Habitat- and lifestyle-dependent structural and functional characteristics of viruses in mangrove wetlands of different functional zonings.

Mangrove wetlands, as one of the natural ecosystems with the most ecological services, have garnered widespread attention about their microbial driven biogeochemical cycling. Urbanization have led to different spatial patterns of environmental conditions and microbial communities in mangroves. However, viruses, as the pivotal drivers of biogeochemical cycling in mangroves, remain inadequately explored in terms of how their ecological potential and complex interactions with host respond to functional zonings. To address this knowledge gap, we conducted a comprehensive investigation on the structural and functional properties of temperate and lytic viruses in mangrove wetlands from different functional zonings by jointly using high-throughput sequencing, prokaryotic and viral metagenomics. Multiple environmental factors were found to significantly influence the taxonomic and functional composition, as well as lysogen-lysis decision-making of mangrove viruses. Furthermore, enriched auxiliary metabolic genes (AMGs) involved in methane, nitrogen and sulfur metabolism, and heavy metal resistance were unveiled in mangrove viruses, whose community composition was closely related to lifestyle and host. The virus-host pairs with different lifestyles were also discovered to react to environmental changes in different ways, which provided an empirical evidence for how virus and bacteria dynamics were specific to viral lifestyles in nature. This study expands our comprehension of the intricate interactions among virus, prokaryotic host and the environment in mangrove wetlands from multiple perspectives, including viral lifestyles, virus-host interactions, and habitat dependence. Importantly, it provides a new ecological perspective on how mangrove viruses are adapted to the stress posed by urbanization.

Effects of different hydrological conditions on the taxonomic structure and functional traits of mollusk communities in a large floodplain wetland.

Floodplain wetlands are critical to the conservation of aquatic biodiversity and the ecological integrity of river networks. However, increasing drought severity and frequency caused by climate change can reduce floodplain wetlands' resistance and recovery capacities. Mollusks, which are common inhabitants of floodplain wetlands, are among the most vulnerable species to drought. However, the response of mollusk communities to drought has received little attention. Here, we investigated how the structure and functional traits of mollusk communities changed in response to varying hydrological conditions, including a flash drought (FD) in the Poyang Lake floodplain wetland. Our findings showed that FD strongly reduced mollusk abundance and biomass, decreased both α- and ß-diversity, and resulted in the extinction of bivalve taxa. A sudden shift in community trait structure was discovered due to the extinction of many species. These traits, which include deposit feeding, crawling, scraping, aerial respiration, and dormancy, help mollusks survive in FD and tolerate completely dry out of their Changhuchi habitat. Finally, we discovered that dissolved oxygen was an important controlling variable for mollusk communities during drought. Our findings provide a scientific basis for the management and conservation of floodplain wetland biodiversity in the context of increasing drought frequency and intensity.

Machine learning prediction on wetland succession and the impact of artificial structures from a decade of field data.

The artificial structures can influence wetland topology and sediment properties, thereby shaping plant distribution and composition. Macrobenthos composition was correlated with plant cover. Previous studies on the impact of artificial structures on plant distribution are scarce in incorporating time-series data or extended field surveys. In this study, a machine-learning-based species distribution model with decade-long observation was analyzed to investigate the correlation between the shift in the distribution of B. planiculmis, artificial structure-induced elevation changes and the expansion of other plants, as well as their connection to soil properties and crab composition dynamics under plants in Gaomei Wetland. Long short-term memory model (LSTM) with Shapley additive explanations (SHAP) was employed for predicting the distribution of B. planiculmis and explaining feature importance. The results indicated that wetland topology was influenced by both artificial structures and plants. Areas initially colonized by B. planiculmis were replaced by other species. Soil properties showed significant differences among plant patches; however, principal component analysis (PCA) of sediment properties and niche similarity analysis showed that the niche of plants was overlapped. Crab composition was different under different plants. The presence probability of B. planiculmis near woody paths decreased according to LSTM and field survey data. SHAP analysis suggested that the distribution of other plants, historical distribution of B. planiculmis and sediment properties significantly contributed to the presence probability of B. planiculmis. A sharp decrease in SHAP values with increasing NDVI at suitable elevations, overlap in PCA of sediment properties and niche similarity indicated potential competition among plants. This decade-long time-series field survey revealed the joint effects of artificial structure and vegetation on the topology and soil properties dynamics. These changes influenced the plant distribution through potential plant competition. LSTM with SHAP provided valuable insights in the underlying the mechanisms of artificial structure effects on the plant zonation process.

Winter harvesting reduces methane emissions and enhances blue carbon potential in coastal phragmites wetlands.

Enhancing the ability of coastal blue carbon to accumulate and store carbon and reduce net greenhouse gas emissions is an essential component of a comprehensive approach for tackling climate change. The annual winter harvesting of Phragmites is common worldwide. However, the effects of harvesting on methane (CH4) emissions and its potential as an effective blue carbon management strategy have rarely been reported. In this study, the effects of winter Phragmites harvesting on the CH4 and carbon dioxide (CO2) fluxes and the underlying mechanisms in coastal Phragmites wetlands were investigated by comparing the eddy covariance flux measurements for three coastal wetlands with different harvesting and tidal flow conditions. The results show that harvesting can greatly reduce the CH4 emissions and the radiative forcing of CH4 and CO2 fluxes in coastal Phragmites wetlands, suggesting that winter Phragmites harvesting has great potential as a nature-based strategy to mitigate global warming. The monthly mean CH4 fluxes were predominantly driven by air temperature, gross primary productivity, and latent heat fluxes, which are related to vegetation phenology. Additionally, variations in the salinity and water levels exerted strong regulation effects on CH4 emissions, highlighting the important role of proper tidal flow restoration and resalinization in enhancing blue carbon sequestration potential. Compared with the natural, tidally unrestricted wetlands, the CH4 fluxes in the impounded wetland were less strongly correlated with hydrometeorological variables, implying the increased difficulties of predicting CH4 variations in impounded ecosystem. This study facilitates the improved understanding of carbon exchange in coastal Phragmites wetlands with harvesting or impoundment, and provides new insights into effective blue carbon management strategies beyond tidal wetland restoration for mitigating the effects of climate change.

Potential Of Biochar And Humic Substances For Phytoremediation Of Trace Metals In Oil Sands Process Affected Water.

Oil sands process affected water (OSPW) is produced during bitumen extraction and typically contains high concentrations of trace metals. Constructed wetlands have emerged as a cost effective and green technology for the treatment of metals in wastewaters. Whether the addition of amendments to constructed wetlands can improve metal removal efficiency is unknown. We investigated the synergistic effects of carbon based amendments and wetland plant species in removal of arsenic, cadmium, cobalt, chromium, copper, nickel, and selenium from OSPW. Three native wetland species (Carex aquatilis, Juncus balticus, Scirpus validus) and two amendments (canola straw biochar, nano humus) were investigated in constructed wetland mesocosms over 60 days. Amendment effect on metal removal efficiency was not significant, while plant species effect was. Phytoremediation resulted in removal efficiencies of 78.61 to 96.31 % for arsenic, cadmium, and cobalt. Carex aquatilis had the highest removal efficiencies for all metals. Amendments alone performed well in removing some metals and were comparable to phytoremediation for cadmium, cobalt, copper, and nickel. Metals were primarily distributed in roots with negligible translocation to shoots. Our work provides insights into the role of plants and amendments during metal remediation and their complex interactions in constructed treatment wetlands.

Constructed wetlands as nature-based solutions in managing per-and poly-fluoroalkyl substances (PFAS): Evidence, mechanisms, and modelling.

Per- and poly-fluoroalkyl substances (PFAS) have emerged as newly regulated micropollutants, characterised by extreme recalcitrance and environmental toxicity. Constructed wetlands (CWs), as a nature-based solution, have gained widespread application in sustainable water and wastewater treatment and offer multiple environmental and societal benefits. Despite CWs potential, knowledge gaps persist in their PFAS removal capacities, associated mechanisms, and modelling of PFAS fate. This study carried out a systematic literature review, supplemented by unpublished experimental data, demonstrating the promise of CWs for PFAS removal from the influents of varying sources and characteristics. Median removal performances of 64, 46, and 0 % were observed in five free water surface (FWS), four horizontal subsurface flow (HF), and 18 vertical flow (VF) wetlands, respectively. PFAS adsorption by the substrate or plant root/rhizosphere was deemed as a key removal mechanism. Nevertheless, the available dataset resulted unsuitable for a quantitative analysis. Data-driven models, including multiple regression models and machine learning-based Artificial Neural Networks (ANN), were employed to predict PFAS removal. These models showed better predictive performance compared to various mechanistic models, which include two adsorption isotherms. The results affirmed that artificial intelligence is an efficient tool for modelling the removal of emerging contaminants with limited knowledge of chemical properties. In summary, this study consolidated evidence supporting the use of CWs for mitigating new legacy PFAS contaminants. Further research, especially long-term monitoring of full-scale CWs treating real wastewater, is crucial to obtain additional data for model development and validation.

Effectiveness assessment of China's coastal wetland ecological restoration: A meta-analysis.

Due to the coastal wetland degradation caused by human activities and environmental changes, many coastal wetland restoration studies have been carried out in China to restore the degraded ecosystems, but it still lacks a comprehensive assessment of restoration effectiveness at national scale. In this study, a meta-analysis of 78 field studies was conducted to quantitatively assess the restoration effectiveness of biodiversity and ecosystem services in China's coastal wetlands. At the same time, we evaluated the impact factors such as ecosystem types, restoration methods and measures, and restoration time on restoration effectiveness. The results show that coastal wetland ecological restoration has improved the biodiversity and ecosystem services by 36.8 % and 38.2 % respectively within the time range reported in the research literature, but neither has returned to the level of natural ecosystems. Biodiversity recovery is significantly positively correlated with the recovery of ecosystem services, indicating the simultaneous recovery outcome. Compared with degraded wetlands, the effectiveness of passive restoration is better than that of active restoration. In the mangrove ecosystem, invasive species removal is the most effective among the restoration measures, and the restoration effectiveness of polyculture plantations is better than that of monoculture plantations. When time ranges from 0 to 20 years, the recovery level of coastal wetlands tends to increase with the extension of restoration time. However, when the restoration time is >20 years, the recovery level decreases, which may be related to the lack of maintenance and management measures in the later stage. Our study showcases the scientific evidence for future coastal wetland ecological restoration in China.

Constructed wetlands for the removal of organic micropollutants from wastewater: Current status, progress, and challenges.

In this work, the practical utility of constructed wetlands (CWs) is described as a promising treatment option for micropollutants (MPs) in wastewater with the aid of their eco-friendly, low-energy, economically feasible, and ecologically sustainable nature. This paper offers a comprehensive review on CW technology with respect to the key strategies for MP removal such as phytoremediation, substrate adsorption, and microbial degradation. It explores the important factors controlling the performance of CWs (e.g., in terms of configurations, substrates, plant-microbe interactions, temperature, pH, oxygen levels, hydraulic loading rate, and retention time) along with the discussions on the pivotal role of microbial populations in CWs and plant-microbe cooperative remediation dynamics, particularly in relation to diverse organic MP patterns in CWs. As such, this review aims to provide valuable insights into the key strategies for optimizing MP treatment and for enhancing the efficacy of CW systems. In addition, the process-based models of constructed wetlands along with the numerical simulations based on the artificial neural network (ANN) method are also described in association with the data exploratory techniques. This work is thus expected to help open up new possibilities for the application of plant-microbe cooperative remediation approaches against diverse patterns of organic MPs present in CWs.

Enhancing nitrogen removal in constructed wetlands: The role of influent substrate concentrations in integrated vertical-flow systems.

Recent advancements in constructed wetlands (CWs) have highlighted the imperative of enhancing nitrogen (N) removal efficiency. However, the variability in influent substrate concentrations presents a challenge in optimizing N removal strategies due to its impact on removal efficiency and mechanisms. Here we show the interplay between influent substrate concentration and N removal processes within integrated vertical-flow constructed wetlands (IVFCWs), using wastewaters enriched with NO3--N and NH4+-N at varying carbon to nitrogen (C/N) ratios (1, 3, and 6). In the NO3--N enriched systems, a positive correlation was observed between the C/N ratio and total nitrogen (TN) removal efficiency, which markedly increased from 13.46 ± 2.23% to 87.00 ± 2.37% as the C/N ratio escalated from 1 to 6. Conversely, in NH4+-N enriched systems, TN removal efficiencies in the A-6 setup (33.69 ± 4.83%) were marginally 1.25 to 1.29 times higher than those in A-3 and A-1 systems, attributed to constraints in dissolved oxygen (DO) levels and alkalinity. Microbial community analysis and metabolic pathway assessment revealed that anaerobic denitrification, microbial N assimilation, and dissimilatory nitrate reduction to ammonium (DNRA) predominated in NO3--N systems with higher C/N ratios (C/N ≥ 3). In contrast, aerobic denitrification and microbial N assimilation were the primary pathways in NH4+-N systems and low C/N NO3--N systems. A mass balance approach indicated denitrification and microbial N assimilation contributed 4.12-47.12% and 8.51-38.96% in NO3--N systems, respectively, and 0.55-17.35% and 7.83-33.55% in NH4+-N systems to TN removal. To enhance N removal, strategies for NO3--N dominated systems should address carbon source limitations and electron competition between denitrification and DNRA processes, while NH4+-N dominated systems require optimization of carbon utilization pathways, and ensuring adequate DO and alkalinity supply.

Effects of stock enhancement on the macrobenthic community and ecological health in the intertidal zone of the estuarine wetland in Nanhui, China.

Nanhui Dongtan Wetland is an important part of Yangtze Estuary Wetland, and its species diversity has been affected by reclamation in recent years. To increase the diversity of species in reclamation areas, stock enhancement was implemented in the Nanhui Dongtan Wetland in May 2020 as a method of ecological restoration. We investigated macrobenthos before and after release, analysed changes in the macrobenthos and evaluated the ecological health of the sampled area. The diversity index showed species were more abundant and community structure were more diversified after release. Functional groups and redundancy analysis showed that the effects of stock enhancement on macrobenthos in Nanhui Dongtan wetland may be based on changes in secondary productivity. Stock enhancement may promote the resistance of macrobenthic communities to organic pollution without negatively affecting ecological health. As a method of ecological restoration, stock enhancement will play a positive role in the restoration of macrobenthic communities.

Ecophysiological responses of Phragmites australis populations to a tidal flat gradient in the Yangtze River Estuary, China.

Phragmites australis is a prevalent species in the Chongming Dongtan wetland and is capable of thriving in various tidal flat environments, including high salinity habitats. P. australis population displays inconsistent ecological performances, highlighting the need to uncover their survival strategies and mechanisms in tidal flats with diverse soil salinities. Upon comparing functional traits of P. australis at multiple tidal flats (low, middle, and high) and their responses to soil physicochemical properties, this study aimed to clarify the salt-tolerant strategy of P. australis and the corresponding mechanisms. These results showed that leaf characteristics, such as specific leaf area and leaf dry matter content, demonstrated more robust stability to soil salinity than shoot height and dry weight. Furthermore, as salt stress intensified, the activities of superoxide dismutase (SOD), catalase (CAT) and peroxisome (POD) in P. australis leaves at low tidal flat exhibited an increased upward trend compared to those at other tidal flats. The molecular mechanism of salt tolerance in Phragmites australis across various habitats was investigated using transcriptome sequencing. Weighted correlation network analysis (WGCNA) combined with differentially expressed genes (DEGs) screened out 3 modules closely related to high salt tolerance and identified 105 core genes crucial for high salt tolerance. Further research was carried out on the few degraded populations at low tidal flat, and 25 core genes were identified by combining WGCNA and DEGs. A decrease in the activity of ferroptosis marker gonyautoxin-4 and an increase in the content of Fe3+ in the degenerated group were observed, indicating that ferroptosis might participate in degradation. Furthermore, correlation analysis indicated a possible regulatory network between salt tolerance and ferroptosis. In short, this study provided new insights into the salt tolerance mechanism of P. australis population along tidal flats.

Naïve and induced tolerance of 15 amphibian populations to three commonly applied insecticides.

Human impacts on ecological communities are pervasive and species must either move or adapt to changing environmental conditions. For environments polluted by contaminants, researchers have found hundreds of target pest species evolving increased tolerance, but we have substantially fewer cases of evolved tolerance in non-target species. When species do evolve increased tolerance, inducible tolerance can provide immediate protection and favor the evolution of increased tolerance over generations via genetic assimilation. Using a model larval amphibian (wood frogs, Rana sylvatica), we examined the tolerance of 15 populations from western Pennsylvania and eastern New York (USA), when first exposed to no pesticide or sublethal concentrations and subsequently exposed to lethal concentrations of three common insecticides (carbaryl, chlorpyrifos, and diazinon). We found high variation in naïve tolerance among the populations for all three insecticides. We also discovered that nearly half of the populations exhibited inducible tolerance, though the degree of inducible tolerance (magnitude of tolerance plasticity; MoTP) varied. We observed a cross-tolerance pattern of the populations between chlorpyrifos and diazinon, but no pattern of similar MoTP among the pesticides. With populations combined from two regions, increased tolerance was not associated with proximity to agricultural fields, but there were correlations between proximity to agriculture and MoTP. Collectively, these results suggests that amphibian populations possess a wide range of naïve tolerance to common pesticides, with many also being able to rapidly induce increased tolerance. Future research should examine inducible tolerance in a wide variety of other taxa and contaminants to determine the ubiquity of these responses to anthropogenic factors.

Enhanced nitrogen removal by an isolated aerobic denitrifying strain in a vertical-flow constructed wetland.

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 NO3- 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.

The fate of plastic wraps in constructed wetland: Surface structure and microbial community.

The high use of plastic wraps leads to significant environmental pollution. In this study, the surface structure and microbial community evolution of commercially available plastic wraps [polyethylene (PE), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), and polylactic acid (PLA)] in constructed wetlands (CWs) were investigated. The results indicated that all plastic wraps gradually decreased in molecular weight, crystallinity, melting, and crystallization temperatures, whereas a gradual increase was observed in the surface roughness, polymer dispersity index (PDI), carbonyl index (CI) and Shannon index of microorganisms colonizing the CWs. The aging rate of the plastic wrap was in the order: PLA > PVC > PE > PVDC, at the same site in the CWs, and it was in the order: soil surface > plant roots > subsoil, for the same plastic wrap. The diversity of microorganisms colonizing the same plastic wrap was in the order: plant roots > subsoil > soil surface. The Shannon indices of microorganisms on plastic wraps were lower than those in the soil, indicating that the diversity of microorganisms colonizing plastic wraps is limited. Additionally, the microbial community structure on the plastic surface was co-differentiated by the plastic type, placement position in the CWs, and aging time. Significantly different microbial community structures were found on the PVC and PVDC wrap surfaces, revealing that the chlorine in plastics limits microbial diversity. Unclassified members of Rhizobiaceae and Pseudomonadaceae were the dominant genera on the surface of the plastic wraps, suggesting that they may be the microorganisms involved in plastic degradation processes. The study provides valuable perspectives to facilitate a comprehensive understanding of the migration, fate, and environmental risks associated with microplastics (MPs) in wetlands.

Linking carbon storage with land use dynamics in a coastal Ramsar wetland.

Coastal wetland ecosystems make an important contribution to the global carbon pool, yet their extent is declining due to aquaculture-related land use changes. We conducted an extensive investigation into the carbon stock and area coverage of macrophytes in a tropical coastal Ramsar wetland, Kolleru in Andhra Pradesh, India. A total of 72 quadrats of size 1 × 1 m2 were laid in the wetland, 19 species of macrophytes were collected and analyzed for carbon content using a CNHS analyzer. To assess changes in the wetland macrophytes, Normalized Difference Vegetation Index (NDVI) was estimated using Landsat time series data from 1975 to 2023. The importance value index (IVI) of macrophytes scored highest for the Ipomoea aquatica (41.4) and the lowest for Ottelia alismoides (1.9). Non-metric multidimensional scaling (NMDS) significantly (r = 0.1905, p = 0.0361) revealed a clear separation of macrophytes in ordination space. ANOVA indicated highly significant (p < 0.0001) variations in the carbon content of aboveground and belowground components of macrophytes. Among the different macrophytes, the highest carbon content was found in Phragmites karka (0.6 g. g-1) and the lowest was recorded in Utricularia stellaris (0.2 g. g-1). On an average, emergents in the Kolleru wetland sequester 1525 ± 181 g C m-2 yr-1, rooted floating species sequester 858 ± 101 g C m-2 yr-1, submerged macrophytes sequester 480 ± 60 g C m-2 yr-1, and free-floating macrophytes sequester 221 ± 90 g C m-2 yr-1. Land cover mapping revealed a decrease in spread of aquatic vegetation from 225.2 km2 in 1975 to 100.6 km2 in 2023. Although macrophytes are vital carbon sinks, the wetland conversion into fishponds has resulted in a loss of 55.3 % of carbon storage. Therefore, immediate restoration of macrophyte cover is vital for the proper functioning of carbon sequestration and mitigation of climate change impacts.

Using stacked pot connection of wetland microbial fuel cells to charge the battery: Potential and effecting factor.

In the practical application of wetland microbial fuel cells (WMFCs), suitable designs and stacked connection systems have consistently been employed to increase and harvest power generation. Our study compares different WMFCs designs and demonstrates that the cylinder pot design outperforms the small hanging pot design in terms of electrical energy production. Moreover, power generation from the cylinder pot can be further optimized through separator modification and stacked connections. The stacked WMFCs design exhibited no voltage reversal, with an average power output ranging from 0.03 ± 0.01 mW (single pot) to 0.11 ± 0.05 mW (stacked connection of 5 pots) over a 60-day operational period. Additionally, our study identifies distinct patterns in both anodic and cathodic physiochemical factors including electrical conductivity (EC), pH, and nitrate (NO3-), highlighting the significant influence of plant involvement on altering concentrations and levels in different electrode zones. The WMFCs bioelectricity production system, employing 15 pots stacked connections achieves an impressive maximum power density of 9.02 mW/m2. The system's practical application is evidenced by its ability to successfully power a DC-DC circuit and charge a 1.2 V AAA battery over a period of 30 h, achieving an average charging rate of 0.0.2 V per hour.

Enhancing nitrogen removal through macrophyte harvest and installation of woodchips-based floating beds in surface-flow constructed wetlands.

Wetland management maintains nitrogen (N) removal capacity in mature and overgrown constructed wetlands (CWs). We evaluated whether CW management by macrophyte harvesting, and subsequent installation of woodchips-based floating beds (WFBs) planted with Glyceria maxima and Filipendula ulmaria improved N removal. In sixteen heavily overgrown experimental CWs, we applied four treatments: i) only macrophyte harvesting, ii) 5% of the harvested-CW surface covered with WFBs, iii) 20% WFBs cover, and iv) a control treatment (heavily overgrown). N removal was determined in all wetlands at nine occasions. Plant biomass accrual, N assimilation, and denitrification genes nirS, nirK, nosZI and nosZII on plant roots and woodchips from WFBs were estimated. Macrophyte harvesting improved N removal of heavily overgrown CWs, whereas subsequent WFB installation only sometimes improved N removal. Mean N removal efficiencies (± standard deviation) overall were 41 ± 15 %, 45 ± 20 %, 46 ± 16 % and 27 ± 8.3 % for treatments i to iv, respectively. Relative biomass production, root length and root surface area for G.maxima (mean ± standard deviation: 234 ± 114 %, 40 ± 6.5 cm, 6308 ± 1059 cm2g-1, respectively) were higher than those for F. ulmaria (63 ± 86 %, 28 ± 12 cm, 3131 ± 535 cm2g-1, respectively) whereas biomass N assimilation was higher for F. ulmaria (1.8 ± 0.9 gNm-2 of WFB) than for G. maxima (1.3 ± 0.5 gNm-2 of WFB). Denitrification gene abundance was higher on plant roots than on woodchips while G. maxima hosted higher root denitrification gene abundance than F. ulmaria. We conclude that macrophyte harvesting improves N removal in heavily overgrown CWs. WFBs installation has the potential to support plant growth and denitrification in surface-flow constructed wetlands. Further studies need to evaluate the long-term effects of macrophyte harvesting and WFB installation on N removal in CWs.

Non-flooding conditions caused by water table drawdown alter microbial network complexity and decrease multifunctionality in alpine wetland soils.

Several soil functions of alpine wetland depend on microbial communities, including carbon storage and nutrient cycling, and soil microbes are highly sensitive to hydrological conditions. Wetland degradation is often accompanied by a decline in water table. With the water table drawdown, the effects of microbial network complexity on various soil functions remain insufficiently understood. In this research, we quantified soil multifunctionality of flooded and non-flooded sites in the Lalu Wetland on the Tibetan Plateau. We employed high-throughput sequencing to investigate the microbial community responses to water table depth changes, as well as the relationships between microbial network properties and soil multifunctionality. Our findings revealed a substantial reduction in soil multifunctionality at both surface and subsurface soil layers (0-20 cm and 20-40 cm) in non-flooded sites compared to flooded sites. The α-diversity of bacteria in the surface soil of non-flooded sites was significantly lower than that in flooded sites. Microbial network properties (including the number of nodes, number of edges, average degree, density, and modularity of co-occurrence networks) exhibited significant correlations with soil multifunctionality. This study underscores the adverse impact of non-flooded conditions resulting from water table drawdown on soil multifunctionality in alpine wetland soils, driven by alterations in microbial community structure. Additionally, we identified soil pH and moisture content as pivotal abiotic factors influencing soil multifunctionality, with microbial network complexity emerging as a valuable predictor of multifunctionality.

Augmentation of saline wastewater treatment via functional enrichment of bacteria and optimized distribution in constructed wetlands combined with slag-sponges at different temperatures.

China's aquatic environment continues to face several difficulties. Ecological constructed wetland systems (CWs) can be used to treat polluted saline water to alleviate water shortages regionally and globally. However, the performance is limited by low temperatures. To expand the use of CWs, we introduced a slag-sponge, a flaky material derived from alkaline waste slag, to create a newly constructed wetland system that can operate at both low and high temperatures. We evaluated its effectiveness by placing it at different heights in our devices. The results showed that the treatment was effective for saline wastewater with multiple contaminants. The efficiency was 20% higher than that of traditional CWs. Slag-sponges were found to carry pore structures and exhibit thermal insulation, which led to the enrichment of functional microbial communities (Chryseobacterium and Exiguerium) at low temperatures according to the microbial species analysis. The enhanced CWs offer another option for the treatment of polluted saline water in the environment and provide promising strategies for the utilization of waste slag.

Monitoring and evaluation of vegetation restoration in the Ebinur Lake Wetland National Nature Reserve under lockdown protection.

For a long time, human activities have been prohibited in ecologically protected areas in the Ebinur Lake Wetland National Nature Reserve (ELWNNR). The implementation of total closure is one of the main methods for ecological protection. For arid zones, there is a lack of in-depth research on whether this measure contributes to ecological restoration in the reserve. The Normalized Difference Vegetation Index (NDVI) is considered to be the best indicator for ecological monitoring and has a key role to play in assessing the ecological impacts of total closure. In this study, we used Sentinel-2, Landsat-8, and Moderate Resolution Imaging Spectroradiometer (MODIS) remote sensing data to select optimal data and utilized Sen slope estimation, Mann-Kendall statistical tests, and the geographical detector model to quantitatively analyze the normalized difference vegetation index (NDVI) dynamics and its driving factors. Results were as follows: (1) The vegetation distribution of the Ebinur Lake Wetland National Nature Reserve (ELWNNR) had obvious spatial heterogeneity, showing low distribution in the middle and high distribution in the surroundings. The correlation coefficients of Landsat-8 and MODIS, Sentinel-2 and MODIS, and Sentinel-2 and Landsat-8 were 0.952, 0.842, and 0.861, respectively. The NDVI calculated from MODIS remote sensing data was higher than the value calculated by Landsat-8 and Sentinel-2 remote sensing images, and Landsat-8 remote sensing data were the most suitable data. (2) NDVI indicated more degraded areas on the whole, but the ecological recovery was obvious in the localized areas where anthropogenic closure was implemented. The ecological environment change was the result of the joint action of man and nature. Man-made intervention will change the local ecological environment, but the overall ecological environment change was still dominated by natural environmental factors. (3) Factors affecting the distribution of NDVI in descending order were as follows: precipitation > evapotranspiration > land use type > elevation > vegetation type > soil type > soil erosion > slope > temperature > slope direction. Precipitation was the main driver of vegetation change in ELWNNR. The synergistic effect of the factors showed two-factor enhancement and nonlinear enhancement, and the combined effect of the driving factors would increase the influence on NDVI.