DNA metabarcoding and morphological methods show complementary patterns in the metacommunity organization of lentic epiphytic diatoms.

Diatoms are important organisms in freshwater ecosystems due to their position as primary producers and therefore, analyzing their assemblages provides relevant information on ecosystem functioning. Diatoms have historically been identified based on morphological traits, which is time-consuming and requires well-trained specialists. Nevertheless, DNA barcoding offers an alternative approach to overcome some limitations of the morphological method. Here, we assess if both approaches are comparable methods to study patterns and mechanisms (including environmental filtering and dispersal limitation) of epiphytic diatom metacommunities using a comprehensive dataset from 22 Mediterranean ponds at different taxonomic resolutions. We used a fragment of rbcL barcode gene combined with High-Throughput Sequencing to infer diatom community composition. The overall degree of correspondence between both approaches was assessed by Procrustean rotation analysis and Procrustean randomization tests, whereas the role of local environmental variables and geographical distances was studied using a comprehensive combination of BIOENV, Mantel tests and distance-based redundancy analysis. Our results showed a relatively poor correspondence in the compositional variation of diatom metacommunity between both approaches. We speculate that the incompleteness of the reference database and the bioinformatics processing are the biases most likely affecting the molecular approach, whereas the limited counting effort and the presence of cryptic species are presumably the major biases related with the morphological method. On the other hand, variation in diatom community composition detected with both approaches was strongly related to the environmental template, which may be related with the narrow community-environment relationships in diatoms. Nevertheless, we found no significant relationship between compositional variation and geographical distances. Overall, our work shows the complementary nature of both approaches and highlights the importance of DNA metabarcoding to address empirical research questions of community ecology in freshwaters, especially once the reference databases include most genotypes of occurring taxa and bioinformatics biases are overcome.

Author Correction: Water sports could contribute to the translocation of ranaviruses.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Large-scale geographical and environmental drivers of shallow lake diatom metacommunities across Europe.

Disentangling the relative role of species sorting and dispersal limitation in biological communities has become one of the main issues for community ecologists and biogeographers. In this study, we analysed a data set of epiphytic diatoms comprising 34 lakes from six European countries. This data set covers a relatively large latitudinal gradient to elucidate which processes are affecting the distribution of diatom communities on a broad spatial extent. Our results show strong environmental effects on the composition of the diatom communities, while the spatial factor effects were weak, emphasising that compositional variation was mainly due to species turnover. Our data support information from the literature that local abiotic factors are the main predictors controlling the compositional variation of diatom assemblages in European shallow lakes. More specifically, changes in species composition were driven mainly by nutrient content in Northern Europe, whereas lakes located in Southern Europe were more affected by conductivity and lake depth. Our results solve pending questions in the spatial ecology of diatoms by proving that species turnover is stronger than nestedness at any spatial scale, and give support to the use of epiphytic diatoms as biological indicators for shallow lakes.

Bridging population genetics and the metacommunity perspective to unravel the biogeographic processes shaping genetic differentiation of Myriophyllum alterniflorum DC.

The degree to which dispersal limitation interacts with environmental filtering has intrigued metacommunity ecologists and molecular biogeographers since the beginning of both research disciplines. Since genetic methods are superior to coarse proxies of dispersal, understanding how environmental and geographic factors influence population genetic structure is becoming a fundamental issue for population genetics and also one of the most challenging avenues for metacommunity ecology. In this study of the aquatic macrophyte Myriophyllum alterniflorum DC., we explored the spatial genetic variation of eleven populations from the Iberian Plateau by means of microsatellite loci, and examined if the results obtained through genetic methods match modern perspectives of metacommunity theory. To do this, we applied a combination of robust statistical routines including network analysis, causal modelling and multiple matrix regression with randomization. Our findings revealed that macrophyte populations clustered into genetic groups that mirrored their geographic distributions. Importantly, we found a significant correlation between genetic variation and geographic distance at the regional scale. By using effective (genetic) dispersal estimates, our results are broadly in line with recent findings from metacommunity theory and re-emphasize the need to go beyond the historically predominant paradigm of understanding environmental heterogeneity as the main force driving macrophyte diversity patterns.

Water sports could contribute to the translocation of ranaviruses.

Ranaviruses have been identified as the cause of explosive disease outbreaks in amphibians worldwide and can be transmitted between hosts both via direct and indirect contact, in which humans might contribute to the translocation of contaminated material. The aim of this study was to evaluate the possible role of water sports in the human translocation of ranavirus, Batrachochytrium dendrobatidis (Bd), and B. salamandrivorans (Bsal). A total of 234 boats were sampled during the spring Spanish Canoe Championship which took place in Pontillón de Castro, a reservoir with a history of ranavirosis, in May 2017. Boats were tested for the presence of ranavirus and Batrachochytrium spp. DNA, using quantitative real-time polymerase chain reaction techniques (qPCR). A total of 22 swabs (22/234, 9.40%) yielded qPCR-positive results for Ranavirus DNA while Bd or Bsal were not detected in any of the samples. We provide the first evidence that human-related water sports could be a source of ranavirus contamination, providing justification for public disinfecting stations in key areas where human traffic from water sports is high.

Behaviour of pharmaceuticals and personal care products in constructed wetland compartments: Influent, effluent, pore water, substrate and plant roots.

Seven mesocosm-scale constructed wetlands (CWs) with different design configurations, dealing with primary-treated urban wastewater, were assessed for the concentration, distribution and fate of ten pharmaceutical and personal care products (PPCPs) [ibuprofen, ketoprofen, naproxen, diclofenac, salicylic acid, caffeine, carbamazepine, methyl dihydrojasmonate, galaxolide and tonalide] and eight of their transformation products (TPs). Apart from influent and effluent, various CW compartments were analysed, namely, substrate, plant roots and pore water. PPCP content in pore water depended on the specific CW configuration. Macrophytes can take up PPCPs through their roots. Ibuprofen, salicylic acid, caffeine, methyl dihydrojasmonate, galaxolide and tonalide were present on the root surface with a predominance of galaxolide and caffeine in all the planted systems. Naproxen, ibuprofen, salicylic acid, methyl dihydrojasmonate, galaxolide and tonalide were uptaken by the roots. In order to better understand the removal processes, biomass measurement and biodegradability studies through the characterization of internal-external isomeric linear alkylbenzenes present on the gravel bed were performed. Three TPs namely, ibuprofen-amide, 3-ethylbenzophenone and 4-hydroxy-diclofenac were identified for the first time in wetland pore water and effluent water, which suggests de novo formation (they were not present in the influent). Conversely, O-desmethyl-naproxen was degraded through the wetland passage since it was detected in the influent but not in the subsequent treatment stages. Biodegradation pathways are therefore suggested for most of the studied PPCPs in the assessed CWs.

Chemical pollution in inland shallow lakes in the Mediterranean region (NW Spain): PAHs, insecticides and herbicides in water and sediments.

The possible effect of land uses and human-related geographic patterns (presence of roads and urban settlements) on chemical pollution was evaluated in the waters and sediments of fifty-three Mediterranean shallow lakes. The presence of fifty-nine pollutants (belonging to PAHs, insecticides and herbicides groups) was analysed in these lakes by GC-MS. The studied lakes had similar pollutant concentrations to other lakes worldwide. The distribution of the compounds between water and sediment compartments was strongly influenced by log K(ow) values (an average of 3.61 for compounds found in water and of 4.69 for compounds found in sediments). A multivariate analysis suggested that the concentration of PAHs in water could be related to agricultural activities and not related to local road traffic. When assessing nutrient levels in the lakes, it was observed that eutrophicated lakes [>300 µg L(-1) total phosphorus (TP)] appeared in areas affected by urban or industrial use (at least 2% urban use in a 1-km radius around the lake), whilst lakes with lower TP concentrations were placed in forest areas (60% of forest use in a 1-km radius); in addition, the aqueous concentrations of Σ(PAH) were lower in lakes with higher TP concentrations (>150 µg L(-1) TP), which could be related to the adsorption capacity of PAHs onto suspended matter which is present in mesotrophic and eutrophic lakes, thus being removed from the aqueous phase.

Prevalence of antibiotic-resistant fecal bacteria in a river impacted by both an antibiotic production plant and urban treated discharges.

In this study, the abundance and spatial dynamics of antibiotic-resistant fecal bacteria (Escherichia coli, total coliforms and Enterococcus spp.) were determined in water and sediment samples from a river impacted by both antibiotic production plant (APP) and urban wastewater treatment plant (WWTP) discharges. Agar dilution and disk diffusion methods were also used for antimicrobial susceptibility testing. Two antimicrobial agents, cephalexin (25 µg/ml) and amoxicillin (50 µg/ml), were evaluated using the agar dilution method for E. coli, total coliforms (TC) and Enterococcus spp., whereas the degree of sensitivity or resistance of E. coli isolates to penicillin (10 U), ampicillin (10 µg), doxycycline (30 µg), tetracycline (30 µg), erythromycin (15 µg), azithromycin (15 µg) and streptomycin (10 µg) was performed using the disk diffusion method. Real-time PCR assays were used to determine the prevalence of three antibiotic-resistance genes (ARGs). The agar dilution method showed that most E. coli isolates and TC were resistant to amoxicillin, especially after receiving the APP discharges. Antibiotic resistances to amoxicillin and cephalexin were higher after the APP discharge point than after the WWTP effluent. The disk diffusion method revealed that 100% of bacterial isolates were resistant to penicillin and erythromycin. Multidrug-resistant bacteria were detected and showed a higher proportion at the WWTP discharge point than those in the APP. Highly multidrug-resistant bacteria (resistance to more than 4 antibiotics) were also detected, reaching mean values of 41.6% in water samples and 50.1% in sediments. The relative abundance of the blaTEM, blaCTX-M and blaSHV genes was higher in samples from the treatment plants than in those collected upstream from the discharges, especially for water samples collected at the APP discharge point. These results clearly demonstrate that both the APP and the WWTP contribute to the emergence and spread of antibiotic resistance in the environment.

Limitation and facilitation of one of the world's most invasive fish: an intercontinental comparison.

Purposeful species introductions offer opportunities to inform our understanding of both invasion success and conservation hurdles. We evaluated factors determining the energetic limitations of brown trout (Salmo trutta) in both their native and introduced ranges. Our focus was on brown trout because they are nearly globally distributed, considered one of the world's worst invaders, yet imperiled in much of their native habitat. We synthesized and compared data describing temperature regime, diet, growth, and maximum body size across multiple spatial and temporal scales, from country (both exotic and native habitats) and major geographic area (MGA) to rivers and years within MGA. Using these data as inputs, we next used bioenergetic efficiency (BioEff), a relative scalar representing a realized percentage of maximum possible consumption (0-100%) as our primary response variable and a multi-scale, nested, mixed statistical model (GLIMMIX) to evaluate variation among and within spatial scales and as a function of density and elevation. MGA and year (the residual) explained the greatest proportion of variance in BioEff. Temperature varied widely among MGA and was a strong driver of variation in BioEff. We observed surprisingly little variation in the diet of brown trout, except the overwhelming influence of the switch to piscivory observed only in exotic MGA. We observed only a weak signal of density-dependent effects on BioEff; however, BioEff remained < 50% at densities > 2.5 fish/m2. The trajectory of BioEff across the life span of the fish elucidated the substantial variation in performance among MGAs; the maximum body size attained by brown trout was consistently below 400 mm in native habitat but reached approximately 600 mm outside their native range, where brown trout grew rapidly, feeding in part on naive prey fishes. The integrative, physiological approach, in combination with the intercontinental and comparative nature of our study, allowed us to overcome challenges associated with context-dependent variation in determining invasion success. Overall our results indicate "growth plasticity across the life span" was important for facilitating invasion, and should be added to lists of factors characterizing successful invaders.

The Duero Diatom Index (DDI) for river water quality assessment in NW Spain: design and validation.

Diatom indices developed in certain geographic regions are frequently used elsewhere, despite the strong evidence that such metrics are less useful when applied in regions other than that where species-environment relationships were originally assessed, showing that species have particular autoecological requirements in different geographic areas. The goal of this study was to develop a new metric, the Duero Diatom Index (DDI), aimed at monitoring water quality in Duero basin watercourses (NW Spain). In summer 2008 and 2009, a total of 355 epilithic diatom samples were collected following standard protocols. The 2008 samples were used to develop the DDI, whereas the samples collected during 2009 were used in the index testing. Weighted averages method was used to derive the autoecological profiles of diatoms with respect to pH, conductivity, biological oxygen demand, ammonia, nitrates, and phosphates. The optimum and tolerance values for the measured environmental variables were determined for 137 taxa with abundances and frequencies of occurrence above 1%, and subsequent trophic indicator and sensitivity values were defined for the DDI. The correlation between the observed and the diatom-inferred nutrient concentrations was highest for phosphates (ρ (S) = 0.72). Significant statistical relationship were observed between DDI values and the chemistry-based General Quality Index values (p = 0.006) and the specific pollution index (SPI) diatom metric (p = 0.04). DDI has demonstrated a better correlation with water chemistry than SPI diatom metric.

Effect of climatic conditions, season and wastewater quality on contaminant removal efficiency of two experimental constructed wetlands in different regions of Spain.

The aim of this study was to examine the effects of climate, season and wastewater quality on contaminant removal efficiency of constructed wetlands implemented in Mediterranean and continental-Mediterranean climate region of Spain. To this end, two experimental horizontal subsurface flow constructed wetlands located in Barcelona and León (Spain) were compared. The two constructed wetland systems had the same experimental set-up. Each wetland had a surface area of 2.95 m(2), a water depth of 25 cm and a granular medium of D(60)=7.3 mm, and was planted with Phragmites australis. Both systems were designed in order to operate with a maximum organic loading rate of 6 g(DBO) m(-2) d(-1). Experimental systems operated with a hydraulic loading rate of 28.5 and 98 mm d(-1) in Barcelona and León, respectively. Total suspended solids, biochemical oxygen demand and ammonium mass removal efficiencies followed seasonal trends, with higher values in the summer (97.4% vs. 97.8%; 97.1% vs. 96.2%; 99.9% vs. 88.9%, in Barcelona and León systems, respectively) than in the winter (83.5% vs. 74.4%; 73.2% vs. 60.6%; 19% vs. no net removal for ammonium in Barcelona and León systems, respectively). During the cold season, biochemical oxygen demand and ammonium removal were significantly higher in Barcelona system than in León, as a result of higher temperature and redox potential in Barcelona. During the warm season, statistical differences were observed only for ammonium removal. Results showed that horizontal subsurface flow constructed wetland is a successful technology for both regions considered, even if winter seemed to be a critical period for ammonium removal in continental climate regions.

Comparison of interannual removal variation of various constructed wetland types.

Seven mesocosm-scale (1m(2)) constructed wetlands (CWs) of different configurations were operated outdoors for thirty-nine months under the same conditions to assess their ability to remove organic matter and nutrients from urban wastewaters. CWs differed in some design parameters, namely the presence of plants, the species chosen (i.e., Typha angustifolia or Phragmites australis), the flow configuration (i.e., surface flow or subsurface flow) and the presence/absence of a gravel bed. It was observed that, in general, removal efficiencies decreased with the aging of the system and that seasonality had a great influence on CWs. A comparison was made in order to figure out which kind of CW was more efficient for the removal of every pollutant in the long term. Planted systems were clearly better than unplanted systems even in winter. Efficiency differences among CWs were not extremely great, especially after a few years. However, some types of CWs were more adequate for the removal of certain pollutants. The effect of the aging on the main parameters involved in pollutant removal in CWs (temperature, pH, conductivity, dissolved oxygen concentration and redox potential) was assessed. The efficiency of CWs should not be evaluated based on short monitoring periods (1-2 years) after the start-up of the systems, but on longer periods.

Temporal evolution in PPCP removal from urban wastewater by constructed wetlands of different configuration: a medium-term study.

Pharmaceuticals and personal care products (PPCPs) are widely distributed in urban wastewaters and can be removed to some extent by constructed wetlands (CWs). The medium-term (3-5 years) behaviour of these systems regarding PPCP removal is still unknown. Seven mesocosm-scale (1 m(2)) CWs of different configurations were operated outdoors for 39 months under the same conditions to assess their PPCP removal ability and temporal evolution. CWs differed in some design parameters, namely plant presence, species chosen (Typha angustifolia vs Phragmites australis), flow configuration and presence/absence of gravel bed (floating macrophytes surface flow, FM-SF; free-water surface flow, FW-SF; free-water subsurface flow, FW-SSF; or conventional horizontal subsurface flow, SSF). PPCP efficiencies decreased throughout time and performance differences among CWs disappeared with the systems aging. This could be due to a homogenization process in the systems caused by detrimental factors like saturation, clogging and shading. Winter efficiencies were lower than summer ones for salicylic acid, caffeine, methyl dihydrojasmonate, galaxolide and tonalide, and seasonal biological activities seem key factors to explain this fact. Maximal removal efficiencies were achieved in an unplanted-FW-SSF for ketoprofen (47-81%), naproxen (58-81%) and salicylic acid (76-98%); in an unplanted-SSF for caffeine (65-99%); in a Phragmites-FM-SF for ibuprofen (49-96%) and diclofenac (16-68%); in a Typha-FM-SF for carbamazepine (35-71%); and in a Typha-FW-SSF for methyl dihydrojasmonate (71-96%), galaxolide (67-82%) and tonalide (55-74%). Photodegradation could be involved in ketoprofen, naproxen, ibuprofen and diclofenac removal. Carbamazepine and diclofenac were moderately removed by the most efficient CWs studied. Carbamazepine might be eliminated by vegetal uptake.

Removal of antibiotics from urban wastewater by constructed wetland optimization.

Seven mesocosm-scale constructed wetlands (CWs), differing in their design characteristics, were set up in the open air to assess their efficiency to remove antibiotics from urban raw wastewater. A conventional wastewater treatment plant (WWTP) was simultaneously monitored. The experiment took place in autumn. An analytical methodology including HPLC-MS/MS was developed to measure antibiotic concentrations in the soluble water fraction, in the suspended solids fraction and in the WWTP sludge. Considering the soluble water fraction, the only easily eliminated antibiotics in the WWTP were doxycycline (61±38%) and sulfamethoxazole (60±26%). All the studied types of CWs were efficient for the removal of sulfamethoxazole (59±30-87±41%), as found in the WWTP, and, in addition, they removed trimethoprim (65±21-96±29%). The elimination of other antibiotics in CWs was limited by the specific system-configuration: amoxicillin (45±15%) was only eliminated by a free-water (FW) subsurface flow (SSF) CW planted with Typha angustifolia; doxycycline was removed in FW systems planted with T. angustifolia (65±34-75±40%), in a Phragmites australis-floating macrophytes system (62±31%) and in conventional horizontal SSF-systems (71±39%); clarithromycin was partially eliminated by an unplanted FW-SSF system (50±18%); erythromycin could only be removed by a P. australis-horizontal SSF system (64±30%); and ampicillin was eliminated by a T. angustifolia-floating macrophytes system (29±4%). Lincomycin was not removed by any of the systems (WWTP or CWs). The presence or absence of plants, the vegetal species (T. angustifolia or P. australis), the flow type and the CW design characteristics regulated the specific removal mechanisms. Therefore, CWs are not an overall solution to remove antibiotics from urban wastewater during cold seasons. However, more studies are needed to assess their ability in warmer periods and to determine the behaviour of full-scale systems.

Statistical modelling of organic matter and emerging pollutants removal in constructed wetlands.

Multiple regression models, clustering tree diagrams, regression trees (CHAID) and redundancy analysis (RDA) were applied to the study of the removal of organic matter and pharmaceuticals and personal care products (PPCPs) from urban wastewater by means of constructed wetlands (CWs). These four statistical analyses pointed out the importance of physico-chemical parameters, plant presence and chemical structure in the elimination of most pollutants. Temperature, pH values, dissolved oxygen concentration, redox potential and conductivity were related to the removal of the studied substances. Plant presence (Typha angustifolia and Phragmites australis) enhanced the removal of organic matter and some PPCPs. Multiple regression equations and CHAID trees provided numerical estimations of pollutant removal efficiencies in CWs. These models were validated and they could be a useful and interesting tool for the quick estimation of removal efficiencies in already working CWs and for the design of new systems which must fulfil certain quality requirements.

Mechanisms for parasites removal in a waste stabilisation pond.

A waste stabilisation pond (WSP) system formed by two anaerobic ponds, a facultative pond and a maturation pond was studied from December 2003 to September 2004 in north-western Spain in order to evaluate its efficiency in the removal of faecal indicator bacteria (total coliforms, Escherichia coli, faecal streptococci), coliphages, helminth eggs and protozoan (oo)cysts (Cryptosporidium and Giardia). Furthermore, sediment samples were collected from the bottom of the ponds to assess the settling rates and thus determine the main pathogen removal mechanisms in the WSPs system. The overall removal ranged from 1.4 log units for coliphages in the cold period to 5.0 log units for E. coli in the hot period. Cryptosporidium oocysts were reduced by an average of 96%, Giardia cysts by 98% and helminth eggs by 100%. The anaerobic ponds showed significantly higher surface removal rates (4.6, 5.2 and 3.7 log (oo)cysts/eggs removed m(-2) day(-1), respectively) than facultative and maturation ponds. Sunlight and water physicochemical conditions were the main factors influencing C. parvum oocysts removal both in the anaerobic and maturation ponds, whereas other factors like predation or natural mortality were more important in the facultative pond. Sedimentation, the most commonly proposed mechanism for cyst removal had, therefore, a negligible influence in the studied ponds.

Coagulation/flocculation-based removal of algal-bacterial biomass from piggery wastewater treatment.

Two conventional chemical coagulants (FeCl3 and Fe2(SO4)3) and five commercial polymeric flocculants (Drewfloc 447, Flocudex CS/5000, Flocusol CM/78, Chemifloc CV/300 and Chitosan) were comparatively evaluated for their ability to remove algal-bacterial biomass from the effluent of a photosynthetically oxygenated piggery wastewater biodegradation process. Chlorella sorokiniana, Scenedesmus obliquus, Chlorococcum sp. and a wild type Chlorella, in symbiosis with a bacterial consortium, were used as model algal-bacterial consortia. While the highest biomass removals (66-98%) for the ferric salts were achieved at concentrations of 150-250 mg L(-1), dosages of 25-50 mg L(-1) were required for the polymer flocculants to support comparable removal efficiencies. Process efficiency declined when the polymer flocculant was overdosed. Biomass concentration did not show a significant impact on flocculation within the concentration range tested. The high flocculant requirements herein recorded might be due to the competition of colloidal organic for the flocculants and the stationary phase conditions of biomass.

Optimization of performance assessment and design characteristics in constructed wetlands for the removal of organic matter.

Some of the most used constructed wetland (CW) configurations [conventional and modified free-water (FW) flow, surface flow, conventional horizontal subsurface flow (SSF) and soilless systems with floating macrophytes (FM)] were assessed in order to compare their efficiencies for the removal of organic pollutants [COD, filtered COD (FCOD), BOD and total suspended solids (TSS)] from urban sewage under the same climatic and wastewater conditions. The removal performance was calculated using three approaches: effluent concentrations, areal removed loads and mass removal. Results were very different depending on the approach, which indicates that the way to present CW efficiency should be considered carefully. All CW-configurations obtained BOD effluent concentrations below 25 mg L(-1) in summer, with a FW-CW with effluent leaving through the bottom of the tank being the only one maintaining low BOD effluent concentrations even in winter and under high organic loading conditions. In this kind of CW, the presence of plants favoured pollutant removal. SSF-CWs were the most efficient for the removal of COD. FM systems can be as efficient as some gravel bed CWs. Typhaangustifolia worked better than Phragmitesaustralis, at least when the systems were at the beginning of their operation period.

Influence of flue gas sparging on the performance of high rate algae ponds treating agro-industrial wastewaters.

The influence of flue gas sparging (7% CO(2)) on the performance of two 465 L High-Rate Algal Ponds (HRAPs) treating diluted swine manure at 10 days of hydraulic retention time was evaluated under continental climatic conditions (Castilla y León, Spain). COD, NH(4)(+), and PO(4)(3-) removal efficiencies were not significantly affected by flue gas input (at 2.2 and 5.5 L min(-1)), which suggests that CO(2) sparging does not compromise wastewater treatment in HRAPs. In this particular study, COD and NH(4)(+) removal efficiencies of 56+/-31% (near to maximum swine manure biodegradability) and 98+/-1%, respectively, were consistently maintained, regardless of the environmental and operational conditions. CO(2) sparging resulted however in lower pH values (approximately 2 units lower) and an enhanced NH(4)(+) nitrification (higher NO(3)(-) and NO(2)(-) concentrations) compared to the system operated in the absence of flue gas supply. Biomass concentration was only higher (approximately 30% than in the control HRAP) when flue gases were supplied at 5.5 L min(-1), probably due to the fact that the higher irradiances and temperatures prevailing within this experimental period resulted in an inorganic carbon-limited scenario in the control HRAP. Therefore, it can be concluded that CO(2) assimilation would be ultimately dependent on the occurrence of inorganic carbon limitation and will never occur in light, COD or nutrients-limited scenarios.

Comprehensive assessment of the design configuration of constructed wetlands for the removal of pharmaceuticals and personal care products from urban wastewaters.

Seven mesocosm-scale constructed wetlands (CWs) of different configurations were operated outdoors for nine months to assess their ability to remove pharmaceuticals and personal care products (PPCPs) from urban wastewaters. CWs differed in some design parameters, namely the presence of plants, the species chosen (i.e., Typha angustifolia vs Phragmites australis), flow configuration (i.e., surface flow vs subsurface flow) and the presence of a gravel bed. A nearby conventional activated-sludge wastewater treatment plant (WWTP) fed with the same sewage was simultaneously monitored for comparison. The PPCPs ketoprofen, naproxen, ibuprofen, diclofenac, salicylic acid, carbamazepine, caffeine, galaxolide, tonalide and methyl dihydrojasmonate were monitored. The presence of plants favoured the removal of some PPCPs. The performance of the mesocosm studied was compound-dependant, soilless CWs showing the highest removal efficiency for ketoprofen, ibuprofen and carbamazepine, while free-water CWs with effluent leaving through the bottom of the tank performed well for the degradation of ketoprofen, salicylic acid, galaxolide and tonalide. Finally, subsurface horizontal flow CWs were efficient for the removal of caffeine. Significant linear correlations were observed between the removal of some PPCPs and temperature or redox potential. Hence, microbiological pathways appear to be the most probable degradation route for PPCPs in the CWs studied.