Sistemas capilares basados en líquidos iónicos para extracción de metales

La determinación de metales traza como el cobre en aguas naturales, presenta una serie de limitaciones, debido a su baja concentración y al efecto matriz de la muestra. Esto hace que, de forma general, sea necesaria una etapa de preparación de las muestras previa a la determinación instrumental, como la extracción líquido-líquido. Esta técnica presenta inconvenientes debidos a un empleo excesivo de disolventes, bajos factores de preconcentración del analito y excesiva manipulación de las muestras. Una alternativa para mejorar las características de estos sistemas es su miniaturización, para aumentar la preconcentración del metal, y disminuir el exceso de reactivos empleados, en lo que se conoce como microextracción líquida (LPME). Existen diferentes tipos de microextracción líquida, de entre los cuales se eligió y empleó para este trabajo la microextracción en fase líquida con capilares de fibra hueca (HF-LPME). El sistema emplea un soporte polimérico microporoso que separa la muestra y unos pocos microlitros de disolución acuosa receptora. El transporte tiene lugar a través de los poros de la pared, que alberga una disolución orgánica a modo de membrana líquida soportada. A pesar del potencial de la técnica, presenta una serie de limitaciones: montaje complejo, baja estabilidad y prolongados tiempos de ensayo. Sin embargo, existen diferentes alternativas como el uso de la técnica en una configuración de barras de disolvente (SBME) o el uso de nuevos sistemas de reactivos, como los líquidos iónicos, que permiten mejorar su aplicabilidad. Para la preconcentración de cobre se ha utilizado di-2-piridilcetona-benzoíhidrazona (dPKBH) disuelto en octanol, como disolución orgánica o membrana líquida, en un sistema SBME. El objeto de este trabajo es evaluar si la adición del líquido iónico hexafluorofosfato de 1-hexil-3-metilimidazolio ([Hmim][PF6]) a la disolución orgánica favorece el transporte de cobre libre (Cu2+). También se evaluó su aplicabilidad, teniendo en cuenta el efecto de la salinidad y la concentración de materia orgánica en la muestra sobre el transporte de cobre. Finalmente, el líquido iónico no tuvo efecto en el transporte de cobre al incluirlo en la disolución orgánica. Con este sistema se obtiene un factor de enriquecimiento (F.E.) de 79,46 ± 4,98 independientemente de la salinidad de la muestra. La presencia de materia orgánica provocó una disminución del F.E., mostrando una relación lineal que permite estimar la fracción libre de cobre en la muestra, y el cobre total de forma indirecta.The determination of trace metals such as copper in natural waters, presents several limitations because of its low concentration and the sample matrix effect. This means that a preparation step (as liquid-liquid extraction) is required before the instrumental determination of copper in the samples. This technique is disadvantageous due to excessive use of solvents, low analyte preconcentration factors and excessive sample handling. An alternative to improve the characteristics of these systems is their miniaturization, to increase the preconcentration of the analyte and to reduce the excess of reagents. It is known as liquid phase microextraction (LPME). There are different types of liquid phase microextraction. Hollow Fiber Liquid Phase Microextraction (HF-LPME) was selected and employed for this work. The system employs a microporous polymeric support that separates the sample and a few microliters of aqueous receiving solution. Transport occurs through the pores of the fiber‟s wall, containing an organic solution as a supported liquid membrane. Despite of the potential of the technique, it prensents some limitations: complex assembly, low stability and long test times. However, there are different alternatives such as the Solvent Bar Microextraction (SBME) or using new reagent systems, as ionic liquids, which improve its applicability. For copper preconcentration, di-2pyridylketone benzoylhydrazone (dPKBH) dissolved in octanol as organic solution has been used in a solvent bar configuration (SBME). The objective of this project is to evaluate if the addition of 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF6]) in the organic solution will favor the free copper transport (Cu2+). Additionally, it was evaluated the effect of salinity and organic matter concentration on copper transport. Finally, the ionic liquid included in the organic solution showed not effect on the copper transport. With this method an enrichment factor of 79,46 ± 4,98 is obtained regardless of the sample salinity. The presence of organic matter reduced E.F., showing a lineal relation that allowed to estimate the fraction of free copper in the sample, and while total copper was indirectly estimated.El documento presenta una extensión de 33 página

Artisanal trawl fisheries as a sentinel of marine litter pollution

Systematic seafloor surveys are a highly desirable method of marine litter monitoring, but the high costs involved in seafloor sampling are not a trivial handicap. In the present work, we explore the opportunity provided by the artisanal trawling fisheries to obtain systematic data on marine litter in the Gulf of Cadiz between 2019 and 2021. We find that plastic was the most frequent material, with a prevalence of single-use and fishing-related items. Litter densities decreased with increasing distance to shore with a seasonal migration of the main litter hotspots. During pre-lockdown and post-lockdown stages derived from COVID-19, marine litter density decreased by 65 %, likely related to the decline in tourism and outdoor recreational activities. A continuous collaboration of 33 % of the local fleet would imply a removal of hundreds of thousands of items each year. The artisanal trawl fishing sector can play a unique role of monitoring marine litter on the seabe

Author Correction: Floating macrolitter leaked from Europe into the ocean (Nature Sustainability, (2021), 4, 6, (474-483), 10.1038/s41893-021-00722-6)

During the preparation of the Supplementary Data spreadsheet “S. Data 3_Regression data,” the mean and median confidence intervals (CI) of FML (items yr−1) were misplaced in relation to their corresponding river names. The Supplementary Data file has now been updated in the HTML version of the article. This update does not alter the results or conclusions of this article.Correction to: Nature Sustainability https://doi.org/10.1038/s41893-021-00722-6, published online 10 June 2021. During the preparation of the Supplementary Data spreadsheet “S. Data 3_Regression data,” the mean and median confidence intervals (CI) of FML (items yr−1) were misplaced in relation to their corresponding river names. The Supplementary Data file has now been updated in the HTML version of the article. This update does not alter the results or conclusions of this article.Peer reviewe

Floating macrolitter leaked from Europe into the ocean

International audienceRiverine systems act as converging pathways for discarded litter within drainage basins, becoming key elements in gauging the transfer of mismanaged waste into the ocean. However, riverine litter data are scarce and biased towards microplastics, generally lacking information about larger items. Based on the first ever database of riverine floating macrolitter across Europe, we have estimated that between 307 and 925 million litter items are released annually from Europe into the ocean. The plastic fraction represented 82% of the observed litter, mainly fragments and single-use items (that is, bottles, packaging and bags). Our modelled estimates show that a major portion of the total litter loading is routed through small-sized drainage basins (<100 km2), indicating the relevance of small rivers, streams and coastal run-off. Moreover, the major contribution of high-income countries to the macrolitter inputs suggests that reducing ocean pollution cannot be achieved only by improving waste management, but also requires changing consumption habits and behaviour to curb waste generation at source. The inability of countries with well-developed recovery systems to control the leakage of waste into the environment further supports the need to regulate the production and use of plastic on a global scale

An inshore–offshore sorting system revealed from global classification of ocean litter

The surge of research on marine litter is generating important information on its inputs, distribution and impacts, but data on the nature and origin of the litter remain scattered. Here, we harmonize worldwide litter-type inventories across seven major aquatic environments and find that a set of plastic items from take-out food and beverages largely dominates global litter, followed by those resulting from fishing activities. Compositional differences between environments point to a trend for litter to be trapped in nearshore areas so that land-sourced plastic is released to the open ocean, predominantly as small plastic fragments. The world differences in the composition of the nearshore litter sink reflected socioeconomic drivers, with a reduced relative weight of single-use items in high-income countries. Overall, this study helps inform urgently needed actions to manage the production, use and fate of the most polluting human-made items on our planet, but the challenge remains substantial

An inshore–offshore sorting system revealed from global classification of ocean litter

The surge of research on marine litter is generating important information on its inputs, distribution and impacts, but data on the nature and origin of the litter remain scattered. Here, we harmonize worldwide litter-type inventories across seven major aquatic environments and find that a set of plastic items from take-out food and beverages largely dominates global litter, followed by those resulting from fishing activities. Compositional differences between environments point to a trend for litter to be trapped in nearshore areas so that land-sourced plastic is released to the open ocean, predominantly as small plastic fragments. The world differences in the composition of the nearshore litter sink reflected socioeconomic drivers, with a reduced relative weight of single-use items in high-income countries. Overall, this study helps inform urgently needed actions to manage the production, use and fate of the most polluting human-made items on our planet, but the challenge remains substantial