Interaction of microplastics with metal(oid)s in aquatic environments: What is done so far?

Microplastics (MPs) are being recognized as an emergent route of contaminants to aquatic environments, which initially attracted the research interest on their interactions with organic pollutants. Lately, a turning point of attention is evident, with more published studies reporting the presence of metal(oid)s in plastics. This review assembles the mechanisms occurring on microplastics surfaces that enhance sorption of hazardous elements (i.e., metals and metalloids) over environmental exposure. Reported findings of experimental studies are of major importance to understand the factors controlling the sorption/desorption of metal(oid)s to/from microplastics as much as determination of metal(oid)s in environmental plastics. Existence or formation of oxygen-containing functional groups and complexes from surface coatings strongly allow bond of metal(oid)s on reactive surfaces while sorption dynamics are strongly controlled by water chemistry parameters. Moreover, the present work evidences the potential impacts caused by metal(oid)s-MPs interactions to aquatic organisms, prioritizing the need of environmental realistic parameters to test. Bioaccumulation of metal(oid)s desorbed from ingested MPs prove the significant influence of these plastic particles in the bioavailability of pollutants to aquatic biota. In this way, this is a comprehensive manuscript committed to the estimation of the potential ecological risk of MPs to aquatic environments due to their association with metal(oid)s.Versión del edito

Improvement of the ultra-trace voltammetric determination of Rh in environmental samples using signal transformation

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Tissue distribution of mercury and its relationship with selenium in atlantic bluefin tuna (Thunnus thynnus l.)

Mercury (Hg) is an important heavy metal to consider in marine predators, while selenium (Se) has a natural antagonistic effect on this metal in fish. The Atlantic bluefin tuna (ABFT, Thunnus thynnus) is a pelagic top-level predator of the trophic web and their Hg muscular content is an object of concern in food safety. Nevertheless, little is known about levels of this metal in remaining tissues, which may be important as by-product source, and its relationship with Se. Thus, concentration of both elements in liver, kidney, brain, gill and bone, in addition to muscle, of ABFT were determined. The kidney was the tissue with the highest concentration of Hg (Total-Hg, THg) and Se, and the Se/THg concentration ratio was similar in all tissues, except bone and muscle. The Selenium Health Benefit Value (HBVSe ) was positive in each specimen and tissue, indicating that the Se plays an important role against Hg not only in the muscle. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Preprin

LEAD ACCUMULATION AND SUBCELULAR DISTRIBUTION IN THE SCALLOP AEQUIPECTEN OPERCULARIS

The scallop Aequipecten opercularis accumulates high concentrations of lead (Pb) in its tissues, what has led to the ban of its extraction in the Ría de Vigo (Galicia, Spain) for feeding purposes. The Ría de Vigo presents higher levels of Pb than other industrialized Galician Rías, mainly due to a ceramic factory that was operating in the inner part of the Ría from 1961 to 2001 (Álvarez-Iglesias et al., 2003). This study aims at testing the dynamics of bioaccumulation of Pb in this species, its tissue distribution and the subcellular partitioning Pb, with the aim of enhancing our understanding of the mechanisms that provoke the high Pb levels reached in its tissues. Scallops originating from a clean area were exposed in cages in two places in the Ría de Vigo (one harbour and a less impacted location) and 10 individuals were collected every month over a three months period. The bioaccumulation of Pb and other metals was studied including its distribution in several tissues: gills, digestive gland, kidney, muscle, gonad and rest. The results showed that scallops accumulated similar levels of Pb in both locations, and that about 76% of the Pb was found in the kidney. Subcellular partitioning of kidney samples additionally showed that around a 60-70% of Pb in the kidneys was included in metal rich granules, indicating that this is probably the reason of the high levels of Pb observed in this species, as occurs for other bivalves (Darriba and Sánchez-Marín, 2013). Concerning other metals analysed, it was observed that Zn was also mainly accumulated in the kidney, while Cd content was highest in the digestive gland. Cu and Ni were preferentially accumulated in the digestive gland or kidney, depending on the location, and As was mainly found in the muscle. Results will be discussed on the basis of metal pollution in both locations and according to detoxification strategies used by scallops

Platinum in salt marsh sediments: Behavior and plant uptake

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Microplastic and an associated metal contaminant (Palladium) impair the immune response against pathogenic bacteria of the marine bivalve Mytilus galloprovincialis

Microplastics (MPs) are widely distributed in marine environments and have been reported to cause harmful physiological effects in marine bivalves including immune modulation. While Mytilus galloprovincialis is a model species in environmental monitoring studies, little is known regarding the effects of MPs and palladium (Pd), an emerging contaminant, metal on the immune functioning of this species. In this study, gills and gland samples of specimens of M.ytilus galloprovincialis which were exposed to the same particle concentration (2.5 x 10 66 μm3μm /mL) of Control (microalgae), MP (virgin microplastics) and MP-Pd (Pd spiked microplastics) once an hour during 4 hours. Thus, mussels were exposed to 6095 ng of Pd/mussel. Samples analyzed were collected after 4 and 24 hours of exposure and after 24, 48 and 144 hours of depuration. Several innate immune activities (lysozymes, peroxidase, protease, antiprotease, and bactericidal activities) were analyzed. Our data demonstrated that after 24 hours of exposure to MP, a decrease in lysozymes and peroxidase activities occurred, but not in the bactericidal activity which increased. However, when MP-Pd was used, an increase in all these activities was observed compared to MP levels group. These data suggest that when MP are spiked with Pd, the latter compound might induce an inflammatory process that will results in higher levels of most of all the immune activities analyzed. In the gland, however, most of the activity levels were decreased upon MP-Pd treatment compared to MP levels at different time point of exposure depending on the activity. Interestingly, after 24 hours of removing the pollutants from the water, most of the activity levels in both tissues, gills and gland, were recovered to control levels, but not the bactericidal activity. Considering this impairment of the bactericidal activity against possible pathogenic bacteria, a potential threat to mussels population in a polluted scenario is highly plausible

Use of the Sentinel‐2 and Landsat‐8 Satellites for Water Quality Monitoring: An Early Warning Tool in the Mar Menor Coastal Lagoon

During recent years, several eutrophication processes and subsequent environmental crises have occurred in Mar Menor, the largest hypersaline coastal lagoon in the Western Mediterranean Sea. In this study, the Landsat‐8 and Sentinel‐2 satellites are jointly used to examine the evolution of the main water quality descriptors during the latest ecological crisis in 2021, resulting in an important loss of benthic vegetation and unusual mortality events affecting different aquatic species. Several field campaigns were carried out in March, July, August, and November 2021 to measure water quality variables over 10 control points. The validation of satellite biogeochemical variables against on‐site measurements indicates precise results of the water quality algorithms with median errors of 0.41 mg/m3 and 2.04 FNU for chlorophyll‐a and turbidity, respectively. The satellite preprocessing scheme shows consistent performance for both satellites; therefore, using them in tandem can improve mapping strategies. The findings demonstrate the suitability of the methodology to capture the spatiotemporal distribution of turbidity and chlorophyll‐a concentration at 10– 30 m spatial resolution on a systematic basis and in a cost‐effective way. The multitemporal products allow the identification of the main critical areas close to the mouth of the Albujon watercourse and the beginning of the eutrophication process with chlorophyll‐a concentration above 3 mg/m3. These innovative tools can support decision makers in improving current monitoring strategies as early warning systems for timely assistance during these ecological disasters, thus preventing detrimental conditions in the lagoon.0,64

Evidence of increased anthropogenic emissions of platinum: time-series analysis of mussels (1991-2011) of an urban beach

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CONSEQUENCES OF SINGULAR ENVIRONMENTAL EVENTS ON THE CYCLE OF METALS IN COASTAL LAGOONS AND THEIR INFLUENCE ON THE INCORPORATION OF METALS BY PRIMARY PRODUCERS

Coastal areas are valuable and sensitive environments subjected to great anthropogenic pressure. Among these pressures, metal pollution is of priority concern as these pollutants can reach concentrations that exceed the levels established to protect sensitive organisms in the ecosystem. In coastal lagoons, shallow systems with a reduced exchange with the open sea, metal concentrations are one or two orders of magnitude higher than in open-waters. In addition, these systems are subjected to physicochemical variations that can alter the biogeochemical cycling of the metals. Singular environmental events such as strong winds cause metal resuspension, torrential rain events provoke the entrance of solutes and pollutants, and phytoplankton blooms dramatically increase the concentration of organic matter. These events provoke alterations in the concentration and speciation of metals in the water column. This will have a direct impact in the organisms living in the area, since metal toxicity and bioavailability depends on the chemical speciation. Dissolved organic matter (DOM) is the most important variable influencing metal speciation and bioavailability in seawater. However, the effects of DOM on metal bioavailability have not been yet unravelled and contrasting results have been reported, some showing that DOM protects against metal toxicity and others showing the opposite. The present study was designed to study how the biogeochemical cycling of trace metals in the water column of coastal lagoons is influenced by these singular environmental events and how this affects the incorporation of metals by the primary producers, in this case, microalgae, with particular focus on the effect of dissolved organic matter on metal biouptake. The proposed work combines field sampling and analytical work in the Mar Menor lagoon (SE Spain). This project will substantially contribute to widen our knowledge about the behaviour of metals in coastal areas and to determine how the presence of DOM affects their toxicity

Effect of dissolved organic matter (DOM) of contrasting origins in Cu and Pb speciation and toxicity to Paracentrotus lividus larvae

Original research paperWater samples of contrasting origin, including natural seawater, two sediment elutriates and sewage-influenced seawater, were collected and obtained to examine the effect of the dissolved organic matter(DOM) present on metal bioavailability. The carbon content (DOC) and the optical properties (absorbanceand fluorescence) of the coloured DOM fraction (CDOM) of these materials were determined. Cu and Pbcomplexation properties were measured by anodic stripping voltammetry (ASV) and the effect of DOMon Cu and Pb bioavailability was studied by means of theParacentrotus lividusembryo-larval bioassay.Sediment elutriates and sewage-influenced water (1) were enriched 1.4–1.7 times in DOC; (2) absorbedand reemitted more light; and (3) presented higher Cu complexation capacities (LCu) than the naturalseawater used for their preparation.LCuvaried from 0.08 M in natural seawater to 0.3 and 0.5 Min sediment elutriates and sewage-influenced water, respectively. Differences in DOC, CDOM and Cucomplexation capacities were reflected in Cu toxicity. DOM enriched samples presented a Cu EC50of0.64 M, significantly higher than the Cu EC50of natural and artificial seawater, which was 0.38 M. Theprotecting effect of DOM on Cu toxicity greatly disappeared when the samples were irradiated with highintensity UV-light. Cu toxicity could be successfully predicted considering ASV-labile Cu concentrationsin the samples. Pb complexation by DOM was only detected in the DOM-enriched samples and causedlittle effect on Pb EC50. This effect was contrary for both elutriates: one elutriate reduced Pb toxicity incomparisonwiththecontrolartificialseawater,whiletheotherincreasedit.UVirradiationofthesamplescaused a marked increase in Pb toxicity, which correlated with the remaining DOC concentration. DOMparameterswererelatedtoCuspeciationandtoxicity:goodcorrelationswerefoundbetweenDOCandCuEC50, whileLCucorrelated better with the fluorescence of marine humic substances. The present resultsstress the importance of characterizing not only the amount but also the quality of seawater DOM tobetter predict ecological effects from total metal concentration dataSpanish Ministry of Education and Science (CTM2006-13880-C03-01/MAR), Xunta of Galicia (PGIDIT-05MA40201) and Basque Government (predoctoral grant)Versión del editor3,76