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 (Zc) 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.

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.

Accumulation potential and tolerance response of Typha latifolia L. under citric acid assisted phytoextraction of lead and mercury.

Chelate-assisted phytoextraction by high biomass producing macrophyte plant Typha latifolia L. commonly known as cattail, is gaining much attention worldwide. The present study investigated the effects of Lead (Pb) and Mercury (Hg) on physiology and biochemistry of plant, Pb and Hg uptake in T. latifolia with and without citric acid (CA) amendment. The uniform seedlings of T. latifolia were treated with various concentrations in the hydroponics as: Pb and Hg (1, 2.5, 5 mM) each alone and/or with CA (5 mM). After four weeks of treatments, the results revealed that Pb and Hg significantly reduced the plant agronomic traits as compare to non-treated plants. The addition of CA improved the plant physiology and enhanced the antioxidant enzymes activities to overcome Pb and Hg induced oxidative damage and electrolyte leakage. Our results depicted that Pb and Hg uptake and accumulation by T. latifolia was dose depend whereas, the addition of CA further increased the concentration and accumulation of Pb and Hg by up to 22 & 35% Pb and 72 & 40% Hg in roots, 25 & 26% Pb and 85 & 60% Hg in stems and 22 & 15 Pb and 100 & 58% Hg in leaves respectively compared to Pb and Hg treated only plants. On other hand, the root-shoot translocation factor was ≥1 and bioconcentration factor was also ≥2 for both Pb & Hg. The results also revealed that T. latifolia showed greater tolerance towards Hg and accumulated higher Hg in all parts compared with Pb.

Chronic effects of microcystin-LR at environmental relevant concentrations on photosynthesis of Typha angustifolia Linn.

Understanding the growth and development of aquatic plants in eutrophic water is of great significance for the selection of potential candidate plant for use in the phytoremediation of eutrophic aquatic ecosystems. The present study aimed to investigate the chronic effects of microcystin-LR (MC-LR) on photosynthesis in the leaves of Typha angustifolia Linn. Photosynthetic activity was stimulated in the leaves following exposure to 4.6 µg L-1 MC-LR for six weeks based on the enhancement of Ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) activity and net photosynthetic rate (PN). However, PN decreased significantly after exposure to 49.1 or 98.3 µg L-1 MC-LR, via non-stomatal limitation by reducing the chlorophyll a and b contents and Rubisco activity. In addition, glycolate oxidase (GO) and serine:glyoxylate aminotransferase (SGAT) activities decreased significantly, indicating that the photorespiration pathway was affected adversely. The intercellular carbon dioxide (Ci) concentration decreased significantly following exposure to 98.3 µg L-1 MC-LR, accompanied with decreases in PN and stomatal conductivity (gs), indicating that stomatal limitation on the photosynthesis system in T. angustifolia L. was observed after exposure to 98.3 µg L-1 MC-LR. Under long-term exposure to MC-LR (49.1-98.3 µg L-1), oxidation stress was severe in the aquatic plant, and non-stomatal limitation or stomatal limitation effects on the photosynthesis system were obvious, resulting in decreases in photosynthesis rates.

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.

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.

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.

The ethylene receptor regulates Typha angustifolia leaf aerenchyma morphogenesis and cell fate.

MAIN CONCLUSION: Ethylene receptor is crucial for PCD and aerenchyma formation in Typha angustifolia leaves. Not only does it receive and deliver the ethylene signal, but it probably can determine the cell fate during aerenchyma morphogenesis, which is due to the receptor expression quantity. Aquatic plant oxygen delivery relies on aerenchyma, which is formed by a programmed cell death (PCD) procedure. However, cells in the outer edge of the aerenchyma (palisade cells and septum cells) remain intact, and the mechanism is unclear. Here, we offer a hypothesis: cells that have a higher content of ethylene receptors do not undergo PCD. In this study, we investigated the leaf aerenchyma of the aquatic plant Typha angustifolia. Ethephon and pyrazinamide (PZA, an inhibitor of ACC oxidase) were used to confirm that ethylene is an essential hormone for PCD of leaf aerenchyma cells in T. angustifolia. That the ethylene receptor was an indispensable factor in this PCD was confirmed by 1-MCP (an inhibitor of the ethylene receptor) treatment. Although PCD can be avoided by blocking the ethylene receptor, excessive ethylene receptors also protect cells from PCD. TaETR1, TaETR2 and TaEIN4 in the T. angustifolia leaf were detected by immunofluorescence (IF) using polyclonal antibodies. The result showed that the content of ethylene receptors in PCD-unsusceptible cells was 4-14 times higher than that one in PCD-susceptible cells, suggesting that PCD-susceptible cells undergo the PCD programme, while PCD-unsusceptible cells do not due to the content difference in the ethylene receptor in different cells. A higher level of ethylene receptor content makes the cells insensitive to ethylene, thereby avoiding cell death and degradation.

Insight into chronic exposure effects of nanosized titanium dioxide on Typha angustifolia leaf litter decomposition.

Advancement in nanotechnology has increased production of nanoparticles which initiates concerns for freshwater ecosystems. Nanosized TiO2 is one of the most used materials and its ecotoxicity has been extensively studied. Here, a freshwater microcosm experiment was performed to investigate the effects of nanosized (10, 60, and 100 nm) and bulk TiO2 at 1 g L-1 on the alteration in community structure of fungal decomposers and the consequences on litter decomposition of Typha angustifolia leaves. After 209 days of exposure, the decomposition rate was significantly higher in 100 nm TiO2 treatment compared to the control, which was caused by its promotion on fungal biomass and metabolic activity. Therefore, the study provides the multifaceted evidences for different effects of TiO2 with varied sizes on T. angustifolia leaf decomposition and highlights the importance of understanding the potential effects of varying sizes and long-term exposure in nanoparticle risk assessments.

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.

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.

Do Varying Aquatic Plant Species Affect Phytoplankton and Crustacean Responses to a Nitrogen-Permethrin Mixture?

Hydraulically connected wetland microcosms vegetated with either Typha latifolia or Myriophyllum aquaticum were amended with an NH4NO3 and permethrin mixture to assess the effectiveness of both plant species in mitigating effects of the pollutant mixture on phytoplankton (as chlorophyll a) and Hyalella azteca. Phytoplankton grew in response to increased NH4NO3 in the presence of all plant species, but was unaffected by exposure to permethrin. H. azteca responses occurred rapidly (0.17 days), was mitigated within 1-2 days, and aqueous toxicity was unaffected by plant species type. A toxic unit model approach ascertained primary toxicity was permethrin with minimal additional toxicity from NH4NO3. Varying aquatic plant species had only modest influences on phytoplankton responses and no observable influence on animal responses during nitrogen-permethrin mixture exposures. As a result, both T. latifolia and M. aquaticum can be used as part of an effective agricultural best-management practice system for mitigating pollutant impacts of agricultural run-off.

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.

[Effect of Arbuscular Mycorrhiza (AM) on Tolerance of Cattail to Cd Stress in Aquatic Environment].

Hygrophytes are planted more and more in landscaping and greening in many cities, but they often encounter threat from environmental pollution. Arbuscular mycorrhiza ( AM ) have been confirmed to enhance the tolerance of terrestrial plants to environmental pollution in many previous studies, but it is unclear how they affect hygrophytes. In the present study, a hydroponic culture experiment was carried out to investigate the effects of AM fungi (Glomus etunicatum) inoculation on the tolerance of cattail (Typha latifolia) to different concentrations Cd2+ (0, 2.5, 5.0 mg x L(-1)). The aim was to provide reference for evaluating whether mycorrhizal technology can be used to enhance the tolerance of hygrophytes to environmental pollution. The results showed that symbiotic association was well established between AM fungi and cattail roots, and the mycorrhizal colonization rates (MCR) were beyond 30%. However, MCR presented downward trend one month after mycorrhizal cattails were transported to solution, and the maximal decrease was 25.5% (P < 0.05). AM increased pigment concentrations and peroxidase (POD) activity in cattail leaves, and also increased roots radial oxygen loss. However, AM only produced significant effect on increase of fresh weight in 5 mg x L(-1) Cd2+ solution. Although plant growth was inhibited by 5 mg x L(-1) Cd2+ and MCR was lower, AM increased Cd uptake of cattail at the two Cd2+ levels, and the maximal increments were 40.24% and 56.52% in aboveground and underground parts, respectively. This study indicates that AM has potential to enhance the tolerance of hygrophytes to environmental pollution and might be used to remedy heavy metal pollution.

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.

Comparative responses of freshwater organisms to exposures of a commercial naphthenic acid.

Comparative toxicity studies using unconfounded exposures can prioritize the selection of sensitive sentinel test species and refine methods for evaluating ecological risks of complex mixtures like naphthenic acids (NAs), a group of organic acids associated with crude oils and energy-derived waters that have been a source of aquatic toxicity. The objectives of this study were to compare responses of freshwater aquatic organisms (vertebrate, invertebrates, and a macrophyte; in terms of acute toxicity) to Fluka commercial NAs and to compare measured toxicity data with peer-reviewed toxicity data for other commercial NA sources and energy-derived NA sources. Exposures were confirmed using high performance liquid chromatography. Responses (7-d LC50s/EC50) ranged from 1.9 mg L(-1) for Pimephales promelas to 56.2 mg L(-1) for Typha latifolia. Following P. promelas in order of decreasing sensitivity were Ceriodaphnia dubia (7-d LC50 = 2.8 mg L(-1)), Hyalella azteca (7-d LC50 = 4.1 mg L(-1)), Chironomus dilutus (7-d LC50 = 6.5 mg L(-1)), and T. latifolia (7-d EC50 = 56.2 mg L(-1)), indicating that in terms of sensitivities, fish > invertebrates > plant for Fluka NAs in this study. Factors that affect exposures and measurements of exposures differ among commercial and energy-derived NAs and constrain comparisons. Despite differences in exposures, fish and invertebrates were relatively sensitive to both commercial and energy-derived NA sources (based on laboratory measurements and peer-reviewed data) and could be appropriate sentinel species for risk evaluations.

The inhibition and adaptability of four wetland plant species to high concentration of ammonia wastewater and nitrogen removal efficiency in constructed wetlands.

Four plant species, Typha orientalis, Scirpus validus, Canna indica and Iris tectorum were selected to assess their physiological response and effects on nitrogen and COD removal to high total ammoniacal nitrogen (TAN) in constructed wetlands. Results showed that high TAN caused decreased relative growth rate, net photosynthetic rate, and leaf transpiration. C. indica and T. orientalis showed higher TAN adaptability than S. validus and I. tectorum. Below TAN of 200 mg L(-1), growth of C. indica and T. orientalis was less affected or even stimulated at TAN range 100-200 mg L(-1). However, S. validus and I. tectorum was obviously suppressed when TAN was above 100 mg L(-1). High TAN generated obvious oxidative stress showing increased proline and malondialdehyde contents, and superoxide dismutase was inhibited. It indicated that the threshold for plant self-bioremediation against high TAN was 200 mg L(-1). What's more, planted CWs showed higher nitrogen and COD removal. Removal rate of C. indica and T. orientalis was higher than S. validus and I. tectorum.

Influence of Typha domingensis in the removal of high P concentrations from water.

A greenhouse experiment was conducted to evaluate the removal of high P concentration from water by vegetated and unvegetated wetlands. Reactors containing 4 kg of sediment and two plants of Typha domingensis (vegetated treatments) and reactors containing only sediment (unvegetated treatments) were arranged. Reactors were dosed with 100 and 500 mg L(-1) of P-PO4. The studied concentrations tried to simulate an accidental dump. Controls without P addition were also disposed. Water samples were collected periodically and analyzed for phosphorus. Sediment (0-3 (surface), 3-7 (medium) and 7-10 cm (deep)) and plant samples (roots, rhizomes, submerged leaves and aerial leaves) were collected at the beginning and at end of the experiment and were analyzed for total phosphorus. P fractionation was performed in the surface sediment layer. Relative growth rate (RGR) was calculated in each treatment considering initial and final plant height. P was efficiently removed from water in both, vegetated and unvegetated treatments. However, the major P removal was achieved in vegetated treatments. T. domingensis has a high capacity to tolerate and accumulate high P concentrations, especially in leaves, causing P accumulation in sediment to be significantly low in vegetated treatments. P accumulation was produced in the surface sediment layer (0-3 cm) in all treatments, mainly retained as iron-bound P. Present results point the large removal capacity of phosphate of systems planted with T. domingensis. Therefore T. domingensis is suitable for phytoremediation practice, being capable to tolerate high P concentration.

High Pb concentration stress on Typha latifolia growth and Pb removal in microcosm wetlands.

When constructed wetlands are used to treat high-Pb wastewater, Pb may become a stress to wetland plants, which subsequently reduces treatment performance and the other ecosystem services. To facilitate the design and operation of constructed wetlands for treatment of Pb-rich wastewater, we investigated the irreversible inhibitory level of Pb for Typha latifolia through experiments in microcosm wetlands. Seven horizontal subsurface flow constructed wetlands were built with rectangular plastic tanks and packed with marble chips and sand. All wetlands were transplanted with nine stems of Typha latifolia each. The wetlands were batch operated in a greenhouse with artificial wastewater (10 L each) for 12 days. Influent to the seven wetlands had different concentrations of Pb: 0 mg/L, 10 mg/L, 25 mg/L, 50 mg/L, 100 mg/L, 200 mg/L, and 500 mg/L, respectively. The results suggested that leaf chlorophyll relative content, relative growth rate, photosynthetic characteristics, activities of superoxide dismutase, peroxidase, and content of malondialdehyde were not affected when initial Pb concentration was at 100 mg/L and below. But when initial Pb concentration was above 100 mg/L, all of them were seriously affected. We conclude that high Pb concentrations wastewater could inhibit the growth of Typha latifolia and decrease the removal rate of wetlands.

Comparative study on the impact of copper sulphate and copper nitrate on the detoxification mechanisms in Typha latifolia.

The present study focused on cupric sulphate and cupric nitrate uptake in Typha latifolia and the impact of these copper species on the plant's detoxification capacity. When the plants were exposed to 10, 50 and 100 µM cupric sulphate or cupric nitrate, copper accumulation in T. latifolia roots and shoots increased with rising concentration of the salts. Shoot to root ratios differed significantly depending on the form of copper supplementation, e.g. if it was added as cupric (II) sulphate or cupric (II) nitrate. After incubation with 100 µM of cupric sulphate, up to 450 mg Cu/kg fresh weight (FW) was accumulated, whereas the same concentration of cupric nitrate resulted in accumulation of 580 mg/kg FW. Furthermore, significant differences in the activity of some antioxidative enzymes in Typha roots compared to the shoots, which are essential in the plant's reaction to cope with metal stress, were observed. The activity of peroxidase (POX) in roots was increased at intermediate concentrations (10 and 50 µM) of CuSO4, whereas it was inhibited at the same Cu(NO3)2 concentrations. Ascorbate peroxidase (APOX) and dehydroascorbate reductase (DHAR) increased their enzyme activity intensely, which may be an indication for copper toxicity in T. latifolia plants. Besides, fluorodifen conjugation by glutathione S-transferases (GSTs) was increased up to sixfold, especially in roots.