River Deltas as hotspots of microplastic accumulation: The case study of the Ebro River (NW Mediterranean)

Microplastics (MPs) are considered pollutants that are ubiquitously distributed in aquatic environments. One of the key hotspot areas to understand fluxes of MPs entering into the oceans are transitional systems, between fresh and marine waters, where river estuaries in particular play an important role. In this study we analyzed MPs occurrence in the Ebro River Delta, Northeastern Iberian Peninsula, one of the largest wetland areas in the NW Mediterranean Basin. Microplastic profile, abundance, distribution, and characteristics were screened across different environmental matrices. MPs were collected in sandy beaches on the northern edge of the delta, in estuarine benthic sediments, and in surface waters of the Ebro River, with a mean abundance of 422 ± 119 MPs·kg^-1 DW, 2052 ± 746 MPs·kg^-1 DW and 3.5 ± 1.4 MPs·m^-3, respectively. Fibers were found to be the largest class (70 ± 22%) of the three different environmental matrices investigated. We estimated that the Ebro surface water represents an input of 2.14 × 10⁹ MPs·yr^-1 to the Mediterranean Sea. The main contribution of this study is a new insight on the distribution of MPs across different environmental matrices in river estuaries, where estuarine benthic sediments were identified as a potential important sink for MPs.

Spatio-temporal patterns of pesticide residues in the Turia and Júcar Rivers (Spain)

A study was conducted on the occurrence of 50 pesticides in water and sediments of Turia and Júcar Rivers (Valencian Community, Eastern Spain) for a period of two consecutive years each, 2010/2011 and 2012/2013, respectively to assess the contribution of agriculture and urban activities on pesticide pollution. The results showed that mean concentrations of pesticides ranged from <LOQ up to 200 ng/L. Chlorpyrifos was the most frequent pesticide whereas imazalil, thiabendazole, tolclofos methyl, ethion and carbofuran were those found at higher concentrations. Ubiquitous pesticides are those with long half-lives. The most polluted parts of the rivers were the headwaters and the mouth, which could be related to the agricultural practices and rainfall. Contrarily, in the abrupt part of the rivers of difficult access the contamination is low. Other quality parameters monitored in this study also corroborate the worst water quality in the alluvial plains that coincides with higher anthropic pressure. The temporal variations also indicated a strong relation of pesticide concentrations with hydrology, the higher the river flow, the higher number and frequency of pesticides but at lower concentrations. On the contrary, at lower river flows higher pesticide concentrations were detected. The risk assessment for aquatic biota pointed out that organophosphorus and fungicides are a threat to fish and daphnia and herbicides and fungicides are hazards for algae. Thus, the strict control of pesticide concentrations is important to preserve the aquatic ecosystems health.

Concentration and risk of pharmaceuticals in freshwater systems are related to the population density and the livestock units in Iberian Rivers

Considerable amounts of pharmaceuticals are used in human and veterinary medicine, which are not efficiently removed during wastewater and slurries treatment and subsequently entering continuously into freshwater systems. The intrinsic biological activity of these non-regulated pollutants turns their presence in the aquatic environment into an ecological matter of concern. We present the first quantitative study relating the presence of pharmaceuticals and their predicted ecotoxicological effects with human population and livestock units. Four representative Iberian River basins (Spain) were studied: Llobregat, Ebro, Júcar and Guadalquivir. The levels of pharmaceuticals were determined in surface water and sediment samples collected from 77 locations along their stream networks. Predicted total toxic units to algae, Daphnia and fish were estimated for pharmaceuticals detected in surface waters. The use of chemometrics enabled the study of pharmaceuticals for: their spatial distribution along the rivers in two consecutive years; their potential ecotoxicological risk to aquatic organisms; and the relationships among their occurrence and predicted ecotoxicity with human population and animal farming pressure. The Llobregat and the Ebro River basins were characterized as the most polluted and at highest ecotoxicological risk, followed by Júcar and Guadalquivir. No significant acute risks of pharmaceuticals to aquatic organisms were observed. However potential chronic ecotoxicological effects on algae could be expected at two hot spots of pharmaceuticals pollution identified in the Llobregat and Ebro basins. Analgesics/antiinflammatories, antibiotics and diuretics were the most relevant therapeutic groups across the four river basins. Among them, hydrochlorothiazide and gemfibrozil, as well as azithromycin and ibuprofen were widely spread and concentrated pharmaceuticals in surface waters and sediments, respectively. Regarding their predicted ecotoxicity, sertraline, gemfibrozil and loratidine were identified as the more concerning compounds. Significantly positive relationships were found among levels of pharmaceuticals and toxic units and population density and livestock units in both surface water and sediment matrices.

Occurrence and trends in concentrations of perfluoroalkyl substances (PFASs) in surface waters of eastern China

Spatial distributions of perfluoroalkyl substances (PFASs) were investigated in surface waters in Shanghai, Jiangsu and Zhejiang Provinces of eastern China during 2011. A total of 39 samples of surface waters, including 29 rivers, 6 lakes and 4 reservoirs were collected. High performance liquid chromatography/negative electrospray ionization-tandem mass spectrometry (HPLC/(-)ESI-MS/MS) was used to identify and quantify PFASs. Concentrations of PFAS were greater in Shanghai than that in Zhejiang Province. Concentrations of the sum of PFASs (∑PFASs) in Shanghai and Kunshan ranged from 39 to 212 ng L(-1), while in Zhejiang Province, concentrations of ∑PFASs ranged from 0.68 to 146 ng L(-1). Perfluorooctanoic acid (PFOA) was the prevalent PFAS in Shanghai. In contrast, PFOA and perfluorohexanoic acid (PFHxA) were the prevalent PFASs in Zhejiang Province. Concentrations of perfluorooctane sulfonate (PFOS) ranged from <0.07 to 9.7 ng L(-1). Annual mass of ∑PFASs transported by rivers that flow into the East China Sea were calculated to be more than 4000 kg PFASs. Correlation analyses between concentrations of individual PFASs showed the correlation between PFHxA and PFOA was positive, while the correlation between PFHxA and perfluorooctane sulfonamide (FOSA) was negative in Shanghai, which indicated that PFHxA and PFOA have common sources. Principal component analysis (PCA) was employed to identify important components or factors that explain different compounds, and results showed that PFHxA and FOSA dominated factor loadings.

Occurrence of pharmaceutical compounds and pesticides in aquatic systems

This paper deals with the detection and quantification of APIs and other priority substances in the Arade River estuary (Portugal) providing the usefulness of Polar Organic Compound Integrative Samplers (POCIS). Thirteen APIs were detected whose variation was site and time dependent. Caffeine was at the highest concentration (804±209 ng/L) followed by theophylline (184±44 ng/L). Other APIs were analgesic, anticonvulsant, non-steroidal anti-inflammatory drugs, anti-lipidemic, anxiolytic and antidepressants. Twenty pesticides comprising atrazine, diuron, isoproturon, terbutryn and simazine included in the Water Framework Directive priority list were also site and time dependent. Carbendazim occurred at the highest concentration (45±18 ng/L at site 1) but atrazine, diuron, isoproturon and simazine levels were below the Environmental Quality Standards. Although the summer impact was unclear, the results highlighted POCIS suitability for profiling these contaminants. This is to our knowledge the first study concerning APIs and pesticides in this area.

Environmental monitoring and risk assessment of pesticide residues in surface waters of the Louros River (N.W. Greece)

Estuarine environments are being constantly stressed by new sources of pollution (e.g. pesticides) derived from activities of industry and intensive agriculture. The present study aims at quantify pesticides of three different categories (fungicides, herbicides and insecticides) in the Louros River (Epirus region, North-Western Greece). A monitoring study of 34 compounds was carried out in surface river waters from June 2011 until May 2012. Seven water sampling stations were established and 35 water samples were collected. A solid-phase extraction (SPE) method coupled with gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS), depending on the compound, was developed and validated. During the monitoring study 25 pesticides were detected (13 herbicides, 9 insecticides, 3 fungicides). The most commonly encountered pesticides were quizalofop-ethyl, trifluralin and pendimethaline. Tebufenpyrad was found in all sampling stations and seasons, with the highest concentrations of 0.330 μg/L at Tsopeli Lagoon exceeding the rather low concentrations reported nationwide. Regarding the environmental risk due to the presence of target compounds in surface waters, this was estimated by calculating risk quotients (RQs) for different aquatic organisms (algae, zooplankton and fish). The results denoted a possible threat for the aquatic environment, rendering in this way the RQ method as a useful screening tool. In any case, further extensive study is needed for acetochlor, pirimiphos-methyl, endosulfan-a and azinphos-ethyl in order to better correlate their occurrence and potential toxic effects in aquatic life and humans.

Toxicity of naproxen sodium and its mixture with tramadol hydrochloride on fish early life stages

Pharmaceuticals occur in water bodies as a consequence of their incomplete removal during waste water treatment processes. The occurence of pharmaceuticals in surface waters as well as their possible impact on aquatic vertebrates have received considerable attention in recent years. However, there is still a lack of informations on the chronic effects of widely used drugs as well as their possible mixture toxicity on non-target aquatic vertebrates as well as their possible mixture toxicity. The aim of this study was to assess the effects of naproxen sodium on early life stages of fish and evaluate its mixture toxicity with tramadol hydrochloride, which was assessed in our earlier study as a single substance. Two embryo-larval toxicity tests with common carp (Cyprinus carpio) were performed according to the OECD guideline 210 (Fish, Early-life Stage Toxicity Test) in order to assess the subchronic toxicity of naproxen sodium and tramadol hydrochlorid-naproxen sodium mixture at the concentrations of 10; 50; 100 and 200 μg/L. These experiments were conducted for 32 days. The subchronic exposure to naproxen sodium and naproxen sodium and tramadol hydrochloride mixture had a strong effect on the early life stages of common carp. Hatching, developmental rate, morphology, histopathology and, in the case of the naproxen sodium and tramadol hydrochloride mixture, mortality were influenced. The bioindicators of oxidative stress were also influenced. The LOEC was determined at 10 μg/L for both naproxen sodium and naproxen sodium and tramadol hydrochloride mixture.

Antibiotics and antidepressants occurrence in surface waters and sediments collected in the north of Portugal

To our knowledge, this is the first study in Portugal for the analysis of both antibiotics and psychiatric drugs in river waters from Douro and Leça rivers and its sediments. Samples were extracted using solid phase extraction and QuEChERS procedures and the analysis was performed using liquid chromatography with tandem mass spectrometry. Higher number of pharmaceuticals and higher concentrations were found in the Leça river for the two matrices under study. The highest detection frequency for the twenty-seven pharmaceuticals was observed for fluoxetine with 83.3% in both matrices. None of the studied antibiotics were detected in water collected in the Douro river however six antibiotics (azithromycin, ciprofloxacin, clarithromycin, moxifloxacin, ofloxacin, and trimethoprim) were found in the Leça river. Further, the analysis of sediments exhibits the occurrence of sulfamethoxypyridazine in the Douro river and azithromycin in the Leça river. The highest concentration was observed in Leça river for azithromycin in the river water (2,819 ng/L) and sediments (43.2 ng/g). Carbamazepine, citalopram, fluoxetine, sertraline, trazodone, and venlafaxine were the psychiatric drugs detected in river waters and sediments with more diazepam as water river contamination. Concentrations ranged from <method detection limit (MDL)) to 2.0 ng/L (river waters) and <MDL to 0.251 ng/g (sediments) in Douro river and between < MDL to 354 ng/L (river waters) and <MDL to 6.35 ng/g (sediments) in Leça river. To identify the possible sources of pollution more monitoring studies should be performed along the studied rivers.

Human pharmaceuticals in Portuguese rivers: The impact of water scarcity in the environmental risk

Pharmaceuticals occurrence and environmental risk assessment were assessed in Portuguese surface waters, evaluating the impact of wastewater treatment plants (WWTPs) and river flow rates. Twenty three pharmaceuticals from 6 therapeutic groups, including metabolites and 1 transformation product, were analysed in 72 samples collected from 20 different sites, upstream and downstream the selected WWTPs, in two different seasons. Analysis was performed by solid phase extraction followed by liquid chromatography coupled to tandem mass spectroscopy. Pharmaceuticals were detected in 27.8% of the samples. Selective serotonin reuptake inhibitors (SSRIs), anti-inflammatories and antibiotics presented the highest detection frequencies (27.8, 23.6 and 23.6%, respectively) and average concentrations (37.9, 36.1 and 33.5ngL^-1, respectively). When assessing the impact of WWTPs, an increase of 21.4% in the average concentrations was observed in the samples located downstream these facilities, when compared with the upstream samples. Increased detection frequencies and concentrations were observed at lower flow rates, both when comparing summer and winter campaigns and by evaluating the different rivers. Risk quotients (RQs) higher than one were found for two pharmaceuticals, concerning two trophic levels. However, since Iberian rivers are highly influenced by water scarcity, in drought periods, the flow rates in these rivers can decrease at least ten times from the lowest value observed in the sampling campaigns. In these conditions, RQs higher than 1 would be observed for 5 pharmaceuticals, additionally, all the detected pharmaceuticals (11) would present RQs higher than 0.1. These results emphasize that the river flow rate represents an important parameter influencing pharmaceuticals concentrations, highlighting the ecotoxicological pressure, especially due to water scarcity in drought periods. This should be a priority issue in the environmental policies for minimizing its impact in the aquatic environment.

Amines and amine-related compounds in surface waters: a review of sources, concentrations and aquatic toxicity

This review compiles available information on the concentrations, sources, fate and toxicity of amines and amine-related compounds in surface waters, including rivers, lakes, reservoirs, wetlands and seawater. There is a strong need for this information, especially given the emergence of amine-based post-combustion CO2 capture technologies, which may represent a new and significant source of amines to the environment. We identify a broad range of anthropogenic and natural sources of amines, nitrosamines and nitramines to the aquatic environment, and identify some key fate and degradation pathways of these compounds. There were very few data available on amines in surface waters, with reported concentrations often below detection and only rarely exceeding 10 μg/L. Reported concentrations for seawater and reservoirs were below detection or very low, while for lakes and rivers, concentrations spanned several orders of magnitude. The most prevalent and commonly detected amines were methylamine (MA), dimethylamine (DMA), ethylamine (EA), diethylamine (DEA) and monoethanolamine (MEAT). The paucity of data may reflect the analytical challenges posed by determination of amines in complex environmental matrices at ambient levels. We provide an overview of available aquatic toxicological data for amines and conclude that at current environmental concentrations, amines are not likely to be of toxicological concern to the aquatic environment, however, the potential for amines to act as precursors in the formation of nitrosamines and nitramines may represent a risk of contamination of drinking water supplies by these often carcinogenic compounds. More research on the prevalence and toxicity of amines, nitrosamines and nitramines in natural waters is necessary before the environmental impact of new point sources from carbon capture facilities can be adequately quantified.

Spatial variation of floatable plastic debris and microplastics in the Pearl River Estuary, South China

The estuaries of populated catchments have been documented as hotspots of plastic pollution. In this study, microplastics (0.355-5.0 mm) and large plastic debris (>5.0 mm) of surface water collected from the Inner Lingding Bay of the Pearl River Estuary (PRE) were quantified and categorized according to their size, shape, colour and composition. Both microplastics and large plastic debris were detected at all sampling sites with mean abundances of 2.376 ± 0.700 n/m³ and 0.110 ± 0.039 n/m³, respectively. Microplastics constitute 95.4% of the total abundance by number. The average microplastic concentration in the inner PRE was almost 3.5 times higher than that in the central PRE, indicating a positive correlation between plastic concentration and proximity to the river mouth. This result reveals the important role of rivers in transporting plastic debris from land to the oceans.

Occurrence and abundance of meso and microplastics in sediment, surface waters, and marine biota from the South Pacific region

Data on the occurrence and abundance of meso and microplastics for the South Pacific are limited and there is urgent need to fill this knowledge gap. The main aim of the study was to apply a rapid screening method, based on the fluorescence tagging of polymers using Nile red, to determine the concentration of meso and microplastics in biota, sediment and surface waters near the capital cities of Vanuatu and Solomon Islands. A spatial investigation was carried out for sediment, biota and water as well as a temporal assessment for sediment for two consecutive years (2017 and 2018). Accumulation zones for microplastics were identified supported by previous hydrodynamic models. Microplastics were detected for all environmental compartments investigated indicating their widespread presence for Vanuatu and Solomons Islands. This method was in alignment with previous recommendations that the Nile red method is a promising approach for the largescale mapping of microplastics in a monitoring context.

Screening of human and veterinary pharmaceuticals in estuarine waters: A baseline assessment for the Tejo estuary

We investigated the presence of 66 human and veterinary pharmaceuticals from seven therapeutic groups in surface waters of the Tejo estuary. Collection sites covered the entire estuary and included areas near main river inflows and wastewater treatment outfalls, traversing urban, agriculture, aquaculture, and nature reserve areas. Detection of pharmaceuticals was performed via UHPLC-TOF-MS. Pharmaceuticals were found in all sites (32 different compounds in total). Antibiotics, β-blockers, antihypertensives and anti-inflammatories were the most frequently detected (>90%), with variation in concentrations reflecting the multifaceted nature of estuarine surroundings (accumulated site contamination between 15 and 351 ng L^-1). Higher concentrations of antidepressant Sertraline (304 ng L^-1), non-steroidal anti-inflammatory Diclofenac (51.8 ng L^-1), lipid regulator Gemfibrozil (77.0 ng L^-1), antihypertensive Ibersartan (161.9 ng L^-1) or antibiotic Doxycycline (128.0 ng L^-1), among others, though localized may potentially impact key estuarine functions or services. Ultimately, results provide a baseline for regulatory information and future biota evaluations.

Sources of aminomethylphosphonic acid (AMPA) in urban and rural catchments in Ontario, Canada: Glyphosate or phosphonates in wastewater?

Correlation analysis suggests that occurrences of AMPA in streams of southern Ontario are linked mainly to glyphosate in both urban and rural settings, rather than to wastewater sources, as some previous studies have suggested. For this analysis the artificial sweetener acesulfame was analyzed as a wastewater indicator in surface water samples collected from urban and rural settings in southern Ontario, Canada. This interpretation is supported by the concurrence of seasonal fluctuations of glyphosate and AMPA concentrations. Herbicide applications in larger urban centres and along major transportation corridors appear to be important sources of glyphosate and AMPA in surface water, in addition to uses of this herbicide in rural and mixed use areas. Fluctuations in concentrations of acesulfame and glyphosate residues were found to be related to hydrologic events.

In situ measurement of perfluoroalkyl substances in aquatic systems using diffusive gradients in thin-films technique

To better understand the environmental impact of ubiquitous perfluoroalkyl substances (PFASs) in waters, reliable and robust measurement techniques are needed. As one of the most widely used passive sampling approaches, diffusive gradients in thin-films (DGT) is not only easy to handle but also provides time-weighted analyte concentrations. Based on DGT with XAD18 as a binding agent, we developed a new methodology to measure two frequently detected PFASs in surface waters and wastewaters, i.e. perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Their diffusion coefficients in the diffusive gel, measured using an independent diffusion cell, were 4.37 × 10^-6 and 5.08 × 10^-6 cm² s^-1 at 25 °C, respectively. DGT had a high capacity for PFOA and PFOS at 196 and 246 μg per gel disk, suggesting the DGT sampler was suitable for deployment of several weeks. Time-integrated concentrations of PFOA and PFOS in a natural lake and river, and a municipal wastewater treatment plant effluent using DGT samplers deployed in situ for 12-33 d were comparable to those measured by a solid-phase extraction method coupled with high-frequency grab sampling. This study demonstrates that DGT is an effective tool for in situ monitoring of PFASs in natural waters and wastewaters.

First report of occurrence, distribution, and composition of microplastics in surface waters of the Sea of Marmara, Turkey

Plastic is produced today in large quantities and used for many purposes. At the end of use, a large part of it gets into the environment, often into the sea and there it is fragmented into the smallest fragments, so-called microplastic (MP). MPs pose a serious challenge to the marine environment such as the sources and properties of MP particles, their impact on marine organisms, and the challenges of environmental pollution. This work, carried out in the fourteen sites in the area, is the first reference to the detection of MP distribution at surface waters in the Sea of Marmara, Turkey. As a result of this study, the average level of MP in the surface was determined to be 1.263 item/m². The results were higher compared of the most other adjacent regions and show that the Sea of Marmara started to face that problem.

Occurrence of non-steroidal anti-inflammatory drugs in Tehran source water, municipal and hospital wastewaters, and their ecotoxicological risk assessment

Pharmaceuticals are becoming widely distributed in waters and wastewaters and pose a serious threat to public health. The present study aimed to analyze non-steroidal anti-inflammatory drugs (NSAIDs) in surface waters, drinking water, and wastewater in Tehran, Iran. Thirty-six samples were collected from surface waters, tap water, and influent and effluent of municipal and hospital wastewater treatment plants (WWTP). A solid-phase extraction (SPE) followed by liquid chromatography-tandem mass spectrometry method was used for the determination of pharmaceuticals, namely ibuprofen (IBP), naproxen (NPX), diclofenac (DIC), and indomethacin (IDM). IBP was found in most of the samples and had the highest concentration. The highest concentrations of NSAIDs were found in the municipal WWTP influents and hospital WWTP effluents. In the municipal WWTP influent samples, the concentrations of IBP, NPX, DIC, and IDM were 1.05, 0.43, 0.23, and 0.11 μg/L, respectively. DIC was found only in one river sample. All NSAIDs were detected in tap water samples. However, their concentration was very low and the maximum values for IBP, NPX, DIC, and IDM were 47, 39, 24, and 37 ng/L, respectively, in tap water samples. Results showed that the measured pharmaceuticals were detected in all rivers with low concentrations in nanograms per liter range, except DIC which was found only in one river. Furthermore, this study showed that the aforementioned pharmaceuticals are not completely removed during their passage through WWTPs. A potential environmental risk of selected NSAIDs for the urban wastewater has been discussed. However, given their low measured concentrations, no ecotoxicological effect is suspected to occur.

Presence of antibiotic resistance genes and its association with antibiotic occurrence in Dilúvio River in southern Brazil

It is known that antibiotics are widely used in human and veterinary medicine. In some countries the use is controlled, however few restrictions to their use are enforced in many countries. Antibiotics and their metabolites can reach the water bodies through sewage systems, especially in those countries with partial or absent wastewater treatment systems. The overuse and misuse of antibiotics has been linked with the increase of antibiotic resistant bacteria. The relation between the occurrence of antibiotics and resistance genes in surface waters has been widely studied worldwide evincing the great importance of this subject. In this work, a methodology for quantification of 40 antibiotics of 5 different classes, in river water, by SPE-LC-MS/MS was validated. Samples were taken during a two-year period from Dilúvio River, a stream that crosses the city of Porto Alegre (RS - Brazil) and receives in nature domestic effluent. The methodology met the requirements of validation, with Limit of Quantification varying from 20 ng L^-1 to 100 ng L^-1. A total of 48 samples was analyzed for the presence of antibiotics for two years. From the 40 antibiotics analyzed, 8 of them (Azithromycin, Cephalexin, ciprofloxacin, clindamycin, norfloxacin, sulfadiazine, sulfamethoxazole and trimethoprim) were present in all sampling points in the range of <LOQ to 344 ng L^-1. The occurrence of antibiotics resistance genes in the sampling points was determined using qPCR. Specific primers were utilized to detected resistance genes to the β-lactam cephalexin (bla_TEM gene), to the quilonones ciprofloxacin and norfloxacin (qnrS gene), to the macrolides azithromycin and clindamycin (ermB gene), and to the sulfonamides sulfadiazine and sulfamethoxazole (sulI gene), which were quantified the selected water samples. Quantitative PCR analysis revealed the presence of ARGs in all samples, with the highest concentration found for bla_TEM.

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.

Phytoestrogens and mycoestrogens in surface waters--Their sources, occurrence, and potential contribution to estrogenic activity

This review discusses the potential contribution of phytoestrogens and mycoestrogens to in vitro estrogenic activities occurring in surface waters and in vivo estrogenic effects in fish. Main types, sources, and pathways of entry into aquatic environment of these detected compounds were summarized. Reviewed concentrations of phyto/mycoestrogens in surface waters were mostly undetectable or in low ng/L ranges, but exceeded tens of μg/L for the flavonoids biochanin A, daidzein and genistein at some sites. While a few phytosterols were reported to occur at relatively high concentrations in surface waters, information about their potencies in in vitro systems is very limited, and contradictory in some cases. The relative estrogenic activities of compounds (compared to standard estrogen 17β-estradiol) by various in vitro assays were included, and found to differ by orders of magnitude. These potencies were used to estimate total potential estrogenic activities based on chemical analyses of phyto/mycoestrogens. In vivo effective concentrations of waterborne phyto/mycoestrogens were available only for biochanin A, daidzein, formononetin, genistein, equol, sitosterol, and zearalenone. The lowest observable effect concentrations in vivo were reported for the mycoestrogen zearalenone. This compound and especially its metabolites also elicited the highest in vitro estrogenic potencies. Despite the limited information available, the review documents low contribution of phyto/mycoestrogens to estrogenic activity in vast majority of surface waters, but significant contribution to in vitro responses and potentially also to in vivo effects in areas with high concentrations.

Occurrence, distribution, and characterization of suspended microplastics in a highly impacted estuarine wetland in Argentina

Microplastics have been a global concern due to their potential and widespread risks to organisms and environments. In this study, we investigated the abundance, distribution, and characteristics of microplastics (MPs) in the surface waters of the Bahía Blanca Estuary (BBE), specifically in its inner and middle zone. The results showed the dominant shape of MPs were fibers, being black, transparent, and blue the main colors. The concentrations of MPs ranged from 182 to 33,373 items m^-3 with a mean value of 6162 items m^-3. The highest concentrations of MPs were detected in the middle zone of the estuary, a site that receives untreated sewage effluents from the city. The most abundant size ranges were from 0.5 to 1.5 mm (44.21%) and ˂0.5 mm (40.21%) and were predominant at all the sampling sites. The concentration of mesoplastics in the inner zone (16 items m^-3) presented larger values than in the middle zone (5 items m^-3). A wide variety of polymeric materials with predominance of microfibers such as cellulose-based, polyacrylonitrile, polyethylene terephthalate, and polypropylene were identified. Polyester/alkyd resins and poli(vinyl chloride) were also found. The analysis of MPs surface through SEM/EDX detected a variety of elements such as C, O, Si, Al, K, Ca, Cl, Ti, Fe, S, and P, indicating potential contaminant carriers in the water column. Some plastic particles presented a high degree of degradation on their surface morphology. Untreated sewage discharges appear to be a significant input of MPs. Therefore, the results provided in the present study should be considered by stakeholders interested in the management and conservation of this large coastal wetland with significant ecological and economic value.

Occurrence, fate, and mass balance of selected pharmaceutical and personal care products (PPCPs) in an urbanized river

The identification and quantification of pharmaceutical and personal care products (PPCPs) in aquatic ecosystems is critical to further studies and elucidation of their fate as well as the potential threats to aquatic ecology and human health. This study used mass balances to analyse the sources, transformation, and transport of PPCPs in rivers based on the population and consumption habits of residents, the removal level of sewage treatment, the persistence and partitioning mechanisms of PPCPs, hydrological conditions, and other natural factors. Our results suggested that in an urbanized river of Guangzhou City, China, the daily consumption of PPCPs was the main reason for the variety of species and concentrations of PPCPs. Through the determination of PPCPs in the river water samples and a central composite design (CCD) methodology, the dominant elimination mechanisms of caffeine and carbamazepine from river water were photolysis and biodegradation, but that of triclosan was sorption rather than biodegradation. The mass data of 3 PPCPs were estimated and corroborated using the measured data to evaluate the accuracy of the mass balance. Finally, caffeine, carbamazepine and triclosan discharged from the Shijing River into the Pearl River accounted for 97.81%, 99.52%, and 28.00%, respectively, of the total mass of these three compounds in the surface water of Shijing River. The results suggest that photolysis are the main process of natural attenuation for selected PPCPs in surface waters of river systems, and the transfer processes of PPCPs is mainly attributed to riverine advection. In addition, the low concentration of dissolved oxygen inhibited the degradation of PPCPs in the surface water of Shijing River.

Impacts of climate and land use changes on the water quality of a small Mediterranean catchment with intensive viticulture

Studies that address the potential effects of climate and land use changes on surface water quality are scarce in the Mediterranean region. In the present work, the impacts of climate and land use changes on nutrient and copper exports from a humid Mediterranean catchment (São Lourenço) were evaluated using the SWAT model. SWAT reproduced reasonably well total nitrogen (TN), phosphorus (TP) and copper (Cu) exports in São Lourenço, providing an adequate baseline scenario as well as a suitable model parameterization for assessing the impacts of climate and land use changes under the A1B and B1 emission scenarios for the end of the 21st century (2071-2100). Land use changes scenarios were generated along the same storylines as climate change scenarios to assess the combined effects of the two stressors. Climate changes itself led to a decline in annual TN and TP exports under both emission scenarios mostly due to a decrease in runoff and erosion induced by a reduction in rainfall, but it hardly affected Cu exports largely due to its strong immobilization in soils. Land use changes per se resulted in an increase in streamflow, but the changes in water quality varied markedly according to the scenarios. A substantial decrease in TN, TP and Cu exports was observed under scenario A1B, due to a reduction in vineyard areas. Under scenario B1, however, TP exports decreased much less while TN exports hardly changed, reflecting differences in the preferential transport pathways of these compounds. Cu exports also remained the same, as no changes occurred in the vineyard areas. The combination of climate and land use change scenarios revealed additive impacts on the exports of all three contaminants, emphasizing the importance of integrated approaches to define adaptive land management practices that can ensure the future sustainability of Mediterranean water resources.

Pesticides in surface waters of tropical river basins draining areas with rice-vegetable rotations in Hainan, China: Occurrence, relation to environmental factors, and risk assessment

Pesticides are heavily applied in rice-vegetable rotations in tropical China, yet publicly available information on the contamination and risk of currently used pesticides (CUPs) and legacy pesticides (LPs) in surface waters of river basins draining these areas is very limited. Therefore, in two tropical river basins (Nandu River and Wanquan River basins) dominated by rice-vegetable rotations in Hainan, China, pesticides were analyzed in 256 surface water samples in wet and dry seasons. Forty-one pesticides were detected, and total concentrations ranged from not detectable to 24.2 μg/L. Carbendazim and imidacloprid were the two most prevalent CUPs, detected in 59.8% and 17.7%, respectively, of surface water samples at concentrations above 0.1 μg/L. Chlorpyrifos was the main LP, detected in 9.0% of samples at a concentration above 0.05 μg/L. The fungicides difenoconazole and emamectin benzoate, the herbicide butachlor, and the insecticide acetamiprid occurred in ≥12.5% samples at concentrations above 0.1 μg/L. Surface waters typically (85.2%) contained 5 to 15 residues, with an average of nine. Seasonally, the concentrations of the 41 pesticides were in the order January > July > November > September. Spatially, the composition of the main CUPs (not LPs) was significantly different depending on position in the drainage, which also changed with seasons. Crop and pest types and wet and dry seasons were the key factors controlling the spatiotemporal distribution of CUPs and LPs in surface waters. On the basis of evaluations of the exposures to individual pesticides and the dominant combinations with ≥8 pesticides, multiple pesticides were likely a significant risk to aquatic organisms, although noncarcinogenic and carcinogenic risks to humans were low. This study provides valuable data to better understand pesticide occurrence and ecological risks in river basins draining areas with rice-vegetable rotation systems in tropical China.

Abundance and composition of floating marine macro litter on the eastern sector of the Mediterranean Sea

Floating marine litter is known to be currently a widespread pollution problem, especially in the Mediterranean basin, but records on the levels of floating debris in the eastern part are less known. By using an observation platform (32 days, 137 transects, 1784 km), this study provides evidence of a high amount of floating debris in the Levantine sub-basin, within the eastern Mediterranean Sea. The density of floating litter varied between 18 and 1593 items km^-2 (average 232 ± 325 items km^-2), and small plastic debris accounted for >90% of the items surveyed. These values tend to be higher than densities reported for the central and western Mediterranean areas, which may be related to the circulation patterns and inputs from coastal sources. Significant correlations of floating macro litter density with wind force and sea state were found, thus strengthening the need to standardise protocols (including oceanographic variables) of visual surveys of floating debris.