Douro River Estuary Research Articles

Early warning system for floods at estuarine areas: combining artificial intelligence with process-based models

AbstractFloods are among the most common natural disasters, causing countless losses every year worldwide and demanding urgent measures to mitigate their impacts. This study proposes a novel combination of artificial intelligence and process-based models to construct a flood early warning system (FEWS) for estuarine regions. Using streamflow and rainfall data, a deep learning model with long short-term memory layers was used to forecast the river discharge at the fluvial boundary of an estuary. Afterwards, a hydrodynamic process-based model was used to simulate water levels in the estuary. The river discharge predictors were trained using different forecasting windows varying from 3 h to 36 h to assess the relationship between the time window and accuracy. The insertion of attention layers into the network architecture was evaluated to enhance forecasting capacity. The FEWS was implemented in the Douro River Estuary, a densely urbanised flood-prone area in northern Portugal. The results demonstrated that the Douro Estuary FEWS is reliable for discharges up to 5000 m3/s, with predictions made 36 h in advance. For values higher than this, the uncertainties in the model predictions increased; however, they were still capable of detecting flood occurrences.

Assessment of the potential for hydrokinetic energy production in the Douro river estuary under sea level rise scenarios

For being densely populated and urbanized, and for concentrating high-value economic activities, estuarine regions have an increased energy demand, which boosts the claim for new, efficient, renewable, and safe energy production. Among these technologies, hydrokinetic energy conversion systems are potentially well-suited for estuaries. However, in the actual context of climate change, it is important to know how changes in mean sea level may affect hydrokinetic energy production. This work proposes a methodology to assess the hydrokinetic energy potential for future scenarios using numerical hydrodynamic modeling techniques. Applied to the Douro estuary, several scenarios considering present conditions, as well as medium (2050) and long-term (2100) predictions under different Shared Socioeconomic Pathways are proposed. The results revealed that the studied region maintains a high dependence on freshwater discharge until 2100, although tidal oscillation is also significantly perceived in the entire estuary. Overall, hydrokinetic power potential will not increase with the mean sea level rise and will instead be considerably lower. Therefore, a decline in the kinetic energy available for exploitation is expected with increasing CO2 emissions, along with the associated intensification of sea level rise. Results reinforce the need to perform local studies to evaluate future trends in hydrokinetic energy production.

Myxozoan survey of thicklip grey mullet Chelon labrosus reinforces successful radiation of Myxobolus in mugiliform hosts.

A myxozoan survey was performed on specimens of thicklip grey mullet Chelon labrosus (Risso) captured from the Douro River estuary, northern Portugal. Eleven new species, all belonging to the genus Myxobolus Bütschli, 1882 (M. abdominalis n. sp., M. aestuarium n. sp., M. caudalis n. sp., M. chelonari n. sp., M. cucurbitiformis n. sp., M. douroensis n. sp., M. intestinicola n. sp., M. invictus n. sp., M. labicola n. sp., M. peritonaei n. sp., and M. pinnula n. sp.) are described based on microscopic and molecular data, confirming the known high radiation of these myxozoans in mullets. Additionally, Myxobolus pupkoi Gupta et al., 2022 is reported for the first time from C. labrosus, bringing forth a novel case of morphological plasticity between geographic isolates. We consider that molecular-based comparisons are imperative for the description of mugiliform-infecting Myxobolus, with distance estimation further matching two of the novel Myxobolus spp. with sphaeractinomyxon types previously reported from another Portuguese estuary. This finding supports sphaeractinomyxon as specific life cycle counterparts of Myxobolus that infect mullets. Phylogenetic analyses of 18S rDNA retrieved a monophyletic clade of mugiliform-infecting myxobolids comprising well-supported lineages of species parasitizing mullets from the genera Chelon, Mugil, Crenimugil, and Planiliza. The existence of more than one Chelon- and Planiliza-infecting lineage reveals that myxobolids parasitized members of these genera multiple times during their evolution. Lastly, the elevated number of unmatched sphaeractinomyxon sequences included in the Chelon-infecting lineages clearly shows that Myxobolus diversity hosted by this genus remains underrated.

Occurrence and risk assessment of endocrine-disrupting compounds in fish muscle: The case study of the Douro River estuary (North East Atlantic Ocean)

This work was focused on evaluating the occurrence of endocrine-disrupting compounds (EDCs) in fish muscles, such as bisphenol analogues, personal care products, including some UV-filters and musk fragrances, and selected pesticides. A total of 238 muscle samples of three fish species (Platichthys flesus, Mugil cephalus, and Dicentrarchus labrax) of an important estuary ending in the North East Atlantic Ocean (Douro River estuary, Portugal), in different seasons of the year, was analysed. M. cephalus was the species with a greater occurrence of contaminants, mainly in fishes collected during the spring. Bisphenol A was the main bisphenol analogue detected with an average content of 23.1 μg/kg wet weight (w.w.). Among chemicals used in personal care products, galaxolide, tonalide, and 2-ethylhexyl salicylate, were the most often found, being present in 15.9% (2.2–538.4 μg/kg w. w.), 4.6% (1.1–57.8 μg/kg w. w.) and 3.4% (3.9–56.1 μg/kg w. w.) of the samples, respectively. About 14% of the samples contained residues of at least one pesticide, being alachlor, aldrin, p,p’-DDT, permethrin, and prochloraz the main chemicals observed, varying from 0.1 μg/kg w. w. (p,p’-DDT) to 37.8 μg/kg w. w. (prochloraz). The daily intake estimates of the most frequent EDCs found in the fish muscles suggested that there are no health concerns, based on the recommended weekly consumption of fish for adults.

Annual Evaluation of 17 Oestrogenic Endocrine Disruptors and Hazard Indexes in the Douro River Estuary—The Atlantic Discharge of the Highest-Flow River of Southwestern Europe

The concentrations of seventeen endocrine disruptor compounds (EDCs) that included oestrogens, phytoestrogens, sitosterol, and banned industrial pollutants were investigated at ten sites of the Douro River estuary. Surface waters were collected during 2019. After evaluating the physicochemical data (ammonia, nitrates, nitrites and phosphates), the waters were filtrated and submitted to solid-phase extraction (SPE) to extract and pre-concentrate (4000-fold) the EDCs. The extracts were derivatized with BSTFA + 1% TMS and analysed by gas chromatography-mass spectrometry (GC-MS). All EDCs showed a high detection rate (97%, on average), exhibiting ubiquity in this estuary. The finding of biologically relevant amounts of oestrogens (up to 8.5 ng/L for oestradiol, E2), phytoestrogens (up to 827 ng/L for biochanin A, BIO-A) and industrial pollutants (up to 2.7 µg/L for nonylphenol di-ethoxylated, NP2EO) strongly support ongoing risks of endocrine disruption for the local aquatic wildlife. Globally, there was an E2-equivalents (E2-EQs) concentration of 25 ng/L and a hazard index (HI) of 26, which further indicates considerable potential for adverse effects on local biota. Moreover, the physicochemical data suggest direct sewage discharges. Beyond possible toxicological effects on fauna, the detected contaminants may pose risks to humans via direct contact (bathing at local fluvial beaches) or by ingestion (local fish).

Assessment of the Potential for Hydrokinetic Energy Production in the Douro River Estuary Under Sea Level Rise Scenarios

Assessment of the Potential for Hydrokinetic Energy Production in the Douro River Estuary Under Sea Level Rise Scenarios

Gas Chromatography Multiresidue Method for Enantiomeric Fraction Determination of Psychoactive Substances in Effluents and River Surface Waters

Determination of psychoactive substances (PAS) and/or their metabolites in surface waters is crucial for environmental risk assessment, and disclosure of their enantiomeric fractions (EF) allows discrimination between consumption, direct disposal, and synthesis pathways. The aim of this study was to develop and validate an indirect method by gas chromatography coupled to mass spectrometry (GC–MS) based on derivatization using (R)-(−)-α-methoxy-α-(trifluoromethyl) phenylacetyl chloride as chiral derivatization reagent, for enantiomeric quantification of amphetamine (AMP), methamphetamine (MAMP), 3,4-methylenedioxymethamphetamine (MDMA), norketamine, buphedrone (BPD), butylone, 3,4-dimethylmethcathinone (3,4-DMMC), 3-methylmethcathinone, and quantification of 1-benzylpiperazine and 1-(4-metoxyphenyl)-piperazine. The method allowed to evaluate the occurrence, spatial distribution, and the EF of the target chiral PAS in Portuguese surface waters and in effluents from 2 wastewater treatment plants (WWTP). For that, water samples were pre-concentrated by solid phase extraction using OASIS® MCX cartridges, derivatized and further analyzed by GC–MS. Both enantiomers of AMP, (R)-MDMA, (S)-MAMP, and the first eluted enantiomer of BPD (configuration not assigned) were found in surface waters, while effluent samples showed both enantiomers of MDMA, (S)-MAMP, (R)-AMP, and the first eluted enantiomer of BPD and 3,4-DMMC. According to our knowledge, this is the first multiresidue analytical method by CG–MS enrolling cathinones, amphetamines, and piperazines. The presence of illicit synthetic cathinones in Douro River estuary is here reported for the first time, along with other amphetamine derivatives. The potential of the method to monitor consumption of the target PAS was demonstrated.

Assessing contamination from maritime trade and transportation on Iberian waters: Impact on Platichthys flesus

Maritime trade and transportation of hazardous and noxious substances (HNS) have been increasing in European waters, augmenting the risk of accidental spills from ships or in harbours. Despite their reported toxicity and hazardousness, information on HNS levels in the aquatic environment is still lacking. Therefore, an assessment combining a chemical and a multi-biomarker evaluation on HNS contamination was done in NW Iberian estuaries of Rivers Minho, Lima and Douro using Platichthys flesus (flounder). Of the twenty-five HNS measured, fifteen were found in flounder liver and muscle, and a few in sediments, though at generally low levels. Principal component analysis produced a clear distinction among sites, with Douro River estuary arising as the most impacted. Oxidised proteins and antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase) were the biomarkers contributing to site discrimination. Correlations between biomarkers and HNS levels provided important baseline information for the study area and potential biological effects of HNS on this sentinel species.

Dual enantioselective LC–MS/MS method to analyse chiral drugs in surface water: Monitoring in Douro River estuary

This work presents the development of an enantioselective method to quantify chiral drugs (CDs) in surface water and its application in the Douro River estuary monitoring. Different classes of CDs were targeted, including 23 compounds, namely beta-blockers, antidepressants, one beta2-adrenergic agonist, non-steroidal anti-inflammatory drugs, stimulants, and some illicit drugs as cocaine (COC) and its metabolites, and amphetamines. The analytical method was based on an innovative application of solid phase extraction (SPE), followed by liquid chromatography-tandem mass spectrometry (LC–MS/MS) using a triple quadrupole analyzer. The ground-breaking approach of SPE consists in the use of Oasis® MCX cartridges to pre-concentrate 500 mL of water samples, allowing the simultaneous extraction of acidic, basic and neutral analytes, rather than the conventional recovery of basic compounds only. Two chiral columns were used for enantiomeric separation in reverse elution mode, a Chirobiotic™V and a Pirkle type Whelk-O®1, for basic and acidic compounds, respectively. The method validation demonstrated good linearity (r2 > 0.99), selectivity and sensitivity, with method detection limits between 0.01 and 2.66 ng L−1 and method quantification limits between 0.02 and 5.71 ng L−1. The developed method was successfully applied to monitor daily variations along one week in surface waters collected in 5 locations of the Douro River estuary. Tramadol (TRM) and its metabolite N-desmethyltramadol (NDT), presented high concentrations near the affluent of a tributary river, while the second eluted enantiomer of O-desmethyltramadol (ODT) was found at high concentrations at the mouth of the Douro River. The metabolite NDT was quantified at higher concentrations than TRM. Venlafaxine (VNF) was found at high concentrations near the affluent of the same tributary river, but its metabolite, O-desmethylvenlafaxine (ODV), was found at concentrations 3 times higher. COC was found every day at all sampling points along the estuary, with slight variations.

Two Models Solutions for the Douro Estuary: Flood Risk Assessment and Breakwater Effects

Estuarine floods are one of the most harmful and complex extreme events occurring in coastal environments. To predict the associated effects, characterize areas of risk, and promote population safety, numerical modeling is essential. This work performs a comparison and a combination of two 2-dimensional depth-averaged estuarine models (based on openTELEMAC-MASCARET and Delft3D hydrodynamic software packages), to develop a two-model ensemble approach that will improve forecast robustness when compared to a one-model approach. The ensemble was applied to one of the main Portuguese estuaries, the Douro river estuary, to predict the expected water levels associated with extreme river discharges in the present-day configuration with the new breakwaters. This is a region that is periodically under heavy flooding, which entails economic losses and damage to protected landscape areas and hydraulic structures. Both models accurately simulated water levels and currents for tidal- and flood-dominated validation simulations, with correlation values close to 1, RMSE below 15%, and small Bias and Skill coefficient close to 1. The two-model ensemble results revealed that the present-day estuarine mouth configuration will produce harsher effects for the riverine populations in case identical historical river floods take place. This is mainly due to the increase in the area and volume of the estuary’s sand spit related to the construction of the new breakwaters.

Biodegradation of oxytetracycline and enrofloxacin by autochthonous microbial communities from estuarine sediments

This work investigated the potential of microbial communities native to an estuarine environment to biodegrade enrofloxacin (ENR) and oxytetracycline (OXY). Sediments collected from two sites in the Douro river estuary (Porto, Portugal) were used as inocula for the biodegradation experiments. Experiments were carried out for one month, during which ENR and OXY (1 mg L−1) were supplemented individually or in mixture to the cultures at 10-day intervals. Acetate (400 mg L−1) was added to the cultures every 3 days to support microbial growth. A series of experimental controls were established in parallel to determine the influence of abiotic breakdown and adsorption in the removal of the antibiotics. Removal of antibiotics was followed by measuring their concentration in the culture medium. Additionally, next-generation sequencing of the 16S rRNA gene amplicon was employed to understand how microbial communities responded to the presence of the antibiotics. At the end of the biodegradation experiments, microbial cultures derived from the two estuarine sediments were able to remove up to 98% of ENR and over 95% of OXY. The mixture of antibiotics did not affect their removal. ENR was removed mainly by biodegradation, while abiotic mechanisms were found to have a higher influence in the removal of OXY. Both antibiotics adsorbed at different extents to the estuarine sediments used as inocula but exhibited a higher affinity to the sediment with finer texture and higher organic matter content. The presence of ENR and OXY in the culture media influenced the dynamics of the microbial communities, resulting in a lower microbial diversity and richness and in the predominance of bacterial species belonging to the phylum Proteobacteria. Therefore, microbial communities native from estuarine environments have potential to respond to the contamination caused by antibiotics and may be considered for the recovering of impacted environments through bioremediation.

Assessment of Douro and Ave River (Portugal) lower basin water quality focusing on physicochemical and trace element spatiotemporal changes

ABSTRACTWater quality of Douro and Ave lower basin was evaluated regarding physicochemical parameters (pH, conductivity, dissolved oxygen and temperature), nutrient compounds (nitrates, nitrites, ammonium and orthophosphates), chlorophyll a and occurrence of trace elements (Li, Be, Al, Ti, V, Cr, Co, Ni, Cu, Zn, Se, Mo, Ag, Cd, Sb, Ba, Tl, Pb, Th and U). To study spatiotemporal variations and possible anthropogenic sources, estuarine samples were collected at nine sampling sites in Douro and five in Ave distributed along the estuaries at four sampling campaigns (spring, summer, fall and winter). According to the water quality standards for aquatic life and recreation, Douro and Ave river water quality was found out of safe limits regarding several parameters. Nitrate levels were systematically high (> 50 mg L−1 in a significant number of samples) and mean levels of trace elements were higher than the established values of Canadian Environmental Quality Guidelines for aquatic life protection for Al, Cu, Se, Ag, Cd and Pb in Douro and Ave, and also Zn in Ave. Significant spatial differences were found in Ave river estuary for trace elements with a clear trend for higher values from upstream to downstream found. Seasonal differences were also observed particularly in Douro river estuary with higher levels in spring for most elements.

Distribution and environmental assessment of trace elements contamination of water, sediments and flora from Douro River estuary, Portugal

The present study evaluated the content and distribution of several trace elements (Li, Be, Al, V, Cr, Co, Ni, Cu, Zn, Se, Mo, Ag, Cd, Sb, Ba, Tl, Pb, and U) in the Douro River estuary. For that, three matrices were collected (water, sediments and native local flora) to assess the extent of contamination by these elements in this estuarine ecosystem. Results showed their occurrence in estuarine water and sediments, but significant differences were recorded on the concentration levels and pattern of distribution among both matrices and sampling points. Generally, the levels of trace elements were higher in the sediments than in the respective estuarine water. Nonetheless, no correlation among trace elements was determined between water and sediments, except for Cd. Al was the trace element found at highest concentration at both sediments and water followed by Zn. Pollution indices such as geo-accumulation (Igeo), enrichment factor (EF) and contamination factor (CF) were determined to understand the levels and sources of trace elements pollution. Igeo showed strong contamination by anthropogenic activities for Li, Al, V, Cr, Ni, Cu, Zn, Ba and Pb at all sampling points while EF and CF demonstrated severe enrichment and contamination by Se, Sb and Pb. Levels of trace elements were compared to acceptable values for aquatic organisms and Sediment Quality Guidelines. The concentration of some trace elements, namely Al, Pb and Cu, were higher than those considered acceptable, with potential negative impact on local living organisms. Nevertheless, permissible values for all trace elements are still not available, demonstrating that further studies are needed in order to have a complete assessment of environmental risk. Furthermore, the occurrence and possible accumulation of trace elements by local plant species and macroalgae were investigated as well as their potential use as bioindicators of local pollution and for phytoremediation purposes.

PAHs in water and surface sediments from Douro River estuary and Porto Atlantic coast (Portugal)-impacts on human health.

This study investigated the presence of 16 priority polycyclic aromatic compounds (PAHs) in waters from the Douro River estuary and nearby Atlantic seacoast, which both bath the Porto metropolis. In the area, there is an oil refinery, an important harbour, an intense maritime traffic, small marinas and highly inhabited cities. For the analysis of PAHs, water samples were taken from four sampling sites, at six different times of the year (2011), and extracted by solid-phase extraction (dissolved fraction) and by ultrasound technique (suspended fraction), before their quantification by gas chromatography-mass spectrometry. Results not only proved the ubiquitous distribution of all analysed PAHs in the present habitat, but also that their global amounts (∑16PAHs) were extremely high at all sampling sites. Their average concentrations attained ≈55ng/L and ≈52μg/g dry weight (dw), respectively, in water and surface sediments. Accordingly, the surveyed area was classified as highly polluted by these organics and so, in view of the concentrations, mutagenic/carcinogenic responses in both humans and aquatic animals are possible to occur. The percentages of carcinogenic PAHs for humans (group 1) dissolved in water and in surface sediments were ca. 5 and 6%, respectively. These results are the first reported in the area and can be used as a baseline for future control of the PAHs levels locally while serving the building of global scenarios of PAHs pollution in Europe. Graphical abstract Percentage of PAHs, from different categories acordingly to WHO (2016), in both surface sediments and surface waters from Douro River estuary and Porto Atlantic seacoast; group 1 - carcinogenic, group 2A - probably carcinogenic, group 2B - possibly carcinogenic, and group 3 - not classifiable as carcinogenic to humans.

Determination of 54 pesticides in waters of the Iberian Douro River estuary and risk assessment of environmentally relevant mixtures using theoretical approaches and Artemia salina and Daphnia magna bioassays

As a case study, the estuary of the international Douro River (Iberian Peninsula) was sampled over a year (2010) at six sampling sites to determine the presence of 56 pesticides of different categories (insecticides, herbicides, and fungicides). 96% of measured pesticides were detected in 79% of the quantified samples. Individual average pesticide concentrations ranged from 39 to 1 265ng/L, indicating a ubiquitous presence of the selected compounds; moreover, twelve pesticides were above the 2013/39/EU Directive limits. Due to its highly impacted profile, a theoretical hazard assessment was done considering the average and maximum environmental mixtures of all measured pesticides to identify the most sensitive trophic level. For both environmental mixtures, the theoretical approach suggested that invertebrates were the most sensitive group. Therefore, short-time exposure assays using both invertebrates Artemia salina and Daphnia magna, were done using the referred mixtures. Data demonstrated significant toxic effects ─ high mortality rate and abnormal swimming behaviour ─ of the exposed animals. Both approaches (theoretical and experimental) support the analytical results, alerting for an intervention on this estuarine environment and of other comparable.

Contribution to the determination of the place of death by drowning – A study of diatoms' biodiversity in Douro river estuary

The role of the investigation of diatoms' presence in organs and body fluids of an individual found dead in a liquid medium and the relevant contribution to the forensic diagnosis of drowning remain controversial. Furthermore, the absence of an exact and well-defined method for diatoms' analysis makes its study a challenging task.Considering this medico-legal problem and the absence of forensic studies on this subject in Portugal, this work aimed to determine the drowning place of dead individuals based on the analysis of diatom species found in different tissues (lung, liver, kidney, bone marrow) and stomach content. Diatom species found in biological samples were compared with those present in the liquid medium where the corpses were found. A total of 37 cases of death by drowning in Oporto metropolitan area were studied. A seasonal database of the diatom species found in Douro river estuary was built based on water samples collected at nine selected places. Diatoms' extractions were performed by a chemical method using 37% (w/w) hydrochloridric acid for the biological samples and 96% (w/w) sulfuric acid for water samples.Diatoms were found in 63% of total cases but only in lung and gastric content samples. The absence of diatoms in other organs is probably related with a quick death, which may have stopped blood circulation almost immediately, preventing diatom contamination of the other organs.A strong relationship between the diatom species found in the biological samples and those found in water samples of the respective drowning place was observed. Due to the high anthropogenic influence on the Douro estuary no significant differences were observed between the five sampling places, making it extremely difficult to determine the exact estuary location of the drowning.The importance of the creation of a diatom database of the potential drowning places (e.g., rivers, seas, lakes) becomes clear in this study. It also shows that, in cases of drowning, the collection of a water sample from the drowning place is crucial. This is the only way to allow a rigorous comparison of the diatom species in water and biological samples.

Occurrence of persistent organic pollutants in sediments and biota from Portugal versus European incidence: A critical overview

ABSTRACTPersistent organic pollutants (POPs) are widespread compounds, such as organohalogenated compounds, polycyclic aromatic hydrocarbons (PAHs) and pesticides, which can be found in all types of environmental compartments. Their presence in the aquatic environment is a worldwide problem, with emphasis on sediments which act as depository and consequently as a source of hydrophobic, recalcitrant and harmful compounds. Besides, these pollutants might affect the reproduction and mortality of living organisms, diverging in their potential to bioaccumulate in tissues. The present paper aims to review the occurrence of POPs in sediments and biota from the coastal, estuarine and river areas of Portugal. The list of the studied compounds comprises organohalogenated compounds, PAHs, organometallic compounds, pesticides, sterols, fatty acids and pharmaceutical compounds. The contamination of sediments by various pollutants is presented, such as PAHs up to 7,350 ng g−1 found in Sado estuary and polychlorinated biphenyls up to 62.2 ng g−1 in the case of sediments collected in Ria de Aveiro. The occurrence of these persistent toxic substances in sediments demonstrates aquatic contamination from agricultural, industrial and urban discharges and the concern about the potential risks to aquatic organisms, wildlife and humans. In fact, several classes of POPs have also been found in biota, such as polychlorinated biphenyls up to 810.9 ng g−1 in sentinel fish from the Douro River estuary and pesticides in bivalves from the Sado River estuary. The importance of further systematic research on sediments and biota is here highlighted to compare the contamination of these two reservoirs; to assess their spatial and temporal variation; and to determine other classes of POPs that were not investigated yet (e.g., industrial compounds, estrogens and many classes of pharmaceuticals).

Occurrence of Natural Contaminants of Emerging Concern in the Douro River Estuary, Portugal.

Many studies demonstrated the presence of diverse environmental contaminants in the Douro River estuary, such as natural and synthetic estrogens, pharmaceuticals, industrial compounds and pesticides. This estuary is located between two densely populated cities and is highly impacted due to anthropogenic activities, such as industry and agriculture. Although the presence of mycotoxins and phytoestrogens, such as lignans and coumestrans, in the aquatic environment is reported by some authors, their occurrence in Portuguese waters was not investigated yet. To evaluate the presence of phytoestrogens, phytosterols and mycotoxins in Douro River estuary, water samples were collected seasonally at nine sampling points, preconcentrated by solid phase extraction and analysed by gas chromatography mass spectrometry. Local flora was collected on the riverside, in the same sampling points, for identification and evaluation of the possible relation to the presence of phytoestrogens and/or phytosterols in the estuarine water. Results showed the ubiquitous presence of mycotoxins, namely deoxynivalenol up to 373.5ngL(-1). Both phytoestrogens and phytosterols showed a possible seasonal fluctuation, which is in accordance to the life cycle of the local flora and agricultural practices. Physicochemical parameters werealso determined for water quality evaluation. This study revealed for the first time the presence of mycotoxins and lignans in estuarine waters from Portugal, and highlights the need to consider natural contaminants in future monitoring programs.

Development and validation of a gas chromatography mass spectrometry method for the analysis of phytoestrogens, phytosterols and mycotoxins in estuarine water samples

Many pollutants currently released into the environment may cause adverse effects on exposed organisms leading to disruption of the endocrine system. Among them are natural compounds such as phytoestrogens and phytosterols, found in various plants and mycotoxins produced by a wide range of fungal species. The presence of some classes of phytoestrogens and phytosterols has been demonstrated in environmental samples while little information can be found about the presence of mycotoxins. Due to the complexity of environmental matrices and the low concentrations normally found, sensitive and selective methods are required for an unequivocal quantification of this type of compounds. The aim of this study was to develop and validate an analytical method for the simultaneous quantification of seven phytoestrogens, two phytosterols and three mycotoxins in estuarine water samples. The method consisted of the preconcentration of estuarine water samples (1 L) on 200 mg OASIS HLB cartridges, followed by a clean-up step in 1 g silica cartridges and quantification by gas chromatography with mass spectrometry ion trap analyser. Validation parameters were evaluated and the method demonstrated to be selective and linear with correlations higher than 0.99. Method detection limits were in the ng L−1 levels ranging from 18.0 to 90.0 ng L−1, recovery rates ranged from 59.8% to 99.5% and precision (RSD) from 5.5% and 9.7%. The feasibility of the method was demonstrated in surface water samples from Douro River estuary, a polluted estuary, with reported incidence of endocrine-disrupting phenomena.

Sprainting sites and feeding habits of the otter (Lutra lutra) in the Douro River estuary, Portugal

1. Instituto de Investigacion en Recursos Cinegeticos (IREC; CSIC-UCLM-JCCM), Ronda de Toledo s/n, 13071 Ciudad Real, Spain 2. Centro de Investigaciones Biologicas del Noroeste, Avda. Mar Bermejo 195, 23090 La Paz, B.C.S., Mexico 3. MEDIODES Consultoria Ambiental y Paisajismo S.L., Boulevar Louis Pasteur 1, Bloq.2-1o-1, 29010 Malaga, Spain 4. Grupo de Investigacion Marismas y Playas, codigo PAI RNM 358, Universidad de Huelva, Huelva, Spain 5. Parque Natural de Somiedo, 33840 Somiedo, Asturias, Spain 6. Research Unit of Biodiversity (UO, CSIC, PA), Campus de Mieres, Universidad de Oviedo, Oviedo, Spain 7. Estacion Biologica de Donana CSIC, C/ Americo Vespucio s/n, 41092 Sevilla, Spain