PHYTOEXTRACTION OF CADMIUM BY ATRIPLEX HALIMUS

The possibility of remediating contaminated soils through the use of high biomass-generating, native plant species capable of removing heavy metals is receiving increased attention. The capacity of accumulation cadmium (Cd) of Atriplex halimus was tested by growing transplanted specie in a pine bark compost substrate (pH 5.6) contaminated with 100 mg Cd kg-1. After 70 days, the increase in biomass in the plant enhanced the phytoextraction of Cd. The leaf Cd concentration reached 35 mg Cd kg-1. The normal growth shown by this specie in the presence of high concentration of Cd and under conditions of high temperature and acidic pH, suggests that this specie may be used to generate a green cover on soils contaminated by metals and may contribute to their remediation

Movilidad de metales pesados en sustratos de restos de poda y bisólidos: ensayos de fitoextracción con "Rosmarinus officinalis" y "Atriplex halimus"

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Agrícola, Geología y Geoquímica. Fecha de lectura: 14-12-200

Fitoacumulacion de arsénico en plantas terrestres del desierto de Chile

El objetivo de este trabajo fue mostrar la capacidad de 4 especies de plantas terrestres: Atriplex atacamensis, Atriplex halimus, Lupinus microcarpus y Tessaria absinthioides para acumular arsénico en suelos agrícolas de la Región de Antofagasta, Chile, para ser utilizadas en fitorremediación y/o revegetación para la recuperación de suelos contaminados, así como también mostrar los efectos del arsénico en las especies L. microcarpus, A. halimus y A. atacamensis a través de bioindicadores de estrés. Los resultados indican que A. atacamensis y A. halimus resisten la contaminación por arsénico, acumulando el metaloide principalmente en las raíces, pero no en el caso de L. microcarpus. Síntomas visuales de toxicidad por arsénico, tales como clorosis y necrosis en las hojas, hojas arrugadas y decrecimiento, fueron observados en la especie L. microcarpus

COVID-19 attributed mortality and ambient temperature: a global ecological study using a two-stage regression model.

A negative correlation between ambient temperature and COVID-19 mortality has been observed. However, the World Meteorological Organization (WMO) has reinforced the importance of government interventions and warned countries against relaxing control measures due to warmer temperatures. Further understanding of this relationship is needed to help plan vaccination campaigns opportunely. Using a two-stage regression model, we conducted cross-sectional and longitudinal analyses to evaluate the association between monthly ambient temperature lagged by one month with the COVID-19 number of deaths and the probability of high-level of COVID-19 mortality in 150 countries during time t = 60, 90, and 120 days since the onset. First, we computed a log-linear regression to predict the pre-COVID-19 respiratory disease mortality to homogenize the baseline disease burden within countries. Second, we employed negative binomial and logistic regressions to analyze the linkage between the ambient temperature and our outcomes, adjusting by pre-COVID-19 respiratory disease mortality rate, among other factors. The increase of one Celsius degree in ambient temperature decreases the incidence of COVID-19 deaths (IRR = 0.93; SE: 0.026, p-value<0.001) and the probability of high-level COVID-19 mortality (OR = 0.96; SE: 0.019; p-value<0.001) over time. High-income countries from the northern hemisphere had lower temperatures and were most affected by pre-COVID respiratory disease mortality and COVID-19 mortality. This study provides a global perspective corroborating the negative association between COVID-19 mortality and ambient temperature. Our longitudinal findings support the statement made by the WMO. Effective, opportune, and sustained reaction from countries can help capitalize on higher temperatures' protective role including the timely rollout of vaccination campaigns

Rice grain cadmium concentrations in the global supply-chain

One 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 Africa

Social and space border moving and practices between Arica and Tacna. From the sense of frontier to transfrontericidad between cities

The study of human mobility between border cities strains notions of border and calls into question ideas that have long been used in migration studies. Border social practices show that the transborder nature of two cities (Arica and Tacna) are mainly the result of their inhabitants' desire to take advantage of the act of crossing, which leads to various types of mobilities. The disparities and asymmetries of the cities and strong sense of border that exists there do not prevent people from crossing daily, weekly or monthly to work or sell goods in Arica or decrease the cost of living, seek medical care or enjoy cuisine and recreational activities in Tacna. As such, mobility at the border and socio-spatial practices as well as space-time continuity form the basis of the constitution of Arica and Tacna as Transborder Urban Complexes.El estudio de la movilidad entre ciudades fronterizas tensiona las nociones de frontera y discute las ideas que por largo tiempo se han utilizado en los estudios migratorios. Así las prácticas sociales fronterizas demuestran que la transfrontericidad de dos ciudades (Arica y Tacna) están dadas fundamentalmente por el afán de los habitantes de uno y otro lado de aprovechar las ventajas del cruce, dando lugar a distintos tipos de movilidades. Las disparidades y asimetrías entre ciudades y el notorio sentido de frontera no impide que las personas crucen diaria, semanal o mensualmente para trabajar o comerciar en Arica o abaratar el costo de la vida, visitar al médico o disfrutar de la gastronomía y el ocio en Tacna. De modo que la movilidad en la frontera y las prácticas socioespaciales como continuidad espacio-temporal son la base de la constitución de Arica y Tacna como Complejos Urbanos Transfronterizos

Preliminary use of a fulvic acid, as a strategy to improve water use in saline soils: Preliminary use of a fulvic acid, as a strategy to improve water use in saline soils

An evaluation of a fulvic acid (FA) was made in a Loam soil, by selecting the best dose to achieve salt displacement under a drip emitter. In trial 1, PVC columns were filled with a loam soil and irrigated with a KCl solution of electrical conductivity (EC) of 12.5 dS m-1. Once the soil solution EC reached the value of the KCl solution, FA doses of 0, 2.1, 5.3 and 10.5 kg ha-1 were applied. The bulk electric conductivity and soil chemical properties were evaluated after 6 irrigation cycles. In trial 2, the same soil salinized with the KCl solution was placed in 0.8 m3 containers. Two irrigations treatments were performed: a control and the best FA dose from trial 1. The displacement of the salt bulb created from irrigation with a dropper in the soil profile was characterized. In trial 1, the dose of 5.3 kg ha-1 reached the lowest EC after the third irrigation. In trial 2, the selected dose reduced EC until 3.75 dS m-1 at 0.3 m depth at the third irrigation, saving 246 L of water compared to control. Additionally, the salinity bulbs were more horizontally extended in the FA treatment. Highlights: Application of FA (5.3 kg ha -1) reduced the water use by 50% compared to leaching carried out exclusively with water. The use of Fulvic acid showed to be an alternative to consider in the recovery of saline soils under drip irrigation when irrigation water is scarce. Little or not residual effect was found after the use of Fulvic acid.An evaluation of a fulvic acid (FA) was made in a Loam soil, by selecting the best dose to achieve salt displacement under a drip emitter. In trial 1, PVC columns were filled with a loam soil and irrigated with a KCl solution of electrical conductivity (EC) of 12.5 dS m-1. Once the soil solution EC reached the value of the KCl solution, FA doses of 0, 2.1, 5.3 and 10.5 kg ha-1 were applied. The bulk electric conductivity and soil chemical properties were evaluated after 6 irrigation cycles. In trial 2, the same soil salinized with the KCl solution was placed in 0.8 m3 containers. Two irrigations treatments were performed: a control and the best FA dose from trial 1. The displacement of the salt bulb created from irrigation with a dropper in the soil profile was characterized. In trial 1, the dose of 5.3 kg ha-1 reached the lowest EC after the third irrigation. In trial 2, the selected dose reduced EC until 3.75 dS m-1 at 0.3 m depth at the third irrigation, saving 246 L of water compared to control. Additionally, the salinity bulbs were more horizontally extended in the FA treatment. Highlights: Application of FA (5.3 kg ha -1) reduced the water use by 50% compared to leaching carried out exclusively with water. The use of Fulvic acid showed to be an alternative to consider in the recovery of saline soils under drip irrigation when irrigation water is scarce. Little or not residual effect was found after the use of Fulvic acid

The emergence of a circulatory territory at the Chile-Peru border: study of socio-spatial practices of frontier

Este trabajo corresponde a los resultados de una encuesta aplicada en el paso fronterizo de Chacalluta, ubicado en el límite norte de Chile con Perú. A partir de esta información, datos de la Policía de Investigaciones y fuentes secundarias postulamos que, a pesar del carácter separador de la frontera chileno-peruana, las prácticas socio-espaciales fronterizas de chilenos y peruanos que cruzan y habitan la frontera entre Tacna y Arica producen un “territorio circulatorio” que da lugar a una continuidad transfronteriza a nivel territorial. A partir de los resultados de la encuesta se presentará el perfil de los cruzadores, los motivos, los tipos y formas de cruce, así como la descripción de las movilidades y prácticas socio-espaciales productivas y reproductivas encontradas, con el fin de visualizar el surgimiento del territorio circulatorio producto de las diversidad de movilidades.This article presents the results of a survey conducted at the Chacalluta border crossing on Chile's northern border with Peru. Based on the survey, data collected by the police, and secondary sources, we postulate that although the Chile-Peru border separates the two countries, the socio-spatial border practices of the Chileans and Peruvians who cross and inhabit the border between Tacna and Arica produce a circulatory territory that generates cross-border continuity at the territorial level. Drawing on the survey results, we examine the profiles of these border crossers, their motivations, and the ways that they cross and provide a description of the socio-spatial productive and reproductive practices identified. All of this allows us to visualize the emergence of a circulatory territory as a result of the diversity of mobilities

Net Nitrogen Mineralisation in Maize-Cover Crop Rotations in Mediterranean Central Chile

The main aim of this study was to evaluate the effects of the maize-cover crop rotation (Zm-cc) in the soil net nitrogen mineralisation (NNM) by measuring in situ NNM incubation in the upper soil (0-25 cm) during spring-summer (October-March) and autumn-winter (April-September) seasons and compared with other rotation in Mediterranean Central Chile. The study was carried out at 5 experimental fields (only irrigated in spring-summer period), where four common soil use or maize-based rotations were evaluated: permanent fallow (F-F); maize-fallow (Zm-F); maize-cover crop (Zm-cc); and permanent cover crops (cc-cc). In these fields were carried out NNM in situ determinations in F-F (n = 18), Zm-F (n = 31), Zm-cc (n = 43), and cc-cc (n = 51) combinations (totalise n = 143), which were collected during spring-summer and autumn-winter in different periods between 2011 and 2018. During the spring-summer period, it was found that the NNM was highest in the Zm-cc rotations with a mean value of 36 kg N ha(-1), whereas the lowest NNM values were in F-F soil use with and mean of 6 kg N ha(-1). In contrast, during autumn-winter season, the NNM was highest in the F-F soil use with a mean of 34 kg N ha(-1), while the lowest NNM values were found in Zm-cc rotation with a mean of - 38 kg N ha(-1). During the spring-summer period, the Zm-cc rotation had the highest NNM values because cc increased the soil organic matter (SOM) content for microbial activity, whereas in autumn-winter, the Zm-cc rotation had the lowest NNM values because the cc added fresh SOM that increased N immobilisation process.Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) 1150572 Department of Engineering and Soil (University of Chile

El surgimiento de un territorio circulatorio en la frontera chileno-peruana: estudio de las prácticas socio-espaciales fronterizas

This article presents the results of a survey conducted at the Chacalluta border crossing on Chile's northern border with Peru. Based on the survey, data collected by the police, and secondary sources, we postulate that although the Chile-Peru border separates the two countries, the socio-spatial border practices of the Chileans and Peruvians who cross and inhabit the border between Tacna and Arica produce a circulatory territory that generates cross-border continuity at the territorial level. Drawing on the survey results, we examine the profiles of these border crossers, their motivations, and the ways that they cross and provide a description of the socio-spatial productive and reproductive practices identified. All of this allows us to visualize the emergence of a circulatory territory as a result of the diversity of mobilities.Este trabajo corresponde a los resultados de una encuesta aplicada en el paso fronterizo de Chacalluta, ubicado en el límite norte de Chile con Perú. A partir de esta información, datos de la Policía de Investigaciones y fuentes secundarias postulamos que, a pesar del carácter separador de la frontera chileno-peruana, las prácticas socio-espaciales fronterizas de chilenos y peruanos que cruzan y habitan la frontera entre Tacna y Arica producen un "territorio circulatorio" que da lugar a una continuidad transfronteriza a nivel territorial. A partir de los resultados de la encuesta se presentará el perfil de los cruzadores, los motivos, los tipos y formas de cruce, así como la descripción de las movilidades y prácticas socio-espaciales productivas y reproductivas encontradas, con el fin de visualizar el surgimiento del territorio circulatorio producto de las diversidad de movilidades