The Black Sea is a semi-enclosed basin subject to major anthropogenic pressures, including marine litter and plastic pollution. Due to numerous large rivers draining into the basin and a population settled along the coast, the region could accumulate significant amounts of floating litter over time. Until now, only limited field data were available, and litter quantities and distribution remained unknown. In this study, floating marine macro litter (FMML) was assessed at the regional Black Sea scale for the first time, showing relatively high litter densities across the basin that reached a weighted mean of 81.5 items/km(2). Monitoring data revealed an accumulation of floating items offshore in the eastern part of the basin, resembling on a small scale a "garbage patch', where litter items were trapped, showing elevated densities in comparison to their surrounding areas. Most of these items were made of plastic materials (ca. 96%) and included large numbers of plastic and poly-styrene fragments of small size ranges (2.5-10 cm). Harmonised field data collection through consistent and regular monitoring programmes across the region is essential to establish baselines and thresholds for large scale assessment at international level.

Plastic pollution in the natural environment is causing increasing concern at both the local and global scale. Understanding the dispersion of plastic through the environment is of key importance for the effective implementation of preventive measures and cleanup strategies. Over the past few years, various models have been developed to estimate the transport of plastics in rivers, using limited plastic observations in river systems. However, there is a large discrepancy between the amount of plastic being modelled to leave the river systems, and the amount of plastic that has been found in the seas and oceans. Here, we investigate one of the possible causes of this mismatch by performing an extensive uncertainty analysis of the riverine plastic export estimates. We examine the uncertainty from the homogenisation of observations, model parameter uncertainty, and underlying assumptions in models. To this end, we use the to-date most complete time-series of macro-plastic observations (macroplastics have been found to contain most of the plastic mass transported by rivers), coming from three European rivers. The results show that model structure and parameter uncertainty causes up to four orders of magnitude, while the homogenisation of plastic observations introduces an additional three orders of magnitude uncertainty in the estimates. Additionally, most global models assume that variations in the plastic flux are primarily driven by river discharge. However, we show that correlations between river discharge (and other environmental drivers) and the plastic flux are never above 0.5, and strongly vary between catchments. Overall, we conclude that the yearly plastic load in rivers remains poorly constrained.

This study investigates the effects of environmentally-relevant concentrations of fluoxetine (FLX, commercial name: Prozac) on wound healing. Pollution of water systems with pharmaceutical and personal care products, including antidepressants such as FLX and other selective serotonin reuptake inhibitors, is a growing environmental concern. Environmentally-relevant FLX concentrations are known to impact physiological functions and behaviour of aquatic animals, however, the effects of exposure on humans are currently unknown. Using a combination of human skin biopsies and a human keratinocyte cell line, we show that exposure to environmental FLX promotes wound closure. We show dose-dependent increases in wound closure with FLX concentrations from 125 ng/l. Using several –omics and pharmaceutical approaches, we demonstrate that the mechanisms underlying enhanced wound closure are increased cell proliferation and serotonin signalling. Transcriptomic analysis revealed 350 differentially expressed genes after exposure. Downregulated genes were enriched in pathways related to mitochondrial function and metabolism, while upregulated genes were associated with cell proliferation and tissue morphogenesis. Kinase profiling showed altered phosphorylation of kinases linked to the MAPK pathway. Consistent with this, phosphoproteomic analyses identified 235 differentially phosphorylated proteins after exposure, with enriched GO terms related to cell cycle, division, and protein biosynthesis. Treatment of skin biopsies and keratinocytes with ketanserin, a serotonin receptor antagonist, reversed the increase in wound closure observed upon exposure. These findings collectively show that exposure to environmental FLX promotes wound healing through modulating serotonin signalling, gene expression and protein phosphorylation, leading to enhanced cell proliferation. Our results justify a transition from the study of behavioural effects of environmental FLX in aquatic animals to the investigation of effects of exposure on wound healing in aquatic and terrestrial animals, including direct impacts on human health. | QRB acknowledges a ‘Happy Chemical’ PhD studentship funded by the University of Hull. BGM would also like to express her gratitude to the Spanish Ministry of Science, Innovation and Universities for the FPI predoctoral contract PRE2019–089339 and to the University of Cantabria for the predoctoral mobility grant Erasmus+ nº 2021-1-ES01-KA131-HED-000005117. The York Centre of Excellence in Mass Spectrometry was created thanks to a major capital investment through Science City York, supported by Yorkshire Forward with funds from the Northern Way Initiative, and subsequent support from EPSRC (EP/K039660/1; EP/M028127/1).

The authors regret that this is not a review document, but a Research Paper. The authors would like to apologise for any inconvenience caused.

A crucial factor in the long-term survival of benthic macrophyte communities under light-reduction stress is how they balance carbon metabolism during photosynthesis and respiration. In turn, the dissolved organic carbon (DOC) released by these communities, which can be highly light-dependent, stands as a source of carbon, fuelling marine communities and playing an important role in the ocean carbon sequestration. This is the first study to evaluate light-reduction stress and recovery in the seagrass Zostera noltei and the macroalga Caulerpa prolifera. Light reduction led to a significant decrease in the production of both communities from autotrophic to heterotrophic. Results indicated that most of the DOC released by vegetated coastal communities comes from photosynthetic activity, and that the net DOC fluxes can be greatly affected by shading events. Finally, both communities showed resilience underpinned by high recovery but low resistance capacity, with C. prolifera showing the highest resilience to unfavourable light conditions.

In the coming years, the use of microalgal biomass as agricultural biofertilizers has shown promising results. The use of wastewater as culture medium has resulted in the reduction of production costs, making microalgae-based fertilizers highly attractive for farmers. However, the occurrence of specific pollutants in wastewater, like pathogens, heavy metals and contaminants of emerging concern (CECs), such as pharmaceuticals and personal care products may pose a risk on human health. This study presents an holistic assessment of the production and use of microalgal biomass grown in municipal wastewater as biofertilizer in agriculture. Results showed that pathogens and heavy metals concentrations in the microalgal biomass were below the threshold established by the European regulation for fertilizing products, except for cadmium. Regarding CECs, 25 out of 29 compounds were found in wastewater. However, only three of them (hydrocinnamic acid, caffeine, and bisphenol A) were found in the microalgae biomass used as biofertilizer. Agronomic tests were performed for lettuce growth in greenhouse. Four treatments were studied, comparing the use of microalgae biofertilizer with a conventional mineral fertilizer, and also a combination of both of them. Results suggested that microalgae can help reducing the mineral nitrogen dose, since similar fresh shoot weights were obtained in the plants grown with the different assessed fertilizers. Lettuce samples revealed the presence of cadmium and CECs in all the treatments including both negative and positive controls, which suggests that their presence was not linked to the microalgae biomass. On the whole, this study revealed that wastewater grown microalgae can be used for agricultural purposes reducing mineral N need and guaranteeing health safety of the crops. | This research was supported by the European Commission (FERTILWASTES-EFA307/19) and the Spanish Ministry of Science and Innovation (CYRCLE-PID2020-113866RA-I00). E. Uggetti and R. Díez- Montero would like to thank the Spanish Ministry of Industry and Economy for their research grants [RYC2018-025514-I and ICJ2019- 042069-I, respectively]. A. Álvarez-González kindly acknowledge the Departament de Recerca i Universitats de la Generalitat de Catalunya for her PhD scholarship (FI AGAUR, 2022FI_B 00488). E. Gonzalez-Flo would like to thank the European Union-NextGenerationEU, Ministryof Universities and Recovery, Transformation and Resilience Plan for her research grant (2021UPF-MS-12). M. Escolà Casas wants to thank the Beatriu de Pinós 2018 grant-programme (MSCA grant agreement number 801370) for the funding.

Numerical models point to the south-east Bay of Biscay as a convergence area for floating particles, including plastics. The few existing studies on plastic abundance in the area mainly focus on open waters and yet information on the coastal area is limited. To fill this gap, neustonic samples were taken along the coastal waters of the south-east Bay of Biscay (2017-2020) to define the spatial distribution of plastic abundances and composition. Results show an average plastic abundance of 739,395 +/- 2,625,271 items/km(2) (998 +/- 4338 g/km(2)). French waters were more affected, with five times higher plastic abundances than Spanish coasts. Microplastics represented 93 % of the total abundance of plastic items (28 % in weight), mesoplastics 7 % (26 %) and macroplastics 1 % (46 %). This study demonstrates that this area is a hotspot for plastic with levels in coastal waters similar to those in the Mediterranean Sea or other litter aggregation areas.

Surfactants, after use, enter the environment through diffuse and point sources such as irrigation with treated and non-treated waste water and urban and industrial wastewater discharges. For the group of non-ionic synthetic surfactant alcohol ethoxylates (AEOs), most of the available information is restricted to the levels and fate in aquatic systems, whereas current knowledge of their behavior in soils is very limited. Here we characterize the behavior of different homologs (C12-C18) and ethoxymers (E03, E06, and E08) of the AEOs through batch experiments and under unsaturated flow conditions during infiltration experiments. Experiments used two different agricultural soils from a region irrigated with reclaimed water (Guadalete River basin, SW Spain). In parallel, water flow and chemical transport were modelled using the HYDRUS-1D software package, calibrated using the infiltration experimental data. Estimates of water flow and reactive transport of all surfactants were in good agreement between infiltration experiments and simulations. The sorption process followed a Freundlich isotherm for most of the target compounds. A systematic comparison between sorption data obtained from batch and infiltration experiments revealed that the sorption coefficient (K-d) was generally lower in infiltration experiments, performed under environmental flow conditions, than in batch experiments in the absence of flow, whereas the exponent (beta) did not show significant differences. For the low clay and organic carbon content of the soils used, no clear dependence of K-d on them was observed. Our work thus highlights the need to use reactive transport parameterization inferred under realistic conditions to assess the risk associated with alcohol ethoxylates in subsurface environments. (C) 2020 The Authors. Published by Elsevier Ltd.

This paper presents a novel method to select the optimal combination of grid resolution and number of Lagrangian elements (LEs) required in numerical modelling of oil concentrations at sea. A sensitivity analysis in terms of grid resolution and the number of LEs, was carried out to understand the uncertainty that these userdependent parameters introduce in the numerical results. A dataset of 211,200 simulations performed under 400 metocean patterns, 6 initial volumes, 11 grid resolutions, and different numbers of LEs (100 to 500,000), was used to analyze the sensitivity of the model along different Thresholds of Concern. Results show the importance of a correct selection of the number of LEs and the grid resolution in Lagrangian modelling of surface oil concentrations. The method proposed will allow selecting the optimal combination of these parameters to find an optimal balance between the accuracy and the computational cost of the simulation. | This work was partly carried out in the framework of the project PID2020-117267RB-I00 (COIL) funded by MCIN/AEI/10.13039/501100011033// and the project PDC2021-120892-I00 (BLOWHAZARD) funded by MCIN/AEI/10.13039/501100011033 and by European Union Next GenerationEU/PRTR.

This study compares the role of salinity regime and chemical pollution in the biodiversity patterns of estuarine benthic communities. A specific field survey allowed us to explain the response of organisms to mixtures of chemicals and the effects of salinity regime and extreme events on the richness and composition of macroinvertebrate assemblages. The patterns obtained provide further evidence that both stress sources are key factors in macroinvertebrate communities' organization, but the type and magnitude of the changes differ. The abundance of opportunistic species increased according to the pollution gradient, while this indicator was less sensitive to salinity descriptors. In contrast, biotic indices responded to the salinity regime but did not show a consistent pattern in response to pollutants. Multivariate analyses reflected both environmental stress gradients. Overall, the results suggested that diversity increased in the habitats where the frequency and duration of extreme drought and flood events were low. | This research was part of the PREVEMAR project (BIA2015-67298-R) and ECOTOPO project (RTI2018-096409-B-I00) funded by the Spanish Ministry of Science and Innovation through the National Plan for Scientific Research. The authors want to specially thank the Port Authority of Santander for the information provided.