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The Doñana Protected Area, Western Europe's largest protected wetland and UNESCO World Heritage Site, is of great importance for the Spanish biodiversity. Despite its ecological value, there is a noticeable scarcity of scientific and technical information about its hydrology and expected climate change effects, as highlighted by several authors. This article reviews the existing research on the Guadalquivir River and Doñana National Park, examining the interplay between hydrodynamics, climate change scenarios, and the potential impact of the removal of the current dike which was built to limit tidal flooding. In this context, the hydrodynamic changes predicted by a hydrodynamic model were examined under both present (including the current mean sea level and the presence of the dike) and predicted future conditions (encompassing a mean sea level rise of 0.84 m and the removal of the dike). These hydrodynamic changes were assessed in terms of the maximum predicted water levels, mean velocity, amplitude, and phase of M2 and M4 tidal constituents, tidal asymmetry, and tidal prims. The results reveal that the removal of the dike and a sea level rise will have a significant impact on the protected area, resulting in the complete flooding of the Doñana national marshes during spring tides. Such changes could have negative impacts, as increased environmental alterations would require more demanding adaptation measures. [ABSTRACT FROM AUTHOR]

Coastal municipalities and industries often discharge poorly treated wastewater into proximate marine and estuarine environments. The urban and/or effluent input can lead to eutrophication and lower water quality, as it holds high concentrations of nutrients and pollutants. One widely applied tool to increase effluent dispersion and direct it away from coastal areas, thus causing fewer impacts on human activities, is sea outfall. In Aveiro, Portugal, the São Jacinto sea outfall construction was completed in 1998; however, limited literature regarding the sea outfall's monitoring using satellite data is available. The methodology in this study involved collecting four years' worth (2016–2019) of satellite data to investigate visible traces of the interaction between the S. Jacinto sewage water mass and the Ria de Aveiro lagoon ecosystem using ocean color and spectral analysis, and producing new qualitative data regarding sea outfall plume dispersion monitoring through high-resolution Sentinel-2 imagery. The results showed a clear spectral signature of the sewage water mass, and a seasonal pattern was observed in which the plume was more evident in winter and autumn. Additionally, the coastal longshore current and the Aveiro lagoon's runoff were able to restrict the marine outfall's dispersion superficially. Ocean color data were revealed to be a factual and cost-effective tool to monitor the plume water. Finally, an exchange between the marine outfall water mass and Ria de Aveiro lagoon could happen in high tide under northern wind conditions. Therefore, it is important to monitor the water quality to ensure the coastal ecosystem's good environmental state. [ABSTRACT FROM AUTHOR]

The interaction between tide, river runoff, and wind in coastal lagoons induces complex salinity gradients, which are remarkable when the meteorological forcing is exacerbated. This work aims to characterize the salinity structure under extreme freshwater and wind events in the Ria de Aveiro coastal lagoon (Portugal). The Delft3D model was implemented and validated in 3D mode and used to perform simulations forced with extreme freshwater and wind scenarios. Results show that forcing conditions determine salinity stratification intensity and location. Generally, stratification increases as the freshwater increases, while the salinity intrusion moves downstream. Extreme wind tends to destroy stratification but fails to promote full-depth mixing, which is also dependent on the wind direction, as shown for the Espinheiro channel. The salinity intrusion is also impacted by wind events, being NW storms responsible for an upstream salt transport along the Mira channel and a downstream transport along the Espinheiro channel, and SW storms for an upstream displacement of the salinity intrusion along the São Jacinto channel. Finally, it is observed that the advection of a freshwater plume from the Vouga River into the middle of the São Jacinto channel under high freshwater scenarios causes an unusual local salinity pattern. This plume can either be pushed upstream or prevented from entering the channel, depending on the wind direction. [ABSTRACT FROM AUTHOR]

A large number of estuarine systems provide favorable conditions for aquaculture, including high nutrient content, sheltered waters, and favorable water temperatures. In this context, the main objective of this work is to identify the most suitable areas within the Ria de Alvor for bivalve and fish aquaculture production considering present and future conditions in a climate change context. A suitability index was developed based on the results of an annual simulation with the Delft3D model and the thresholds and optimal values of development of each species were analyzed. Generally, results suggest that the most suitable areas for aquaculture were located along the axis of the lagoon's main channel, although seasonal variability was presented depending on the species. During winter and autumn, bivalves (oysters and mussels) are more susceptible to environmental conditions than fish. Conversely, spring presents the most favorable environmental conditions for the production of all species considered. Future projections indicate a general decrease in aquaculture suitability, particularly during winter for both bivalve species and during summer for Mussels, mostly due to the predicted increase in water temperature. [ABSTRACT FROM AUTHOR]

In recent decades, several studies have highlighted the importance of the temporal and spatial structure of upwelling in defining the high levels of productivity of coastal upwelling systems. This work intends to assess the temporal and spatial trends of upwelling along the west and south Portuguese coasts from 1979 to 2020, comparing the patterns between these regions. Two different methodologies to calculate the upwelling indexes (UI), based on wind and sea surface temperature (SST) data, were applied to relate the wind-induced upwelling-favourable conditions (UIET) with the expected response on superficial waters, as indicated by the SST patterns (UISST). The upwelling-favourable conditions are quite consistent and more frequent and intense on the west coast than on the south coast. Spatially, it was verified from the UIET that upwelling-favourable conditions are more intense in association with the main west coast capes and that there is an intensification of favourable winds towards Cape São Vicente, both on the west and south coasts. Seasonally, upwelling-favourable UIET was found to be more consistent in the summer on both coasts. However, it also exists in the winter months. In terms of interannual variations, it should be highlighted that between 1992 and 2005 more intense favourable conditions and an apparent change in the seasonality after 2015 were found. Although some of the results derived from the UIET are corroborated by the UISST (namely, the main spatial trends and interannual variations in the upwelling intensity), several uncertainties are associated with the last index that interfere with its interpretation. For future works, it is advisable to develop a more robust SST-based index that can circumvent the uncertainties pointed out in the present study. [ABSTRACT FROM AUTHOR]

During the winter of 2013, the Tagus estuary was under the influence of intense winds and extreme freshwater discharge that changed its hydrodynamics and, consequently, the salt and heat transport. Moreover, the dynamics of the estuary may change due to climate change which will increase the frequency of heat waves and increase the mean sea level. Therefore, it is of utmost importance to study the impact of the future increase in air temperature and mean sea level under extreme events, such as that in the winter of 2013, to ascertain the foreseen changes in water properties transport within the estuary and near coastal zone. Several scenarios were developed and explored, using the Delft3D model suite, considering the results of the CMIP6 report as forcing conditions. Before the event, the mixing region of the estuary presented well-mixed conditions and its marine area a slight stratification. During the event, the estuary was filled with freshwater and the mixing region migrated toward the coast, leading to lower water temperature values inside the estuary. SLR has a higher impact on the salinity and stratification patterns than the air temperature increase. The response of water temperature is directly related to the increase in air temperature. The estuary mouth and the shallow regions will be more prone to changes than the upstream region of the estuary. The projected changes are directly linked to the future CO2 emissions scenarios, being intensive with the highest emission scenario. [ABSTRACT FROM AUTHOR]

Tanning wastewater was subjected to different unit operations to select the best treatment sequences. Textile membrane filtration (TMF), microfiltration (MF), and ultrafiltration (UF) were complemented by screening, flocculation or flotation operations. The general chemical characterization determined that the wastewater had a high organic load. The ecotoxicological study classified the wastewater as highly ecotoxic. The sequence of screening-TMF-UF was found to be the optimal treatment for wastewaters of the first and second soaking stages, while the sequence of screening-TMF-flotation-UF proved to be adequate for the liming wastewater concerning productivity and water quality. Larger pore sizes MF membrane or higher molecular weight cut off (MWCO) OF membranes with higher permeability to pure water showed lower permeation fluxes for tanning wastewater. After membrane treatments, a decrease in the ecotoxicity was measured. The use of membrane treatment technology showed to be promising in removing organic pollutants and allowing the reuse of water and chemicals in the process. Key words: chemicals recovery, ecotoxicity, leather industry, microfiltration, ultrafiltration, water recycling. Les eaux residuelles de l'industrie de tannerie ont ete soumises a differentes operations de facon choisir les meilleures sequences de traitement possibles. La filtration par des membranes textiles, la microfiltration et l'ultrafiltration ont ete complementees par des operations de tamisage, de floculation ou de flottation. La caracterisation chimique generale a montre un effluent avec une charge organique elevee. Aussi, la caracterisation ecotoxicologique autorise une classification hautement ecotoxique. Du point de vue du traitement, la sequence tamisage/ filtration par membranes textiles/ultrafiltration s'est averee etre le traitement optimal pour les eaux residuelles des premiers et seconds stages de trempage, tandis que la sequence tamisage/filtration par membranes textiles/flottation/ ultrafiltration a ete la plus adequate pour l'eau residuelle de chaulage en raison de la productivite et la qualite de l'eau. Pour ces eaux residuelles de tannerie, les plus basses valeurs des fluxs de permeabilite ont ete obtenues avec des membranes de microfiltration de large porosite ou des membranes d'ultrafiltration avec un seuil de coupure superieur, lesquelles presentent une permeabilite elevee pour l'eau pure. Apres les traitements par membranes des eaux residuelles, on a mesure une diminution de l'ecotoxicite. L'utilisation de la technologie de traitement par membranes pour le retrait des polluants organiques s'est revelee interessante en permettant la reutilisation de l'eau et des produits chimiques dans le processus. Mots-cles: recuperation de produits chimiques, ecotoxicite, industrie du cuir, microfiltration, ultrafiltration, recyclage de l'eau., Introduction The tanning industry that converts animal skins into leather is highly demanding in terms of water and chemical usage and produces wastewaters that need a complex decontamination process before [...]

The mode of action for nanoparticle (NP) toxicity in aquatic organisms is not yet fully understood. In this work, a strategy other than toxicity testing was applied to Daphnia magna exposed to TiO2-NPs: the use of nuclear microscopy and the assessment of protein profile. D. magna is a keystone species broadly used as a model system in ecotoxicology. Titanium (Ti) was found in the D. magna digestive tract, mainly in the gut. The penetration of Ti into the epithelial region was greater at higher exposure levels and also observed in eggs in the brood pouch. The protein profile of individuals exposed to different concentrations showed that 2.8 and 5.6 mg/L TiO2-NP concentrations induced an over-expression of the majority of proteins, in particular proteins with molecular weight of ∼120, 85 and 15 kDa, while 11.2 mg/L TiO2-NP had an inhibitory effect on protein expression. The Matrix-assisted laser desorption ionization with tandem time of flight mass spectrometry (MALDI-TOF/TOF MS) analysis of these proteins consistently identified them as vitellogenin (Vtg)-like proteins, associated with enzymes involved in redox balance. These results indicate that Vtg-like proteins are up-regulated in D. magna exposed to TiO2-NPs. Vitellogenesis is associated with the reproduction system, suggesting that TiO2-NP exposure can impair reproduction by affecting this process. The precise mode of action of TiO2-NPs is still unclear and the results from this study are a first attempt to identify specific proteins as potential markers of TiO2-NP toxicity in D. magna, providing useful information for future research. [ABSTRACT FROM AUTHOR]

Abstract: Although rising global sea levels will affect the estuarine flooded areas over the coming decades, the local and regional-scale processes will also induce important changes in these coastal systems. The main aim of this work is to investigate possible tidal changes in estuarine systems induced by local geomorphologic modifications, analysing the particular case of Ria de Aveiro which is in risk of inundation. Located in the Portuguese west coast, this tidally driven lagoon has a large area of mostly abandoned salt pans, which are in progressive degradation caused by the lack of maintenance and by the strong currents which erode their protective walls. To explore possible tidal changes the hydrodynamic model ELCIRC was applied to Ria de Aveiro to simulate and analyse the impact in the lagoon hydrodynamics of this degradation which results in the enlargement of the lagoon flooded area. A high-resolution grid (grid spacing of the order of 1m) was developed in order to represent the narrow channels adjacent to the salt pans. The hydrodynamic model was then successfully calibrated and assessed for skill for the Aveiro lagoon through comparison between measurements and model results and quantification of the numerical accuracy. The model was subsequently used to investigate the effect of the flooded lagoon area enlargement on tidal propagation in Ria de Aveiro. Simulations were performed for three geomorphologic configurations, representing the reference or present situation and two flooded scenarios. Results were compared through the analysis of tidal currents, tidal asymmetry and tidal prism. The increase of the lagoon flooded area results in an intensification of the tidal currents, tidal prism and tidal asymmetry. Results also indicate that the tidal prism further increases when the flooding depth increases. Otherwise, changes in tidal currents and in tidal asymmetry pattern are negligible with the increase of the flooded area depth. These results indicate that modifications of the flooded area of estuarine systems will result in tidal changes, with an intensification of the actual tidal patterns induced by the enlargement of inundation areas. [Copyright &y& Elsevier]

A global evaluation of wastewaters should include ecotoxicological tests to complement the chemical characterization, with advantages especially in the case of complex wastewaters. A European project developed in Trancão River Basin (Portugal), integrated the ecotoxicological and physicochemical studies of wastewater samples from two municipal sewer networks and respective wastewater treatment plants. Wastewater samples were analysed for physicochemical parameters, ecotoxicological acute and chronic tests performed and the potential for endocrine disruption evaluated. Organic load parameters and total suspended solids showed significant correlations with Microtox and ThamnoToxKit test results. Data analysis showed that treated treatment plant effluent samples are associated with less organic contamination and less toxicity in ThamnoToxKit test. Chronic toxicity test and endocrine disruption assay of treatment plant effluent samples indicated that, in a long term, potential population effects could arise in the receiving waters. A test battery to monitor this type of wastewaters is proposed, including tests with a bacterium, an alga and a crustacean. In a screening phase the most sensitive test, Microtox, can be used. The use of an ecotoxicological approach can have added value to hazard and risk assessment of discharges to the receiving waters and can contribute to the environmental management of the treatment plant. [Copyright &y& Elsevier]

The article discusses findings of an integrated ecotoxicological, physical and chemical study of wastewaters from different industrial sectors in the Trancão River Basin in Lisbon, Portugal. The results of the study will be used to propose a test battery that will be used in wastewater evaluation. Examples of test batteries proposed in the study include the Microtox test, Daphnia test and an algal test. The use of Whole Effluent Assessment (WEA) tests is being supported by the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR Convention), to be applied to the entire effluent sample instead of the individual substances.

The fresh water crustacean Daphnia magna is widely used as a test organism in aquatic toxicology to assess the adverse effects of individual substances or complex mixtures, e.g. industrial wastewaters. Cultures are held in several European testing laboratories and testing is typically carried out according to internationally standardised protocols. However, despite accounting for many potential confounding factors these guidelines do not currently take into account any specification related to the use of a specific clone. Cultures from seven laboratories were used to assess genetic variability by random-amplified polymorphic DNA polymerase chain reaction. Results pointed out the existence of two main clone clusters Responses in the acute Daphnia immobilisation test showed no direct correlation with genetic clusters resulting from random genetic markers (random-amplified polymorphic DNA) analysis. Considering that genetic differences are the most probable cause for the ecotoxicological test data, further analysis concerning gene expression and genetic stability should be performed. [Copyright &y& Elsevier]

Shallow coastal lagoons driven by tidal processes are extremely dynamic environments prone to continuous natural and anthropogenic pressures. The hydrodynamics of these systems deeply depends on the effect of local morphology on the tidal propagation, so their permanent evolution constantly changes tidal dependent processes. For this reason, the present work aims to review the main characteristics of Ria de Aveiro hydrodynamics, a shallow lagoon located at the Atlantic Coast of Portugal, evaluating its evolution over the last 30 years (between 1987 and 2020) and investigating the main morphological changes in its origin. For this purpose, a comparative analysis is performed to determine the main process, including the observed hydrodynamic changes: Deepening of the inlet channel or of the main lagoon channels. To achieve these goals, the authors explored a remarkable database including bathymetric, tide gauge, and salinity data from 1987 until the present. This analysis is completed by the exploitation of a hydrodynamical model (Delft3D), validated against field data. Several simulations were performed to analyse changes in tidal propagation along the lagoon channels (considering the main semi-diurnal constituent M2), tidal asymmetry, tidal currents, tidal prism, and salinity patterns. The results show that the general deepening of the lagoon observed between 1987 and 2020 led to important changes in the lagoon hydrodynamics, namely the increase/decrease of the M2 constituent amplitude/phase, as well as the increase of tidal currents and salt intrusion within the entire lagoon, with the changes being amplified towards the head of the main channels. Although the inlet deepening partially contributed to the modifications found, the results revealed that the deepening of the main lagoon channels had the most significant contribution to the changes observed during the last 30 years. [ABSTRACT FROM AUTHOR]

Estuarine systems currently face increasing pressure due to population growth, rapid economic development, and the effect of climate change, which threatens the deterioration of their water quality. This study uses an open-source model of high transferability (Delft3D), to investigate the physics and water quality dynamics, spatial variability, and interrelation of two estuarine systems of the Portuguese west coast: Mondego Estuary and Óbidos Lagoon. In this context, the Delft3D was successfully implemented and validated for both systems through model-observation comparisons and further explored using realistically forced and process-oriented experiments. Model results show (1) high accuracy to predict the local hydrodynamics and fair accuracy to predict the transport and water quality of both systems; (2) the importance of the local geomorphology and estuary dimensions in the tidal propagation and asymmetry; (3) Mondego Estuary (except for the south arm) has a higher water volume exchange with the adjacent ocean when compared to Óbidos Lagoon, resulting from the highest fluvial discharge that contributes to a better water renewal; (4) the dissolved oxygen (DO) varies with water temperature and salinity differently for both systems. On the one hand, for Mondego Estuary during winter the DO levels mainly fluctuate with salinity. On the other hand, for Óbidos Lagoon, DO distribution is determined by both water temperature and salinity. During summer, the high residence time and water temperature limit the DO levels in both systems. The high transferability and superior stability of Delft3D make this model a foundation for realistic simulation and research of distinct estuarine systems, giving support to their maintenance and restoration. [ABSTRACT FROM AUTHOR]