Tolerance to mild shading levels in cattail as related to increased photosynthesis and changes in its leaf area and anatomy.

Shading is an environmental factor that has been little investigated regarding its effects on emergent aquatic plants. Typha domingensis Pers. is an emergent macrophyte that demonstrates some plasticity for self-shading, and as it can shade other species in the same area, the effect of shading on its traits deserves further investigation. The objective of the present study was to evaluate the gas exchange, leaf anatomy, and growth of T. domingensis cultivated under increasing shading intensities. The plants were collected and propagated in a greenhouse, and the clones were subjected to four shading intensities: 0% (unshaded), 35%, 73%, and 83% shading created by black nets. Growth traits, clonal production, photosynthesis, transpiration, and leaf anatomy were evaluated. The 73% and 83% shading promoted the death of all plants, but all plants survived in the 35% and unshaded treatments. Compared with the unshaded treatment, the 35% shading treatment promoted a higher photosynthetic rate and greater transpiration, supporting increased growth and production of clones. The increase in the photosynthetic rate in the 35% shading was related to the increase in leaf area which increased the photosynthesis of the whole plant. The 73% and 83% treatments inhibited the development of photosynthetic parenchyma and stomata in T. domingensis, leading to a drastic reduction in photosynthesis and energy depletion. Therefore, T. domingensis does not tolerate intense shading, but its photosynthetic characteristics and growth are favored by mild shading, a factor that may be of great importance for its competitiveness and invasive behavior.

Cattail (Typha domingensis) silage improves feed intake, blood profile, economics of production, and growth performance of beef cattle.

Sixteen Rahaji breed beef cattle (112.00 ± 0.15 kg body weight (BW)) were randomly assigned to one of four rations differing in the degree of substitution of sorghum straw with Cattail (Typha domingensis) silage. Growth performance, feed intake, blood profile, and economics of production were evaluated. Completely randomized design was used, and the feeding trial lasted for 42 days. Cattle were fed a total mixed ration of roughage:concentrate (400:600) g/kg dry matter and gamba hay free choice. The control diet (T0) contained 400 g/kg sorghum straw, expressed on a dry matter basis (DM). For additional treatments, Typha silage (TS) was included at 100 (T10), 200 (T20), and 300 (T30) g/kg of the mix replacing an equal DM weight of sorghum straw. Growth rate was similar (P > 0.05) regardless of the TS level. DM (5160.77-5524.96 g/d) and crude protein (846.36-955.82 g/d) intakes were higher (P < 0.05) in T20 and T30 diets, while the acid detergent fiber intake (471.27-512.46 g/d) reduced (P < 0.05) in TS-based diets. Red blood cell concentrations of cattle fed TS-based diets increased (P < 0.05). The mean corpuscular hemoglobin concentrations of cattle fed T20 diet decreased (P < 0.05) in comparison with the control. Sodium and albumin concentrations were higher (P < 0.05) in cattle fed TS-based diets. Total cost of feeding ($ 49.60-61.62) decreased (P < 0.05) in TS-based diets, while the gross benefit of cattle fed 300 g/kg TS diet ($ 74.98) was enhanced relative to cattle fed T0 and T10 diets. TS can be considered a new resource of feed for cattle.

Application of the thermal time model for different Typha domingensis populations.

BACKGROUND: Cattail (Typha domingensis Pers.) is a perennial emergent plant which is used in Green Floating Filters (GFFs), one of the most innovative systems of wastewater treatment to bioremediate eutrophic waters and produce biomass as biofuel feedstocks. The establishment of cattails in GFFs depends on the seed germination and plant responses under conditions of a new habitat. This study analysed the germination responses of four different populations of cattails through a thermal time model to know their basic parameters of germination and which population would be more adapted to the conditions tested. RESULTS: Seeds from the Badajoz (Ba), Cuenca (Cu), Madrid (Ma), Seville (Se) and Toledo (To) populations were exposed to different thermal regimes (constant, and alternating temperatures between 15 and 30 °C) and different darkness treatments (between 0 and 20 days with 24 h dark photoperiod, then exposed to light with 12 h light/dark photoperiod) to determine the parameters of the thermal model from germination levels in each treatment. To population was used to validate the thermal time parameters of other populations. Regardless of the other parameters, no germination occurred in total darkness. The mean value of base temperature (Tb) was 16.4 ± 0.2 °C in all treatments. Optimum temperature (To) values in Ma and Ba were 25 °C, and those in Cu and Se were 22.5 °C. The germination response decreased when the temperature approached Tb and increased when it was close to To. In comparison to alternating temperatures, constant temperatures had the highest germination response and lowest thermal time (θT(50)). Darkness treatments had a direct relationship with θT(50). The population origin also affected seed germination; Cu had the highest values of To and germination response but had a lower θT(50), which coincides with the lowest mean ambient temperatures. CONCLUSION: According to these results, the germination response of cattails was high in all populations under optimal conditions but was affected to a greater or lesser extent depending on thermal regimes, darkness treatments, and populations. The thermal time model allowed us to determine that To was between 22.5-25 °C and that Cu is the best population regarding the germination response under the conditions tested.

Horizontal subsurface flow constructed wetland for tertiary treatment of dairy wastewater: Removal efficiencies and plant uptake.

There are different physicochemical and biological methods to treat effluents. However, their efficiency is not enough to meet the effluents discharge limits. For this reason, it could be possible to employ a polished treatment. A suitable alternative for this goal could be constructed wetlands (CWs). The aim of the present research was to evaluate contaminants removal efficiency of a pilot scale horizontal subsurface flow constructed wetland (HSSFW) for tertiary treatment of dairy wastewater. A vegetation study was also conducted in order to determine the role of plants on nutrient removal. A pilot scale HSSFW planted with Typha domingensis was built in a dairy factory, after the biological treatment. The substrate used was river gravel. During a seven-month research period, thirty-two samples (influent and effluent) were taken and analyzed to determine physicochemical and microbiological parameters as well as removal efficiencies. Biomass, TP, TKN and organic matter content in plants was determined at the beginning and end of the monitoring period. Suspended solids showed significant differences between inlet and outlet, with a mean removal efficiency of 78.4%. For BOD and COD, mean removal efficiencies were respectively 57.9 and 68.7%. Removal percentages for TKN, Nitrates and TP were lower than other parameters (25.7%, 47.8% and 29.9%, respectively). Fecal Coliform bacteria decreased one order of magnitude in final effluent. In the case of Escherichia coli and Pseudomona aeruginosa results were variable. Total biomass increased 4.6 times at the end of the monitoring period. The study of plants indicated its important contribution in terms of contaminant uptake and retention. HSSFW would be an advisable alternative as a tertiary treatment of dairy wastewater.

Accounting for the Impact of Management Scenarios on Typha Domingensis (Cattail) in an Everglades Wetland.

The coupled regional simulation model, and the transport and reaction simulation engine were recently adapted to simulate ecology, specifically Typha domingensis (Cattail) dynamics in the Everglades. While Cattail is a native Everglades species, it has become invasive over the years due to an altered habitat over the last few decades, taking over historically Cladium jamaicense (Sawgrass) areas. Two models of different levels of algorithmic complexity were developed in previous studies, and are used here to determine the impact of various management decisions on the average Cattail density within Water Conservation Area 2A in the Everglades. A Global Uncertainty and Sensitivity Analysis was conducted to test the importance of these management scenarios, as well as the effectiveness of using zonal statistics. Management scenarios included high, medium and low initial water depths, soil phosphorus concentrations, initial Cattail and Sawgrass densities, as well as annually alternating water depths and soil phosphorus concentrations, and a steadily decreasing soil phosphorus concentration. Analysis suggests that zonal statistics are good indicators of regional trends, and that high soil phosphorus concentration is a pre-requisite for expansive Cattail growth. It is a complex task to manage Cattail expansion in this region, requiring the close management and monitoring of water depth and soil phosphorus concentration, and possibly other factors not considered in the model complexities. However, this modeling framework with user-definable complexities and management scenarios, can be considered a useful tool in analyzing many more alternatives, which could be used to aid management decisions in the future.

Plant species influences the composition of root system microbiome and its antibiotic resistance profile in a constructed wetland receiving primary treated wastewater.

Introduction: Constructed wetlands (CWs) are nature-based solutions for wastewater treatment where the root system microbiome plays a key role in terms of nutrient and pollutant removal. Nonetheless, little is known on plant-microbe interactions and bacterial population selection in CWs, which are mostly characterized in terms of engineering aspects. Methods: Here, cultivation-independent and cultivation-based analyses were applied to study the bacterial communities associated to the root systems of Phragmites australis and Typha domingensis co-occurring in the same cell of a CW receiving primary treated wastewaters. Results and discussion: Two endophytic bacteria collections (n = 156) were established aiming to find novel strains for microbial-assisted phytodepuration, however basing on their taxonomy the possible use of these strains was limited by their low degrading potential and/or for risks related to the One-Health concept. A sharp differentiation arose between the P. australis and T. domingensis collections, mainly represented by lactic acid bacteria (98%) and Enterobacteriaceae (69%), respectively. Hence, 16S rRNA amplicon sequencing was used to disentangle the microbiome composition in the root system fractions collected at increasing distance from the root surface. Both the fraction type and the plant species were recognized as drivers of the bacterial community structure. Moreover, differential abundance analysis revealed that, in all fractions, several bacteria families were significantly and differentially enriched in P. australis or in T. domingensis. CWs have been also reported as interesting options for the removal of emerging contaminants (e.g, antibiotic resistance genes, ARGs). In this study, ARGs were mostly present in the rhizosphere of both plant species, compared to the other analyzed fractions. Notably, qPCR data showed that ARGs (i.e., ermB, bla TEM, tetA) and intl1 gene (integrase gene of the class 1 integrons) were significantly higher in Phragmites than Typha rhizospheres, suggesting that macrophyte species growing in CWs can display a different ability to remove ARGs from wastewater. Overall, the results suggest the importance to consider the plant-microbiome interactions, besides engineering aspects, to select the most suitable species when designing phytodepuration systems.

Subsurface flow constructed wetlands for treating of simulated cadmium ions-wastewater with presence of Canna indica and Typha domingensis.

The presence of toxic cadmium ions in the wastewater resulted from industrial sector forms the critical issue for public health and ecosystem. This study determines the ability of four vertical subsurface flow constructed wetlands units in the treatment of simulated wastewater laden with cadmium ions. This was achieved through using sewage sludge byproduct as alternative for the traditional sand to be substrate for aforementioned units in order to satisfy the sustainable concepts; however, Canna indica and Typha domingensis can apply to enhance the cadmium removal. The performance of constructed wetlands has been evaluated through monitoring of the pH, dissolved oxygen (DO), temperature, and concentrations of cadmium (Cd) in the effluents for retention time (0.5-120 h) and metal concentration (5-40 mg/L). The results demonstrated that the Cd removal percentage was exceeded 82% beyond 5 days and for concentration of 5 mg/L; however, this percentage was decreased with smaller retention time and higher metal concentration. The Grau second-order kinetic model accurately simulated the measurements of effluent Cd concentrations as a function of retention times. The FT-IR analysis indicated the existence of certain functional groups capable of enhancing the Cd removal. The treated wastewater's pH, DO, temperature, total dissolved solids (TDS), and electrical conductivity (EC) all meet the requirements for irrigation water.

Biological pilot treatment reduces physicochemical and microbiological parameters of dairy cattle wastewater.

The objectives of the present study were to characterize and evaluate a pilot treatment unit (PTU) for dairy cattle wastewater (DCW) in relation to its efficiency in reducing the physicochemical and microbiological parameters and possible application of this fertilizer in organic production. A PTU was set up, composed of the following elements: a dung pit of 7.8 m3, already in place; a septic tank; a set of anaerobic biological filters comprising an upflow filter and a downward-flow filter filled with fragments PVC corrugated conduit; and two constructed wetland systems (CWSs) of horizontal subsurface flow in two parallel routes (Routes 1 and 2), controlled by means of a flow rate divider box. Route 1 passed through CWS 1 cultivated with cattail (Typha domingensis) and Route 2 passed through CWS 2 cultivated with vetiver grass (Chrysopogon zizanioides). To evaluate the treatment stages, biweekly investigations were carried out to collect effluent samples. The results of monitoring, in absolute values, were evaluated by means of the medians and variation coefficients and compared by means of Kruskal-Wallis non-parametric test followed by the Student Newman Keuls test. The treatment efficiencies of Routes 1 and 2 were calculated. The influence of vetiver on the removal of nutrients from the DCW was analyzed and the productivity estimate (t.ha-1) was performed. CWS 1 was not able to reduce the organic load indices, but it was able to retain fatty material and sodium. CWS 2 showed a reduction in nitrogenous forms and also for other nutrients, achieving the greatest removal of sodium and greatest decay of fecal contamination indicators, thermotolerant coliforms (56.13%), and E. coli (46.82%).

In silico analysis of Typha domingensis Pers. phytocompounds against wound healing biomarkers and ascertaining through in vitro cell migration assay.

Typha domingensis Pers. is known for its medicinal properties. Although traditionally T. domingensis Pers. has been used for wound healing, yet scientific investigations reporting its ability to heal wounds are lacking. Phytochemical profiling of T. domingensis Pers. inflorescence crude extract was carried out by LC-MS analysis. Ten phytochemicals were selected for in silico analysis based on retention time, mass-to-charge ratio and resolution of mass spectrum. Molecular docking of all ten compounds was done against selected wound healing biomarkers viz., interleukin 6(IL-6), interleukin ß (IL-ß), insulin-like growth factor tyrosine kinase receptor (IGF-1R) and transformation growth factor ß (TGF-ß). Based on this, catechin, mesalazine and piperazine were subjected for in vitro cell migration assay (3T3 L1 mouse fibroblast cell line) to assess their wound healing potentials. Molecular docking revealed that mesalazine, catechin, and piperazine have potential ligands based on lowest docking energy (ranging from - 4.1587 to - 0.972), Glide E score (ranging from - 26.929 to - 57.882), Glide G score (ranging from - 4.16 to - 7.972) and numbers of hydrogen bonds compared to other compounds studied. The migration assay revealed that, compared to control (52.5%), T. domingensis Pers. inflorescence crude extract showed maximum wound healing potential (80%) followed by Catechin (66.8%) Mesalazine (58.3%) and Piperazine (51.2%). The combined in silico and in vitro approach opens new dimension for designing innovative therapeutics to manage different types of wounds.

Enzymatic hydrolysis for the systematic production of second-generation glucose from the dual polysaccharide reserves of an anti-pollutant plant.

In this study, the anti-pollutant macrophyte Typha domingensis is exploited for the production of highly concentrated second-generation glucose. A two-stage starch and cellulose enzymatic hydrolysis process is compared for the first time with a single-stage simultaneous starch and cellulose hydrolysis approach, with the former achieving enhanced glucose production, making it more promising for large-scale deployment. The proposed two-stage process is optimized via the Box-Behnken response surface methodology achieving glucose yield values of 74.4% and 71.7% with respect to the starch and cellulose fraction, respectively. Elevated shaking rates are shown to exert a positive effect on both starch and cellulose enzymatic hydrolysis only under high initial substrate concentrations and high initial enzyme to substrate ratios, indicating the importance of accounting for the synergies between key process variables when aiming to increase glucose production. The findings of the presented experimental framework aspire to support future scale-up studies and techno-economic assessments.

Ecological Risk Assessment of Heavy Metals along Three Main Drains in Nile Delta and Potential Phytoremediation by Macrophyte Plants.

The use of drainage water in the irrigation of agroecosystem is associated with environmental hazards, and can pose threats to human health. Nine heavy metals (Fe, Mn, Zn, Cu, Co, Cr, Ni, Cd and Pb) along three main drains in the middle Nile Delta were measures in the sediments, roots and shoots of three common macrophytes (Echinochloa stagnina, Phragmites australis and Typha domingensis). The physicochemical characteristics, as well as the enrichment factor (Ef), contamination factor (Cf), geoaccumulation index (Igeo), ecological risk factor (Er), degree of contamination (Dc) and potential ecological risk index (PERI), were determined for sediment. The metal bioaccumulation factor (BAF) and translocation factor (TF) were assessed for plants. Data revealed high contents of Cr, Zn and Cd in the upstream of the drains, while Mn, Cu and Ni were recorded in high concentrations in the downstream. Mn, Cr, Co, Cu, Ni and Zn were recorded to be within EU (2002), CSQGD (2007) and US EPA (1999) limits, while Cd and Pb showed high a ecological risk index. This high concentration of pollutants could be attributed to unremitting industrial activities, which can bioaccumulate in the food chains and cause serious problems for humans. The root of P. australis showed the effective accumulation of most of the elements, while T. domingensis revealed the highest accumulation of Pb. However, the highest BAF shoot value was found in T. domingensis for most of the heavy metals, except for Fe and Zn in P. australis and Mn in E. stagnina. Thus, P. australis could be used as a potential phytoextractor of these hazardous metals, as an eco-friendly and cost-efficient method for remediation of the polluted drains. Further, T. domingensis could be integrated as a hyperaccumulator of Pb. Strict laws and regulations must be taken into consideration by the policymaker against unmanaged industrial activities, particularly near the water streams in the Nile Delta.

Ecohydrogeochemical functioning of coastal freshwater herbaceous wetlands in the Protected Natural Area, Ciénaga del Fuerte (American tropics): Spatiotemporal behaviour.

Coastal zones are characterized by the interactions between continents and oceans and, therefore, between fresh and salt surface and groundwater. The wetlands of coastal zones represent transitional ecosystems that are affected by these conditions, although little is known about the hydrogeochemistry of wetlands, especially coastal wetlands. In the present study, the hydrogeochemical characterization of coastal freshwater herbaceous wetlands in the Ciénaga del Fuerte Protected Natural Area in Veracruz, Mexico, in the American tropics was carried out per plant community. Four herbaceous wetlands (alligator flag, saw grass, cattail, and floodplain pasture) were monitored to understand the origin of the water feeding these ecosystems, the hydrogeochemical composition of groundwater, and the relationship between the groundwater and ecology of these ecosystems during dry and rainy seasons. The results indicate that Ciénaga del Fuerte is located in a regional discharge area and receives local recharge, so it is fed by both regional and local flows. The chemical composition varied temporally and spatially, creating unique conditions that determined the habitat occupied by the hydrophytic vegetation. The spatiotemporal behaviour of groundwater is one factor that, along with the hydroperiod, determines wetland dynamics and affects wetland biota (ecohydrogeochemistry). Generalist plant communities established in zones of local recharge, whereas other more specialized and/or plastic communities inhabited zones receiving regional flows with greater ion concentrations. This information forms the basis for establishing an appropriate scale (municipal, state, or larger regions) for the sustainable management of goods and services provided by the wetlands.

Cutting frequency effect on barium phytoextraction by macrophytes in flooded environment: A field trial.

In anoxic environmental conditions and with a drastic reduction of the redox potential, the barium sulphate used in petroleum drilling fluids becomes a hazard to the ecosystem. A field study was conducted in Brazil in an area with a history of accidental Barium (Ba) contamination to evaluate the role of frequent plant cutting on phytoremediation. The plant species Typha domingensis and Eleocharis acutangula, cultivated in a combined plantation, were subjected to four different cut frequencies: every 90 days (four cuts), 120 days (three cuts), 180 days (two cuts), or 360 days (one cut). The total amount of Ba extracted from the soil by the plants was evaluated for each treatment and at different soil depths Overall, total Ba in the soil decreased the most dramatically for cut frequencies of 120 (37.83%) and 180 (47.73%) days at 0-0.2 m below the surface, and with cut frequencies of 120 (51.98%) and 360 (31.79%) at 0.2-0.4 m depth. Further, total Ba in the plant biomass was greatest in the 120 and 360-days frequency groups. Thus, cuts at intervals of 120 days or more are associated with high levels of Ba in the plant tissue and a decrease of soil Ba.

Mercury species accumulation and distribution in Typha domingensis under real field conditions (Almadén, Spain).

Monomethylmercury (MeHg) is one of the most toxic and the most commonly occurring organomercury compound and the wetlands are one of the main areas of generation of this Hg form. Concretely, it is in the macrophyte root system where better conditions are given for its generation. However, the knowledge of absorption and subsequent distribution of mercury (Hg) and monomethylmercury in aquatic plants is still limited. Mercury mining district such as Almadén (Ciudad Real, Spain) is a natural laboratory where different rivers flow and the species Typha domingensis Pers. is a common macrophyte which grows in their riverbanks. The aim of the present work is to apply a recently developed method specially designed to analyze Hg species in plant tissues to the different fractions of T. domingensis under real field conditions and to study the accumulation and distribution of Hg species (inorganic Hg and MeHg) within the plant. The results proved that whatever Hg species has preference to be accumulated in the belowground fractions and demonstrated a high efficiency in the accumulation of MeHg.

A re-circulating horizontal flow constructed wetland for the treatment of synthetic azo dye at high concentrations.

A re-circulating horizontal flow constructed wetland (RHFCW) system was developed in a greenhouse. This system was operated with Typha domingensis to study the phytoremediation capacity of this macrophyte species in different developing stages for synthetic textile wastewater with the pollutant type, the amaranth (AM) azo dye. Experiments were applied with a fixed flow rate Q = 10 L/h corresponding to a theoretical residence time of 3 h. The synthetic feeding to the RHFCW container was re-circulated back until the required water quality was achieved. The performance of this pilot-scale system was compared to an unplanted RHFCW. The effect of the initial dye concentration was studied using four dye concentrations (10, 15, 20, and 25 mg/L). The following parameters pH, color, COD, BOD5, NO3-, NO2-, and NH4+ were monitored during treatment. The maximum efficiencies obtained for discoloration, COD, NO3-, and NH4+ were 92 ± 0.14%, 56 ± 1.12%, 92 ± 0.34%, and 97 ± 0.17% respectively. Experiences demonstrate a decrease of removal efficiencies of studied parameters with the increase of dye concentrations, leading to an increase of the duration of treatment. Changes in activities of antioxidant enzymes (superoxide dismutase (SOD), guaiacol peroxidase (GPX), catalase (CAT), ascorbic peroxidase (APX), and glutathione reductase (GR)) and their relation to plant defense system against stress were studied. Enzymes were evaluated in leaves of T. domingensis during the remediation of the azo dye (amaranth). During treatment, an increase of enzymes activities was observed in accordance with the high removal efficiency.

Phytoremediation of barium-affected flooded soils using single and intercropping cultivation of aquatic macrophytes.

Aquatic macrophytes are potentially useful for phytoremediation on flooded areas. A field study in Brazil was conducted to evaluate Eleocharis acutangula (E), Cyperus papyrus (C) and Typha domingensis (T) in monocropping and intercropping, aiming to phytoremediate barium-polluted flooded soils. The treatments were: monocroppings (E, C and T); double intercroppings (EC, ET and CT); and triple intercropping (ECT). The 180-d field trial was performed in a flooded area with high barium content, with a randomized complete block design and three replicates. Plant stand size, biomass yield, and Ba concentration aboveground/Ba concentration in roots (translocation factor - TF) as well as Ba mass aboveground/Ba mass in roots (mass translocation factor - mTF) were determined. Most of the treatments did not differ on dry biomass, except for EC, which showed the lowest yield. Consistently with its biology, E. acutangula in monocropping showed the largest plant stand. Otherwise, intercroppings with T. domingensis achieved the highest amounts of barium absorbed from the soil and transferred most of the barium content from belowground to aboveground (mTF > 1.0), especially ET, which showed the highest mTF among the intercroppings (2.03). Remarkably, TF values did not reflect such phytoextraction ability for CT and ECT. Thus, mTF was more appropriate than TF to assess phytoextraction capacity. Furthermore, it was demonstrated that intercropping can increase barium uptake from flooded soils. Particularly, the intercropping ET constituted the most cost-effective treatment, with the cyperaceous species providing high plant coverage while T. domingensis facilitated barium removal by translocating it to the aboveground biomass.

Accumulation of mercury in Typha domingensis under field conditions.

Typha species is a common wetland plant used in the treatment of urban and industrial effluents. But, despite their widespread implementation, there are not many studies based on the behaviour of this plant growing in an areas affected by mercury. The present work investigates the ability of Typha domingensis to accumulate mercury under field conditions. The study area was along the Valdeazogues river which flows through the Almadén mining district (Ciudad Real, Spain) that is considered the largest mercury reservoir in the world. The mercury concentration in different plant fractions was measured as well as the available and total concentration in the bottom sediments. The results showed that the highest mercury concentrations were found in the belowground organs. T. domingensis had a high efficiency to accumulate mercury in their organs although available metal concentrations in the environment did not exceed 0.16 mg kg(-1). Bioaccumulation factors (BAF) ranged between 121 and 3168 in roots. Furthermore, significant correlations were found between mercury concentration in all plant organs and Hg in sediments (both total and available). These results demonstrated that T. domingensis could be used as a biomonitor as well as in phytoextraction technology in areas affected by mercury.

Competition from native hydrophytes reduces establishment and growth of invasive dense-flowered cordgrass (Spartina densiflora).

Experimental studies to determine the nature of ecological interactions between invasive and native species are necessary for conserving and restoring native species in impacted habitats. Theory predicts that species boundaries along environmental gradients are determined by physical factors in stressful environments and by competitive ability in benign environments, but little is known about the mechanisms by which hydrophytes exclude halophytes and the life history stage at which these mechanisms are able to operate. The ongoing invasion of the South American Spartina densiflora in European marshes is causing concern about potential impacts to native plants along the marsh salinity gradient, offering an opportunity to evaluate the mechanisms by which native hydrophytes may limit, or even prevent, the expansion of invasive halophytes. Our study compared S. densiflora seedling establishment with and without competition with Phragmites australis and Typha domingensis, two hydrophytes differing in clonal architecture. We hypothesized that seedlings of the stress tolerant S. densiflora would be out-competed by stands of P. australis and T. domingensis. Growth, survivorship, biomass patterns and foliar nutrient content were recorded in a common garden experiment to determine the effect of mature P. australis and T. domingensis on the growth and colonization of S. densiflora under fresh water conditions where invasion events are likely to occur. Mature P. australis stands prevented establishment of S. densiflora seedlings and T. domingensis reduced S. densiflora establishment by 38%. Seedlings grown with P. australis produced fewer than five short shoots and all plants died after ca. 2 yrs. Our results showed that direct competition, most likely for subterranean resources, was responsible for decreased growth rate and survivorship of S. densiflora. The presence of healthy stands of P. australis, and to some extent T. domingensis, along river channels and in brackish marshes may prevent the invasion of S. densiflora by stopping the establishment of its seedlings.

Phytoremediation of water contaminated with mercury using Typha domingensis in constructed wetland.

The presence of mercury in aquatic environments is a matter of concern by part of the scientific community and public health organizations worldwide due to its persistence and toxicity. The phytoremediation consists in a group of technologies based on the use of natural occurrence or genetically modified plants, in order to reduce, remove, break or immobilize pollutants and working as an alternative to replace conventional effluent treatment methods due to its sustainability - low cost of maintenance and energy. The current study provides information about a pilot scale experiment designed to evaluate the potential of the aquatic macrophyte Typha domingensis in a constructed wetland with subsurface flow for phytoremediation of water contaminated with mercury. The efficiency in the reduction of the heavy metal concentration in wetlands, and the relative metal sorption by the T. domingensis, varied according to the exposure time. The continued rate of the system was 7 times higher than the control line, demonstrating a better performance and reducing 99.6±0.4% of the mercury presents in the water contaminated. When compared to other species, the results showed that the T. domingensis demonstrated a higher mercury accumulation (273.3515±0.7234 mg kg(-1)) when the transfer coefficient was 7750.9864±569.5468 L kg(-1). The results in this present study shows the great potential of the aquatic macrophyte T. domingensis in constructed wetlands for phytoremediation of water contaminated with mercury.

Optimización del tratamiento de aguas residuales de cultivos de flores usando humedales construidos de flujo subsuperficial horizontal / Optimization of wastewater treatment from a flower crops using a horizontal sub-surface flow constructed wetland / Otimização do tratamento de águas residuárias em plantações de flores usando alagados construídos de fluxo subsuperficial horizontal

Objetivo: optimizar un sistema de tratamiento de aguas residuales de cultivos de flores, con el fin de mejorar la eficiencia en la remoción de los contaminantes, usando humedales construidos de flujo subsuperficial-horizontal. Metodología: se realizó un estudio de tipo exploratorio experimental en dos etapas, en la primera se efectuó el acondicionamiento fisicoquímico y biológico del sistema de tratamiento, en la segunda, se llevó a cabo el seguimiento de la remoción de los contaminantes durante nueve meses, para lo cual se monitoreó la demanda química de oxígeno, demanda biológica de oxígeno, sólidos totales, sólidos suspendidos totales, pH y oxígeno disuelto. Resultados: Se logró mejorar la eficiencia del sistema de tratamiento en 7,1% para la Demanda biológica de oxígeno, 4,1% Demanda química de oxígeno, 56,9% sólidos totales y 117,2% solidos suspendidos totales. Conclusión: La concentración de DQO disminuyó con el tratamiento primario (Precipitación y oxidación química) y favoreció la eficiencia del sistema de tratamiento secundario, dado que las aguas a tratar tenían valores muy altos de DQO que pueden saturar los humedales con contaminantes persistentes. Se podrían obtener mayores eficiencias, si se logra mejorar el sistema de tratamiento primario.

Objective: to optimize the wastewater treatment system of flower crops in order to improve pollutant removal efficiency, using a horizontal subsurface flow constructed wetland. Methodology: An exploratory experimental study was conducted in two stages; in the first stage the treatment system was conditioned physically, chemically and biologically. In the second stage pollutant removal was monitored for nine months. To achieve this, chemical oxygen demand, biological oxygen demand, total solids, total suspended solids, pH and dissolved oxygen were monitored. Results: It was possible to improve the efficiency of the treatment system in 7.1% for biological oxygen demand, 4.1 % for chemical oxygen demand, 56.9 % for total solids and 117.2 % for total suspended solids. Conclussion: the concentration of COD decreased with the primary treatment (precipitation, chemical oxidation) and favored the efficiency of the secondary treatment system since the water to be treated had very high values of COD which may saturate the wetlands with persistent pollutants. Higher efficiency could be obtained by enhancing the primary treatment system.

Objetivo: optimização do sistema de tratamento das águas residuárias de cultivos de flores, a fim de melhorar a eficiência na remoção dos contaminantes, usando alagados construídos de fluxo subsuperficial horizontal. Metodologia: realizou-se estudos experimentais em duas etapas, na primeira efetuou-se o desenvolvimento fisico-químico e biológico do sistema de tratamento, na segunda, o acompanhamento da remoção dos contaminantes durante nove meses, foi monitorado a demanda química de oxigênio, demanda biológica de oxigênio, sólidos totais, sólidos suspendidos totais, pH e oxigênio dissolvido. Resultados : Foi possível melhorar a eficiência do sistema de tratamento em 7,1% para a demanda biológica de oxigênio, 4,1% demanda química de oxigênio, 56,9% sólidos totais e 117,2% sólidos suspendidos totais. Conclusão: A concentração de DQO diminuiu com o tratamento primário (Precipitação e oxidação química) e favoreceu a eficiência do sistema de tratamento secundário, uma vez que as águas a tratar tinham valores muito altos de DQO que podem saturar os alagados com contaminantes persistentes. Poderiam alcançar maiores eficiências, consegue-se melhorar o sistema de tratamento primário.