Greenhouse gases emissions and carbon budget estimation in horizontal subsurface flow constructed wetlands with different plant species

Constructed wetlands (CWs) are pivotal for wastewater treatment due to their high efficiency and numerous advantages. The impact of plant species and diversity on greenhouse gas (GHG) emissions from CWs requires a more comprehensive evaluation. Moreover, controversial perspectives persist about whether CWs function as carbon sinks or sources. In this study, horizontal subsurface flow (HSSF) CWs vegetated with Cyperus alternifolius, Typhae latifolia, Acorus calamus, and the mixture of these three species were constructed to evaluate pollutant removal efficiencies and GHG emissions, and estimate carbon budgets. Polyculture CWs can stably remove COD (86.79 %), NH4+-N (97.41 %), NO3--N (98.55 %), and TP (98.48 %). They also mitigated global warming potential (GWP) by suppressing N2O emissions compared with monoculture CWs. The highest abundance of the Pseudogulbenkiania genus, crucial for denitrification, was observed in polyculture CWs, indicating that denitrification dominated in nitrogen removal. While the highest nosZ copy numbers were observed in CWs vegetated with Cyperus alternifolius, suggesting its facilitation of denitrification-related microbes. Selecting Cyperus alternifolius to increase species diversity is proposed for simultaneously maintaining the water purification capacity and reducing GHG emissions. Carbon budget estimations revealed that all four types of HSSF CWs were carbon sinks after six months of operation, with carbon accumulation capacity of 4.90 ± 1.50 (Cyperus alternifolius), 3.31 ± 2.01 (Typhae latifola), 1.78 ± 1.30 (Acorus calamus), and 2.12 ± 0.88 (polyculture) kg C/m2/yr. This study implies that under these operation conditions, CWs function as carbon sinks rather than sources, aligning with carbon peak and neutrality objectives and presenting significant potential for carbon reduction efforts.

Phytoremediation of an integrated poultry and aquaculture wastewater using sub-surface constructed wetland planted with Phragmites karka and Typha latifolia

This study focused on assessing the effectiveness of vertical subsurface constructed wetlands (VSFCW) in purifying integrated poultry and aquaculture wastewater (PAW) in a tropical region. This evaluation encompassed the treatment of physico-chemical, heavy metal, and microbiological pollutants across three distinct climatic seasons and hydraulic retention time (HRT: 21 days). Parameters such as BOD (29.50 mg/L), COD (56.67 mg/L), Zn (2.97 mg/L), Cr (0.24 mg/L), Cu (1.78 mg/L), Pb (0.21 mg/L), total fecal coliform (866.67 cfu/mL), total coliform (1666.67 cfu/mL), E. coli (1133.33 cfu/mL), and Salmonella/Shigella (700 cfu/mL) exceeded the discharge limits for wastewater into nearby surface water bodies. Significant removal efficiencies were observed for all parameters tested in the CW planted with both Phragmites karka and Typha latifolia. The macrophytes showed similar removal efficiencies for all tested parameters, and there was no significant difference in the initial concentrations of the parameters based on the experimental season, except for microbial properties. This suggests that weather conditions did not significantly impact the concentration of physical and chemical properties in the wastewater. Consequently, this study successfully demonstrates the potential of using a VSFCW for effective treatment of PAW.

Rare flavanone-diarylheptanoid hybrids from Typha angustifolia shows anti breast cancer activity via activating TGF-β1/Smad signaling pathway

Four new flavanone-diarylheptanoid hetero dimers, typhatifolins A-D (1-4), were separated from the pollen of a widely distributed medicinal plant Typha angustifolia. Structures of these rare hybrids were elucidated by detailed interpretation of spectroscopic data, and their absolute configurations were determined on the basis of Mosher's method and ECD analyses. All the four compounds showed moderate to significant cytotoxicities against a panel of tumor cell lines with IC50 values ranging from 0.67 to 12.48 μM. Further in vitro antitumor evaluation for typhatifolin B (TTB, 2) on two breast cancer cells (4T1 and MDA-MB231) revealed that it could remarkably induce cell apoptosis and G0/G1 cycle arrest, as well as block cell migration and invasion. Mechanistically, TTB could exert its antitumor effect via activating the TGF-β1 (transforming growth factor beta 1) signaling pathway as evidenced by RNA-seq analysis and immunoblotting experiments, which was further corroborated by treating cancer cells with a TGF-β signaling inhibitor. Lastly, the in vivo anti breast cancer activity was demonstrated by applying the mixture of typhatifolins A-D to a preclinical animal model.

Cr(III) and Cr(VI) removal in floating treatment wetlands (FTWs) using Typha domingensis

Floating treatment wetlands (FTWs) are a cost-effective ecological engineering tool for the restoration of polluted water bodies. The aims of this work were to evaluate the removal of Cr(III) and Cr(VI) by FTWs using Typha domingensis, and to assess Cr accumulation and distribution in plant tissues and sediment. Treatments were 5 and 10 mg L-1 of Cr(III), and 5 and 10 mg L-1 of Cr(VI), with and without FTWs, and biological control (BC) with FTW without Cr addition. Both Cr species were efficiently removed from water in all treatments (Cr removal > 80%). Cr concentration in sediments of treatment without FTWs was significantly higher than in sediments of treatments with FTWs, indicating that T. domingensis was directly involved in Cr removal. In sediment, Cr was mainly bound to the organic matter in all treatments with a low risk of future release under FTW conditions. T. domingensis demonstrated tolerance to both Cr species at 5 and 10 mg L-1 with Cr accumulated mainly in the roots in all treatments. The use of FTWs planted with T. domingensis is a suitable tool to remediate water bodies contaminated with Cr.

Phytoremediation of micropollutants by Phragmites australis, Typha angustifolia, and Juncus effuses

Micropollutants (MPs) include organic chemicals, for example, pharmaceuticals and personal care products. MPs have been detected in the aquatic environment at low concentrations (ng/L-µg/L), which may lead to negative impacts on the ecosystem and humans. Phytoremediation is a green clean-up technology, which utilizes plants and their associated rhizosphere microorganisms to remove pollutants. The selection of plant species is important for the effectiveness of the phytoremediation of MPs. The plant species Phragmites australis, Typha angustifolia, and Juncus effuses are often used for MP removal. In this study, batch experiments were conducted to select plant species with an optimal ability to remove MPs, study the effect of temperature on MP removal in plants and the phytotoxicity of MPs. This study also explored the degradation of a persistent MP propranolol in plants in more detail. Data show that all three investigated plant species removed most MPs efficiently (close to 100 %) at both 10 and 21.5 °C. The tested plant species showed a different ability to translocate and accumulate propranolol in plant tissues. Typha angustifolia and Juncus effuses had a higher tolerance to the tested MPs than Phragmites australis. Typha angustifolia and Juncus effuses are recommended to be applied for phytoremediation of MPs.Novelty statement The novelty of this study is the selection of Typha angustifolia and Juncus effuses as proper plant species for phytoremediation of micropollutants (MPs). These two plant species were selected due to their good ability to remove MPs, tolerate low temperature, and resist the toxicity of MPs. The outcomes from this study can also be applied for constructed wetlands in removing MPs from wastewater. This study demonstrates the uptake and degradation processes of persistent MP propranolol in plants in more detail. Understanding the degradation mechanisms of a MP in plants is significant not only for the application of phytoremediation on MP removal but also for the development of constructed wetland studies.

Algae, shrimp grazing, and fecal pellets synergistically increase microbial activity and enhance N immobilization during Typha angustifolia leaf litter decomposition

Algae play an important role in ecological processes of aquatic ecosystems. Understanding the interactive effects of algae with invertebrates in litter decomposition is important for predicting the effects of global change on aquatic ecosystems. We manipulated Typha angustifolia litter to control exposure to shrimp fecal pellets and/or grazing, and the green alga Chlorella vulgaris were added to test their interactive effects on T. angustifolia litter decomposition. Our results showed that algae largely shortened microbial conditioning time and improved litter palatability (increasing litter quality), resulting in greater decomposition and higher fecal pellet production. Fecal pellets enhanced grazing effects on decomposition by increasing litter ash content. The effects of algae and especially fecal pellets on decomposition were dependent on or mediated by grazing. Without grazing, algae slightly promoted decomposition and marginally offset the negative effect of fecal pellets on litter decomposition. Shrimp grazing dramatically decreased microbial activity (extracellular enzyme activity and microbial respiration) at microbial conditioning stage while enhanced microbial activity after 84 days especially with both algae and fecal pellets present. Algae significantly upregulated N- and P-acquiring and slightly downregulated C-acquiring enzyme activity. Fecal pellets significantly depressed recalcitrant C-decomposition enzyme activity. Nevertheless, the three factors synergistically and significantly increased C loss and most enzyme activities, microbial respiration, and N immobilization, resulting in the decrease of litter C:N. Our results reveal the synergistic action of different trophic levels (autotrophs, heterotrophs, and primary consumers) in the complicated nutrient pathways of litter decomposition and provide support for predicting the effects of global changes (e.g., N deposition and CO₂ enrichment), which have dramatically effects on alga dynamics and on ecological processes in aquatic ecosystems.

Bioindication of soil pollution in the delta of the Don River and the coast of the Taganrog Bay with heavy metals based on anatomical, morphological and biogeochemical studies of macrophyte (Typha australis Schum. & Thonn)

The results of biogeochemical and bioindication studies on the resistance of natural populations of macrophyte plant-cattail (Typha australis Schum. & Thonn) on the coast of the Taganrog Bay of the Sea of Azov and the sea edge of the Don River delta with regard to local pollution zones are presented. Plant resistance has been assessed through manifestation of their protective functions in relation to heavy metals. An excess in the lithospheric Clarkes and MPC in Zn, Cd and Pb in Fluvisols has been found. The total index of soil pollution (Z_c) has made it possible to identify areas with different categories of contamination within the study area exposed to human impact. High mobility of Zn, Cd, Pb, Cr and Ni in Fluvisols has been revealed, which is confirmed by the significant bioavailability of Zn, Cr and Cd that are accumulated in the macrophyte plant tissues. The absorption of heavy metals by cattail plants is allowed for both the soil and the water of the nearby reservoir, where aquatic systems are a kind of "biological filter" contributing to water purification from pollutants. The impact of the environmental stress factor has been found to be manifested not only in the features of heavy metal accumulation and distribution in plant tissues, but also at the morphological and anatomical level according to the type of prolification. Changes in the cell membranes as well as in main cytoplasmic organelles (mitochondria, plastids, pyroxis, etc.) of the root and leaf cells have been identified, the most significant changes in the ultrastructure being noted in the tissues of leaf chlorenchyma. It is assumed that the identified structural changes contribute to slowing down of the ontogenetic development of plants and reduction in their morphometric parameters when exposed to anthropogenic pollution. Therefore, cattails can be effectively used as biological indicators while determining environmental pressures.

In situ barium phytoremediation in flooded soil using Typha domingensis under different planting densities

The management of initial planting density can be a strategy to increase barium phytoextraction from soil, reducing the time required for soil decontamination. To delimit the ideal planting density for barium (Ba) phytoremediation using Typha domingensis, we conducted a 300-day experiment in an area accidentally contaminated with barite. Four initial planting densities were tested: 4, 8, 12, and 16 plantsm^-2 (D4, D8, D12, and D16 treatments, respectively). Plant development was evaluated periodically, and the phytoextraction efficiency was determined at the end of the trial. The initial planting density affected Ba phytoremediation by T. domingensis monoculture. Phytoextraction potential was better represented by the mass-based translocation factor (mTF) than the concentration-based translocation factor. D16 promoted the highest final number of plants and biomass production, but the mass of Ba in the aerial part did not differ among D8, D12, and D16. D4 resulted in more Ba accumulated belowground than aboveground (6.3 times higher), whereas D12 and D16 achieved the greatest mTFs. Higher absorption of Ba from soil can be achieved using less T. domingensis individuals at the beginning of the treatment (D4 and D8) but with high accumulation in belowground tissues. We conclude that the D8 density is considered the most appropriate if considering the phytoextraction potential and field management facilitated using fewer plants.

Sulfamethoxazole sorption by cattail and switchgrass roots

Sorption to roots is one of several mechanisms by which plant-assisted attenuation of antibiotics can be achieved. The objectives of this study were to (1) evaluate the sorption of sulfamethoxazole (SMX) by cattail and switchgrass roots, (2) determine the kinetics of SMX sorption by cattail and switchgrass roots, and (3) characterize the temperature-dependency of SMX sorption. A batch sorption experiment was conducted to measure SMX sorption by roots of the two plant species using five initial antibiotic concentrations (2.5, 5, 10, 15, and 20 µg L^-1) and eight sampling times (0, 0.5, 1, 2, 4, 8, 12, and 24 h). Another batch experiment was conducted at three temperatures (5, 15, and 25 °C) to determine the effect of temperature on sorption kinetics. SMX sorption followed pseudo-second-order kinetics. The pseudo-second-order rate constant (k2) decreased with increasing temperature for both plant species. The rate constant followed the order: 5 °C = 15 °C > 25 °C for cattail and 5 °C > 15 °C = 25 °C for switchgrass. Results from this study show that switchgrass roots are more effective than cattail roots in the removal of SMX. Therefore, the use of switchgrass in systems designed for phytoremediation of contaminants might also provide an efficient removal of some antibiotics.

Influence of plant radial oxygen loss in constructed wetland combined with microbial fuel cell on nitrobenzene removal from aqueous solution

This study investigated the effects of radial oxygen loss (ROL) of three different plants on nitrobenzene (NB) wastewater treatment and bioelectricity generation performance in constructed wetland-microbial fuel cell (CW-MFC). ROL and root biomass from wetland plants showed positive effects on NB wastewater compared to unplanted CW-MFC. Scirpus validus exhibited higher tolerance to NB than Typha orientalis and Iris pseudacorus at 20-200 mg/L NB. As NB concentration reached 200 mg/L, the CW-MFC with Scirpus validus had relatively high DO (2.57 ± 0.17 mg/L) and root biomass (16.42 ± 0.18 g/m²), which resulted in the highest power density and voltage (19.5 mW/m², 590 mV) as well as NB removal efficiency (93.9 %) among four reactors. High-throughput sequencing results suggested that electrochemically active bacteria (EAB) (e.g., Geobacter, Ferruginibacter) and dominant NB-degrading bacteria (e.g., Comamonas, Pseudomonas) could be enhanced by wetland plants, especially in CW-MFC with Scirpus validus. Therefore, Scirpus validus was a good option for simultaneously treating NB wastewater and producing bioelectricity.

Arsenic Distribution, Accumulation and Tolerance Mechanisms of Typha angustifolia in Different Phenological Growth Stages

Variations of phytoaccumulation and tolerance in different growth stages of plant are important factors for effective removal of pollutants in phytoremediation. The present work investigated arsenic (As) accumulation, As-tolerance and the physiological tolerance mechanisms of Typha angustifolia under different As-level during the seedling, fast-growing and breeding stages. The results showed that As mainly distributed in the underground part and total As accumulation increased with growth stages. Maximum growth rates under lower As occurred in seedling stage, whereas occurred in breeding stage under higher As. T. angustifolia exhibited the highest tolerance ability under 150 mg kg^-1 As and tolerance index (TI) varied from seedling to breeding stages. During seedling stage, TI was affected by plant height (H_shoot) and net photosynthesis, which control biomass production. During fast-growing stage, H_shoot and root glutathione (GSH) co-regulated plant As-tolerance. During breeding stage, physiological metabolic processes, especially GSH-mediated processes, played a critical role in improving plant As-tolerance.

Transcriptome -wide modulation combined with morpho-physiological analyses of Typha orientalis roots in response to lead challenge

Lead (Pb) is a common pollutant in many environments, including in the soil, water, and/or air. Typha orientalis Presl, a large emergent aquatic plant, has been reported to function as a Pb-tolerant and Pb-accumulating plant; however, very little molecular information regarding the tolerance of T. orientalis towards Pb is known. In this study, Pb accumulation and key factors involved in the Pb stress response at different Pb concentrations were investigated. Pb was primarily accumulated in the roots and was mainly located in the cell wall and membrane systems. Differentially expressed genes (DEGs) were identified in T. orientalis roots after Pb exposure via RNA-seq analyses. In the 0.10 mM and 0.25 mM Pb²⁺-treated groups, a total of 3275 DEGs were detected relative to the control. Many of these genes were associated with oxidation-reduction processes, metal transport, protein kinase/phosphorylation, and DNA binding transcription factors, which were shown to be Pb-responsive DEGs. Mapping Kyoto Encyclopedia of Genes and Genomes (KEGG) database, "phenylpropanoid biosynthesis" was analyzed as the major pathway of the important modules of overlapping DEGs of 0.10 mM and 0.25 mM Pb²⁺ treatments. Furthermore, a lead response gene named ToLR1 with unknown function was of particular interest. The full-length of ToLR1 sequence was cloned using rapid amplification of cDNA ends (RACE) and overexpressed in Arabidopsis thaliana, which resulted in enhanced resistance to Pb stress. This is the first report providing genomic information detailing Pb responsive genes in T. orientalis. Moreover, this study provides novel insights into the molecular mechanisms underlying the response of T. orientalis and other accumulators towards Pb stress. The key genes identified in this study may serve as potential targets for genetic engineering targeting phytoremediation.

Selenite antagonizes the phytotoxicity of Cd in the cattail Typha angustifolia

The Phytotoxicity of and mechanism underlying selenite-mediated tolerance to Cd stress in Typha angustifolia were studied hydroponically with respect to metal uptake and translocation, photosynthesis-related parameters, contents of proline and O₂^•-, products of lipid peroxidation, cell viability, enzymatic and non-enzymatic antioxidants, glyoxalases and phytochelatins. T. angustifolia were exposed to 25, 50 and 100 μM of Cd alone and in conjunction with 5 mg L^-1 of selenite in full-strength Hoagland's nutrient solution for 30 days. Results showed that Cd contents in T. angustifolia leaves and roots increased in a dose-dependent manner and were higher in roots, but those of BAC, BCF and TF changed in a contrary pattern. Addition of selenite to Cd-containing treatments further reduced Cd levels in T. angustifolia leaves and roots, as well as BAC, BCF and TF. A diphasic effect was found in T. angustifolia for the contents of total chlorophyll, GSH, PC and GSSG, as well as activities of CAT, POD, SOD and GR, in response to Cd stress alone and in conjunction with selenite supplementation, but the same effect was not observed for Pn, Cond, Tr, Ci, Fv/Fm and ϕPSII. In contrast, exogenous selenite supplementation enhanced the contents of total chlorophyll and the non-enzymatic antioxidants, as well as activities of enzymatic antioxidants, while the values of photosynthetic fluorescence parameters were rescued. Selenite addition decreased Cd-induced cell death. Proline contents and Gly I activities in T. angustifolia leaves kept increasing in a dose-dependent manner of Cd concentrations in the growth media and selenite addition further enhanced both parameters. Addition of selenite could quench Cd-mediated generation of MDA, O₂^•- and MG in T. angustifolia leaves and reduce Cd-induced Gly II activity. A U-shaped GSH/GSSG ratio in T. angustifolia leaves suggests a possible trade-off between PC synthesis and GR activity since both share the same substrate GSH. Therefore, confined BAC, BCF and TF were a mechanism that confers T. angustifolia tolerance to Cd stress, and that exogenous selenite supplementation could depress Cd-induced stress in T. angustifolia by rescuing the photosynthetic fluorescence, enhancing non-enzymatic and enzymatic antioxidants that scavenge O₂^•- and MG, and potentiating PC synthesis that chelates Cd.

Typha latifolia and Thelypteris palustris behavior in a pilot system for the refinement of livestock wastewaters: A case of study

In animal livestock heavy metals are widely used as feed additives to control enteric bacterial infections as well as to enhance the integrity of the immune system. As these metals are only partially adsorbed by animals, the content of heavy metals in manure and wastewaters causes soil and ground water contamination, with Zn²⁺ and Cu²⁺ being the most critical output from pig livestock. Phytoremediation is considered a valid strategy to improve the purity of wastewaters. This work studied the effect of Zn²⁺ and Cu²⁺ on the morphology and protein expression in Thelypteris palustris and Typha latifolia plants, cultured in a wetland pilot system. Despite the absence of macroscopic alterations, remodeling of cell walls and changes in carbohydrate metabolism were observed in the rhizomes of both plants and in leaves of Thelypteris palustris. However, similar modifications seemed to be determined by the alterations of different mechanisms in these plants. These data also suggested that marsh ferns are more sensitive to metals than monocots. Whereas toleration mechanisms seemed to be activated in Typha latifolia, in Thelypteris palustris the observed modifications appeared as slight toxic effects due to metal exposure. This study clearly indicates that both plants could be successfully employed in in situ phytoremediation systems, to remove Cu²⁺ and Zn²⁺ at concentrations that are ten times higher than the legal limits, without affecting plant growth.

Bioaccumulation of heavy metals from wastewater through a Typha latifolia and Thelypteris palustris phytoremediation system

Animal production is a source of heavy metals in livestock wastewater and also a key link in the food chain, with negative impacts on human and animal health. In intensive animal production systems, the most critical elements are zinc and copper. In order to development of innovative non-invasive strategies to reduce the environmental impact of livestock, this study assessed the ability of two plants, Typha latifolia and Thelypteris palustris, to bioaccumulate the heavy metals used in animal nutrition, from wastewater. Four mesocosms (width 2.0 m, length 2.0 m, 695 L of water, 210 kg of soil) were assembled outdoors at the Botanical Garden. Two of them were planted with T. latifolia (TL treated, n = 30; TL control, n = 30) and two with T. palustris (TP treated, n = 60; TP control, n = 60). In T0 a solution of a mineral additive premix (Zn 44.02 mg/L; Cu 8.63 mg/L) was dissolved in the treated mesocosms. At T0, d 15 (T1) and d 45 (T2) samples of roots, leaves, stems, soil and water were collected, dried, mineralized and analyzed using ICP-MS in order to obtain HMs content. We found that T. latifolia and T. palustris accumulate and translocate Zn, Cu from contaminated wastewater into plant tissues in a way that is directly related to the exposure time (T2 for Zn: 271.64 ± 17.70, 409.26 ± 17.70 for Cu: 47.54 ± 3.56, 105.58 ± 3.56 mg/kg of DM, respectively). No visual toxicity signs were observed during the experimental period. This phytoremediation approach could be used as an eco-sustainable approach to counteract the output of heavy metals.

Thermophilic anaerobic digestion of cattail and hydrothermal carbonization of the digestate for co-production of biomethane and hydrochar

Thermophilic anaerobic digestion (AD) of cattail followed by hydrothermal carbonization (HTC) was studied. The intent of the research was to develop agricultural waste-based biorefining technologies for bioenergy production along with value-added products. Cattail was anaerobically digested at 55 °C for 14 days and protein and cellulose components were partially degraded. The average methane yield was 230-280 mL/g volatile solids and the total solids decreased by 33-55%. When the particle size of cattail was reduced from 1 in. to 1 mm, the lag phase was shortened from 1.48 to 0 d. Following the AD process of cattail, the AD digestate was hydrothermally carbonized at 250 °C for 4 h, yielding approximately 6.7-7.5 wt % gaseous products, 64 wt % liquid products and 28 wt % hydrochar. The gaseous products contained >5000 ppm H₂S and liquid products possessed fewer chemicals and higher ratio of phenolic compounds compared to the liquid products from HTC of original cattail. The hydrochar had a higher carbon content (76.8-79.8%) and a higher specific surface area (∼10 m²/g) than those of the feedstock. Hydrochar was further activated by using Na₂CO₃, NaHCO₃ and NaCl. The activation process increased the carbon content and specific surface area to 84-93% and 250-630 m²/g, respectively.

Assessment of Typha capensis for the remediation of soil contaminated with As, Hg, Cd and Pb

The use of macrophytes has been identified as one of the eco-friendly means of remediating soils contaminated with heavy metal(loid)s. This study sought to ascertain the synergistic influences of Hg, As, Cd and Pb on the uptake capacity of Typha capensis in remediating soils contaminated with these pollutants. Uptake of Hg, As, Cd and Pb by this aquatic plant species in metal(loid)-contaminated water and soil was studied in batch culture experiment. The plants were irrigated with standard heavy metal(loid)-simulated solutions. After 20, 40 and 60 days, plant samples were subjected to heavy metal(loid) analysis by a Unicam 969 atomic absorption spectrometer (AAS). The macrophytes were able to remediate all the four selected heavy metal(loid)s when they either existed as individual or when all the four were in the solution; however, the level of uptake by the plant was inhibited when either two of the heavy metals existed in the solution. Typha capensis performs better in the absorption of mercury, arsenic, cadmium and lead in large quantities from polluted water and soil.

Bioaccumulation behaviour of pharmaceuticals and personal care products in a constructed wetland

Pharmaceuticals and personal care products (PPCPs) is an important class of environmental contaminants and has gained increasing concerns in recent years. The bioaccumulation behaviour of PPCPs in wetland plants is not well understood. In the present study we report results of a field investigation to assess the bioaccumulation behaviour and phytoremediation efficacy of several PPCPs in Lorong Halus Wetland, a large-scale constructed wetland system in Singapore, constructed for the treatment of landfill leachate. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) based methods were employed to quantify concentrations of target PPCPs in leachate and flowing water, as well as wetland plants (roots and shoots), at different locations in the wetland system. The results indicated the presence of several PPCPs in leachate, water and vegetation in the wetland. Bioconcentration factors (BCFs) in the dominant wetland plant, Typha angustifolia, ranged between approximately 60 and 2000. Results indicated that Cattail Typha angustifolia was capable of remediating PPCPs to various extends, with bioconcentration factors ranging up to 2000. The suitability for phytoremediation depends on the physical chemical properties such as hydrophilicity and lipophilicity of these PPCPs.

Effects of antibiotics on nitrogen uptake of four wetland plant species grown under hydroponic culture

To investigate the effects of antibiotics on nitrogen removal and uptake by wetland plants, four typical macrophyte species, Cyperus alternifolius L., Typha angustifolia L., Lythrum salicaria L., and Acorus calamus L., were grown in hydroponic cultivation systems and fed wastewater polluted with 10 μg L^-1 Ofloxacin (OFL) and Tetracycline (TET). Biomass production, nitrogen mass concentration, chlorophyll content, root exudates, and nitrogen removal efficiency of hydroponic cultivation were investigated. The results indicated that in all hydroponic systems, NH₄⁺-N was entirely removed from the hydroponic substrate within 1 day and plant nitrogen accumulation was the main role of the removed NO₃^-. OFL and TET stimulated the accumulation of biomass and nitrogen of A. calamus but significantly inhibited the NO₃^--N removal ability of L. salicaria (98.6 to 76.2%) and T. augustifolia (84.3 to 40.2%). This indicates that A. calamus may be a good choice for nitrogen uptake in wetlands contaminated with antibiotics. OFL and TET improved the concentrations of total organic carbon (TOC), total nitrogen (TN), organic acid, and soluble sugars in root exudates, especially for oxalic acid. Considering the significant correlation between TOC of root exudates and nitrogen removal efficiency, the TOC of root exudates may be an important index for choosing macrophytes to maintain nitrogen removal ability in wetlands contaminated with antibiotics.

Spatial variation of heavy metals and uptake potential by Typha domingensis in a tropical reservoir in the midlands region, Zimbabwe

Pollution of aquatic ecosystems with heavy metals is now of global concern due to their dangers to human health and persistence in the environment. An investigation on the spatial distribution of heavy metals in water and sediments and the bioaccumulation potential of heavy metals by plant parts (i.e. roots, stems and leaves) of aquatic macrophyte Typha domingensis (Pers.) Steud in a tropical reservoir was carried out. The results showed no difference in spatial distribution of heavy metals (Fe, Cu, Cd, Cr, Pb, Zn, Mn) in water and sediments from the riverine to the dam wall. The concentration of heavy metals Fe, Cu, Cr and Zn in T. domingensis was of the order root > stem > leaves, but for Pb, Cd and Mn, it followed the order root > leaf > stem. The metal transfer between roots and shoots of T. domingensis followed the order Zn > Pb > Fe > Cu > Cd > Cr. The bio-concentration factor (BCF) was low (BCF < 1) for all the selected metals while the transfer factor (TF) varied among metals suggesting that T. domingensis is not an accumulator of the studied metals. The high concentration of heavy metals found in the water (0.7-16.14 mg L^-1) and sediments (43.6-569.18 mg kg^-1) present a potential risk to both ecological health and human health for the population living in the area. The results of metal concentration in water and sediments from this study are important as a baseline for future monitoring studies. Further studies on bioavailability of metals to other macrophytes and aquatic organisms are recommended.

Effects of ofloxacin on nitrogen removal and microbial community structure in constructed wetland

Constructed wetlands (CWs) have emerged as a promising technology for the purification of micro-polluted water. However, their nitrogen removal performance can be significantly degraded by design, operational, and environmental factors. The present study investigates the effects of ofloxacin (OFL: 0.1, 10, and 1000 μg L^-1) and plants (Cyperus alternifolius L. and Typha angustifolia L.) on nitrogen removal in a micro-polluted CW system over a duration of 12 weeks. The effects were evaluated by investigating NH₄-N and NO₃-N removal efficiency, nitrification genes (amoA-AOA and amoA-AOB), denitrification genes (nirK and nirS), fungal 18S rRNA gene and microorganism community structure. The results showed that in unplanted CWs, OFL increased the NH₄-N removal efficiency (from 72.6% to 80.7-82.1%), the abundances of amoA-AOA, nirS, nirK and fungal 18S rRNA gene, and the bacterial diversity but decreased the abundance of both amoA-AOB and bacterial richness. In contrast, both the nitrogen removal efficiency (83.4-89.5% for NH₄-N and 33.8-38.5% for NO₃-N) and bacterial diversity/richness were not significantly affected by OFL in planted CWs. In planted systems, OFL increased the relative abundance of Arthrobacter, Pseudomonas, and Enterococcus, which are proven antibiotic-resistant bacteria. This study showed that CWs are able to remove nitrogen from antibiotic-contaminated micro-polluted water, which might primarily be attributed to the presence of plants that protect the microorganism community.

Characterization of Hydrocarbon-Degrading Bacteria in Constructed Wetland Microcosms Used to Treat Crude Oil Polluted Water

Ten plant species were grown in constructed wetlands (CWs) to remediate water containing 2% (w/v) crude oil. The plant species with better growth and biomass production were Typha latifolia and Cyperus laevigatus, and they were significantly correlated (R² = 0.91) with hydrocarbon degradation. From T. latifolia and C. laevigatus, 33 hydrocarbon-degrading bacterial strains were isolated from the rhizosphere, and root and shoot interiors. More diversified bacteria were found in the rhizosphere and endosphere of C. laevigatus than those of T. latifolia. The predominant cultural hydrocarbon-degrading bacteria were shown to belong to the genera Pseudomonas, Acinetobacter and Bacillus. In addition to genes involved in hydrocarbon degradation, most of the bacteria displayed multiple plant growth promoting (PGP) activities. This study suggests the importance of selecting suitable bacterial strains with hydrocarbon degradation and PGP activities for improving the efficacy of CWs used in remediating water contaminated with crude oil.

Nitrogen and phosphorus removal and Typha domingensis tolerance in a floating treatment wetland

The aim of this work was to study the efficiency of microcosms-scale floating treatment wetlands (FTWs) in the N and P removal from a synthetic runoff effluent and to evaluate the effluent tolerance of Typha domingensis. Each FTW consisted of a raft constructed with a plastic net where T. domingensis plants were installed. In order to evaluate the plant role, reactors with FTWs and without FTWs (controls) were used. P and N additions were carried out as follows: 5 mg L^-1 P (P5 and P5-control); 10 mg L^-1 N (N10 and N10-control); 5 mg L^-1 P + 10 mg L^-1 N (P5N10 and P5N10-control). Also, a biological control (B-control) without contaminant addition was used. The removal of soluble reactive phosphorus and total phosphorus were significantly higher in the FTWs than in the controls. Ammonium and nitrate concentrations were not significantly different between FTWs and controls at the end of the experiment. However, nitrate concentrations showed significant differences between FTWs and controls during the experiment. N and P were mainly accumulated in plant tissues and not in the sediment. Plants tolerated the effluent conditions and showed a positive growth rate. The use of FTWs is a promising strategy for the sustainable treatment of water bodies affected by runoff waters.

Enhancement of oil field-produced wastewater remediation by bacterially-augmented floating treatment wetlands

Plants and bacteria individually as well as in synergism with each other hold a great potential to degrade a wide range of environmental pollutants. Floating treatment wetlands (FTWs) is an efficient and low-cost technology that uses the synergistic interaction between plant roots and microbes for in situ remediation of wastewater. The present study aims to assess the feasibility of FTW-based remediation of oil field-produced wastewater using an interaction between two plant species, Typha domingensis and Leptochloa fusca, in partnership with a consortium of crude oil-degrading bacterial species, Bacillus subtilis LORI66, Klebsiella sp. LCRI87, Acinetobacter Junii TYRH47, and Acinetobacter sp. BRSI56. All the treatments reduced contaminant levels, but T. domingensis, in combination with bacterial inoculation, exhibited the highest reduction in hydrocarbon (95%), COD (90%), and BOD content (93%) as compared to L. fusca. This combination maximally promoted increases in fresh biomass (31%), dry biomass (52%), and length (25%) of plants as well. This effect was further signified by the persistence of bacteria (40%) and considerable abundance (27%) and expression (28.5%) of the alkB gene in the rhizoplane of T. domingensis in comparison to that of L. fusca. The study, therefore, suggests that T. domingensis, in combination with bacterial consortium, has significant potential for treatment of oil field-produced water and can be exploited on large scale in FTWs.

Removal of chlorpyrifos in recirculating vertical flow constructed wetlands with five wetland plant species

The removal efficiency of the pesticide chlorpyrifos (50 and 500 μg L^-1) by five wetland plant species (Cyperus alternifolius, Canna indica, Iris pseudacorus, Juncus effusus and Typha orientalis) was studied in recirculating vertical flow constructed wetland systems (RVFCWs). Results reveal that for chlorpyrifos at different concentrations, good removal efficiencies (94-98%) were observed using the same plant systems, while no significant differences in removal efficiencies were seen between the different plant systems. In addition, the chlorpyrifos removal efficiency of the planted systems increased significantly compared with the unplanted controls. The chlorpyrifos removal efficiency for wetland systems over time fit to the first-order kinetic model, with the first-order kinetic constant (k) ranging from 0.045 to 0.065 h^-1. The half-life of chlorpyrifos in the systems ranged from 10.66-15.43 h. The shortest chlorpyrifos half-life was detected in the wetland system containing C. indica, followed by that with C. alternifolius and I. pseudacorus. The main pathways to remove chlorpyrifos in these wetland systems were sorption (accounting for 64.6-86.4% of the total removal efficiency) and biodegradation (8.1-33.7%). Plants can enhance chlorpyrifos removal through enhanced biodegradation in the system. Plants with high biomass and transpiration were able to accelerate the removal of chlorpyrifos and conventional pollutants. Hence, C. indica, C. alternifolius and I. pseudacorus could be used as optimal plants for pesticide removal in wetland systems.

Microbial removal and plant uptake of nitrogen in constructed wetlands: mesocosm tests on influencing factors

Macrophytes and bacteria are key drivers of nitrogen removal in constructed wetlands. Through mesocosm experiments with vegetated submerged beds and free water surface wetlands in various operational modes, wetland configurations, and system layouts, this study developed empirical models for non-destructive estimation of plant biomass growth and associated nitrogen assimilation and explored the combined effects of multiple factors that influence microbial nitrogen removal. The above-ground biomass of individual plants was a power function of plant height for both Cyperus alternifolius and Typha angustifolia. Below- to above-ground biomass ratio was 0.38 for C. alternifolius and 2.73 for T. angustifolia. Because of greater tolerance to ammonia stress, C. alternifolius and C. papyrus grew faster than T. angustifolia. There were no significant effects of wetland type, vegetation, and plant species on microbial nitrogen removal. Microbial nitrogen removal was inhibited by free ammonia at 13.3-16.2 mg N/L. Denitrification and anammox were suppressed at dissolved oxygen greater than 1.9 mg/L. Microbial removal of ammonia in vegetated submerged beds was sensitive mainly to dissolved oxygen, pH, and influent ammonia concentration, while in free water surface wetlands, it was sensitive to influent ammonia concentration, pH, and temperature.

Long-term study of Cr, Ni, Zn, and P distribution in Typha domingensis growing in a constructed wetland

The aim of this work was to study Cr, Ni, Zn, and P bioaccumulation in different compartments of Typha domingensis plants and sediment in a free-water surface constructed wetland for the treatment of a metallurgical effluent for 5 years. Removal efficiencies were satisfactory. To increase metal tolerance, its transport from belowground to aboveground tissues is reduced, being metal concentrations in the roots and rhizomes significantly higher than in the aerial and submerged parts of leaves. Regarding belowground tissues, metals were retained in the roots, while P was mainly accumulated in rhizomes. Bioaccumulation factors (BAFs) of Cr and Ni showed values near 1, and BAF of Zn and P were above 1 in several samplings, indicating bioaccumulation in the roots. Translocation factors (TFs) of Cr, Ni, and Zn were below 1, showing a scarce translocation from the roots to the aerial parts of the leaves, while the TF of P were above 1 in many samplings, indicating that this element is necessary for plant metabolism. The study of plant tissues where contaminants are accumulated allows gaining insight into the constructed wetland operation. The high translocation of P in T. domingensis makes this species suitable for its phytoextraction, while the low metal translocation makes T. domingensis suitable for phytostabilization.

Municipal wastewater treatment potential and metal accumulation strategies of Colocasia esculenta (L.) Schott and Typha latifolia L. in a constructed wetland

This paper elucidates phytoremediation potential of two wetland plants (Colocasia esculenta (L.) Schott and Typha latifolia L.) for municipal wastewater treatment using constructed wetland (CW) mesocosms. The concentrations (mg L^-1) of chemical oxygen demand (COD), total kjeldahl nitrogen (TKN), Cu, Cd, Cr, Zn, and Pb in municipal wastewater were higher than permissible Indian standards for inland surface water disposal; however, Mn and Ni were within the permissible limits. The pollutant removal efficiencies of planted CWs varied as electrical conductivity (EC) 67.8-71.4%; COD 70.7-71.1%; TKN 63.8-72.3%; Cu 75.3-83.4%; Cd 73.9-83.1%; Mn 74.1-74.5%; Cr 64.8-73.6%; Co 82.2-84.2%; Zn 63.3-66.1%; Pb 71.4-77.9%; and Ni 76-80%. Mass balance analysis revealed that the loss of metals from wastewater was equivalent to net accumulation in plants and natural degradation of metals. Metal accumulation strategies of plants were investigated using bioconcentration factor (BCF) and translocation factor (TF) of metals which indicated that both plants could be employed for phytostabilization (BCF > 1 and TF < 1) of Cu, Cd, Co, Pb, and Ni and phytoextraction (BCF > 1 and TF > 1) of Mn and Zn. The study demonstrated that a reduction of pollutants (except Pb) was observed within permissible levels (BIS) and suggested disposal of municipal wastewater into the inland surface water bodies after 20 days of treatment. The study concluded that both the plants could potentially be used for an efficient municipal wastewater treatment using constructed wetlands.

Assisted phytoremediation of heavy metal contaminated soil from a mined site with Typha latifolia and Chrysopogon zizanioides

Chemically assisted phytoremediation is fast gaining attention as a biotechnology to accelerate heavy metal removal from contaminated substrates, but how different chemical amendments affect the process remains an important research question. Here, bioaccumulation factor (BAF), translocation factor (TF), removal efficiency (RE) and uptake of Hg, As, Pb, Cu and Zn by cattail (Typha latifolia) and vetiver (Chrysopogon zizanioides) were quantified in a potted experiment to determine the effects of amendments on the phytoremediation success. Baseline concentrations of heavy metals within the studied mined site were determined. The experiment involved three soil treatments (each comprising 16 samples amended with 0.05mol/L ethylene di-aminetetraacetic acid (EDTA), 3g of aluminum sulfate [Al₂(SO₄)₃], and unamended control) transplanted with equal numbers of vetiver and cattail. Growth performance (height) of plant species was monitored every two weeks. Sixteen weeks after transplanting, heavy metal levels in plant and soil samples were quantified following standard protocols, and the biomass and root length measured for each plant species. Results indicated strong negative impact of mining activities on heavy metal levels of soil in the study area. Soil amendment considerably enhanced the BAF, TF, RE and uptake but the effect varied with plant species and heavy metal in question. The amendment also stimulated strong positive correlation between RE and BAF, TF and metal uptake, and generally did not show any negative effects on plant growth performance. In general, soil amendment aided the accumulation and translocation of heavy metals in the plant species studied, and could be explored for cleaning up contaminated sites.

Synergistic phytoremediation of wastewater by two aquatic plants (Typha angustifolia and Eichhornia crassipes) and potential as biomass fuel

The ability of a mixture of Typha angustifolia and Eichhornia crassipes to remove organics, nutrients, and heavy metals from wastewater from a Thailand fresh market was studied. Changes in physicochemical properties of the wastewater including pH, temperature, chemical oxygen demand, dissolved oxygen, biochemical oxygen demand (BOD), total P, TOC, conductivity, total Kjeldahl nitrogen, NO₃^--N, NH₃-N, and metal (Pb, Cd, and Zn) concentrations were monitored. In the aquatic plant (AP) treatment, 100% survival of both species was observed. Dry biomass production and growth rate of T. angustifolia were approximately 3.3× and 2.7× of those for E. crassipes, respectively. The extensive root system of the plants improved water quality as determined by a marked decrease in turbidity in the AP treatment after 7 days. BOD content served as a useful indicator of water quality; BOD declined by 91% over 21 days. Both T. angustifolia and E. crassipes accumulated similar quantities of metals in both roots and shoots. Accumulation of metals was as follows: Zn > Cd > Pb. A study of calorific value and biomass composition revealed that T. angustifolia and E. crassipes possessed similar carbon content (~ 35%), hydrogen content (~ 6%), and gross calorific value. E. crassipes contained up to 16.9% ash and 65.4% moisture. Both species are considered invasive in Thailand; however, they may nonetheless provide practical benefits: In addition to their combined abilities to treat wastewater, T. angustifolia holds potential as an alternative energy source due to its high biomass production.

Removal of 1,2-Dichloroethane from real industrial wastewater using a sub-surface batch system with Typha angustifolia L

1,2-Dichloroethane (1,2-DCA) is widely present in urban wastewaters and can be remediated by green technology. Subsurface batch system constructed wetlands (SSCWs) using macrophyte species of T. angustifolia L. were examined to remove 1,2-DCA using real wastewater from a petrochemical industry with a 1,2-DCA concentration of 390mg/L. We conducted an experiment with four pilot-scale constructed wetlands (0.81m²) in a greenhouse. Three SSCWs (T2, T3 and T4) were fed with real wastewater, and another one (T1) was fed with tap water (as plant control) to assess the role of T. angustifolia L. and their associated rhizobacteria to remediate 1,2-DCA. Tank T2 contained only sand without plants acting as contaminant control, tank T3 contained sand with plants and finally tank T4 contained plants with mixture of sand, soil and compost (3:2:1). The results show that the green technology has improved the removal of 1,2-DCA from the contaminated water through biodegradation with a remediation efficiency of 100% in T4 within 42 days. The removal efficiency was enhanced in T4 with 18% more than in T3 due to the compost addition, giving evidence for the potential application of SSCWs to treat chlorinated hydrocarbon in real field.

Macrophytes as potential biomonitors in peri-urban wetlands of the Middle Parana River (Argentina)

The aims of this study were to measure the concentrations of nutrients and pollutants in peri-urban wetlands, to analyze the plant morphology of the most representative macrophyte species, and to determine their potential use as biomonitors. Four wetlands in the Middle Paraná River floodplain evidencing contamination or anthropogenic impact were studied. The studied species were Typha domingensis Pers., Eichhornia crassipes (Mart.) Solms., Alternanthera philoxeroides (Mart.) Griseb., and Pistia stratiotes L. Besides, the same plant species from an uncontaminated wetland considered as control were studied. A. philoxeroides showed the highest total phosphorus (TP) concentration in leaves throughout the study, while the other species showed a higher TP concentration in roots than in leaves. Since metal concentration in A. philoxeroides tissues was always higher than in sediment, further studies focused on its phytoremediation capacity should be carried out. T. domingensis exhibited the highest Zn concentrations in roots followed by Pb, and E. crassipes presented the highest values of Pb concentrations in roots. The aerial part height of the plants from peri-urban wetlands was significantly higher than that of the plants from the control, while the root length was significantly lower. The root length of P. stratiotes showed a negative correlation with soluble reactive phosphorus (SRP) concentration in water. All the root anatomical parameters of T. domingensis and E. crassipes showed a positive correlation with nitrate and ammonium concentrations in water. The studied macrophytes evidenced a high tolerance, enabling them to grow and survive in peri-urban wetlands that receive pollution from different sources. The use of aquatic and wetland plants as contaminant bioindicators and bioaccumulators in the Middle Paraná River floodplain is completely feasible.

Glyphosate (Ab)sorption by Shoots and Rhizomes of Native versus Hybrid Cattail (Typha)

Wetlands in the Prairie Pothole Region of North America are integrated with farmland and contain mixtures of herbicide contaminants. Passive nonfacilitated diffusion is how most herbicides can move across plant membranes, making this perhaps an important process by which herbicide contaminants are absorbed by wetland vegetation. Prairie wetlands are dominated by native cattail (Typha latifolia) and hybrid cattail (Typha x glauca). The objective of this batch equilibrium study was to compare glyphosate absorption by the shoots and rhizomes of native versus hybrid cattails. Although it has been previously reported for some pesticides that passive diffusion is greater for rhizome than shoot components, this is the first study to demonstrate that the absorption capacity of rhizomes is species dependent, with the glyphosate absorption being significantly greater for rhizomes than shoots in case of native cattails, but with no significant differences in glyphosate absorption between rhizomes and shoots in case of hybrid cattails. Most importantly, glyphosate absorption by native rhizomes far exceeded that of the absorption occurring for hybrid rhizomes, native shoots and hybrid shoots. Glyphosate has long been used to manage invasive hybrid cattails in wetlands in North America, but hybrid cattail expansions continue to occur. Since our results showed limited glyphosate absorption by hybrid shoots and rhizomes, this lack of sorption may partially explain the poorer ability of glyphosate to control hybrid cattails in wetlands.

Co-plantation of aquatic macrophytes Typha angustifolia and Paspalum scrobiculatum for effective treatment of textile industry effluent

Field treatment of textile industry effluent was carried out in constructed drenches (91.4m×1.2m×0.6m; 65.8m³) planted independently with Typha angustifolia, Paspalum scrobiculatum and their co-plantation (consortium-TP). The in situ treatment of effluent by T. angustifolia, P. scrobiculatum and consortium-TP was found to decrease ADMI color value by 62, 59 and 76%, COD by 65, 63 and 70%, BOD by 68, 63 and 75%, TDS by 45, 39 and 57%, and TSS by 35, 31 and 47%, respectively within 96h. Heavy metals such as arsenic, cadmium, chromium and lead were also removed up to 28-77% after phytoremediation. T. angustifolia and P. scrobiculatum showed removal of Congo Red (100mg/L) up to 80 and 73%, respectively within 48h while consortium-TP achieved 94% decolorization. Root tissues of T. angustifolia and P. scrobiculatum revealed inductions in the activities of oxido-reductive enzymes such as lignin peroxidase (193 and 32%), veratryl alcohol oxidase (823 and 460%), laccase (492 and 182%) and azo reductase (248 and 83%), respectively during decolorization of Congo Red. Anatomical studies of roots, FTIR, HPLC, UV-vis Spectroscopy and GC-MS analysis verified the phytotransformation. Phytotoxicity studies confirmed reduced toxicity of the metabolites of Congo Red.

Performance of five plant species in removal of nitrogen and phosphorus from an experimental phytoremediation system in the Ningxia irrigation area

Agricultural non-point source (ANPS) pollution is an important contributor to elevated nitrogen (N) and phosphorus (P) in surface waters, which can cause serious environmental problems. Considerable effort has therefore gone into the development of methods that control the ANPS input of N and P to surface waters. Phytoremediation has been extensively used because it is cost-effective, environmentally friendly, and efficient. The N and P loads from agricultural drainage are a potential threat to the water quality of the Yellow River in Ningxia, China. Yet, phytoremediation has only rarely been applied within the Ningxia irrigation area. In an experimental set-up, five species (Ipomoea aquatica, IA; Lactuca sativa, LS; Oryza sativa, OS; Typha latifolia, TL; Zizania latifolia, ZL) were evaluated for their ability to reduce N and P loads over 62 days and five observation periods. Total N and P concentrations, plant biomass, and nutrient content were measured. The results showed that OS, LS, and IA performed better than ZL and TL in terms of nutrients removal, biomass accumulation, and nutrients storage. The highest overall removal rates of N and P (57.7 and 57.3%, respectively) were achieved by LS treatment. In addition, plant uptake contributed significantly to nutrient removal, causing a 25.9-72.0% reduction in N removal and a 54.3-86.5% reduction in P removal. Thus, this study suggests that OS, LS, and IA would be more suitable than ZL and TL for controlling nutrient loads in the Ningxia irrigation area using phytoremediation.

Occurrence, distribution and bioaccumulation behaviour of hydrophobic organic contaminants in a large-scale constructed wetland in Singapore

This study involved a field-based investigation to assess the occurrence, distribution and bioaccumulation behaviour of hydrophobic organic contaminants in a large-scale constructed wetland. Samples of raw leachate, water and wetland plants, Typha angustifolia, were collected for chemical analysis. Target contaminants included polychlorinated biphenyls (PCBs), organochlorine pesticides (OCP), as well as several halogenated flame retardants (HFRs) and personal care products (triclosan and synthetic musks). In addition to PCBs and OCPs, synthetic musks, triclosan (TCS) and dechlorane plus stereoisomers (syn- and anti-DPs) were frequently detected. Root concentration factors (log RCF L/kg wet weight) of the various contaminants ranged between 3.0 and 7.9. Leaf concentration factors (log LCF L/kg wet weight) ranged between 2.4 and 8.2. syn- and anti-DPs exhibited the greatest RCF and LCF values. A strong linear relationship was observed between log RCF and octanol-water partition coefficient (log K_OW). Translocation factors (log TFs) were negatively correlated with log K_OW. The results demonstrate that more hydrophobic compounds exhibit higher degrees of partitioning into plant roots and are less effectively transported from roots to plant leaves. Methyl triclosan (MTCS) and 2,8-dichlorodibenzo-p-dioxin (DCDD), TCS degradation products, exhibited relatively high concentrations in roots and leaves., highlighting the importance of degradation/biotransformation. The results further suggest that Typha angustifolia in this constructed wetland can aid the removal of hydrophobic organic contaminants present in this landfill leachate. The findings will aid future investigations regarding the fate and bioaccumulation of hydrophobic organic contaminants in constructed wetlands.

Post-remediation use of macrophytes as composting materials for sustainable management of a sanitary landfill

To increase the remediation ability and life expectancy of a leachate channel in a sanitary landfill, the plants used for remediation were composted as a post-remediation management technique. Phragmites australis or Typha angustifolia used for phytoremediation in a landfill leachate channel was harvested and used as a co-composting material with sewage sludge. The macrophyte compost was applied to the slope of a landfill on which plants were introduced for revegetation and to plants grown in pots to test for acute effects of the compost. The compost of the macrophytes successfully increased soil moisture and nutrient contents both on the landfill slope and in the soil of the pot experiment. Additionally, the rates of photosynthesis and the nutrient contents increased for plants grown in macrophyte compost. Thus, the revegetation or restoration management of the landfill would improve with the macrophyte compost used as a soil conditioner. The harvest of the macrophytes has the additional benefit of improving the remediation function of the leachate channel. Therefore, to sustainably manage both the leachate channel and the landfill, the composting of post-remediation macrophytes is an environmentally friendly and economically affordable method.

Structure and function of the bacterial communities during rhizoremediation of hexachlorobenzene in constructed wetlands

Vertical flow constructed wetlands (VF CWs) are considered to be effective for treating organic pollutants. The rhizosphere of macrophytes such as Phragmites sp., Typha sp. serves as an active and dynamic zone for the microbial degradation of organic pollutants. However, it is still not clear how soil bacterial communities respond to macrophytes and pollutants during the process. For this purpose, the seedlings of Phragmites australis and Typha angustifolia were planted respectively in the VF CWs added with HCB at a dose of 2 mg/kg. During 96 days of cultivation, we monitored hexachlorobenzene (HCB) removal efficiency by GC/MS and the structure of the rhizosphere bacterial communities in the different VF CWs by denaturing gradient gel electrophoresis (DGGE), and constructed bacterial clone library based on PCR-amplified 16S rRNA gene. As expected, the rhizosphere bacterial communities also remained insensitive to HCB exposure in the wetland soil. The diversity of these microbes presented two stages, from the varied up and down to equilibrium in the entire experimental period. Molecular analysis revealed that the phylum Firmicutes dominated over the bacterial communities. The genera that increased under HCB stress included the well-known HCB-degrading bacteria (Pseudomonas sp. and Alcaligenes sp.) and other common bacteria found in contaminated soil but with lesser known practical functions (Burkholderia sp., Lysinibacillus fusiformis, and Bacillus cereus). Furthermore, there was a certain variance in the relative abundances of the bacterial phyla and HCB removal efficiency among different VF CW treatments. The degradation of HCB in T. angustifolia microcosms was faster than that in P. australis and unvegetated wetlands, and the highest bacterial diversity and richness was found in the VF CWs comprising T. angustifolia.

Typha latifolia as potential phytoremediator of 2,4-dichlorophenol: Analysis of tolerance, uptake and possible transformation processes

2,4-Dichlorophenol (2,4-DCP) is considered a priority pollutant due to its high toxicity. Therefore, it is urgent to develop technologies for the disposal of this pollutant. Various remediation processes have been proposed for the elimination of 2,4-DCP in contaminated water, however, most of them involve high costs of operation and maintenance. This study aimed to determine the capacity of remediation of 2,4-DCP in water by Typha latifolia L. wild plants. For that, the tolerance, removal, accumulation and biotransformation of 2,4-DCP by T. latifolia were investigated. The plants were exposed to 2,4-DCP solutions with a concentration range from 1.5 to 300 mgL^-1 for 10 days. They exhibited a reduction in chlorophyll levels and growth rate when 2,4-DCP solutions were ≥30 mgL^-1 and ≥50 mgL^-1, respectively. The removal of contaminant was dose-depended, being 99.7% at 1.5-3 mgL^-1, 59-70% at 10-70 mgL^-1 and 35-42% at 100-300 mgL^-1 of 2,4-DCP in the solution. Studies indicated that 2,4-DCP was mainly accumulated in root tissue rather than in shoot tissue. Acid hydrolysis of biomass extracts suggests 2,4-DCP bioconjugates formation in root tissue as a response mechanism. Additionally, an increment in glutathione S-transferase (GST) activity could indicate a 2,4-DCP conjugation with glutathione as a detoxification mechanism of T. latifolia.

Phytoremediation of biosolids from an end-of-life municipal lagoon using cattail (Typha latifolia L.) and switchgrass (Panicum virgatum L.)

Land spreading of biosolids as a disposal option is expensive and can disperse pathogens and contaminants in the environment. This growth room study examined phytoremediation using switchgrass (Panicum virgatum L.) and cattail (Typha latifolia L.) as an alternative to land spreading of biosolids. Seedlings were transplanted into pots containing 3.9 kg of biosolids (dry wt.). Aboveground biomass (AGB) was harvested either once or twice during each 90-day growth period. Switchgrass AGB yield was greater with two harvests than with one harvest during the first 90-day growth period, whereas cattail yield was not affected by harvest frequency. In the second growth period, harvesting frequency did not affect the yield of either plant species. However, repeated harvesting significantly improved nitrogen (N) and phosphorus (P) uptake by both plants in the first period. Phytoextraction of P was significantly greater for switchgrass (3.9% of initial biosolids P content) than for cattail (2.8%), while plant species did not have a significant effect on N phytoextraction. The trace element accumulation in the AGB of both plant species was negligible. Phytoextraction rates attained in this study suggest that phytoremediation can effectively remove P from biosolids and offers a potentially viable alternative to the disposal of biosolids on agricultural land.

Functionality of microbial communities in constructed wetlands used for pesticide remediation: Influence of system design and sampling strategy

The objective of this study was to compare the microbial community metabolic function from both unsaturated and saturated constructed wetland mesocosms (CWs) when treating the pesticide tebuconazole. The comparison was performed for both interstitial water and substrate biofilm by community level physiological profiling (CLPP) via BIOLOG™ EcoPlates. For each CW design (saturated or unsaturated), six mesocosms were established including one unplanted and five planted individually with either Juncus effusus, Typha latifolia, Berula erecta, Phragmites australis or Iris pseudacorus. Microbial activity and metabolic richness of interstitial water from unsaturated CWs were significantly lower than that from saturated CWs. However, in general, the opposite result was observed for biofilm samples. Wetland plants promoted significantly higher biofilm microbial activity and metabolic richness than unplanted CWs in both CW designs. Differences in the microbial community functional profiles between plant species were only found for saturated CWs. Biofilm microbial metabolic richness was generally statistically higher than that of interstitial water in both unsaturated (1.4-24 times higher) and saturated (1.2-1.7 times higher) CWs. Carbon source (guild) utilization patterns were generally different between interstitial water and biofilm samples. Functionality of the biofilm microbial community was positively correlated to the removal of all pollutants (TN, NH₄⁺-N, TP, TOC and tebuconazole) for both unsaturated and saturated CWs, suggesting the biofilm plays a more important role in pollutant removal than the interstitial water microbial community. Thus, merely observing the interstitial water microbial communities may underestimate the role of the microbial community in CW performance. Interestingly, the ability for the biofilm microbial community to utilize amino acids and amines/amides was positively correlated with tebuconazole removal in all system types.

Remediation of mercury-polluted soils using artificial wetlands

Mexico's mercury mining industry is important for economic development, but has unfortunately contaminated soils due to open-air disposal. This case was seen at two sites in the municipality of Pinal de Amoles, State of Queretaro, Mexico. This paper presents an evaluation of mercury dynamics and biogeochemistry in two soils (mining waste soil) using ex-situ wetlands over 36 weeks. In soils sampled in two former mines of Pinal de Amoles, initial mercury concentrations were 424 ± 29 and 433 ± 12 mg kg^-1 in La Lorena and San Jose, former mines, respectively. Typha latifolia and Phragmites australis were used and 20 reactors were constructed (with and without plants). The reactors were weekly amended with a nutrient solution (NPK), for each plant, at a pH of 5.0. For remediation using soils from San Jose 70-78% of mercury was removed in T. latifolia reactors and 76-82% in P. australis reactors, and for remediation of soils from La Lorena, mercury content was reduced by 55-71% using T. latifolia and 58-66% in P. australis reactors. Mercury emissions into the atmosphere were estimated to be 2-4 mg m^-2 h^-1 for both soils.

Increased lead and cadmium tolerance of Typha angustifolia from Huaihe River is associated with enhanced phytochelatin synthesis and improved antioxidative capacity

Heavy metal contamination of water is an increasing environmental problem worldwide, and the use of aquatic plants for phytoremediation of heavy metal pollution has become an important subject of research. One key to successful phytoremediation is the identification of plants that are efficient at sequestering heavy metals. In this study, we examined the growth and heavy metal accumulation of Typha angustifolia and compared growth characteristics and tolerance mechanisms in plants from the Huaihe and Chaohu Rivers irrigated with different concentrations of lead (Pb) and cadmium (Cd). T. angustifolia from Huaihe River showed enhanced tolerance and accumulation of Pb and Cd and had greater biomass and more vigorous growth than the ecotype from Chaohu River. In addition, higher phytochelatin (PC) content and significantly higher superoxide dismutase and catalase activities were detected in T. angustifolia from Huaihe River than in T. angustifolia from Chaohu River. These findings suggest that high Pb and Cd accumulation and tolerance in T. angustifolia from Chaohu River is associated with its higher PC synthesis and better antioxidative capacity, and that the Huaihe ecotype of T. angustifolia might also be an efficient species for phytoremediation of Pb and Cd in water contaminated by heavy metals.

Lignified and nonlignified fiber cables in the lacunae of Typha angustifolia

The leaves of Typha are noteworthy in terms of their mechanical properties. We determined the mechanical properties of the fiber cables within the leaf. We found that in vegetative plants, the lignified fiber cables isolated from the leaf sheath and nonlignified fiber cables isolated from the leaf blade of Typha angustifolia differ in their diameter, swelling capacity, Young's modulus, tensile strength, and break load. These differing properties are related to their contributions to stability in the two regions of the leaf.

The role of sand, marble chips and Typha latifolia in domestic wastewater treatment - a column study on constructed wetlands

The relative importance of sand, marble chips and wetland plant Typha latifolia is evaluated in constructed wetlands (CWs) for the treatment of domestic wastewater intended for reuse in agriculture. The prototype CWs for the experiments are realized in polyvinyl chloride columns, which are grouped into four treatments, viz. sand (<2 mm) + Typha latifolia (cattail), sand, marble chips (5-20 mm) + cattail and marble chips. The removal percentage of organic and nutritional pollutants from the wastewater is measured at varying hydraulic retention time in the columns. The statistical analysis suggests that the main effects of sand and cattail are found to be significant (p < .05) for the removal of biological oxygen demand and chemical oxygen demand from the wastewater. The presence of cattail significantly (p < .01) contributes to the conversion of total nitrogen in wastewater into [Formula: see text] by fostering the growth of favorable microbes for the nitrification. The removal of [Formula: see text] and turbidity from the wastewater is significantly (p < .01) influenced by sand than the presence of cattail. The maximum [Formula: see text] adsorption capacity of the sand is estimated to be 2.5 mg/g. Marble chips have significantly (p < .01) influenced the removal of [Formula: see text]and its maximum removal capacity is estimated to be 9.3 mg/g. The negative correlation between the filter media biofilm and column hydraulic conductivity is also reported for all the treatments. Thus, the findings of this study elucidate the role of low-cost and easily available filter media and it will guide the environmental practitioners in designing cost-effective CWs for wastewater treatment.

Using aquatic vegetation to remediate nitrate, ammonium, and soluble reactive phosphorus in simulated runoff

Within the agriculturally-intensive Mississippi River Basin of the United States, significant conservation efforts have focused on management practices that reduce nutrient runoff into receiving aquatic ecosystems. Only a small fraction of those efforts have focused on phytoremediation techniques. Each of six different aquatic macrophytes were planted, in monoculture, in three replicate mesocosms (1.2 m × 0.15 m × 0.65 m). Three additional unvegetated mesocosms served as controls for a total number of 21 mesocosms. Over two years, mesocosms were amended once each summer with sodium nitrate, ammonium sulfate, and potassium phosphate dibasic to represent nitrogen and phosphorus in agricultural runoff. System retention was calculated using a simple aqueous mass balance approach. Ammonium retention in both years differed greatly, as Panicum hemitomon and Echinodorus cordifolius retentions were significantly greater than controls in the first year, while only Myriophyllum aquaticum and Typha latifolia were significantly greater than controls in the second year. Greater soluble reactive phosphorus retention was observed in T. latifolia compared to controls in both years. Several other significant differences were observed in either the first or second year, but not both years. In the first year's exposure, P. hemitomon was significantly more efficient than the control, Saururus cernuus, and T. latifolia for overall percent nitrate decrease. Results of this novel study highlight inherent variability within and among species for nutrient specific uptake and the temporal variations of species for nutrient retention. By examining this natural variability, scientists may design phytoremediation systems with greater impact on improving agricultural runoff water quality.

Phytoextraction, phytotransformation and rhizodegradation of ibuprofen associated with Typha angustifolia in a horizontal subsurface flow constructed wetland

Widespread occurrence of trace pharmaceutical residues in aquatic environments is of great concerns due to the potential chronic toxicity of certain pharmaceuticals including ibuprofen on aquatic organisms even at environmental levels. In this study, the phytoextraction, phytotransformation and rhizodegradation of ibuprofen associated with Typha angustifolia were investigated in a horizontal subsurface flow constructed wetland system. The experimental wetland system consisted of a planted bed with Typha angustifolia and an unplanted bed (control) to treat ibuprofen-loaded wastewater (∼107.2 μg L(-1)). Over a period of 342 days, ibuprofen was accumulated in leaf sheath and lamina tissues at a mean concentration of 160.7 ng g(-1), indicating the occurrence of the phytoextraction of ibuprofen. Root-uptake ibuprofen was partially transformed to ibuprofen carboxylic acid, 2-hydroxy ibuprofen and 1-hydroxy ibuprofen which were found to be 1374.9, 235.6 and 301.5 ng g(-1) in the sheath, respectively, while they were 1051.1, 693.6 and 178.7 ng g(-1) in the lamina. The findings from pyrosequencing analysis of the rhizosphere bacteria suggest that the Dechloromonas sp., the Clostridium sp. (e.g. Clostridium saccharobutylicum), the order Sphingobacteriales, and the Cytophaga sp. in the order Cytophagales were most probably responsible for the rhizodegradation of ibuprofen.

Evaluation of an innovative approach based on prototype engineered wetland to control and manage boron (B) mine effluent pollution

A major environmental problem associated with boron (B) mining in many parts of the world is B pollution, which can become a point source of B mine effluent pollution to aquatic habitats. In this study, a cost-effective, environment-friendly, and sustainable prototype engineered wetland was evaluated and tested to prevent B mine effluent from spilling into adjoining waterways in the largest B reserve in the world. According to the results, average B concentrations in mine effluent significantly decreased from 17.5 to 5.7 mg l(-1) after passing through the prototype with a hydraulic retention time of 14 days. The results of the present experiment, in which different doses of B had been introduced into the prototype, also demonstrated that Typha latifolia (selected as donor species in the prototype) showed a good resistance to alterations against B mine effluent loading rates. Moreover, we found that soil enzymes activities gradually decreased with increasing B dosages during the experiment. Boron mass balance model further showed that 60 % of total B was stored in the filtration media, and only 7 % of B was removed by plant uptake. Consequently, we suggested that application of the prototype in the vicinity of mining site may potentially become an innovative model and integral part of the overall landscape plan of B mine reserve areas worldwide. Graphical Abstract ᅟ.

An approach to biodegradation of chlorobenzenes: combination of Typha angustifolia and bacterial effects on hexachlorobenzene degradation in water

Although rhizoremediation is an effective approach to remove organic pollutants from the environment, little is known about the mechanism of hexachlorobenzene (HCB) biodegradation in water. In this study, we used Typha angustifolia (T. angustifolia) grown in sterile Hoagland nutrient solution to determine the rhizosphere effects on the ability of bacteria in water to reduce HCB levels. The results revealed that T. angustifolia could facilitate HCB degradation and that the initial HCB concentration was the major factor responsible for HCB degradation in nutrient solution. Furthermore, HCB biodegradation in low-HCB nutrient solution with T. angustifolia fitted the first-order kinetics, owing to the high concentration of total organic carbon, low HCB toxicity, and unique bacterial community in the T. angustifolia rhizosphere. Denaturing gradient gel electrophoresis indicated that the rhizosphere effects and different dosages of HCB have significant effects on the bacterial communities by repressing and favoring certain populations. The most successful bacteria to adapt to HCB contamination was Bacillus sp., while the dominant bacterial phyla in HCB-polluted water were Proteobacteria and Firmicutes.

Uptake, translocation and possible biodegradation of the antidiabetic agent metformin by hydroponically grown Typha latifolia

The increasing load of pharmaceutical compounds has raised concerns about their potential residues in aquatic environments and ecotoxicity. Metformin (MET), a widely prescribed antidiabetic II medicine, has been detected in high concentration in sewage and in wastewater treatment effluents. An uptake and translocation study was carried out to assess the ultimate fate of MET in phytoremediation. MET was removed from media by Typha latifolia, and the removal processes followed first order kinetics. After 28 days, the removal efficiencies were in a range of 74.0±4.1-81.1±3.3%. In roots, MET concentration was increasing during the first two weeks of the experiment but thereafter decreasing. In contrast, MET concentration was continuously increasing in rhizomes and leaves. Bioaccumulation of MET in roots was much higher than in leaves and rhizomes. As degradation product of metformin in the plant, methylbiguanide (MBG) was detected whereas guanylurea was undetectable. Moreover, MBG concentration in roots was increasing with exposure time. An enzymatic degradation experiment showed the degradation rate followed the order of MET<MBG<<guanylurea. This may explain the low concentration of MBG in plant. The findings of this study contribute to understand and evaluate the potential for phytoremediation of such kind of contaminants.