Search

Livestock farming wastewater is complex in composition, containing a large number of pathogenic microorganisms and ammonia nitrogen (NH 4 +-N) with high concentration, which makes biological treatment difficult. In this study, tidal flow constructed wetlands were applied to treat piggery biogas slurry. Compared with a continuous flow constructed wetland, two tidal influent modes (hydraulic retention time: idling time for 12 h:12 h and 20 h:4 h, namely TFCW1 and TFCW2) were set up to explore treatment performances on chromaticity, turbidity, chemical oxygen demand (COD), total nitrogen (TN), NH 4 +-N and total phosphorus (TP), and determine the relationship between nitrogen transfer and dissolved oxygen (DO) contents. The fluorescence spectra of dissolved organic matter (DOM) in constructed wetlands were analyzed by excitation-emission matrix spectroscopy-parallel factor analysis to reveal its composition and content of humus. The results showed that tidal flow constructed wetlands obviously improved the removal of chromaticity and turbidity by 44.6% and 10.1%, in comparison to continuous flow constructed wetland. TFCW2 had enhanced reduction on pollutants, with removal efficiencies of COD, NH 4 +-N and TP at 78.6%, 82.1% and 84.0%, respectively. Furthermore, three fluorescent components were detected in TFCW2, and the value of Fmax was increased in the effluent, among which the Fmax of C3 (Humic-like substances) increased obviously from 0.320 to 9.39. The ratio of C2 (Aquatic fulvic acids) to C3 showed a slow increasing trend in the daily outflow of TFCW2, while C1 (dark-incubation substances) remained relatively constant. Fluorescence index (FI), humification index (HIX) and biological index (BIX) increased from 1.35 to 2.09, 0.210–1.51, and 0.240–1.05, respectively, showing that the effluent from the tidal flow constructed wetland had a high microbial activity. This study provided a new insight for the advanced treatment of livestock biogas slurry with a high NH 4 +-N content. [Display omitted] • Actual piggery biogas slurry was treated by tidal flow constructed wetland. • The changes of DO and pollutant concentrations along the system were detected. • 82.1% of NH 4 +-N and 84.0% of TP were removed by tidal flow constructed wetlands. • Dark-incubation substances, aquatic fulvic acids and humic-like substances were three main components in DOM. [ABSTRACT FROM AUTHOR]

Cities worldwide face resilience challenges as climate risks interact with rapid urbanization, loss of biodiversity and ecosystem services, poverty, and Socioeconomic inequality. This leads to the social, physical, and economic collapse of cities and their systems. Over time, urban resilience challenges are expected to increase, driven by urbanization, land use, and climate change. It is for this reason that the concept of urban resilience is increasingly attracting the attention of governments, and urban planners. Gray infrastructure is not always suitable for profitability, resilience, or sustainability. Now more than ever, green infrastructure is recognized as a nature-based solution (NBS) that plays a significant role in addressing resilience challenges in urban areas. These solutions can be applied through spatial measurements and parameters in and around the city. Constructed wetlands (Cws) are artificial imitations of natural wetlands, one of the most biologically diverse natural ecosystems, and in addition to aesthetics, It provides an effective model for resilient environmental engineering solutions as a low-cost and easy-to-operate alternative to traditional urban management systems. Consequently, the main objective of this research was to define criteria for integrating constructed wetlands (Cws) into the urban landscape as nature-based solutions (NBS) and address the limitations and maximize advantages as well as contribute to replicate best practices of constructed wetlands (Cws) in different Zones (Desert, River's floodplain, coastal) in Egyptian cities for enhancing the urban resilience. [ABSTRACT FROM AUTHOR]

Constructed wetland helps to improve the environmental and social values of the inhabited catchments and their downstream natural water bodies. However, the environmental impacts due to its construction necessitate evidence of how beneficial it would be once operational compared to other water-sensitive urban design (WSUD) components. The study has simulated the reduction of pollutants and runoff in a wetland. Consequently, environmental impacts were estimated using the life cycle assessment (LCA) approach. The catchment settings with and without wetlands were compared with the environmentally viable rainwater harvesting (RWH) systems. Potable supply using watermain was included in the catchment settings to have a common basis for their evaluation, which was not considered in the existing literature. The study demonstrates that the runoff impacts (operational) of the catchment having a watermain (without a wetland system) are 3.6–4.5, 4.0, 3.2–4.7, and 2.7–3.5 times of catchment with wetland-only on ecotoxicity-marine, ecotoxicity-freshwater, human toxicity-carcinogenic, and eutrophication categories. For the same systems, the net impacts (fabrication & installation + operational) of all undertaken impact categories are 3–28.6 times. In contrast, the net impacts of the residual runoff generated by the most viable RWH systems after supplying household demands (i.e., % reliability of the RWH tanks) are mostly 2.3–30.5 times the net impacts of the catchment having wetland-only. In an equivalent assessment, the catchment net impacts of the watermain system (with wetland) as times of impacts of RWH systems are 0.2–0.91 times on eutrophication, ozone depletion, ecotoxicity-marine (in lower series of RWH), and ecotoxicity-freshwater. In contrast, those systems are mostly 1.02–3.12 times on human toxicity-carcinogenic, global warming, ecotoxicity-terrestrial and higher series of ecotoxicity-marine impact categories. The study suggests that wetland or RWH is suitable if emission prevention to water or air is emphasized. [ABSTRACT FROM AUTHOR]

This paper addresses the regulation of water quality influencers such as Organic Nitrogen, Ammonia Nitrogen, Nitrate Nitrogen, Dissolved Organic Carbon and Dissolved Oxygen for a sub-surface flow horizontal wetland in a controlled environment. The plant uncertainty is quantified by using measurement data. The robust control of the process is achieved using a decentralized quantitative feedback theory based control strategy. The control structure also employs a feed-forward mechanism to minimize loop interactions and feedback control to ensure stability, tracking and disturbance rejection. The numerical simulations and hardware-in-loop implementation show that the performance specifications are robustly met. • The control of water quality deciding variables by using a constructed wetland • The parametric uncertainty is quantified using measurement data collected • A decentralized quantitative feedback theory based robust controller is adopted • Each loop is equipped with feed-forward controllers to minimize coupling effects • Performance is verified by numerical simulation and hardware-in-Loop validation [ABSTRACT FROM AUTHOR]

Antibiotics, their transformation products, and the translocation of antibiotic-resistant genes in the environment pose significant health risks to humans, animals, and ecosystems, aligning with the One Health concept. Constructed wetlands hold substantial yet underutilized potential for treating wastewater from agricultural, domestic sewage, or contaminated effluents from wastewater treatment plants, with the goal of eliminating antibiotics. However, the comprehensive understanding of the distribution, persistence, and dissipation processes of antibiotics within constructed wetlands remains largely unexplored. In this context, we provide an overview of the current application of stable isotope analysis at natural abundance to antibiotics. We explore the opportunities of an advanced multiple stable isotope approach, where isotope concepts could be effectively applied to examine the fate of antibiotics in wetlands. The development of a conceptual framework to study antibiotics in wetlands using multi-element stable isotopes introduces a new paradigm, offering enhanced insights into the identification and quantification of natural attenuation of antibiotics within wetland systems. This perspective has the potential to inspire the general public, governmental bodies, and the broader research community, fostering an emphasis on the utilization of stable isotope analysis for studying antibiotics and other emerging micropollutants in wetland systems. [ABSTRACT FROM AUTHOR]

Understanding the controls on uranium (U) mobility in the environment is key to improve the management of sites contaminated by U mining activities. Previous research has shown that natural or engineered wetlands are particularly able to scavenge high amounts of U(VI) and U(IV) under noncrystalline forms. However, questions remain on the respective roles of sorption and reduction processes in the removal of U from running waters in wetlands, as well as on the long-term stability of U storage. Here, we performed a series of geochemical, isotopic (δ238U, (234U/238U)), microscopic (SEM-EDXS, EPMA) and spectroscopic (µ-XRF, µ-XAS, XANES and EXAFS at the U L 3 and M 4 -edges and Fe K -edge) investigations to determine the modes of U accumulation and assess U mobility in a natural exceptionally U-enriched (up to 5000 µg/g) wetland on the shore of Lake Nègre (Mediterranean Alps, France). Uranium (VI) was largely dominant in the two studied soil cores, except a few samples containing as much as ∼50 % U(IV). At the particle scale, U is associated to a variety of organic constituents of the soil matrix with a homogenous oxidation state. Bulk EXAFS spectroscopy at the U L 3 -edge shows that U is mostly mononuclear, with dominant monodentate binding to organic moieties (C neighbors at ∼3.45 Å). An additional minor fraction of U under polymeric forms is inferred from wavelet (CCWT) analysis of the EXAFS data. These observations are reinforced by 1 M bicarbonate extractions that result in the dissolution of 82–96 % of total U, including putative polymeric species. At the wetland scale, similar or slightly fractionated isotopic ratios (δ238U) between the wetland-feeding creek waters and the wetland soils are observed, supporting the idea that U(VI) sorption on organic matter is the primary U scavenging mechanism. Furthermore, it indicates that partial U(VI) reduction to U(IV) occurs as a second step, after sorption. Analysis of U decay chain disequilibria in the cores as a function of depth suggests that U accumulation in this wetland has lasted for several thousand years. We propose that the wetland acts as an active reactor where U has been massively accumulating for ∼14500 years, especially as U(VI) forms associated to organic matter, and is further partly exported to the lake through soil erosion. [ABSTRACT FROM AUTHOR]

Ciprofloxacin (CIP) has received considerable attention in recent decades due to its high ecological risk. However, little is known about the potential response of macrophytes and microbes to varying levels of CIP exposure in constructed wetlands. Therefore, lab-scale manganese ore-based tidal flow constructed wetlands (MO-TFCWs) were operated to evaluate the responses of macrophytes and microbes to CIP over the long term. The results indicated that total nitrogen removal improved from 79.93% to 87.06% as CIP rose from 0 to 4 mg L−1. The chlorophyll content and antioxidant enzyme activities in macrophytes were enhanced under CIP exposure, but plant growth was not inhibited. Importantly, CIP exposure caused a marked evolution of the substrate microbial community, with increased microbial diversity, expanded niche breadth and enhanced cooperation among the top 50 genera, compared to the control (no CIP). Co-occurrence network also indicated that microorganisms may be more inclined to co-operate than compete. The abundance of the keystone bacterium (involved in nitrogen transformation) norank_f__A0839 increased from 0.746% to 3.405%. The null model revealed drift processes (83.33%) dominated the community assembly with no CIP and 4 mg L−1 CIP. Functional predictions indicated that microbial carbon metabolism, electron transfer and ATP metabolism activities were enhanced under prolonged CIP exposure, which may contribute to nitrogen removal. This study provides valuable insights that will help achieve stable nitrogen removal from wastewater containing antibiotic in MO-TFCWs. [Display omitted] • Microbial diversity and niche breadth increased under ciprofloxacin (CIP) exposure. • The cooperation among dominant microbes and keystone species was promoted by CIP. • Enhanced electron transport activity of microbes exposed to MO-TFCW by CIP. • Diversity and cooperation of microbes as drivers of improved nitrogen removal. • Macrophytes and microbes showed adaptive response to CIP exposure. [ABSTRACT FROM AUTHOR]

[Display omitted] • TN removal for TTFCW in mainstream sewage exceeds 70% • Reveal the spatial distribution and migration-transformation of pollutants. • Tidal oxygenation achieves in-situ regeneration of N H 4 + -N adsorption sites. • Tidal operation leads to top–bottom disparity in COD and. N O x - -N • Two-way influent directs the distribution of carbon sources to enhance denitrification. The tidal flow constructed wetland (TFCW) effectively removes nitrogen from mainstream wastewater but encounters limitations in denitrification, resulting in the accumulation of nitrate and nitrite nitrogen (N O x - -N). In this study, we investigated the spatial distribution characteristics of pollutants and migration-transformation processes within the TFCW using the stratified analysis theories proposed. The results indicated that during the influent stage, 82.60 % of ammonia nitrogen (N H 4 + -N) and 87.77 % of COD were adsorbed by the top and middle layers. In the drain stage's oxygen-rich environment, microorganisms and atmospheric oxygen oxidized N H 4 + -N to N O x - -N , achieving in-situ regeneration of N H 4 + -N adsorption sites. Furthermore, 61.87 % of the N O x - -N was washed into the bottom in the next influent stage, subsequently adsorbed by the biofilm, and finally reduced to gaseous nitrogen using carbon source as the electron donor at the drain stage. Consequently, inconsistent locations of carbon source and N O x - -N were identified as limiting factors for denitrification in TFCW. Based on this, the study designed a two-way influent tide flow constructed wetland (TTFCW) by altering the influent pattern. It facilitated targeted carbon source addition for denitrification, resulting in a 3.30-fold improvement in actual carbon source utilization efficiency of TFCW. Ultimately, this approach resulted in a notable increase in N O x - -N removal rate by 64.51 %, accompanied by a 28.32 % reduction in accumulation levels. This study fills the research gap in the internal distribution and migration-transformation of pollutants within TFCW, providing methods support for enhancing nitrogen removal in TFCW and ideas for denitrification in mainstream wastewater. [ABSTRACT FROM AUTHOR]

• TFCWs treated mariculture wastewater, optimizing pH and reducing TDS, EC, SAL. • High removal of COD, TP, and SAs, with best results from zeolite and yellow flag. • Oxygenation and microbial degradation addressed antibiotic adsorption challenges. • Enhanced rhizosphere supported antibiotic-degrading/salt-tolerant bacteria growth. • Efficient SAs biodegradation via selective bacterial enrichment in TFCWs. Antibiotic residues in aquaculture environment pose persistent threats to ecology and human health, exacerbated by salt-alkali mariculture wastewater. Yet, little is known about antibiotic removal in tidal flow constructed wetlands (TFCWs) under salinity stress, especially considering TFCW constitution, configuration, and influent water characteristics. Here, the removal performance and mechanism of different TFCWs for sulfonamide antibiotics (SAs: sulfadiazine, sulfamethazine, sulfamonomethoxine, and sulfamethoxazole) and trimethoprim (TMP) from mariculture wastewater (with low, medium, and high salinity) were evaluated alongside comparisons of environmental factors and microbial responses. Results showed substantial reduction in alkalinity (from 8.25–8.26 to 7.65–8.18), salinity (from 3.67–11.30 ppt to 3.20–10.79 ppt), and SAs concentrations (from 7.79–15.46 mg/L to 0.25–10.00 mg/L) for mariculture wastewater using TFCWs. Zeolite and yellow flag configurations exhibited superior performance in SAs removal from mariculture wastewater. Furthermore, the salt-alkali neutralization and oxygen transport capabilities of zeolite, along with the salt-alkali tolerance and biofilm formation characteristics of yellow flag, promoted the development of a biofilm in the rhizosphere dominated by oxidative stress tolerance and facultative anaerobic traits, thereby improving the TFCW microenvironment. Consequently, aerobic (Sulfuritalea and Enterobacter) and salt-tolerant (Pseudomonas) functional bacteria involved in antibiotic degradation were selectively enriched in the zeolite- and yellow flag-TFCWs, contributing to the effective biodegradation of SAs (achieving removal efficiency of 92–97 %). Besides, the high salt-alkali levels of mariculture wastewater and the strong oxygen-enriched capacity of the TFCWs not only enhanced the aerobic oxidation reaction of SAs, but also bidirectionally inhibited the substrate adsorption and anaerobic reduction process of TMP. These findings address a critical gap by investigating the efficacy of TFCWs in removing antibiotics from mariculture wastewater under various salinity conditions, providing essential insights for optimizing wetland design and improving wastewater management in mariculture environments. [Display omitted] [ABSTRACT FROM AUTHOR]

Upgrading treated wastewater systems can provide reclaimed water for different uses. In this paper, the potential for wetland creation and maintenance is evaluated. The upgrading treatment consists of intensified vertical flow constructed wetlands (VFCWs), where the physicochemical and microbiological water quality is improved, followed by free-water surface constructed wetlands (FWSCWs), where biodiversity is enhanced. This renaturalization system has been implemented in two wastewater treatment plants (WWTPs): Monasterios, where one VFCW 60 m2 and two FWSCWs (50 m2 each) have been built, and Carricola, where two VFCWs in series (20 m2 each) have been constructed. The VFCWs were filled with drinking water treatment sludge (DWTS), a waste produced in drinking water treatment plants, hence the circularity of the project. Data obtained during the first year of operation is presented. The mean hydraulic loading rates in the VFCWs were 0.79 and 0.62 m/d in Monasterios and Carricola, respectively. In FWSCWs, the HLRs were 0.35 and 0.32 m/d in FWSCW1, which receives the effluent of the VFCW, and FWSCW2, which receives the secondary treatment effluent, respectively. In the VFCWs, an important reduction of total phosphorus was achieved, 77% in Monasterios and 70% in Carricola, and other pollutants were fairly reduced as well. In FWSCWs, some pollutants, such as total nitrogen or phosphorus, were reduced, but other, such as total suspended solids or organic matter, increased due to algae growth and external inputs. The critical point is that biodiversity is increased thanks to these systems, aquatic invertebrate presented better diversity indexes in the FWSCW receiving the upgraded water from the intensified VFCW. Birds, amphibians, and reptiles have also colonised the created habitats. • Treated wastewater can be upgraded by intensified vertical flow constructed wetlands. • Drinking water treatment sludge is an appropriate adsorbent material. • Valorisation of drinking water treatment sludge integrates circularity in urban water cycle. • Upgraded water benefits the receiving water bodies, enhancing biodiversity. • Birds use the created wetlands to feed, rest and nest. [ABSTRACT FROM AUTHOR]

This special issue of Ecological Engineering provides an overview of research within the Everglades Stormwater Treatment Areas (STAs) over the past decade to understand the ecology and the biogeochemical processes that affect phosphorus (P) retention in these constructed wetlands. This research was established within the South Florida Water Management District's Restoration Strategies Science Plan (RSSP). The RSSP was developed in 2012, updated in 2018, and produced a total of 21 studies. The goal of RSSP research is improve understanding of the factors contributing to P retention, to support management of the STAs to attain and sustain a stringent outflow total P concentration goal (i.e., the Water Quality Based Effluent Limit or WQBEL) and to maintain the wetland plant communities used to achieve this goal. Compliance with the WQBEL will reduce P loads to the Everglades to support restore and maintain this special ecosystem. This synthesis paper presents an overview of the STAs and their purpose and then summarizes the findings from the publications included in this special issue as well as previous STA related research. From this synthesis, a list of potential management options to enhance P retention in the STAs is presented. • Stormwater Treatment Areas (STAs) built to reduce P in runoff entering the Everglades. • STA discharge must meet strict low P concentration limits. • P biogeochemistry research conducted to support management of the STAs. • P removed by particle settling, biogeochemical processes and plant uptake. • Fauna excretion, bioturbation, and internal loads substantially affect P retention. [ABSTRACT FROM AUTHOR]

The addition of bacterial agents is an effective method for improving nitrogen removal from wetlands. Herein, an aerobic denitrifier, RC-15, was added to a vertical-flow constructed wetland (CW), and the presence of functional genes and microbial communities was investigated at different CW depths. For the RC-15-treated CW, the removal of NO 3 − and TN during the process was significantly greater than in the control. Quantitative PCR revealed that nirS is a dominant denitrifying gene for treating WWTP tailwater. Moreover, the presence of the RC-15 strain significantly enhanced the abundance of the napA gene and nirK gene in the CWs. The napA gene was concentrated in the upper layer of the CWs, and the nirK gene was concentrated in the middle and bottom layers. Compared to the control, the addition of the bacterial agent Trial resulted in a more diverse denitrification pathway, a greater abundance of 16Sr RNA , and a greater number of denitrifying strains. According to the microbial community analysis, Proteobacteria and Chloroflexi dominated denitrification in the CWs. Greater abundances of Thauera , Aeromonas and Ardenticatenales were found at the genus level, indicating that these genera have potential applications in future nitrogen removal projects. [Display omitted] • The isolated biological strain improved the nitrogen removal rate. • The presence of the RC-15 strain promoted the growth of nirK- and napA -containing bacteria. • NirS was the dominant denitrifying gene in the CWs treating WTP tailwaters. • The bacteria with the greatest potential for denitrification in CWs were Thauera , Aeromonas and Ardenticatenales. [ABSTRACT FROM AUTHOR]

• Manganese ore showed higher nitrogen removal in constructed wetlands (CWs). • Manganese ore enhanced ammonia oxidation and nitrate reduction in CWs. • Zeolite and manganese ore selected for distinct bacterial communities in CWs. • Stochastic processes dominated microbial community assembly in CWs. • Manganese ore-based CWs had more keystone microbes and complex interactions. A limited understanding of microbial interactions and community assembly mechanisms in constructed wetlands (CWs), particularly with different substrates, has hampered the establishment of ecological connections between micro-level interactions and macro-level wetland performance. In this study, CWs with distinct substrates (zeolite, CW_A; manganese ore, CW_B) were constructed to investigate the nutrient removal efficiency, microbial interactions, metabolic mechanisms, and ecological assembly for treating rural sewage with a low carbon-to-nitrogen ratio. CW_B showed higher removal of ammonia nitrogen and total nitrogen by about 1.75–6.75 % and 3.42–5.18 %, respectively, compared to CW_A. Candidatus_Competibacter (denitrifying glycogen-accumulating bacteria) was the dominant microbial genus in CW_A, whereas unclassified_f_Blastocatellaceae (involved in carbon and nitrogen transformation) dominated in CW_B. The null model revealed that stochastic processes (drift) dominated community assembly in both CWs; however, deterministic selection accounted for a higher proportion in CW_B. Compared to those in CW_A, the interactions between microbes in CW_B were more complex, with more key microbes involved in carbon, nitrogen, and phosphorus conversion; the synergistic cooperation of functional bacteria facilitated simultaneous nitrification-denitrification. Manganese ores favour biofilm formation, increase the activity of the electron transport system, and enhance ammonia oxidation and nitrate reduction. These results elucidated the ecological patterns exhibited by microbes under different substrate conditions thereby contributing to our understanding of how substrates shape distinct microcosms in CW systems. This study provides valuable insights for guiding the future construction and management of CWs. [Display omitted] [ABSTRACT FROM AUTHOR]

Wetlands play an important role in ecological health and sustainable development, and dynamic monitoring of their spatial distribution is crucial for developing management and conservation measures. The types of coastal wetlands are complex and diverse, natural and artificial wetlands are easily confused, making precise classification more difficult. The coastal wetland of Chongming Island in China, which has diverse types and unique and complex ecological and hydrological characteristics, was deliberately chosen as a challenging case study. The objective of this study was to research effective method of fine classification of coastal wetlands, by constructing feature variables and proposing strategies for multi-level selection and fusion of feature variables. Sentinel-2 data with rich spectral information and high spatial resolution was be used. In this study, firstly, the classification effect of characteristic variables such as vegetation index, water body index, red edge index, and texture index were evaluated. Focusing on the "different objects with same spectra" of the humid planning land and farm growing ponds, the spectral characteristics of them were analyzed and a "water-rich soil index (WRSI)" was established. Subsequently, correlation analysis and J-M distance method were used to multi-level selection for the feature variables and four sets of features combination schemes were established. Finally, random forest (RF) was applied to classify coastal wetlands using different feature combination schemes, and the accuracy of different schemes was compared and verified. The results show the following: 1)Texture features have a promoting effect on improving classification accuracy. The constructed "water rich soil index"(WRSI) has the effectively contribution to identification and classification of farm growing ponds and humid planned land, improving the overall classification accuracy by 6.52%. 2)By multi-level selecting and fusion of feature variable sets, both accuracy and efficiency for classification are improved. For different features combination schemes, the classification accuracy is up to 90.03% by integrating spectral features, spectral index, texture index, and WRSI. This study evaluates the potential of Sentinel-2 data in coastal wetland classification, constructs effective feature parameters, and provides a new idea for wetland information extraction. The resulting classification map can be used for sustainable management, ecological assessment and conservation of the coastal wetland. • Sentinel-2 data holds crucial spectral potential for coastal wetland classification. • Spectral indices and PCA texture features enhance wetland classification. • WRSI index effectively distinguishes between humid planned land and farm growing ponds. • Multi-level screening effectively minimizes feature information redundancy. [ABSTRACT FROM AUTHOR]

The removal of contaminants by constructed wetland (CW) is typically related to the residence time and CW design is based on a stipulated residence time, usually 72 h. Studies have shown that residence time is related to hydraulic performance. Hydraulic performance is an important factor in studying the treatment behaviour of CWs and is influenced by length-to-width ratio, scale and sizing, wetland shape and configuration and the distribution of vegetation. Indices such as nominal hydraulic residence time (t n), tank-in-series (N), hydraulic efficiency (λ), short-circuit (S) and effective volume ratio (e) have been used to characterize hydraulic performance. Most studies on CW emphasise on treatment performance, however, very few studies investigate the link between treatment effectiveness and hydraulic performance, although such a link has been suggested. This review was conducted to establish correlations between treatment performance and hydraulic behaviour as a better understanding of this knowledge gap will lead to better design. Studying hydraulic performance is resource intensive and costly, and for these reasons such studies are often not undertaken. Given the paucity of data, estimates on hydraulic performance were obtained from results obtained in the literature of λ for published studies where wetland configurations were provided. The dataset was divided into CW treating stormwater and wastewater. It is found out that there is a significant (p <.05) correlation between λ with TSS removal for both wastewater (r = 0.86) and stormwater (r = 0.86) applications. For stormwater, the removals of TN (r = 0.08) and TP (r = 0.56) were not found to be significantly (p >.05) correlated, while BOD/COD were strongly correlated (r = 0.97, p <.05), with λ. For wastewater, TN and TP removals were not correlated (r = 0.18 and r = −0.04, respectively, with p >.05 for both parameters). BOD/COD was also not significantly correlated (r = 0.64, p >.05). Given that this is a first study attempting to draw relationships between treatment effectiveness and hydraulic performance, and that there is a general lack of data on hydraulic efficiency, it is recommended that future field-based wetland studies include hydraulic efficiency measurements or at the very least, provide detailed information of the physical features of the constructed wetland under investigation and the planting configuration. Further recommendations for future work include conducting laboratory experiments as a cost-effective way to study hydraulic efficiency and to study the role of vegetation distribution on hydraulic performance. [ABSTRACT FROM AUTHOR]

Managed treatment wetlands technology is now used around the world to treat wastewater and stormwater by removing nutrients and other contaminants to obtain a desired water quality. In this paper we present a brief review of a large-scale application of the nature-based technology known as stormwater treatment areas (STAs). These STAs were constructed to treat agricultural and urban runoff to reduce outflow total phosphorus (TP) concentrations to <20 μg P L−1, which is required to protect downstream water quality and preserve the remaining Everglades ecosystem. Five STAs with a total area of approximately 25,000 ha were built at strategic locations to reduce TP loads to the Everglades Protection Area. For the past three decades, these Everglades STAs have done remarkable job by 70 to 85% TP load reduction, with an average outflow TP concentrations of 15-40 μg P L−1. In this Everglades STAs special issue, we present research findings on the influence of both external and internal drivers influencing STA performance and potential adaptive management strategies to enhance treatment efficiency to further reduce outflow TP concentrations. • Introduction of the Everglades STAs – largest constructed treatment wetland network in the world. • Everglades STAs serve as 'kidneys' of the Everglades ecosystem by reducing phosphorus loads to downstream waterbodies. • Phosphorus loading is one of the key drivers regulating treatment efficiency STAs. [ABSTRACT FROM AUTHOR]

High frequent detection of sulfamethoxazole (SMX) in wastewater cannot be effectively removed by constructed wetlands (CWs) with a traditional river sand substrate. The role of emerging substrate of hematite in promoting SMX removal and the effect of influent SMX loads remain unclear. The removal efficiency of SMX in hematite CWs was significantly higher than that in river sand CWs by 12.7–13.8% by improving substrate adsorption capacity, plant uptake and microbial degradation. With increasing influent SMX load, the removal efficiency of SMX in hematite CWs slightly increased, and the removal pathways varied significantly. The contribution of plant uptake was relatively small (< 0.1%) under different influent SMX loads. Substrate adsorption (37.8%) primarily contributed to SMX removal in hematite CWs treated with low-influent SMX. Higher influent SMX loads decreased the contribution of substrate adsorption, and microbial degradation (67.0%) became the main removal pathway. Metagenomic analyses revealed that the rising influent load increased the abundance of SMX-degrading relative bacteria and the activity of key enzymes. Moreover, the abundance of high-risk ARGs and sulfonamide resistance genes in hematite CWs did not increase with the increasing influent load. This study elucidates the potential improvements in CWs with hematite introduction under different influent SMX loads. [Display omitted] • Hematite CW removed 12.7–13.8% more SMX than river sand CWs. • Influent SMX load in hematite CWs changed the SMX removal pathway. • Contribution of substrate adsorption decreased with the increasing influent SMX load. • Biodegradation mainly contributed to SMX removal under high influent SMX load. • High-risk ARGs showed no difference when increasing the influent SMX load. [ABSTRACT FROM AUTHOR]

• First-time size-fractionated microbial communities have been analyzed in constructed wetlands. • Community analysis reveals microbial niche partitioning on taxonomic and metabolic level. • Constructed wetland effectively immobilized wastewater particle-associated bacteria and associated AMR load. • Free-living bacteria can be a primary escape route of AMR from constructed wetlands. Free-living (FL) and particulate-associated (PA) communities are distinct bacterioplankton lifestyles with different mobility and dissemination routes. Understanding spatio-temporal dynamics of PA and FL fractions will allow improvement to wastewater treatment processes including pathogen and AMR bacteria removal. In this study, PA, FL and sediment community composition and antimicrobial resistance gene (ARG; tetW, ermB, sul1, intI1) dynamics were investigated in a full-scale municipal wastewater free-water surface polishing constructed wetland. Taxonomic composition of PA and FL microbial communities shifted towards less diverse communities (Shannon, Chao1) at the CW effluent but retained a distinct fraction-specific composition. Wastewater treatment plant derived PA communities introduced the bulk of AMR load (70 %) into the CW. However, the FL fraction was responsible for exporting over 60 % of the effluent AMR load given its high mobility and the effective immobilization (1–3 log removal) of PA communities. Strong correlations (r2>0.8, p < 0.05) were observed between the FL fraction, tetW and emrB dynamics, and amplicon sequence variants (ASVs) of potentially pathogenic taxa, including Bacteroides , Enterobacteriaceae, Aeromonadaceae, and Lachnospiraceae. This study reveals niche differentiation of microbial communities and associated AMR in CWs and shows that free-living bacteria are a primary escape route of pathogenic and ARG load from CWs under low-flow hydraulic conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

• NERs was more preferable to form under oxic conditions in sterile sediment. • Biotic SMX removal: oxic ≈ iron-reducing > methanogenic >> nitrate-reducing conditions. • More complexity of microbes-SMX transformation network implies higher transformation. • Natural organic matter did not further influence abiotic and biotic removal of SMX. • Iron-reducing condition achieved optimal and eco-friendly SMX removal from wetland sediment. Redox condition is an important controlling factor for contaminant removal in constructed wetlands; however, the redox-sensitivity of antibiotic removal in wetland sediments under controlled conditions with specific electron acceptors remains unclear. Here, using a 14C radioactive tracer, we explored fate of sulfamethoxazole (SMX) in a wetland sediment slurry under oxic, nitrate-reducing, iron-reducing, and methanogenic conditions. In the sterile treatment, unlike the comparable SMX dissipation from the water phase under four redox conditions, non-extractable residues (NERs) of SMX was highest formed in the sediment under oxic condition, mainly in sequestered and ester/amide-linked forms. Microorganisms markedly promoted SMX transformation in the slurry. The dissipation rate of SMX and its transformation products (TPs) followed the order: oxic ≈ iron-reducing > methanogenic >> nitrate-reducing conditions, being consistent with the dynamics of microbial community in the sediment, where microbial diversity was greater and networks connectivity linking dominant bacteria to SMX transformation were more complex under oxic and iron-reducing conditions. Kinetic modeling indicated that the transformation trend of SMX and its TPs into the endpoint pool NERs depended on the redox conditions. Addition of wetland plant exudates and sediment dissolved organic matter at environmental concentrations affected neither the abiotic nor the biotic transformation of SMX. Overall, the iron-reducing condition was proven the most favorable and eco-friendly for SMX transformation, as it resulted in a high rate of SMX dissipation from water without an increase in toxicity and subsequent formation of significant stable NERs in sediment. Our study comprehensively revealed the abiotic and biotic transformation processes of SMX under controlled redox conditions and demonstrated iron-reducing condition allowing optimal removal of SMX in constructed wetlands. [Display omitted] [ABSTRACT FROM AUTHOR]

The diversity, composition and performance of microbial communities within constructed wetlands (CW) were markedly influenced by spatio-temporal variations. A pilot-scale integrated vertical-flow constructed wetland (IVCW) as the biological purification unit within a recirculating aquaculture system (RAS) was established and monitored in this study. The investigation aimed to elucidate the responses of community structure, co-occurrence networks, and assembly mechanisms of the microbial community to spatial and temporal changes. Spatially, all a -diversity indices and microbial networks complexity were significantly higher in the upstream pool of the IVCW than in the downstream pool. Temporally, the richness increased over time, while the evenness showed a decreasing trend. The number of nodes and edges of microbial networks increased over time. Notably, the stable pollutant removal efficiencies were observed during IVCW operations, despite a -diversity and bacterial community networks exhibited significant variations across time. Functional redundancy emerged as a likely mechanism contributing to the stability of microbial ecosystem functions. Null model and neutral model analyses revealed the dominance of deterministic processes shaping microbial communities over time, with deterministic influences being more pronounced at lower a -diversity levels. DO and inorganic nitrogen emerged as the principal environmental factor influencing microbial community dynamics. This study provides a theoretical foundation for the regulation of microbial communities and environmental factors within the context of IVCW. • The diversity and structure of microbial communities varied significantly with time and space. • Functional redundancy ensured stability of microbial ecosystem functions in constructed wetlands. • Deterministic processes were the main mechanism for microbial community assembly. • DO and inorganic nitrogen were most closely related to the variation of microbial communities. [ABSTRACT FROM AUTHOR]

Bacteria are primarily responsible for biological water treatment processes in constructed wetland systems. Gravel in constructed wetlands serves as an essential substrate onto which complex bacterial biofilms may successfully grow and evolve. To fully understand the bacterial community in these systems it is crucial to properly isolate biofilms and process DNA from such substrates. This study looked at how best to isolate bacterial biofilms from gravel substrates in terms of bacterial richness. It considered factors including the duration of agitation during extraction, extraction temperature, and enzyme usage. Further, the 16S taxonomy data subsequently produced from Illumina MiSeq reads (using the SILVA 132 ribosomal RNA (rRNA) database on the DADA2 pipeline) were compared with the 16S data produced from Oxford Nanopore Technologies (ONT) MinION reads (using the NCBI 16S database on the EPI2ME pipeline). Finally, performance was tested by comparing the taxonomy data generated from the Illumina MiSeq and ONT MinION reads using the same (SILVA 132) database. We found no significant differences in the effective number of species observed when using different bacterial biofilm detachment techniques. However, enzyme treatment enhanced the total concentration of DNA. In terms of wetland community profiles, relative abundance differences within each sample type were clearer at the genus level. For genus-level taxonomic classification, MinION sequencing with the EPI2ME pipeline (NCBI database) produced bacterial abundance information that was poorly correlated with that from the Illumina MiSeq and DADA2 pipelines (SILVA132 database). When using the same database for each sequencing technology (SILVA132), the correlation between relative abundances at genus-level improved from negligible to moderate. This study provides detailed information of value to researchers working on constructed wetlands regarding efficient biofilm detachment techniques for DNA isolation and 16 s metabarcoding platforms for sequencing and data analysis. • Different detachment techniques did not change the effective number of species. • Enzyme treatment enhanced the total concentration of DNA. • Wetland samples showed differences in the genus-level bacterial relative abundance. • Genus-level correlation was poor between MiSeq and MinION using different databases. • Genus-level correlation was moderate between MiSeq and MinION using the same database. [ABSTRACT FROM AUTHOR]

[Display omitted] • Influent wastewater changed substrate bacterial community composition seasonally. • 16S rRNA, nitrification and denitrification genes were stable between seasons. • Microbial systems changed from heterotrophic state to autotrophic state. • Micro- eukaryotes were more sensitive to wastewater fluctuation than bacteria. How microbial communities respond to wastewater fluctuations is poorly understood. Full-scale surface flow constructed wetlands (SFCWs) were constructed for investigating microbial communities. Results showed that influent wastewater changed sediment bacterial community composition seasonally, indicating that a single bacterial taxonomic group had low resistance (especially, Actinobacteriota and Gammaproteobacteria). However, copy numbers of 16S rRNA, ammonia oxidizing archaea, ammonia oxidizing bacteria, nirS and nirK in the first stage SFCWs were 2.49 × 1010, 3.48 × 109, 5.76 × 106, 8.77 × 108 and 9.06 × 108 g−1 dry sediment, respectively, which remained stable between seasons. Moreover, decreases in the nitrogen concentration in wastewater, changed microbial system state from heterotrophic to autotrophic. Micro-eukaryotic communities were more sensitive to wastewater fluctuations than bacterial communities. Overall, results revealed that microbial communities responded to spatio-temporal fluctuations in wastewater through state changes and species asynchrony. This highlighted complex processes of wastewater treatment by microbial components in SFCWs. [ABSTRACT FROM AUTHOR]

This paper aims to conduct a comparative evaluation of evapotranspiration (ET) rates in two experimental pilot-scales vertical flow subsurface constructed wetlands carried out in south east of Algeria (Touggourt), planted separately with P. australis (Ph) and T. latifolia (Ty) in two different substrate types with constant hydraulic loading rate under arid climatic conditions. An estimate of crop coefficient (Kc) for the two macrophytes based on climate conditions and the plant growth was also provided. Two kinds of vertical flow subsurface systems has been tested in the hottest period of the year 2018 over five months (April-August): first with fine gravel (G) (experiment 1), and second with sand (S) (experiment 2). During this period, the cumulative ET Ty-G , ET Ph-G and ET Np-G in the 1st experiment were 206, 276 and 125 mm, whereas in the 2nd experiment; the cumulative ET Ty-S , ET Ph-S and ET Np-S were 833, 968 and 635 mm, respectively. Comparing these results with cumulative reference evapotranspiration (ET 0), ET 0 value (426 mm) was higher than ET in the 1st experiment, and lower than in the 2nd experiment. Cumulative ET values in planted lysimeters were found to be different and higher than unplanted ones. Moreover, the highest accumulated ET value was obtained with P. australis bed which was found to have higher accumulated ET values than T. latifolia bed. Regarding the crop coefficient (Kc), the average seasonal value of Kc in the 1st experiment was relatively smaller than 2nd experiment. The Kc Ph-S value was almost three times the Kc Ph-G, and Kc Ty-S values were also almost four times the Kc Ty-G. In general, this study demonstrated that ET and Kc are dependent on climate conditions, the macrophytes growth as well as on the type of substrate in which the macrophytes are planted. [ABSTRACT FROM AUTHOR]

The First Stage of French Vertical Flow Constructed Wetlands (FS-FVFCW) offers a sustainable solution for treating septage. The system operates through distinct phases: start-up, full operation and final rest. During full operation, factors such as feeding duration, rest periods and percolate impounding significantly affect performance. This study assessed the performance of a pilot-scale Modified FS-FVFCW in Northern Tropical Andes, from start-up to closure stages under three operational scenarios. These scenarios varied in planted/unplanted conditions and percolate drainage/impounding. A four-month start-up phase proved adequate for vegetation growth and adaptation, achieving over 50% COD removal efficiency. Percolate retention (impounding) during operation notably improved COD and TS removal, increasing efficiencies from 49% to approximately 90% for COD and from 39% to around 70% for TS. Plant presence contributed to mosquito control and odour reduction but had minimal impact on removal efficiencies. The pilot demonstrated significant dewatering potential, with sludge deposit samples showing water content below 76% across all scenarios after 24 h; and a 10% reduction in VS/TS ratio during the operational resting period. After a 5-month closure, the sludge deposit layer exhibited organic matter content similar to long-rested sludge, albeit with persistent faecal contamination. • A 4-month start-up with untreated wastewater successfully allows the plants adaptation. • Septage percolate impounding in VFCWs significantly enhances the removal of COD and TS. • Sludge samples reach water content levels below 76% within 24 h. • Faecal contamination persists in sludge samples even after a 5-month closure period. [ABSTRACT FROM AUTHOR]

Improving the treatment performance of mature surface flow constructed wetlands (SFCWs) is critical for long-term sustainability. Nevertheless, the mechanisms of plant species affecting the treatment performance of mature SFCWs remain largely unexplored. In this study, three 6-year-old field-scale SFCWs were subjected to orthogonal tests, with Nelumbo nucifera , Typha angustifolia , and Zizania latifolia as plant species. The aim was to understand how the emergent plant species selected for the newly constructed wetlands influenced the nitrogen and phosphorus treatment performance at maturity. The results showed that plant species significantly affected total nitrogen (TN) treatment performance through dissolved oxygen and water temperature. Typha and Zizania had larger above-ground biomass and denser canopies than Nelumbo, significantly increasing anaerobic zones and water temperature. Therefore, SFCWs with Typha or Zizania had the best organic nitrogen and nitrate nitrogen treatment performance compared to those with Nelumbo. However, the integrated ability of microbes and plants to remove ammonia nitrogen was not affected by internal factors in mature wetlands. Plant species significantly affected total phosphorus (TP) treatment performance through local flow patterns. Although plant species did not significantly affect general hydraulic performance, Zizania had denser tillers and thicker stalks than Nelumbo and Typha , increasing flow velocity near the wetland bottom. Therefore, SFCWs with Nelumbo or Typha were more capable of TP removal than those with Zizania. Overall, Typha was the optimal plant species compared to Nelumbo and Zizania for efficient removal of TN and TP. Therefore, appropriate plant species for newly constructed wetlands are crucial for enhancing nitrogen and phosphorus treatment performance at maturity. From a long-term perspective, SFCWs should be planted with emergent plants with large above-ground parts and sparse tillers. This study provides a mechanistic understanding of the plant species affecting nitrogen and phosphorus in mature SFCWs. [Display omitted] • Plant species affect N and P removal and the physical conditions of water. • Plant species don't affect general hydraulic performance. • Plant-species-induced DO and T contribute to the differences in N removal. • Plant-species-induced local flow patterns result in differences in P removal. • Plant species in new wetlands affect the treatment performance at maturity. [ABSTRACT FROM AUTHOR]

• Nutrient recovery shifts to the 3Rs (reduce, reuse, recycle) from a linear model. • 3Rs highlight significant loss efficiency in current nutrient recovery models. • On-farm circularity is pivotal to address nutrient loss in recovery frameworks. • Eco-innovations accentuate low-carbon footprints in on-farm circularity. • Eco-innovation‒on-farm practices synergy redefines nutrient recovery sustainably. The escalating challenges of resource scarcity and environmental degradation in agroecosystems necessitate innovative strategies for sustainable nutrient management. This review explores the integration of circular economy principles into nutrient recovery frameworks, emphasizing eco-innovative technologies that promote sustainability and resilience in agricultural practices. By examining various on-farm circularity practices and their efficacy in nutrient recovery, we highlight the potential of nature-inspired solutions such as constructed wetlands and algae-based systems to reduce environmental impacts and enhance nutrient use efficiency. The findings advocate for a paradigm shift towards advanced nutrient management strategies that leverage eco-innovation to reduce greenhouse gas emissions, optimize resource use, and align with global sustainability goals. The adoption of these strategies can significantly contribute to the sustainable transformation of the agricultural sector. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • SMX was able to shorten the acclimatisation period of the CW-MFC. • The maximal power density of the CW-MFC was enhanced by 0.1 mg/L SMX. • Bacteria established distinct metabolic states under different concentrations of SMX. • Bacterial cells tended to form biofilms in response to the antibiotic stress. The influence of sulfamethoxazole (SMX) on the electrochemical activity, bacterial community, and metabolic state of anode respiring microbes was investigated in constructed-wetland-coupled microbial fuel cells (CW-MFCs). Results suggested that SMX shortened the acclimatisation period and enhanced the maximal power density of the CW-MFC at 0.1 mg/L. Cyclic voltammetry (CV) results indicated that SMX may trigger an electrocatalytic process related to an extra redox-active compound. Exposure to SMX significantly altered the bacterial communities, leading to decreased abundances of Desulfurivibrio and Pseudomonas , while increasing the contents of Rhodobacter and Anaerovorax. Furthermore, metabolites related to amino acids and nucleotide metabolism were suppressed at 10 mg/L SMX, while the related metabolites increased at 0.1 mg/L SMX. The upregulated pathway of biofilm formation indicated that the bacteria tended to form biofilms under the influence of SMX. This study provides valuable insights into the complex interactions between SMX and electrochemically active bacteria. [ABSTRACT FROM AUTHOR]

[Display omitted] • Detailed insights into algae-CW interactions and their mechanisms are provided. • The role of algae in nitrogen purification was confirmed; other effects varied. • The average removal rates were 74–75 % for COD, NH 4 +-N, and TN and 79 % for TP. • COD and TP removal rates improved by approximately 0.6 % every 10 days. • This review identifies challenges and proposes future directions for enhancements. Integrating algae into constructed wetlands (CWs) enhances wastewater treatment, although the results vary. This review evaluates the role of algae in CWs and the performance of different algae-CW (A-CW) configurations based on literature and meta -analysis. Algae considerably improve N removal, although their impact on other parameters varies. Statistical analysis revealed that 70 % of studies report improved treatment efficiencies with A-CWs, achieving average removal rates of 75 % for chemical oxygen demand (COD), 74 % for total nitrogen and ammonium nitrogen, and 79 % for total phosphorus (TP). This review identifies hydraulic retention times, which average 3.1 days, and their varied impact on treatment efficacy. Mixed-effects models showed a slight increase in COD and TP removal efficiencies of 0.6 % every ten days in the A-CWs. Future research should focus on robust experimental designs, adequate algal storage and separation techniques, and advanced modeling to optimize the treatment potential of algae in CWs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Resting operation stimulates wetland plants root redundancy. • The absorption of pollutants by plants was enhanced under the resting operation. • Resting operation enhanced microbial nitrogen fixation and assimilation. • Excessively long resting period (>5 d) led to limited denitrification function. • Resting operation changed root traits thus regulated rhizosphere microorganisms. The stable operation of subsurface flow (SSF) constructed wetlands (CWs) depends on the adopted maintenance and management strategies. To determine a suitable resting period for SSF CWs, this study investigated and compared the impacts of three resting periods on plant physiological metabolism, wetland purification effectiveness, and microbial responses. The results revealed that resting operations induced morphological adaptations in wetland plants, significantly enhanced the root-shoot ratio and specific root length. A 2-d resting period enhanced oxygen secretion from plant roots, which was beneficial for SSF CW reoxygenation, leading to significant increases in the average removal rates of chemical oxygen demand and total phosphorus. After the resting operation, the inorganic phosphorus solubilization and transporters function of rhizosphere microorganisms were enhanced, resulting in efficient phosphorus removal. The functional genes related to nitrification, nitrogen fixation, and assimilation were increased, and a 2–5 d resting period facilitated the aerobic nitrification in SSF CWs. Inversely, an excessively long resting (>5 d) significantly inhibits plant and microbial activity, resulting in a deteriorated pollutant removal performance. Plants regulate rhizosphere microorganisms by adjusting root traits, which are the key factors and important reference indicators guiding the formulation of the operation and maintenance strategies for SSF CWs during resting periods. [ABSTRACT FROM AUTHOR]

The utilization of microbial fuel cells (MFCs) for regulating greenhouse gas (GHG) emissions in constructed wetlands (CW) has attracted significant attention. The impact of structural modifications, the introduction of iron-carbon materials on pollutant removal and GHG release from MFC-CW has not been systematically studied. In this study, four types of MFC-CWs were constructed, including MFC-CW with separated aerobic and anaerobic zones (SC), MFC-CW with unseparated aerobic and anaerobic zones (IC), SC added with iron-carbon (SFC), and IC added with iron-carbon (IFC). The aim was to investigate the effects of structural changes and electron shuttle additions on the GHG release. The results revealed that IFC simultaneously enhanced pollutant removal and GHG emissions reduction, compared to IC. However, no significant enhancements were observed in SC and SFC. The cumulative emissions of nitrous oxide (N 2 O) and methane (CH 4) in SC were reduced by 51.83% and 89.33% respectively, compared to IC. The modifications made to the structure of MFC-CWs influenced the relationship between functional bacteria (Chlorobium , Azospira , and Denitratisoma) and electrochemically active bacteria (EAB), resulting in increased values of nirS / nosZ and pmoA / mcrA. Comparing the SFC and IFC, despite an improvement in denitrogenation efficiency, the effect of structural alteration on N 2 O reduction was slight. The electrons in the iron-mediated process were not effectively used for N 2 O reduction. This study confirmed the crucial involvement of electron shuttles and the structure of MFC-CWs in controlling contaminant removal and GHG emissions. [Display omitted] • Structural alterations and addition of iron-carbon favored pollutant removal. • Reduced GHG releases due to structural changes or addition of iron-carbon. • Strong interactions between EAB and functional bacteria associated with GHG release. • Structural changes were significantly positively correlated with nirS / nosZ values. • Altered structure may be more suitable for MFC-CWs without added iron-carbon. [ABSTRACT FROM AUTHOR]

Phytoremediation is a low-cost, environmentally friendly, and sustainable technology that can utilize vegetation and microorganisms to avoid eutrophication and purifying water environment. The ability of five different living aquatic plants of nitrogen (N), phosphorus (P), and chemical oxygen demand (COD cr) removal were investigated in pilot scale constructed wetlands (CWs). Aquatic plant mixes significantly improved COD cr removal and plant tissue uptake of nitrogen and phosphorus. The wetland performance of mixed plantings was also influenced by the specific species. The mixed planting of Phragmites australi, Nymphaea Colorado and Myriophyllum verticillatum (PNM)When assessing pollutant removal in CWs, PNM performed better within mixtures, a possible synergistic effect, while TNV Typha orientalis, Nymphaea Colorado, and Vallisneria natans (TNV) performed poorly, a possible antagonist effect. The nutrient uptake within plant tissues byunder mixed plants planting was always ahad synergistic effect. Mixed plantingAquatic plant mixes significantly increased the rhizosphere microbial diversity and promoted the growth of functional denitrifying flora. [Display omitted] • Mixed planting significantly promoted CODcr removal, but had no effect on nitrogen and phosphorus removal. • Mixed planting of plants were always synergistic on plant uptake of nitrogen and phosphorus. • Mixed planting significantly increased the rhizosphere microbial diversity and promoted the growth of denitrifying flora. • Selecting the right mix of plants is an effective means to enhance the efficiency of CWs and improve eutrophication. [ABSTRACT FROM AUTHOR]

The carbon‒oxygen balance has always been problematic in constructed wetlands (CWs), putting pressure on stable and efficient nitrogen removal. In this study, a novel partial siphon operational strategy was developed to further optimize the carbon and oxygen distributions of a partially saturated vertical flow CW (SVFCW) to enhance nitrogen removal. The removal performances of the partial siphon SVFCW (S-SVFCW) were monitored and compared with those of the SVFCWs at different partial siphon depths (15 cm, 25 cm and 35 cm) in both the warm and cold seasons. The results showed that the partial siphon operating strategy significantly facilitated the removal of ammonia and total nitrogen (TN) in both the warm and cold seasons. When the partial siphon depth was 25 cm, the S-SVFCWs had the highest TN removal efficiency in both the warm (71%) and cold (56%) seasons, with an average improvement of 46% and 52%, respectively, compared with those of the SVFCWs. The oxidation‒reduction potential (ORP) results indicated that richer OPR environments and longer hydraulic detention times were obtained in the S-SVFCWs, which enriched the denitrification bacteria. Microbial analysis revealed greater nitrification and denitrification potentials in the unsaturated zone with enriched functional genes (e.g., amo_AOA , amo_AOB , nxr A and nir K), which are related to nitrification and denitrification processes. Moreover, the strengthening mechanism was the intensified oxygen supply and carbon utilization efficiency based on the cyclic nitrogen profile analysis. This study provides a novel partial siphon operational strategy for enhancing the nitrogen removal capacity of SVFCWs without additional energy or land requirements. [Display omitted] • A partial siphon strategy created periodic redox conditions in partial-unsaturated zone. • A partial siphon strategy promoted oxygen supply and carbon utilization abilities in VFCWs. • A partial siphon strategy in VFCWs increased TN removal by 40 % compared to the control. • At low temperature, 25 cm siphon depth improved TN removal by 52 % compared to the control. • A partial siphon strategy enriched DNB population of the unsaturated zone from 17.6 % to 34.5 %. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel Fe-C tidal flow system boosts NH 4 +-N and TN removal in constructed wetlands. • Tidal operation promoted Fe cycling and microbe enrichment, enhancing denitrification. • Fe-C release Fe2+ via galvanic cell reaction to promote denitrification and Feammox. • Notable increase in Fe-reducing, autotrophic denitrifying bacteria and gene abundance. • Autotrophic denitrification pathway enhances TN removal while reducing N 2 O emissions. This study focused on developing a tidal flow constructed wetland (CW) with an iron-carbon (Fe-C) substrate to enhance nitrogen removal efficiency. The results demonstrated significant improvements in the removal of NH 4 +-N and TN in the iron-carbon tidal flow constructed wetland (IC-TFCW) compared to traditional gravel CW. IC-TFCW achieved a 23.82 % and 31.01 % more effective removal, resulting in reductions of 82.45 % and 74.13 %, respectively. The large specific surface area and electron transfer effect of the Fe-C substrate facilitated pollutant retention and proliferation of denitrifying microorganisms. However, the Fe-C substrate inhibited plant growth and rhizosphere microorganisms, reducing plant nitrogen uptake by 2.69-fold. Galvanic cell reaction in the Fe-C substrate facilitated the release of iron and its oxides and promoted iron cycling under the alternating aerobic-anoxic conditions induced by tidal flow. This led to the enrichment of autotrophic denitrifying and Fe-reducing bacteria by 14.89 and 1.1 times, and increase in the relative abundance of denitrification genes nar (narG, narH, narI) and nap (napA, napB) by 60.94 %. The Fe2+ released during the galvanic cell reaction contributed electrons to denitrification, while the reduction of Fe3+ facilitated the Anammox process, resulting in the Feammox reaction. This created an autotrophic denitrification pathway (autotrophic denitrification and Feammox), synergizing with the heterotrophic denitrification pathway and the iron cycling process to significantly increase TN removal and reduce N 2 O emissions per unit of TN removed by up to 36.99 %. These findings elucidate the various denitrification pathways present in CW and provide insights into improving denitrification efficiency. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has resulted in a substantial surge in the usage of disposable plastic masks, generating a significant volume of waste and contributing to environmental pollution. Wetland ecosystems function as crucial repositories for terrestrial pollutants and are highly effective in retaining disposable masks composed mainly of PP material. These masks can endure extended periods in wetlands, experiencing natural degradation that may have potential implications on wetland ecosystems. Our findings demonstrate the natural aging process of disposable masks, resulting in the generation of microplastics (MPs) ranging in diameter from 10 to 30 μm over a 180-day timeframe. Examination of 16S rDNA data unveiled temporal fluctuations in microbial diversity in the wetland ecosystem. Initially, microbial diversity displayed a modest incline, which was succeeded by a subsequent decrease. With the progressive accumulation of plastic within the wetland, an ongoing decline in microbial diversity linked to nitrogen transformation was observed. This study provides valuable insights into the retention of disposable masks by wetlands amidst the COVID-19 pandemic, along with their consequential effects on wetland ecosystems, specifically pertaining to nitrogen cycling. It underscores the urgency of augmenting the safeguarding measures for wetland ecosystems. [Display omitted] • Aging dynamics of polypropylene in constructed wetlands characterized. • Waste from mask disposal decreases wetland microbial community diversity. • Observed impacts may have implications for wetland nitrogen cycling processes. • Wetland managers should further consider the impacts from these waste streams. [ABSTRACT FROM AUTHOR]

• A novel manganese-based CW was established for low C/N ratio wastewater treatment. • TN removal efficiency in MnV-CW was increased by over 11.1–23.9 %. • MnV-CW achieved 16.8–36.5 % GHG emissions reduction. • Optimized ORP was the main reason for enhanced nitrogen removal and mitigated GWP. • MnV-CW improved microbial community related to Mn cycling and nitrogen removal. Manganese oxide (MnO x) is receiving increased interest in the nutrient removal of constructed wetlands (CWs); however, its service effectiveness for simultaneous greenhouse gas (GHG) emissions reduction is still vague. In this study, three vertical flow CWs, i.e., volcanics (C CW), manganese sand uniformly mixing with volcanics (Mn-CW) and MnO x doped volcanics (MnV-CW), were constructed to investigate the underlying mechanisms of MnO x on nutrient removal enhancement and greenhouse gas (GHG) emissions reduction. The results showed that the MnO x doped volcanics optimized the oxidation–reduction potential surrounding the substrate (-164.0 ∼ +141.1 mv), and resulted in the lowest GHG emissions (CO 2 -equivalent) from MnV-CW, 16.8–36.5 % lower than that of Mn-CW and C CW. This was mainly ascribed to mitigation of N 2 O produced during the NO 3 −-N reduction process, according to results of 15N stable isotope labeling. Analysis of the microbial community structure revealed that due to the optimized redox conditions through chemical doping of MnO x on volcanics, the abundance of microbe involved in denitrification and Mn-oxidizing process in the MnV-CW was significantly increased at genus level, which led to a higher Mn cycling efficiency between biogenic MnO x and Mn2+, and enhanced denitrification efficiency and N 2 O emission reduction. This study would help to understand and provide a preferable reference for future applications for manganese-based CW. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A water-type classification procedure integrating shape, landscape patterns, topography, and phenology was proposed. • The distribution and transition of various wetlands in the middle and lower reaches of the Yangtze River Basin were mapped. • Nearly half of the wetlands experienced a significant trend of decrease in water inundation frequency from 1990 to 2020. • Farmland reclamation was the primary anthropogenic factor in natural wetland loss and degradation. Wetlands are crucial to diverse societies and ecosystems but are threatened globally. Natural wetlands in the middle and lower reaches of the Yangtze River Basin (MLRYRB) have long been exploited to meet the increasing food and energy demands, especially in recent decades. However, how their landscapes and hydrological patterns changed over time was poorly qualified, which was crucial to conserving biodiversity and ecosystems. In this study, we proposed a new wetland classification procedure taking advantage of the shape, topography, landscape patterns, and phenology to map the distribution of six wetland types in the MLRYRB in 1990 and 2020 with Landsat images. The transitions among different wetland types and associated driving factors were examined. Artificial wetlands expanded by 3907.6 km2 while natural wetlands decreased by 423.2 km2, resulting in a net area increase of 3484.4 km2. Farmland reclamations, aquacultural activities, urban expansion, and dam constructions induced 70 % of the area's loss of natural wetlands. Meanwhile, spatiotemporal patterns in wetland inundation dynamics were determined with agglomerative hierarchical cluster analysis. Widespread transitions from perennial water to seasonal wetlands were detected. Notably, 47.8 % of the natural wetlands experienced significant drying trends, and as a result, the mean yearly inundated periods for natural wetlands decreased from 303 days in 1990 to 272 days in 2020. Given the substantial structural alterations, wetland destruction was more severe than the area reflected. Our results suggested that category-based changes in wetland areas, inundation patterns, associated driving forces, and underlying ecological consequences should be comprehensively assessed to conduct scientific conservation and prevent "paper offsets." [ABSTRACT FROM AUTHOR]

Increasing aquaculture cultivation produces large quantities of wastewater. If not handled properly, it can have negative impacts on the environment. Constructed wetlands (CWs) are one of the phytoremediation methods that can be applied to treat aquaculture effluent. This research was aimed at determining the performance of Cyperus rotundus in removing COD, BOD, TSS, turbidity, ammonia, nitrate, nitrite, and phosphate from the batch CW system. Treatment was carried out for 30 days with variations in the number of plants (10, 15, and 20) and variations in media height (10, 12, and 14 cm). The result showed that aquaculture effluent contains high levels of organic compounds and nutrients, and C. rotundus can grow and thrive in 100% of aquaculture effluent. Besides that, the use of C. rotundus in CWs with the effect of numbers of plants and media height showed performance of COD, BOD, TSS, turbidity, ammonia, nitrate, nitrite, and phosphate with 70, 79, 90, 96, 64, 82, 92, and 48% of removal efficacy, respectively. There was no negative impact observed on C. rotundus growth after exposure to aquaculture effluent, as indicated by the increase in wet weight, dry weight, and growth rate when compared to the control. Thus, adding aquaculture effluent to CWs planted with C. rotundus supports the growth and development of plants while also performing phytoremediation. [Display omitted] • Cyperus rotundus can withstand 100% aquaculture concentration. • The use of C. rotundus in CW increased the removal of COD, BOD, TSS, turbidity, and phosphate. • Number of plants and medium height variation did not affect the pollutants removal. • The 10 cm media height showed higher RGR as compared to control system. [ABSTRACT FROM AUTHOR]

[Display omitted] • PEI-MBF brought about more stimulation on EPS secreting than Ca-MBF. • Both MBFs caused improvement on microbial community in CWs, particularly PEI-MBF. • Two MBFs caused different impacts on biomarkers and functional bacteria. • Higher NH 4 +-N and TN removal was in CW with Ca-MBF, after long-term operation. • The highest TP removal was not mainly due to microbial promotion by Ca-MBF. Modified basalt fiber (MBF) is a potential material that has been applied in wastewater treatment fields. In this study, superior performances of MBFs by calcium (Ca-MBF) and polyethyleneimine modification (PEI-MBF) were compared in constructed wetlands (CWs). Via chemical grafting, higher biofilm contents were observed on the surface of PEI-MBF, compared to Ca-MBF. Moreover, MBF increased key enzyme activities particularly in lower substrate layer, contributing to positive responses of microbial community in CWs. For instance, PEI-MBF boosted microbial richness and diversity and improved the abundances of denitrifying functional bacteria and biomarkers like Thauera , Vulcanibacillus , and Maritimimonas , probably promoting nitrate removal compared with Ca-MBF group. By contrast, Ca-MBF enriched more functional genera involved in nutrients removal, with the highest removal of ammonium (43.9 %), total nitrogen (66.2 %), and total phosphorus (37.1 %). Overall, this work provided new findings on improved performance of CWs with MBF. [ABSTRACT FROM AUTHOR]

This work assesses the Cr accumulation and tolerance of Typha domingensis after an accidental discharge of wastewater that produced a concentration of Cr(VI) of approximately 120 mg L−1 in a free-water surface wetland. The wetland was constructed for the final wastewater treatment of a metallurgical manufacturing plant. It is 7 m wide, 20 m long, and waterproofed with a geomembrane. A 1.5 m soil layer was placed on top of the geomembrane. Water, plants, and sediment were sampled before and after an accidental discharge. The root anatomical measurements of the plants from the treatment wetland were compared with those of plants from an uncontaminated wetland (control). Roots and dead leaves from the inlet plants showed the highest Cr concentrations after the accidental discharge (12.4 and 11.6 mg g−1, respectively). SEM-EDX mapping determined that Cr was accumulated in root epidermis. Cr accumulation in plant detritus, plant roots, and sediment were the mechanisms for Cr removal. Plants accumulated Cr in belowground tissues demonstrating their potential for phytostabilization. T. domingensis was capable of modifying its morphology to respond to high Cr concentrations. This macrophyte is a suitable species for wetlands constructed for the treatment of a wastewater with high Cr(VI) concentration. The studied system was capable of minimizing the impact and preserving the environment. [Display omitted] • T. domingensis response after a Cr(VI) accidental discharge was assessed in a wetland. • Roots and dead leaves from the inlet plants showed the highest Cr concentrations. • Root morphometric parameters changed in response to high Cr(VI) concentrations. • The wetland was resilient and minimized the Cr discharge demonstrating its robustness. [ABSTRACT FROM AUTHOR]

The effects and mechanism of low concentrations (1 mg·L−1) and high concentration (10 mg·L−1) of sulfamethoxazole (SMX) on nitrogen metabolism in vertical flow constructed wetland (VFCW) were analyzed. The removal efficiencies of 1 and 10 mg·L−1 SMX in VFCW were found to be 98.92 ± 2.74% and 58.63 ± 12.86%, respectively. SMX suppressed the removal of NH 4 +-N (93.90%→93.44%→92.54%), but significantly increased NO 3 --N removal (66.62%→94.63%→89.39%, p < 0.05). Metagenomic analysis certified that 10 mg·L−1 SMX had a remarkable repression effect on the abundance of amo ABC (p < 0.05) and the dissimilatory nitrate reduction was strengthened. Conversely, 1 mg·L−1 SMX remarkable inhibition expression of hao and the dominant role of nitrogen functional gene of amo C, nar GHI and nap AB were significantly enhanced. Moreover, SMX enhanced clustering of microbial communities, and the structural stability was proportional to the concentration of SMX in VFCW. • SMX significantly improved the removal of NO3--N in constructed wetland. • High concentration SMX strengthen the aggregation of microbial community in CW. • Dominant nitrogen functional bacteria changed under SMX stress in CW. • The abundance of hao gene was strongly inhibited under high/low SMX stress. [ABSTRACT FROM AUTHOR]

The scientific significance of this work involved in investigating the removal of contaminants of emerging concern (CECs) and antibiotic resistance genes (ARGs) at pilot-scale with partially saturated vertical flow constructed wetland either bioaugmented or not with the Trichoderma asperellum (strain T34) by means of the non-target liquid chromatography high-resolution mass spectrometry and SmartChip™ Real-Time PCR methodological approaches. Bioaugmentation testing was successful as Trichoderma was able to grow in competitive conditions resulting from the use of secondary treated domestic wastewater. There was a clear relationship between the removal efficiency (RE) and the biodegradability as well as the sorption capacity of the identified compounds. The most easily eliminated compounds were those which are known to be readily biodegradable (e.g., nicotine). Interestingly, from 22 compounds with RE > 65 %, 17 compounds have a log Dow between 0 and 3 (optimal plant uptake). The most significant beneficial effect was observed with benzotriazole and diclofenac. The most difficult compounds to be eliminated were the most polar ones (log Dow < 0) such as melamine. High variability in removal efficiency over the course of a four-week experiment remained the chief constraint for the proper assessment of treatment performances. Transformation products (TPs) were also investigated. N-oxide TPs and 14-hydroxyclarithromycin were formed in wetland treatment while TPs which were prone to undergo further N-dealkylation or hydroxylation reactions were partly eliminated. Bioaugmented wetland treatments caused a shift in the composition of ARGs but there was no statistical difference in average rates of ARGs removal. [Display omitted] • Bioaugmented wetland with Trichoderma was evaluated by non-target LC-HRMS screening. • Trichoderma was able to grow in real competitive conditions. • Removal efficiency higher than 65 % was observed for slow biodegradable contaminants. • N-oxide TPs and 14-hydroxyclarithromycin were formed in treatment wetland. • Treatment wetland failed to reduce the overall bacterial and ARGs loads. [ABSTRACT FROM AUTHOR]

This study proposes a combination of vertical-flow constructed wetlands and solar photo-Fenton catalyzed by Fe-EDTA/DTPA as a greener approach to enhance micropollutant removal from simulated polluted water. In this research, two planted microcosms, one featuring Cyperus haspan and the other Phragmites australis , were examined for their effectiveness in eliminating 5 different micropollutants over varying retention times (2, 4, 7, and 14 days). The goal was to identify the most suitable conditions for an integrated treatment approach. The findings revealed that in all cases the hybrid system provided better removals than the individual treatments, above all for the more recalcitrant compounds. Notably, the combined use of C. haspan and 2 days retention time in the CW, followed by photo-Fenton applying 5 mg L−1 of iron, 50 mg L−1 of H 2 O 2 and 20 min of irradiation achieved total removal of the micropollutants. In contrast, using only the photo-Fenton process, it needed 60 min to remove just 60% of acetamiprid, which is the most resilient of the studied substances. Constructed wetlands, however, required a longer period of contact, up to 14 days, to completely eliminate this pharmaceutical. Ultimately, this hybrid system offers a practical and adaptable solution to meet regulatory limits, tailored to the intended use or destination of the effluent. It combines cost-effectiveness, environmental friendliness, and sustainability. [Display omitted] • The combined system resulted in a rise yields of MPs abatement than sole processes. • Shorter retention times in CW provided superior performances for hybrid system. • The increase in nitrites content in CW affects negatively to photo-Fenton process. • Combined system proves to be an efficient approach for removing micropollutants. • Hybrid system provides an environmentally friendly solution to treat wastewater. [ABSTRACT FROM AUTHOR]

Although the migration and diffusion of antibiotic resistance genes (ARGs) in soil-plant systems have attracted much attention, the migration and diffusion characteristics between constructed wetlands and soil-plant systems differ greatly. Therefore, it is necessary to conduct research on vertical transmission and diffusion of ARGs in constructed wetlands. The vertical distribution and transmission of ARGs in constructed wetlands were explored via metagenomic analysis. The results showed that the proportion of multidrug ARGs was the largest, ranging from 24.2% to 47.5%. The shared characteristics of ARGs were similar to those of bacteria, and there were fewer unique ARGs and microbial species in mesophyll tissue. Sourcetracker analysis revealed that ARGs transfer between plants and atmosphere was bidirectional, but the diffusion of ARGs to atmosphere through plants was relatively weak. ARGs were mainly transmitted to atmosphere/surrounding environment through substrate and influent, and the contributions of substrate to ARGs in atmosphere/surrounding environment were 59.2% and 78.6%, respectively. ARGs involved in foliar attachment mainly originated from peripheral inputs. ARGs showed nonspecific selection for the host at phylum, class and order levels. These findings suggest that more attention should be given to the potential risks of ARGs in constructed wetlands, to formulate effective control and management strategies. [Display omitted] • The transfer of ARGs between plants and the atmosphere is bidirectional. • ARGs diffusion through plants to the surrounding environments is relatively weak. • ARGs exhibit nonspecific selection pattern on hosts at phylum, class and order levels. • ARGs on plant leaf surface mainly originate from peripheral input. [ABSTRACT FROM AUTHOR]

[Display omitted] • Oxido-reductive azo reductase enzyme of plant treat orgaic pollutants. • Plant uptake and storage in stem cells also play role in treatment of pollutants. • Plants do chemisorption of MR dye as indicated by pseudo-second order kinetics. • C. indica shows high tolerance towards MR azo dye toxicity. • Planted CW system peform better than non planted CW. Direct role of macrophyte (aquatic plant) in constructed wetlands has been an issue of serious debate in organic pollutant treatment for last many decades. The present study was performed to investigate the direct role of plants using azo dye methyl red (MR) as a model organic pollutant in constructed wetlands. The study was performed using widely used wetland macrophyte Canna indica L. (Cannaceae) in constructed wetlands with multiple controls experiments. Dye decolourization and ultraviolet–visible spectroscopy (UV–Vis) study revealed that about 99.0 % removal of MR occurred in presence of plants. Results show that C. indica based CW system was able to remove 99.0 % of colour and 75.0 % of COD while the system without C. indica was able to remove 73.6 % of colour and 42.0 % of COD. Simultaneously, accumulation of MR was also observed in the cells of C. indica stem at the end of experimental period. Gas chromatography–mass spectrometry (GC–MS) analysis established that the cleavage of mutagenic azo bond occurred due to the presence of plants. Instead, in absence of plants though discolouration took place, but breakdown of azo bond was not found. Kinetic models depict that plants perform chemisorption mechanism for degradation of MR. Negligible reduction in plant growth and regulatory functions stated that the wetland plants can phyto-remediate and withstand such concentration of MR (50 mg/L) provided during the study. The study affirms that wetland plants can play a direct role in degradation and detoxification of organics pollutant. Results from the experiment revealed that plants play a direct role for the treatment of organic pollutants in constructed wetland treatment system. [ABSTRACT FROM AUTHOR]

Studies have investigated the role of litter type on soil organic nitrogen (SON) mineralization and the resulting chemical composition in aerobic soils; however, the role of anaerobic conditions have been limitedly explored. We determined the SON chemical composition and N mineralization rate with depth of two different vegetation types (emergent aquatic vegetation, EAV and submerged aquatic vegetation, SAV) and prevailing flooded soil conditions in a subtropical treatment wetland. The treatment wetland provided similar water quality and climate conditions across the vegetation types. Three soil depths were sampled, the surficial floc, recently accreted soil, and soil present before constructing the treatment wetland. The surficial floc material created from emergent plants exhibited a mean total carbon (TC) and total N (TN) of 364 g C kg−1 and 27 g N kg−1 vs 185 g C kg−1and 12 g N kg−1 for submerged plants. Despite these differences, there were no significant differences in the proportion of N that was soil organic nitrogen (SON). Mean extractable ammonium was lower (95 mg N kg−1) in SAV systems and may be due to increased pH (~9) during the day compared to EAV systems (207 mg N kg−1). For the chemical composition, the N-associated aromatics comprised 4.8% of the SON in SAV areas compared with just 1.6% for EAV, which suggests an increased SON recalcitrance in SAV created floc. The difference in EAV and SAV chemical composition may be important for the long-term storage of SON and future studies should focus on additional environmental factors that favor the formation of stable recalcitrant SON. • Litter source does not influence resulting soil organic N pools under anaerobic conditions • Litter molecular composition may be important for long-term stability of SON • Organic N mineralization influenced by nitrogen to phosphorus ratio of litter and soil organic matter [ABSTRACT FROM AUTHOR]

There is growing interest in understanding resilience of ecosystems because of the potential of abrupt and possibly irreversible shifts between alternative ecosystem states. Tipping points are observed in systems with strong positive feedback, providing early warning signals of potential instability. These points can be detected through metrics like critical slowing down (CSD), such as increased recovery time, variance, and autocorrelation. These indicators have been tested in laboratory experiments and field settings, ignoring trait changes. Here we present a long-term temporal analysis of several large, intensely monitored constructed wetlands, the Everglades Stormwater Treatment Areas (STAs), in which sudden changes in plant community composition have been observed. Using wavelet analysis, significant increases and decreases of variance properties (long-term flow data, water quality and nutrient TP loads) across these systems can indicate when and which STAs are less resilient to perturbations. In this study, continuous wavelet transform (CWT) was used to determine the periodicity of any cyclical activity in the data and to determine changes in autocorrelation and variance as measures of CSD. The change detection methods were used to find significant changes in variations and correlations across the time series. By employing these techniques, we were able to spot substantial shifts in model-observed wavelet correlation and model residual wavelet variance and thereby identify where these systems exhibit CSD. Although our analysis is limited to historical data, the proposed approach has practical value in that it identifies STAs that may be vulnerable to perturbation. The study also presents one of the few studies in which CSD is observed in practice rather than modelled in theory. • Decline in ecological conditions show statistical signatures of Critical Slowing Down (CSD). • The rising variance coupled to increasing can indicate when and which STA''s are less resilient to perturbations. • These results highlight the importance of accounting risks of tipping point thresholds. • Substantial shifts in model-observed wavelet correlation and model residual wavelet variance identify identify CSD. • Indicators such as variance mitigation and accumulated autocorrelation can determine the resilience of an ecosystem. [ABSTRACT FROM AUTHOR]

The Yellow River Delta (YRD) is a key breeding place for Saunders's Gull (Saundersilarus saundersi), one of the vulnerable birds in the world. Thus, a thorough understanding of the key environmental factors influencing its suitable habitat holds great value for its conservation. Previous researches focused on Saunders's Gull's population changes and habitat features of breeding places in the nature reserve. However, its habitat suitability in the whole YRD has not been studied systematically, hindering the formulation of macro-protection policies to a certain extent. On the basis of occurrence records and environmental variables, we constructed an optimized MaxEnt model using the 'kuenm' R package to investigate the potential distribution of suitable habitat for the Saunders's Gull in the YRD. Results showed that the ideal hyperparameters for the MaxEnt model were a feature combination of linear and quadratic terms, and the regularization multiplier of 0.6 after optimization, indicated a high level of prediction accuracy. The environmental factors that had a significant effect on the Saunders's Gull's distribution were land use and land cover, percentage of beach saline–alkali land (PLAND_55) and distance to coastline (D_coastline). The highly suitable habitat had an area of 258.56 km2, of which 66.63% was located within the YRD National Nature Reserve. The management of constructed wetlands should be combined with the protection of natural wetlands to avoid the disadvantage of 'isolated island-type' protection. The study provides insights into the quantitative relationship between waterfowl and their habitat, providing support for the sustainable development of the YRD, with certain practical significance. • The habitat suitability assessment model of Saunders's Gull (Saundersilarus saundersi) in the Yellow River Delta was built based on an optimized MaxEnt. • Key environmental factors, that is, land use and land cover, percentage of beach saline-alkali land and distance to coastline, were distinguished in the habitat selection of the species. • About 1/3 of the high suitability area are located outside the reserve, suggesting that it is necessary to make a practical plan from a macro perspective to fill the protection gap. [ABSTRACT FROM AUTHOR]

[Display omitted] • Layer position of biochar affects the treatment performance of CW systems • More Cd and Pb were removed by biochar added in bottom layer (BCW) • Cd and Pb concentrations were different in CWs due to the biochar layer position • Microbial diversity and richness were higher in BCW • Microbial community structures were regulated by the layer position of biochar Levels of cadmium (Cd) and lead (Pb) correspond to common composition in acid mine wastewater of Hunan Province of China. The removal path of Cd and Pb and the structure of microbial community were investigated by developing constructed wetlands (CWs) with different layer positions of biochar. The biochar as a layer at the bottom of CW (BCW) system exhibited maximum Cd and Pb removal efficiencies of 96.6–98.6% and 97.2–98.9%, respectively. Compared with original soil, BCW increased the relative proportions of Proteobacteria , Firmicutes , Acidobacteriota , Verrucomicrobiota , Desulfobacterota , Armatimonadota , Bacteroidota , Patescibacteria , Basidiomycota (phylum level) and Burkholderia–Caballeronia–Paraburkholderia , Citrifermentans , Chthonomonadales , Cellulomonas , Geothrix , Terracidiphilus , Gallionellaceae , Microbacterium , Vanrija , Apiotrichum , Saitozyma , Fusarium (genus level). The concentrations of Cd and Pb were positively correlated with the abundance of Verrucomicrobiota , Basidiomycota (phylum level), and Methylacidiphilaceae , Meyerozyma , Vanrija (genus level). This study demonstrates that BCW system can improve removal performance toward Cd and Pb, as well as alter microbial community. [ABSTRACT FROM AUTHOR]

[Display omitted] • Various residence time distribution (RTD) models for wetlands are compared. • Systemic modeling approach is used to describe flow patterns in wetlands. • Model selection criteria are developed based on the shape characteristics of RTD. • Long-tailed and multi-peaked RTD curves are more common in ponds than in ditches. The assessment of wetland performance requires consideration of flow characteristics. Although various systemic models (also known as network of ideal reactors) have been proposed to simulate residence time distribution (RTD) in wetlands, these models have only been tested with very few observations. In addition, the applicability of RTD models is affected by the shape characteristics of RTD curves. However, suitable indexes and quantitative relationships are absent to represent this effect. It remains unclear how to choose a suitable model when using the RTD modeling method to analyze tracer data. This study is designed to (i) test the accuracy of typical systemic models using sufficient observations and (ii) establish model selection criteria based on the shape characteristics of RTD. Firstly, the tanks in series (TIS) model, tanks in series plus delay (TISD) model, tanks in series with exchange (TISE) model, and tanks in series with delay and exchange (TISDE) model are compared using 36 sets of observations from tracer tests in two types of free water surface constructed wetlands (vegetated ditches and vegetated ponds). The results show that the widely used TIS model is unsatisfactory for more than half of the data, the TISD model is effective for rapidly rising RTD curves, the TISE model is preferred for long-tailed RTD curves, and the TISDE model can effectively fit all RTD curves except those with multiple peaks. Then, model selection criteria are established based on ∫ t r t p f (t) d t (the area for the rising stage of RTD), t r t p (the degree of early peak), and t d t p (the degree of long tail), where t r represents the time when tracer concentration begins to rise, t p represents the time of peak concentration, and t d represents the time when concentration decreases to 1/10 of peak concentration. The optimal model for an RTD curve can be identified based on the above three indexes and the corresponding critical conditions. Finally, the relationship between wetland design parameters and RTD shape indexes is examined. The results indicate that low hydraulic loading rates, small aspect ratios, and dense vegetation favor the creation of long tails. Large water depths tend to cause multiple peaks. Long-tailed and multi-peaked RTD curves are more likely to appear in ponds than ditches. Models that account for multiple nonideal flow phenomena are required to simulate water movement in ponds. [ABSTRACT FROM AUTHOR]