1% nZVI, as well as in an hydroponic experiment with the addition of nZVI 0, 25, 50 and 100 mg L−1. nZVI had no negative effects on seed germination or seedling growth, but was associated with an increase in shoot growth and reduction of the elongation inhibition rate (root-dependent) of F. rubra seedlings. However, applications of nZVI in the hydroponic solution had no effects on F. rubra but A. capillaris developed longer roots and more biomass. Increasing nZVI concentrations in the growing solution increased Mg and Fe uptake and reduced the Fe translocation factor. Our results indicate that nZVI has few toxic effects on the studied species

Al-Bustān. Las fincas aristocráticas y la construcción de los paisajes periurbanos de al-Ándalus y Sicilia

Navarro Palazón, Julio, editorLa presente publicación se enmarca en el Proyecto I+D+i «Almunias medievales en el Mediterráneo: Historia y conservación de los paisajes culturales periurbanos» (PID2019-111508GB-I00, dirigido por Julio Navarro Palazón), del Ministerio de Ciencia e Innovación. Agencia Estatal de Investigación. Proyectos de I+D+i, de los Programas Estatales de Generación de Conocimiento y fortalecimiento Científico y Tecnológico del Sistema de I+D+i y de I+D+i Orientada a los Retos de la Sociedad, del Plan Estatal de Investigación Científica y Técnica y de Innovación 2017-2020. Esta obra es también un fruto destacado del trabajo realizado en el marco de la Unidad Asociada de I+D+i Patrimonio Cultural Árabe e Islámico, Consejo Superior de Investigaciones Científicas-Universidad de Granada, a través de la Escuela de Estudios Árabes de Granad

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Adaptación del uso de enmendantes orgánicos en la recuperación de suelos contaminados con metales pesados / Rafael Clemente Carrillo ; dirección Mª Pilar Bernal Calderón y David J.Walker

Tesis-Universidad de Murcia.Consulte la tesis en: BCA. GENERAL. ARCHIVO UNIVERSITARIO. T.M. 2665

Fractionation of heavy metals and distribution of organic carbon in two contaminated soils amended with humic acids

10 pages, 3 figures, 5 tables.The effects of humic acids (HAs) extracted from two different organic materials on the distribution of heavy metals and on organic-C mineralisation in two contaminated soils were studied in incubation experiments. Humic acids isolated from a mature compost (HAC) and a commercial Spaghnum peat (HAP) were added to an acid soil (pH 3.4; 966 mg kg−1 Zn and 9229 mg kg−1 Pb as main contaminants) and to a calcareous soil (pH 7.7; 2602 mg kg−1 Zn and 1572 mg kg−1 Pb as main contaminants) at a rate of 1.1 g organic-C added per 100 g soil. The mineralisation of organic-C was determined by the CO2 released during the experiment. After 2, 8 and 28 weeks of incubation the heavy metals of the soils were fractionated by a sequential extraction procedure. After 28 weeks of incubation, the mineralisation of the organic-C added was rather low in the soils studied (<8% of TOC in the acid soil; <10% of TOC in the calcareous soil). Both humic acids caused significant Zn and Pb immobilisation (increased proportion of the residual fraction, extractable only with aqua regia) in the acid soil, while Cu and Fe were slightly mobilised (increased concentrations extractable with 0.1 M CaCl2 and/or 0.5 M NaOH). In the calcareous soil there were lesser effects, and at the end of the experiment only the fraction mainly related to carbonates (EDTA-extractable) was significantly increased for Zn and decreased for Fe in the humic acids treated samples. However, HA–metal interactions provoked the flocculation of these substances, as suggested by the association of the humic acids with the sand fraction of the soil. These results indicate that humic acid-rich materials can be useful amendments for soil remediation involving stabilisation, although a concomitant slight mobilisation of Zn, Pb and Cu can be provoked in acid soils.This work was financed by the Spanish Ministry of Science and Technology (REN2001-1113-C02-02) and by the Fundación Séneca of the Comunidad Autónoma de Murcia (ref: 00730/CV/99).Peer reviewe

The application of phytoremediation technologies to metal-contaminated soils in Aznalcóllar

El vertido de lodo pirítico procedente de la mina de Aznalcóllar en 1998 afectó a 4286 ha de suelo de los que el 59,7 % eran suelos agrícolas. Los principales elementos responsables de la contaminación fueron As, Cd, Cu, Pb, y Zn, junto con la acidificación de los suelos causada por la oxidación de los sulfuros metálicos. Este caso dramático de contaminación supuso un extraordinario movimiento de la comunidad científica española y extranjera, que permitió poner en práctica técnicas biológicas de recuperación basadas en el uso de plantas (fitorremediación), que permitiera el desarrollo del plan del Corredor Verde del Guadiamar por la Junta de Andalucía. La dificultad del caso estriba en la contaminación múltiple, la escasa estabilidad química de los contaminantes y su carácter acidificante. Este trabajo muestra brevemente algunos trabajos de fitorremediación realizados in situ en parcelas de experimentación. Se ha evaluado la utilidad de diversas técnicas: la fitoextracción mediante mostaza india, una planta agrícola de alta biomasa capaz de acumular los metales en su parte aérea, junto con la mejora de los suelos mediante enmiendas orgánicas y calizas; y la fitoinmovilización mediante el altramuz, que es una leguminosa tolerante a los metales por exclusión en sus raíces y a ciertas condiciones de acidez del suelo.The spill of pyrite sludge from the Aznalcóllar mine in 1998, affected 4286 ha of land, 59.7 % of which was agricultural. The main contaminants were As, Cd, Cu, Pb and Zn, their effects being exacerbated by the soil acidification caused by the oxidation of metallic sulphides. This dramatic case of soil pollution mobilised the Spanish and international scientific communities, with the aim of applying biological techniques for soil remediation based on the use of plants (phytoremediation). These were fundamental in the development of the "Green Corridor of Guadiamar" land recuperation plan by the Andalusian regional government. Difficulties arose from the multi-element contamination, the chemical instability of the contaminants and the acidic nature of the contamination. This article briefly describes some phytoremediation experiments carried out in situ in experimental plots. The feasibility of certain phytoremediation techniques has been evaluated: phytoextraction by Indian mustard, a high-biomass crop able to accumulate metals in its aerial parts, in combination with the improvement of soil properties by the application of organic and calcareous amendments, and phytoimmobilisation using white lupin, a leguminous species tolerant of heavy metals due to their immobilisation in the roots and, to a certain degree, tolerant of soil acidity