Phragmites Australis Research Articles

Simultaneous removal of heavy metals and electricity generation from wastewater in constructed wetland-microbial fuel cells

Constructed wetlands (CWs) are environmentally friendly and cost-effective methods for wastewater treatment. Recently, there have been innumerable efforts to integrate CWs with microbial fuel cells (MFCs) to enhance the removal of pollutants while generating electricity. Constructed Wetland-Microbial Fuel Cells (CW-MFCs) are engineered systems incorporating physical, chemical, and biological processes for wastewater treatment. However, the application of CW-MFCs to remove multiple heavy metals from wastewater is still an active area of research. The present study explores for the first time the utilization of different types of CW-MFCs, including CW-MFC-planted, CW-MFC-unplanted, and CW-sand-filter for simultaneous removal of different concentrations of organic pollutants and multiple heavy metals such as zinc (Zn), cadmium (Cd), copper (Cu), and lead (Pb) from wastewater while generating electricity. The study employed nine CW-MFC microcosms, some of which were planted with Phragmites australis. The initial concentrations of Cu, Pb, Zn, and Cd were maintained at 2, 10, and 30 mg/l, respectively, while initial COD concentrations were 120, 500, and 1000 mg/l. Remarkably, the maximum removal rates achieved were 98.83 %, 95.74 %, 92.91 %, and 90.75 % for Cu, Pb, Zn, and Cd, respectively, and the maximum removal rate of COD was 97.96 % at 10 mg/l of Cu, Pb, Zn, Cd, and 500 mg/l of COD in CW-MFC-planted. The attained highest voltage, current, and power densities reached 687 mV, 4000 mA/m3, and 785.86 mW/m3, respectively, in CW-MFC-planted. This study demonstrates the significant impact of CW-MFC-planted systems on wastewater treatment and electricity generation.

Return of the Phrag-i: evaluating sexual reproduction mechanisms amenable to dieback recovery and potential invasiveness across Phragmites australis haplotypes

Phragmites australis is one of the most invasive wetland plants on the planet with both native and invasive haplotypes occurring in the United States. Three Phragmites haplotypes (Delta-, EU- and Gulf-types) co-occur in marshes of the Mississippi River Delta (MRD), where a recent dieback of Phragmites has prompted investigations about the potential for recolonization by seed. In other areas of the US, the invasive EU-type has been shown to spread by seed, yet little is known about reproduction modes of the Delta- and Gulf-types. We conducted a survey at 35 sites along the Mississippi River Delta region in southeast Louisiana to examine the potential for sexual reproduction across haplotypes as well as the potential for hybridization. Seed and pollen samples were collected from Phragmites populations to examine flowering phenology and determine pollen viability of the three lineages. We also conducted a seedbank assay in stands of three haplotypes to test the potential for recruitment by seed. Despite the observed potential for sexual reproduction in Delta- and EU- types, no Phragmites seedlings germinated from the seedbank. EU was the only haplotype to exhibit germination from seeds collected from seed heads. Both spatial separation and temporal isolation in flowering times indicate that hybridization between Phragmites haplotypes in the lower MRD is unlikely. High pollen production, increased pollen production following dieback, and viable seeds in the EU-type suggest that this invasive haplotype has a greater potential to invade new areas and adapt to stressors through sexual reproduction compared to than Delta-or Gulf haplotypes.

Effects of High Salinity and Water Stress on Wetland Grasses from the Spanish Mediterranean Coast.

The impacts of climate change are reaching unprecedented levels, heightening the risk of species loss and ecosystem service degradation. Wetlands, highly threatened ecosystems, serve vital ecological functions by capturing carbon, filtering water, and harbouring diverse wildlife. Coastal wetlands encounter many challenges, such as increased drought periods and escalating salinity levels, severely impacting plant biodiversity. Assessing how plants respond to various environmental stress factors is imperative for devising successful conservation strategies. In the present study, we examined three representative grass species found in various habitats within the Albufera Natural Park, close to the city of Valencia on the Spanish Mediterranean coast: Imperata cylindrica, Phragmites australis, and Saccharum ravennae. High salinity and water stress conditions were induced by subjecting the plants to irrigation with solutions containing 200, 400, 600, and 800 mM NaCl or withholding irrigation altogether to mimic coastal flooding and drought scenarios. The treatments were maintained until noticeable wilting of the plants occurred, at which point a range of stress biomarkers were determined, including photosynthetic pigments, ions, osmolytes, oxidative stress markers, and antioxidant metabolites, as well as antioxidant enzyme activities. Saccharum ravennae displayed the highest sensitivity to salt stress, whereas I. cylindrica appeared to be the most tolerant. The primary salinity tolerance mechanism observed in I. cylindrica and P. australis was a blockage of ion transport from the root zone to the aerial part, together with the salt-induced accumulation of proline and soluble sugars to high concentrations in the former. No significant effects of the water deficit treatment on the growth or biochemical parameters were observed for any of the analysed species. These findings offer valuable information for the effective management and conservation of coastal wetlands facing the challenges posed by climate change.

Acetonitrile biodegradation and total nitrogen removal in a single-stage airlift bioreactor using bacterial endophytes

This study focused on the biodegradation of acetonitrile (ACN) and subsequent nitrification using a mesophilic microbial consortium isolated from Phragmites australis and Zantedeschia aethiopica plants which were in a nitrile-contaminated habitat. The organisms were identified using 16S rDNA sequencing and were determined to be Bacillus sp., Pseudomonas sp., and Enterobacter sp. organisms. These organisms were used as a consortium in the biodegradation of ACN. The physicochemical conditions including temperature, pH, and ACN concentration were optimized using response surface methodology (RSM). Based on this method, an optimal biodegradation efficiency of 99% was achieved at an optimized temperature of 34.99 °C, pH of 7:03, and an ACN concentration of up to 127.23 mg/L. These optimized parameters were used in the continuous operation over a period of 122 days with increased ACN concentrations of 150–500 mg/L where the biodegradation efficiency exceeded 99% which were accompanied by the production of acetic acid, acetamide, and nitrogenous compounds. Acetic acid and acetamide were completely utilized while total nitrogen (TN) was 1.2 mg/L on the last day of the study.

Nitrate and ammonium removal in constructed wetlands: Experimental insights and zero-dimensional numerical modeling

Constructed wetlands (CWs) have emerged as effective wastewater treatment systems, mimicked natural wetland processes but engineered for enhanced pollutant removal efficiency. Ammonium (NH4+) and nitrate (NO3−) are among common pollutants in wastewater, posing significant environmental and health risks. The primary objective of this study is to compares the performance of CWs using gravel and three sizes of natural pumice, along with phragmites australis, in horizontal and horizontal-vertical CWs for nitrate and ammonium removal in the complementary treatment of domestic wastewater. Additionally, the study aims to develop and validate a numerical model using MATLAB software to predict the removal efficiency of these pollutants, thereby contributing to the optimization of CW design and operation. The model operates as a zero-dimensional model based on the law of mass conservation, treating the wetland as a completely mixed reactor, thus avoiding complexities associated with solute movement in porous media. It accurately could predict removal efficiency of chemical, biochemical, and biological indicators while considering active and passive absorption mechanisms by plant uptake. Notably, the determination of coefficients in the model equation does not rely on potentially error-prone laboratory measurements due to sampling issues. Instead, optimization techniques alongside field data robustly estimate these coefficients, ensuring reliability and practicality. Results indicate that higher pollutant concentrations increase reaction rates, particularly enhancing CW efficiency in ammonium removal. Pumice, especially in larger sizes, exhibits superior absorption due to increased porosity and surface area. Overall, the model accurately predicts nitrates concentrations, demonstrating its potential for CW performance optimization and confirming the significance of effective pollutant removal strategies in wastewater treatment.

The Effect of Irradiation Combined with Sodium Hydroxide Pretreatment on Component, Structure, Utilization Efficiency of Phragmites Australis

The Effect of Irradiation Combined with Sodium Hydroxide Pretreatment on Component, Structure, Utilization Efficiency of Phragmites Australis

Response of dissolved inorganic carbon dynamics to simulated tidal hydrological processes in coastal wetlands

To clarify the impacts of tidal hydrological process shifts caused by sea level rise on the blue carbon cycle, a typical coastal wetland in Jiaozhou Bay was selected for this study. The soils of Suaeda salsa (SS) and Phragmites australis (PA) wetlands were collected to simulate the effects of three types of tidal hydrological processes (Neap tide group, NT; Middle tide group, MT; Spring tide group, ST) on the soil-water dissolved inorganic carbon (DIC) dynamic. The results showed that the concentration of water dissolved inorganic carbon (WDIC) increased rapidly (115% higher) at early stage (days 0–4) under the influence of the tidal hydrological processes. Significant differences were found in WDIC concentration during different tidal hydrological processes (P < 0.05), which were expressed as MT (52.7 ± 13.3 mg L−1) > ST (52.5 ± 12.9 mg L−1) > NT (48.4 ± 10.1 mg L−1). After experiencing the tidal hydrological processes, the soil DIC content showed a net accumulation (55.1 ± 1.29 mg L−1vs. 46.7 ± 1.76 mg L−1, P < 0.001), whereas the soil inorganic carbon (SIC) decreased (2.73 ± 1.64 mg L−1vs. 4.61 ± 1.71 mg L−1), which may be attributed to the dissolution of SIC caused by the uptake of CO2 to form DIC. The accumulation of soil DIC was directly related to the SIC (λ = 1.03, P < 0.01), and indirectly related to soil nutrients (SOC substrate, λ = −0.003) and microbes (microbial biomass, λ = −0.10), and was mainly dominated by abiotic processes (abiotic: 58.1 ± 1.8% to 82.7 ± 2.46% vs. biotic: 17.4 ± 2.46% to 41.9 ± 1.76%). The increase of tidal frequency generally inhibited the accumulation of soil DIC content and promoted the output of WDIC. However, the response of soil DIC in different wetland types to tidal frequency was divergent, which was mainly regulated by the trade-off between soil nutrients and SIC content. Taken together, tidal hydrological processes and their frequency changes reshaped DIC dynamics, promoted the dissolution of SIC and the potential uptake of CO2. These findings enhance the comprehension of the inorganic carbon cycle within coastal wetlands, particularly amidst the backdrop of climate change and the rising sea levels.

Characteristics of Soil Organic Carbon and Its Influencing Factors of Different Plant Communities in the Yellow River Delta

Changes in soil organic carbon （SOC） are of great importance to the evolution of soil quality. The distribution characteristics of soil organic carbon （SOC）, easily oxidizable organic carbon （EOC）, dissolved organic carbon （DOC）, and particulate organic carbon （POC） were investigated in the 0-50 cm soil layer of the Phragmites australis, Suaeda salsa, and Tamarix chinensis communities of the supratidal zone in the Yellow River Delta as the research subjects. Then, the composition and sources of soil dissolved organic matter （DOM） were analyzed based on the UV-vis spectroscopy, three-dimensional excitation emission matrix spectroscopy, and parallel factor analysis （PARAFAC）. Finally, the key factors affecting the characteristics of soil organic carbon and DOM fractions of different plant communities were finally revealed in combination with the physicochemical properties of the soil. The results showed that： ① Comparing different communities, the S. salsa community had the highest ω（SOC） at 7.53 g·kg-1, the T. chinensis community had the highest ω（DOC） at 0.98 g·kg-1, and the P. australis community had significantly higher ω（EOC） and ω（POC） than those of the S. salsa and T. chinensis communities at 1.47 g·kg-1 and 0.65 g·kg-1, respectively. The vertical distribution showed a tendency to decrease with deeper soil layers, except for POC concentration. ② The main components of soil DOM of the P. australis, S. salsa, and T. chinensis communities were humus, protein-like substances, and fulvic acid-like substances, of which exogenous components accounted for 55.80%, 56.41%, and 52.81% in the above communities, respectively. ③ Comparing different communities, the humification degree of the P. australis community was significantly higher than that of the S. salsa and T. chinensi communities, but its aromaticity and proportion of biological sources were significantly lower than those of the T. chinensi community. On the vertical profile of the soil, DOM aromaticity and humification degree gradually increased with the deepening of the soil layer, and the deeper soils were mainly dominated by small molecular weight DOM with a lower proportion of hydrophobic fraction. ④ Redundant analysis showed that N （P<0.01）, NO2--N （P<0.01）, and NH4+-N （P<0.05） were the key factors affecting the changes in soil organic carbon and DOM fractions.

Reed hay as a delicacy

Comparison of yield and nutritional values of Phragmites communis and Festuca pseudovina main crops was carried out in 2022 in Karcag, in a meadow-solonyec soil condition.In terms of yield indicators, the values for cane were demonstrably higher than for the concurrently mown lean bunchgrass in flowering phenophase.The results of the nutrient analysis showed higher N, P, K, Zn and Mn contents in the cane than in the lean samples. However, in terms of Ca, Mg, Na, Cu and Fe contents, lean chenkase samples showed higher values than reed samples.Of course, our results can only be considered as a first step in the refinement of the value metrics for perspective alternative fibre feeds

Floating treatment wetlands to improve the water quality of the Hang Bang canal, Ho Chi Minh City, Vietnam: Effect of plant species

Floating treatment wetlands (FTWs) are artificial platforms that allow aquatic emergent plants to grow in water. Aquatic macrophytes and microorganisms attached to plant roots contribute to the remediation of the contaminated water through physicochemical and biological processes. The pollutant removal treatment performance is affected by various factors, including the plant species. In this study, several plant species, i.e. Canna generalis, Phragmites australis, Pennisetum purpureum, Cyperus alternifolius rottb, Kyllinga brevifolia rottb, and Cyperus ordoratus were investigated for their potential to clean-up water from the Hang Bang canal in Ho Chi Minh City (Vietnam). Canna generalis, Phragmites australis, and Cyperus alternifolius were found to be suitable for FTWs with the highest performance compared to that of other plant species investigated. The organic and nitrogen removal rates amounted to 48–70 g COD m−3 d−1 and 0.7–1.2 g N m−3 d−1, respectively, whereas the reduction of pathogens was around 1.86–3.00 log. Furthermore, FTW systems bring other benefits such as improving ecosystem functioning and biodiversity, producing value-added products from plant biomass, as well as attracting the attention of communities, thus increasing social acceptance of environmental technology interventions.

Evaluation of heavy metal accumulation and tolerance in oxalic acid-treated Phragmites australis wetlands for textile effluent remediation

Water contamination with metals poses significant environmental challenges. The occurrence of heavy metals (HMs) prompts modifications in plant structures, emphasizing the necessity of employing focused safeguarding measures. Cadmium (Cd), lead (Pb), and chromium (Cr) emerge as particularly menacing toxins due to their high accumulation potential. Increasing the availability of organic acids is crucial for optimizing toxic metal removal via phytoremediation. This constructed wetland system (CWs) was used to determine how oxalic acid (OA) treatments of textile wastewater (WW) effluents affected morpho-physiological characteristics, antioxidant enzyme activity, oxidative stress, and HM concentrations in Phragmites australis. Multiple treatments, comprising the application of OA at a concentration of 10 mM and WW at different dilutions (25%, 50%, 75%, and 100%), were employed, with three replications of each treatment. WW stress decreased chlorophyll and carotenoid content, and concurrently enhanced HMs adsorption and antioxidant enzyme activities. Furthermore, the application of WW was found to elevate oxidative stress levels, whereas the presence of OA concurrently mitigated this oxidative stress. Similarly, WW negatively affected soil-plant analysis development (SPAD) and the total soluble proteins (SP) in both roots and shoots. Conversely, these parameters showed improvement with OA treatments. P. australis showed the potential to enhance HM accumulation under 100% WW stress. Specifically, there is an increase in root SP ranging from 9% to 39%, an increase in shoot SP from 6% to 91%, and an elevation in SPAD values from 4% to 64% compared to their respective treatments lacking OA inclusion. The OA addition resulted in decreased EL contents in the root and shoot by 10%–19% and 13%–15%, MDA by 9%–14% and 9%–20%, and H2O2 by 14%–21% and 9%–17%, in comparison to the respective treatments without OA. Interestingly, the findings further revealed that the augmentation of OA also contributed to an increased accumulation of Cr, Cd, and Pb. Specifically, at 100% WW with OA (10 mM), the concentrations of Cr, Pb, and Cd in leaves rose by 164%, 447%, and 350%, in stems by 213%, 247%, and 219%, and in roots by 155%, 238%, and 195%, respectively. The chelating agent oxalic acid effectively alleviated plant toxicity induced by toxins. Overall, our findings demonstrate the remarkable tolerance of P. australis to elevated concentrations of WW stress, positioning it as an eco-friendly candidate for industrial effluent remediation. This plant exhibits efficacy in restoring contaminants present in textile effluents, and notably, oxalic acid emerges as a promising agent for the phytoextraction of HMs.

Horizontal-flow constructed wetlands by phytoremediation using vetiver grass, common reed, and canna lily as tertiary wastewater treatment for the reduction of pollutant concentrations of ammonia, phosphates, and nitrates

Abstract The discharge of untreated wastewater into rivers and water bodies poses significant environmental and public health risks. High concentrations of contaminants like heavy metals and pharmaceuticals disrupt rivers, exacerbating waterborne diseases, and leading to unsafe water in the Philippines. This study proposed the use of horizontal-flow constructed wetlands as a tertiary treatment method utilizing the plants: vetiver grass, common reed, and canna lily, to reduce pollutant concentrations in wastewater. This is to ensure compliance with water quality guidelines and general effluent standards under the Class SB Category, water suitable for fishery, tourist zones, and recreational activities. The research investigated the efficiency of phytoremediation beds in removing pollutants from wastewater under fixed hydraulic retention times. The efficiency of reducing pollutants and adsorption isotherms (Freundlich and Langmuir) were calculated to analyze the results of the sampling. Phytoremediation bed 1 demonstra ted efficient ammonia removal by 64.64%. Phytoremediation bed 2 was proficient in reducing nitrates at 83.85%, while phytoremediation bed 3 effectively reduced phosphate to an average of 26.26%, achieved after a 6-hour retention time. In addition, Freundlich adsorption isotherm was observable in most parameters in phytoremediation bed 1 such as ammonia as nitrogen, TDS, COD, and DO. Phytoremediation bed 3 exhibited the same adsorption isotherm on ammonia as nitrogen. Conclusively, the phytoremediation system met the Department of Environment and Natural Resources - Updated Water Quality Guidelines and General Effluent Standard (GES) for all parameters tested.

Prediction of nitrate, phosphate and ammonia removal in wastewater by phytoremediation-vortex system using artificial neural network

Abstract Clean water is an essential component for human survival. However, the growing global population and the relentless pace of industrial development have resulted in an alarming increase in water contamination. This renders many bodies of water as unfit for consumption or usage. In order to safeguard our natural resources, it is imperative that wastewater should be treated to follow a standard set by environmental specialists. In the Philippines, the enactment of the DAO 2021-19 has updated the requirements for release to more stringent standards. Because of this, a tertiary treatment, such as a phytoremediation bed, can be employed as an additional step in a wastewater treatment process. This study involves a comprehensive approach that consists of a phytoremediation setup, which includes the use of three plant species and specialized soil matrices, and a vortex system. The three plant species, Phragmites australis, Vetiveria zizanioides, and Canna indica are known for their capability for removal of the three pollutants, nitrates, phosphates and ammonia. The phytoremediation-vortex system was able to remove the pollutants and effectively reduce the pollutant concentration that the treated wastewater passes the standards for release. The predictive model, artificial neural network (ANN), was employed to assess the results. By using this technique, the study aimed to not only understand the intricate workings of the vortex system but also to optimise its performance for the effective reduction of pollutants, such as, nitrates, phosphates and ammonia, in wastewater. This research represents a critical step towards developing sustainable and efficient solutions for addressing the pressing challenges posed by water pollution, thereby fostering the availability of clean and potable water for human consumption and various industrial purposes.

Bioconcentration of pharmaceuticals by aquatic flora in an Australian river system

Pharmaceuticals are emerging contaminants in the environment and are a ubiquitous presence in rivers downstream of wastewater treatment plant outfalls. Questions remain about the persistence of pharmaceuticals in rivers, and the uptake and bioconcentration of pharmaceuticals by aquatic plants. Our study took place in the Yarrowee/Leigh/Barwon River system in southeastern Australia. We quantified the concentrations of five pharmaceuticals (carbamazepine, primidone, propranolol, tramadol, and venlafaxine) in surface water at five sites along a 144-km stretch of river, downstream of the presumed primary point source (a wastewater treatment plant outfall). We quantified pharmaceuticals in the leaves of two aquatic plant species (Phragmites australis and Vallisneria australis) sampled at each site, and calculated bioconcentration factors. All five pharmaceuticals were detected in surface waters, and the highest detected concentration exceeded 500 ng.L−1 (tramadol). Four of the pharmaceuticals (all except tramadol) were detected and quantified at all sites, including the furthest site from the outfall (144 km). Carbamazepine showed less attenuation with distance from the outfall than the other pharmaceuticals. Carbamazepine and venlafaxine were quantified in the leaves of both aquatic plant species (range: 10–31 ng.g−1), and there was evidence that bioconcentration factors increased with decreasing surface water concentrations. The study demonstrates the potential long-distance persistence of pharmaceuticals in river systems, and the bioconcentration of pharmaceuticals by aquatic plants in natural ecosystems. These phenomena deserve greater attention as aquatic plants are a potential point of transfer of pharmaceuticals from aquatic ecosystems to terrestrial food webs.

Performance evaluation of pilot phyto-vortex integrated system in the reduction of wastewater pollutants

Abstract Wastewater pollution remediation connects to goal 6 of the United Nations 17 Sustainable Development Goals (SDG) ensuring availability and sustainable management of water and sanitation for all. Conventional and advanced wastewater treatment are quite expensive to operate to fully comply with regulatory standards in the country. Phyto-vortex integrated system is an alternative tertiary wastewater treatment system that interfaces with an oil and grease skimmer and vortex technology, relying on green plants and a variety of soil substrates to remediate wastewater. The research evaluated the potential of the Phyto-vortex system and its performance in the reduction of domestic wastewater pollutants. Plants and soil substrates were selected via Analytic Hierarchy Process (AHP) using one-way sensitivity analysis. Common reed, Vetiver grass, and Canna Lily were planted in constructed reed beds with various soil matrices using substrates laid at different levels. The beds operate continuously as a horizontal subsurface flow treating 5 m3 of a sewage treatment effluent per day with 1-3 days hydraulic retention time (HRT). The vortex unit aerates the water for further removal of gaseous pollutants. Samples were taken at designated points for 18 weeks. Analysis of the results shows a maximum reduction of 92% for biochemical oxygen demand (BOD), 60 % for chemical oxygen demand(COD), and 70 % for total suspended solids (TSS). Concentration of identified heavy metals in the influent are within the regulatory standards except for a rise in zinc concentration which was 97% reduced in the system. The percentage reduction of pollutants varies each week with nitrates decreasing in the range of 50% to 99%, phosphates from 8% to 39.5%, and ammonia from 45.65% to 99%. Varying environmental conditions such as monsoon rains and extreme heat caused algal blooms and plant disease affecting the results. Lower temperatures and lower humidity favor a decrease in the levels of the pollutants while higher temperature, higher humidity favor an increase in the levels of Nitrates, Phosphates, and Ammonia. The overall results show an effective integrated system of phytoremediation coupled with a vortex unit in the reduction of wastewater pollutants.

A dataset of carbon and water fluxes in a Phragmites australis wetland in the Yellow River Delta during 2011–2018

Wetland ecosystems play an important role in mitigating global climate change. The long-term monitoring of carbon and water fluxes based on eddy covariance (EC) would be helpful to better protect and utilize ecosystem services of wetlands. However, related data and studies focusing on carbon and water fluxes in wetland ecosystems are still limited. Hence, there is an urgent need to provide more observational data for researchers. Yellow River Delta Ecological Research Station of Coastal Wetland, Chinese Academy of Sciences, has established an open-path EC system in a Phragmites australis wetland in 2010 and obtained large amounts of flux data to date. In this paper, the EC-based dataset consisted ecosystem-scale carbon and water fluxes at the study site from 2011 to 2018. Moreover, all the data were shown at four time scales, i.e., half-hourly, daily, monthly, and yearly. This dataset is of great importance for estimating carbon and water fluxes in wetland ecosystems and examining the flux variations at different time scales.

Evidence of nitrogen inputs affecting soil nitrogen purification by mediating root exudates of salt marsh plants

Salt marsh has an important ‘purification’ role in coastal ecosystems by removing excess nitrogen that could otherwise harm aquatic life and reduce water quality. Recent studies suggest that salt marsh root exudates might be the ‘control centre’ for nitrogen transformation, but empirical evidence is lacking. Here we sought to estimate the direction and magnitude of nitrogen purification by salt marsh root exudates and gain a mechanistic understanding of the biogeochemical transformation pathway(s). To achieve this, we used a laboratory incubation to quantify both the root exudates and soil nitrogen purification rates, in addition to the enzyme activities and functional genes under Phragmites australis populations with different nitrogen forms addition (NO3−, NH4+ and urea). We found that NO3− and urea addition significantly stimulate P. australis root exudation of total acids, amino acids, total sugars and total organic carbon, while NH4+ addition only significantly increased total acids, amino acids and total phenol exudation. High total sugars, amino acids and total organic carbon concentrations enlarged nitrogen purification potential by stimulating the nitrogen purifying bacterial activities (including enzyme activities and related genes expression). Potential denitrification rates were not significantly elevated under NH4+ addition in comparison to NO3− and urea addition, which should be ascribed to total phenol self-toxicity and selective inhibition. Further, urea addition stimulated urease and protease activities with providing more NH4+ and NO2− substrates for elevated anaerobic ammonium oxidation rates among the nitrogen addition treatments. Overall, this study revealed that exogenous nitrogen could increase the nitrogen purification-associated bacterial activity through accelerating the root exudate release, which could stimulate the activity of nitrogen transformation, and then improve the nitrogen removal capacity in salt marsh.

Effects of coagulation pre-treatment on chemical and microbial properties of water-soil-plant systems of constructed wetlands

Chemical coagulation has gained recognition as an effective technique to enhance the removal efficiency of pollutants in wastewater prior to their entry into a constructed wetland (CW) system. However, its potential impact on the chemical and microbial properties of soil and plant systems within CWs requires further research. This study investigated the impact of using ferric chloride (FeCl3) as a pre-treatment stage for dairy wastewater (DWW) on the chemical and microbial properties of water-soil-plant systems of replicated pilot-scale CWs, comparing them to CWs treating untreated DWW. CWs treating amended DWW had better performance than CWs treating raw DWW for all water quality parameters (COD, TSS, TP, and TN), ensuring compliance with the EU wastewater discharge directives. Soil properties remained mostly unaffected except for pH, calcium and phosphorus (P), which were lower in CWs treating amended DWW. As a result of lower nitrogen (N) and P loads, the plants in CWs receiving FeCl3-amended DWW had lower N and P contents than the plants of raw DWW CWs. However, the lower loads of P into amended DWW CWs did not limit the growth of Phragmites australis, which were able to accumulate trace elements higher than CWs receiving raw DWW. Alpha and Beta-diversity analysis revealed minor differences in community richness and composition between both treatments, with only 3.7% (34 genera) showed significant disparities. Overall, the application of chemical coagulation produced superior effluent quality without affecting the properties of soil and plant of CWs or altering the functioning of the microbial community.

Constructed Wetlands for Municipal Solid Waste Landfill Leachate Treatment with Different Macrophytes in Hot Cimate Regions: A Review

Constructed wetland is a natural, economical and environment friendly option for leachate treatment. The aquatic plants and microorganisms are the main players for the treatment of leachate and are conspicuous favoring feature for any wetland due to their contaminant treatment efficiency. There are several other features which limit or enhance the performance of wetlands. Temperature is one of the factors which influence the performance of any wetland and can improve overall efficiency of the constructed wetland. Deep study of oxygen function reveals that accumulation of oxygen to the liquid or soil of the wetland either by photosynthesis or direct from atmosphere. Organic mailer and nitrification process made possible by transfer of oxygen to rhizosphere through macrophytes and macrophytes grow well in growing season in the presence of sunlight and temperature. The argument is well supported through facts revealed by scientific observations. The natural process of photosynthesis only occurs in the presence of sunlight. Hence main performance of macrophytes depends upon their biomass production and fixation of oxygen to the rhizosphere in growing season, which ultimately enhances the efficiency of wetlands for contaminant removal. This review is to establish the fact that Typha latifolia, Phragmites australis and Scripus Validus are main hydrophytes depict best results in biogeochemical process for contaminant removal from wetlands in hot season except for the Total Suspended Solid (TSS) which does not show considerable difference due to the climate. This fact reveals that the macrophytes are more productive in the warm climate in comparison to cold one. The Typha latifolia, Phragmites australis and Scripus validus are the most common species of macrophytes which are very much affective in contamination removal process especially in temperate or tropical region where climate is above 30oC. The available data of different research papers establishes the fact that wetlands are the low-cost, eco-friendly and efficient solution for majority of contaminants removal. It has also been established that the Tropical and temperate regions enhance efficiency of all parameters up to 10% due to higher temperature.

Superoxide Photoproduction from Wetland Plant-Derived Dissolved Organic Matter: Implications for Biogeochemical Impacts of Plant Invasion.

Although the impacts of exotic wetland plant invasions on native biodiversity, landscape features, and carbon-nitrogen cycles are well appreciated, biogeochemical consequences posed by ecological competition, such as the heterogeneity of dissolved organic matter (DOM) from plant detritus and its impact on the formation of reactive oxygen species, are poorly understood. Thus, this study delves into O2•- photogeneration potential of DOM derived from three different parts (stem, leaf, and panicle) of invasive Spartina alterniflora (SA) and native Phragmites australis (PA). It is found that DOM from the leaves of SA and the panicles of PA has a superior ability to produce O2•-. With more stable aromatic structures and a higher proportion of sulfur-containing organic compounds, SA-derived DOM generally yields more O2•- than that derived from PA. UVA exposure enhances the leaching of diverse DOM molecules from plant detritus. Based on the reported monitoring data and our findings, the invasion of SA is estimated to approximately double the concentration of O2•- in the surrounding water bodies. This study can help to predict the underlying biogeochemical impacts from the perspective of aquatic photochemistry in future scenarios of plant invasion, seawater intrusion, wetland degradation, and elevated solar UV radiation.