Trace elements and legacy and emerging organic contaminants concentrations datasets in sediments cores in L'Albufera Natural Park (Valencia, East of Spain): Association with "in-deep" sediment characteristics and risk assessment to the aquatic biota.

The chronological information provided by sediment cores about the beginning and evolution of anthropogenic contaminants is crucial for understanding the influence of humans on the environment. The dataset provides information about the vertical distribution of heavy metals (HMs), metalloids and various organic contaminants (OCs) including contemporary contaminants of emerging concern (CECs), such as pharmaceuticals and personal care products (PPCPs) and pesticides; as well as persistent organic contaminants (POPs) such as polycyclic aromatic hydrocarbons (PAHs), perfluoroalkyl substances (PFASs), organophosphorus flame retardants (OPFRs) in sediment cores of two different sampling areas (North and South) of L'Albufera lake. Additional information about the 14C-data of the organic matter present in the different layers of the sediment cores, and the 14C-data of the seashells found in some of them are shown. The dataset includes physico-chemical analyses of sediment characteristics at the different selected depth levels such as Organic Carbon (Corg), Inorganic Carbon (IC), Total Nitrogen (TN), Total Sulphur (TS) and texture. Furthermore, ecological risk assessment of these contaminants in surface sediment layers is performed to ascertain is potential toxicity. These data supplement the findings presented and considered in the research article "Exploring Organic and Inorganic Contaminant Histories in Sediment Cores Across the Anthropocene: Accounting for Site/Area Dependent Factors". Therefore, these data altogether are useful for researchers seeking to assess long-term impact of contamination.

Removal and fate of microplastics in permeable pavements: An experimental layer-by-layer analysis.

The increasing prevalence of microplastics (MP) in urban environments has raised concerns over their negative effects on ecosystems and human health. Stormwater runoff, and road dust and sediment, act as major vectors of these pollutants into natural water bodies. Sustainable urban drainage systems, such as permeable pavements, are considered as potential tools to retain particulate pollutants. This research evaluates at laboratory scale the efficiency of permeable interlocking concrete pavements (PICP) and porous concrete pavements (PCP) for controlling microplastics, including tire wear particles (TWP) which constitute a large fraction of microplastics in urban environments, simulating surface pollution accumulation and Mediterranean rainfall conditions. Microplastic levels in road dust and sediments and stormwater runoff inputs were 4762 ± 974 MP/kg (dry weight) and 23.90 ± 17.40 MP/L. In infiltrated effluents, microplastic levels ranged from 2.20 ± 0.61 to 5.17 ± 1.05 MP/L; while tire wear particle levels ranged between 0.28 ± 0.28 and 3.30 ± 0.89 TWP/L. Distribution of microplastics within the layers of PICP and PCP were also studied and quantified. Microplastics tend to accumulate on the pavements surface and in geotextile layers, allowing microplastic retention efficiencies from 89 % to 99.6 %. Small sized (< 0.1 mm) fragment shaped microplastics are the most common in effluent samples. The results indicate that permeable pavements are a powerful tool to capture microplastics and tire wear particles, especially by surface and geotextile layers. The study aims to shed light on the complex mobilisation mechanisms of microplastics, providing valuable insights for addressing the growing environmental concern of microplastic pollution in urban areas.

Exploring organic and inorganic contaminant histories in sediment cores across the anthropocene: Accounting for site/area dependent factors.

Sedimentary records help chronologically identify anthropogenic contamination in environmental systems. This study analysed dated sediment cores from L'Albufera Lake (Valencia, Spain), to assess the occurrence of heavy metals (HMs), polycyclic aromatic hydrocarbons (PAHs), perfluoroalkyl substances (PFASs), organophosphorus flame retardants (OPFRs), pesticides and pharmaceuticals and personal care products (PPCPs). The results evidence the continuing vertical presence of all types of contaminants in this location. The sediment age was difficult to establish. However, the presence of shells together with an historical estimation and the knowledge of sedimentary rates could help. HMs contents are higher in the upper layer reflecting the most recent increase of the industrial and agricultural practices in the area since the middle 20th century. Higher availability index of these HMs in the upper sediment layers is associated with point and diffuse contamination sources in the area. PAHs and OPFRs were homogeneous distributed through the sediments with few exceptions such as phenanthrene in the North and fluoranthene in the South. Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) were detected throughout the sediment core while short-chain PFASs (except perfluoropentanoic acid (PFPeA)) were detected only in the top layer. Pesticides and PPCPs showed appreciable down-core mobility. The vertical concentration profiles of organic contaminants did not exhibit a clear trend with depth, then, it is difficult to develop a direct relationship between sediment age and contaminant concentrations, and to elucidate the historical trend of contamination based on dated sediment core. Consequently, linking contaminant occurrence in sediments directly to their historical use is somewhat speculative at least in the conditions of L'Albufera Lake.

Microplastics occurrence and fate in full-scale treatment wetlands.

Treatment wetlands (TWs) are an efficient technology for removing microplastics (MPs) from wastewater, according to previous studies. This study investigates the dynamics and fate of MPs in two wastewater treatment plants (WWTPs) using TWs, one with horizontal subsurface flow (HF) and another with a floating plant system (FS). Special attention is paid to the retention produced in the sludge and the role of macrophyte roots. The abundance of MPs in the influent to the WWTPs was on average 20.3 ± 0.85 MP/L and 8.4 ± 1.13 MP/L in HF and FS respectively, while the effluent had 0.58 ± 0.07 MP/L and 0.17 ± 0.06 MP/L, thus giving overall efficiencies of 97.42% and 98.13%, respectively. In the HF wetland, sludge samples near the inlet and the outlet were taken, distinguishing between sludge adhered to gravel and sludge attached to roots. In the floating macrophytes, sludge samples from secondary and tertiary treatments were taken. The results indicate that roots play a significant role in MPs retention. In the HF wetland, the complex formed by roots and gravel attached more MPs than gravel alone in the final zone of the wetland. In the FS, roots retained a significant quantity of MPs, both in the secondary and tertiary treatments, thus giving rise to a sludge less concentrated in MPs. This study aims to improve the knowledge of MPs behavior and fate in full-scale TWs, providing valuable information to enhance retention efficiency.

Escherichia coli removal in a treatment wetland - pond system: A mathematical modelling experience.

A full-scale treatment wetland (TW) (100 inhabitants, 14 m3·d-1), composed of two horizontal subsurface flow wetlands (TW1-400 m2 and TW2-200 m2) and a small pond (13 m2), has been evaluated for Escherichia coli (E. coli) removal. The results indicate a global removal from 1.74·106 to 685 MPN·100 mL-1 (3.41 log units), reducing E. coli sufficiently to reach values suitable for reuse purposes such as agricultural reuse, without energy and reagent consumption. The small pond at the end of the treatment train plays an important role in E. coli removal and biodiversity enhancement. Data from TW1 and TW2 have been fitted to the P-k-C* model, giving values of 134 and 100 m·yr-1 for the first-order kinetic reaction coefficient. For the pond, a process-based model using continuous stirred-tank reactor (CSTR) and a 3d-CFD model have been implemented and compared. The models indicate that solar disinfection and predation by daphnids are the most important mechanisms in the studied pond, representing 65% and 25% of the removal respectively. It can be concluded that CSTR can provide good results for small ponds and 3d-CFD model provides extra information, useful to enhance their design.

Fate and removal of microplastics in unplanted lab-scale vertical flow constructed wetlands.

Many studies have reported conventional wastewater treatment plants as one of the main sources of microplastics (MPs). However, constructed wetlands (CWs) as a nature-based wastewater treatment system have received little attention. This study investigated the influence of biofilm, media type and earthworms on the fate and removal of MPs in a short-term (45d) experiment with unplanted lab-scale vertical flow CWs (VFCWs). In sand-filled VFCWs, MPs were retained in the first 10 cm, and the removal efficiency was 100%, regardless of the presence of a biofilm. When gravel was used as filling material, the removal efficiency of MPs was stable at 96%, but the MPs were distributed throughout the 80 cm high VFCWs. In the presence of earthworms, the maximum depth that MPs reached within sand-filled VFCWs increased from 10 to 15 cm. Furthermore, the MPs concentration at a depth of 3-6 cm and 6-10 cm increased 2 and 10 fold respectively compared to the same VFCWs without earthworms. Although no MPs were detected in the sand from deep layers (15-80 cm), transport of MPs from top to the bottom by earthworms was found, and a few MPs were detected in the effluent, leading to a removal efficiency of 99.8%. This study indicated that both a higher media grain size and the presence of earthworms have a small effect on the removal efficiency of MPs in VFCWs, but the effect on the distribution of MPs was considerably. Longer-term studies in full-scale CWs are advised to perform under the influence of more practical factors.

Horizontal subsurface flow constructed wetlands as tertiary treatment: Can they be an efficient barrier for microplastics pollution?

The presence and fate of microplastics (MPs) in wastewater represent a subject of major concern, as wastewater is one of the main inputs of MPs to the environment. This study deals with the ability of horizontal subsurface-flow constructed wetlands (CWs), as tertiary treatment, to reduce the MPs concentration of secondary effluents. Different locations of a wastewater treatment plant (WWTP) including raw wastewater, CW influent and final effluent, were sampled. Macroinvertebrates were collected from the CW to evaluate their potential role in the MPs distribution along the wetland. The global WWTP efficiency for MPs removal was 98%. MPs removal efficiency by CW was on average 88%, causing a significant reduction of the MPs concentration from 6.45 to 0.77 MP/L (p < 0.05), thus preventing them from entering vulnerable aquatic systems. The areal removal rate and the first order areal rate coefficient (kA) were estimated to be 3120 MPs/m2/d and 1.70 m/d, respectively. The most abundant size fraction was the one comprising MPs between 75 and 425 µm (51%), while the other size ranges analysed (40-75 and 425-5600 µm) accounted for 25 and 24%, respectively. Fiber was the most abundant shape in the WWTP influent (75%), the CW influent (54%) and effluent (71%). Non-significant differences were found between sites regarding size and shape distributions (p > 0.05). Macroinvertebrates can ingest a non-negligible quantity of MPs, with an average content of 166.2 MPs/g or 0.13 MPs/individual. Therefore, they could play a certain role in the MPs distribution inside CWs. Fiber was the most abundant shape for macroinvertebrates as well (89%), so attention should be paid to reduce their contamination at source. This study provides the first results on MPs removal in CWs as tertiary treatment and assesses the potential role of macroinvertebrates in their distribution along the CW, thus filling this gap of knowledge.

Influence of rainfall intensity and pollution build-up levels on water quality and quantity response of permeable pavements.

Permeable pavements are part of stormwater management practices known as sustainable urban drainage systems (SUDS). This study describes the influence of several environmental variables, such as the rainfall regime or the pollution build-up level, on the hydraulic and water quality performance of permeable pavements. Four infiltrometers with different configurations of pavement layers were used to study the influence of two rainfall regimes (Atlantic and Mediterranean) and two rainfall intensities (0.5 and 2.2mm/min). The influence of the progressive pollution build-up level was studied by dry sprinkling of road deposited sediments collected with a mechanical street sweeper with a dose of 5g/m2/d. The results show that permeable pavements retained a significant rainwater volume and improved the infiltrated water quality in terms of suspended solids, organic matter and nutrients when compared to the corresponding surface runoff potentially generated from an impervious pavement. The volume of rainwater retained inside them varied between 16 and 66% depending on the variables studied. The water infiltrated from permeable pavements subjected to a Mediterranean rainfall regime contained, in general, higher concentrations of organic matter (22 to 89mg Chemical Oxygen Demand/l) and nutrients (0.6 to 2.1mg Total Nitrogen/l and 0.05 to 0.45mg Total Phosphorus/l) than those under Atlantic regime. However, the latter infiltrated higher loadings in terms of mass. Nitrogen was the substance that infiltrated the most, reaching a 25% of the total mass of nitrogen deposited on the pavements surface. The concentration and mass loading in infiltrated water increased as the pollution build-up level did. The leachability of nutrients and organic matter was greater for high rainfall intensities. The results suggest that it is essential to carry out an adequate cleaning in dry conditions, especially when high intensity rainfall events are foreseen, because of its greater capacity to mobilize pollutants.

Numerical simulation of vertical flow wetlands with special emphasis on treatment performance during winter.

In Austria, single-stage vertical flow (VF) wetlands with intermittent loading are a state-of-the-art technology for treating domestic wastewater. They are designed according to the Austrian design standard with a specific surface area of 4 m2 per person (i.e. 20 g COD/(m2·d)) and thus demand a bigger amount of land to treat the same amount of wastewater compared to intensified technical treatment systems. In order to reduce the amount of land needed, a modified design for VF wetlands has been proposed. The modified design has a specific surface area of 2.5 m2 per person (i.e. 32 g COD/(m2·d)) and it has been shown to be able to meet the Austrian effluent requirements. To allow higher organic loading, more loadings per day but lower volume of a single loading, a constant loading interval, and increased number of openings per m2 are applied. A simulation study using the HYDRUS Wetland Module was carried out to compare the treatment efficiencies of single-stage VF wetlands with classical and modified design. Data from a classical Austrian single-stage VF wetland was used for calibration of the model using the standard parameter set for the CW2D biokinetic model. The influent COD fractionation was calibrated to adapt to the wastewater. The simulations showed a good performance of the modified design compared to a classical VF wetland for COD removal with COD effluent concentrations in winter (effluent water temperature of 4.5 °C) of 35 and 29 mg/L, respectively. The simulation study showed that during high-loading events the VF wetland with modified design has lower maximum NH4-N effluent concentrations. Single-stage VF wetlands with modified design seem to be very effective and allow application of higher organic loads compared to single-stage VF wetlands with classical design.

Characterization of wash-off from urban impervious surfaces and SuDS design criteria for source control under semi-arid conditions.

Knowledge about pollutant wash-off from urban impervious surfaces is a key feature for developing effective management strategies. Accordingly, further information is required about urban areas under semi-arid climate conditions at the sub-catchment scale. This is important for designing source control systems for pollution. In this study, a characterization of pollutant wash-off has been performed over sixteen months, at the sub-catchment scale for urban roads as impervious surfaces. The study was conducted in Valencia, Spain, a city with a Mediterranean climate. The results show high event mean concentrations for suspended solids (98mg/l), organic matter (142mgCOD/l, 25mgBOD5/l), nutrients (3.7mgTN/l, 0.4mgTP/l), and metals (0.23, 0.32, 0.62 and 0.17mg/l for Cu, Ni, Pb, and Zn, respectively). The results of the runoff characterization highlight the need to control this pollution at its source, separately from wastewater because of their different characteristics. The wash-off, defined in terms of mobilized mass (g/m2) fits well with both process-based and statistical models, with the runoff volume and rainfall depth being the main explanatory variables. Based on these results and using information collected from hydrographs and pollutographs, an approach for sizing sustainable urban drainage systems (SuDS), focusing on water quality and quantity variables, has been proposed. By setting a concentration-based target (TSS discharged to receiving waters <35mg/l), the results indicate that for a SuDS type detention basin (DB), an off-line configuration performs better than an on-line configuration. The resulting design criterion, expressed as SuDS volume per unit catchment area, assuming a DB type SuDS, varies between 7 and 10l/m2.

Mid-term variation of vertical distribution of acid volatile sulphide and simultaneously extracted metals in sediment cores from Lake Albufera (Valencia, Spain).

Lake Albufera is one of the most eutrophic bodies of water in Spain due to point and diffuse pollution over past decades, and its sediments are likely to be anoxic because of high organic matter flux. Hence, sulphides can play an important role in limiting the mobility of heavy metals. This study aimed to study the vertical variation of acid volatile sulphide (AVS) and simultaneously extracted metals (SEM) in sediment cores collected from Lake Albufera; other sediment characteristics, such as organic matter, biochemical oxygen, demand or total metals, were also studied. Three sites were selected, and four sampling campaigns were performed to study spatial and temporal variation as well as to obtain information regarding historical variation in the composition of sediments. AVS and SEM were analysed by the purge-and-trap method. The vertical distribution of AVS and SEM varied depending on the sampling site-concentrations of AVS and SEM were higher at sites close to mouths of inflowing channels. A decreasing trend of AVS has been found at these sites over time: In the two first samplings, AVS increased with depth reaching maximum concentrations of 40 and 21 µmol g(-1), but from then on AVS were lower and decreased with depth. SEM decreased with depth from 3 µmol g(-1) in surface layers to approximately 1 µmol g(-1) at deeper segments at these sites. However, the central site was more uniform with respect to depth as well as with time; it presented lower values of SEM and AVS (mean 0.9 and 2.0 µmol g(-1) respectively), and the maximum value of AVS (7 µmol g(-1)) was found at the top layer (0-3 cm). According to the (SEM-AVS)/fOC approach, every site, and throughout the cores, can be classified as containing nontoxic metals because the values were <130 µmol g(-1).