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

En prensa3,498

Significance of interactions between microplastics and POPs in the marine environment: a critical overview

The presence of plastic debris in the ocean is increasing and several effects in the marine environment have been reported. A great number of studies have demonstrated that microplastics (MPs) adsorb organic compounds concentrating them several orders of magnitude than the levels found in their surrounding environment, therefore they could be potential vectors of these contaminants to biota. However, a consensus on MPs as vectors of persistent organic pollutants (POPs) has not been reached since are opposing views among different researchers on this topic. However, all agree that more extensive studies are needed to clarify this relationship. This review reunites information reporting the factors that drive the sorption dynamics between MPs and POPs, which essentially corresponds to polymer properties and surrounding environmental variables. Furthermore, this review highlights several supporting and rebuttal arguments in the direction to clear up the real hazard enforced by the presence of MPs in marine environments.publishe

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

Interaction of mercury with beached plastics with special attention to zonation, degradation status and polymer type

To study the interaction of mercury (Hg) with plastics in coastal marine environments, a total of 353 plastic items were collected from 4 beaches located on the Spanish Mediterranean coast, with different characteristics. Concentrations ranged from 5 to 8216 nmol kg−1 and were greater on beaches more influenced by the mining activity. A preference of Hg for polymers such as polyurethane (PUR) and poly(vinyl chloride) (PVC), and for certain colours such as black, red and brown was observed. The state of degradation proved crucial, as Hg levels increased with the aging of the plastic. Although new commercial plastic items already contain Hg associated with their manufacturing process, they are able to adsorb even more once in the marine environment, by being in contact with larger quantities of this element in the ocean microlayer and acting as vectors of this element to the beaches. Once there, plastics are transported by winds and tides to the middle and high part of the beach, where the sunlight results in the volatilization of Hg to the atmosphere, decreasing the levels of this element in plastics.publishe

Platinum in salt marsh sediments: Behavior and plant uptake

En prensa2,751

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

En prensa3,258

Prevalence of tide-induced transport over other metal sources in a geologically enriched temperate estuarine zone (NW Iberian Peninsula)

10 páginas, 5 tablas, 4 figurasTide-induced transport, diffuse fluxes and river inputs of arsenic, cobalt, chromium, manganese and nickel were studied in an estuarine zone located at the Ria of Ortigueira in the Galician coast of NW Spain to evaluate comparatively the magnitude of trace-element inputs in the estuarine ecosystem. Short-sediment cores and flooding water were collected at the intertidal area of La-Caleira Inlet in spring and summer 2008 during the first 50 min of tidal inundation. High concentrations of dissolved chromium (up to 23 nM) and nickel (256 nM) were found in waters of the Lourido River during 2008. Chromium (up to 795 mg·kg− 1) and nickel (up to 533 mg·kg− 1) in surface sediments of the study area were also high, pointing to natural geological sources (Cape Ortegal Complex). Fluxes associated with molecular diffusion and tide-induced transport across the sediment–water interface were quantified and compared to the river contribution. Mean fluxes from the Lourido River were 0.03 μmol·m− 2·d− 1 for As, 0.02 μmol·m− 2·d− 1 for Co, 0.43 μmol·m− 2·d− 1 for Cr, 0.72 μmol·m− 2·d− 1 for Mn and 5.98 μmol·m− 2·d− 1 for Ni. Diffusive fluxes were negative which indicates the flow of trace elements towards the sediment − 0.47 ± 0.12 μmol·m− 2·d− 1 for As; − 0.007 ± 0.001 μmol·m− 2·d− 1 for Co; − 0.003 ± 0.009 μmol·m− 2·d− 1 for Cr; − 5.44 ± 1.65 μmol·m− 2·d− 1 for Mn; and − 0.02 ± 0.05 μmol·m− 2·d− 1 for Ni. Tide-induced transport of trace metals was up to four orders of magnitude greater than diffusive fluxes. The contributions of trace elements to the estuarine zone from fluvial and benthic origin were quantified, emphasizing the importance of tide-induced transport in estuarine systemsDr Ospina-Alvarez gratefully acknowledges support by a post-doctoral grant from the AXA Research Fund. The CSIC, under the program JAE-Doc (Junta para la Ampliación de Estudios) co-funded by the Fondo SocialEuropeo(FSE), is greatly acknowledged for the post-doctoral contractto Dr. Santos-Echeandía and pre-doctoral contract to Dr. Ospina-Alvarez. This article is a contribution to the Spanish LOICZ program and was supported by CICYT under the INTERESANTE project (ref.CTM2007-62546-C03/MAR) and the Spanish–Portuguese Action (ref. 2007PT0021) both in cooperation with the project‘ Land–sea exchange of trace metals and its importance for marine phytoplankton in an up- welling coast’(ref. CTM2011-28792-C02)financed by the‘Ministerio de Economía y Competitividad’ of Spain. The authors are also grateful to two anonymous referees for their comments and suggestions, which greatly improved the quality of this paperPeer reviewe

Comparative assessment of microplastics and microalgae as vectors of mercury and chlorpyrifos in the copepod Acartia tonsa

Microplastics (MPs) raise concerns not only as pollutants themselves, but also due to their ability to act as vectors of pollutants adsorbed from seawater, transferring them to marine organisms. However, the relevance of MPs as carriers of pollutants compared to microalgae needs further exploration. This study compared the role of MPs (2–10 μm non-oxidized and 10–15 μm oxidized high-density polyethylene) and natural organic particles (Rhodomonas lens microalgae, MA) as carriers of mercury (Hg, 2.3 μg Hg/L) and chlorpyrifos (CPF, 1.0 μg CPF/L) to adult Acartia tonsa copepods, after 24–48 h exposure. Dose-response experiments were first performed with adult female copepods exposed to oxidized MPs (0.25–4.0 mg/L), waterborne Hg (0.01–10.0 μg/L) and Ox MPs + Hg (0.25–4.0 mg oxidized MPs/L + 0.50–8.0 μg Hg/L) for 48 h, to complement previous studies that focused on the pesticide CPF. Effects were evaluated with four replicates for physiological and reproductive responses (6 females/replicate), biochemical techniques (40 individuals/replicate) and Hg/CPF bioaccumulation measurements (1000 individuals/replicate). Copepods accumulated Hg/CPF similarly from dissolved pollutants (6204 ± 2265 ng Hg/g and 1251 ± 646 ng CPF/g) and loaded MPs (3125 ± 1389 ng Hg/g and 1156 ± 266 ng CPF/g), but significantly less from loaded MA (21 ± 8 ng Hg/g and 173 ± 80 ng CPF/g). After 24–48 h, copepods exposed to MPs + Hg/CPF showed generally greater biological effects than those exposed to dissolved Hg/CPF or to MA + Hg/CPF, although differences were not statistically significant. MA + CPF had significantly lower AChE inhibition (1073.4 nmol min−1 mg−1) and MA + Hg lower GRx induction (48.8 nmol min−1 mg−1) compared to MPs + Hg/CPF and dissolved Hg/CPF (182.8–236.4 nmol min−1 mg−1 of AChE and 74.1–101.7 nmol min−1 mg−1 of GRx). Principal component analysis suggested different modes of action for Hg and CPF.Xunta de GaliciaAgencia Estatal de InvestigaciónUniversidade de Vigo/CISU