Evaluation of long-term phosphorus uptake by Schoenoplectus californicus and Phragmites australis plants in pilot-scale constructed wetlands.

The aim of this study was to evaluate long-term phosphorus (P) retention in a pilot-scale system made of four horizontal subsurface flow (HSSF) constructed wetlands for wastewater treatment. Each wetland had an area of 4.5 m2 and was operated for nearly 8 years (2833 days). Two wetlands with Schoenoplectus californicus (HSSF-Sch) and the other two with Phragmites australis (HSSF-Phr) were planted. The P removal efficiency was 18% for both types of HSSF wetlands. The primary factors that correlated with long-term P retention efficiency in HSSF were phosphorus loading rate (PLR), hydraulic loading rate (HLR) and dissolved oxygen (DO). Average biomass production of HSSF-Phr and HSSF-Sch was 4.8 and 12.1 kg dry weight (DW)/m2, respectively. The P uptake by the plant increased over the years of operation from 1.8 gP/m2 to 7.1 gP/m2 for Phragmites and from 3.2 to 7.4 gP/m2 for Schoenoplectus over the same periods. Moreover, the warm season (S/Sm) was more efficient reaching 14% P uptake than the cold season (F/W) with 9%. These results suggest that both plants' P retention capacity in HSSF systems represents a sustainable treatment in the long term.Novelty statement Long-term (8 years) phosphorus uptake by Schoenoplectus californicus and Phragmites australis and retention in pilot-scale constructed wetlands are evaluated. Schoenoplectus californicus is an uncommon species that has been less studied for phosphorus uptake compared to Phragmites australis, a globally known species in constructed wetlands. Moreover, some studies evaluating the performance of constructed wetland systems for domestic wastewater treatment are usually limited in time (1-3 years). Therefore, this long-term study demonstrates that the plant plays an important role in phosphorus retention, especially the species Schoenoplectus californicus. So, the phosphorus uptake by plants can contribute between 9 and 14% of the phosphorus load of constructed wetland systems in early years of operation.

Treatment of municipal wastewater by vertical subsurface flow constructed wetland: Data collection on removal efficiency using Phragmites Australis and Cyperus Papyrus.

The data of this document highlights a comparative analysis between the Phragmites Australis and Cyperus Papyrus planted in vertical subsurface flow constructed wetland (VSSFCW) independently implemented at pilot scale for the treatment of domestic wastewater. At the exit of the primary lagoon a pipe was installed to feed a constant flow of 0.6 m3/day to each of the two constructed wetlands. Each unit had a retention time of 1.12 days and a hydraulic load rate of 0.2 m/day. To evaluate the efficiency of the treatment, physical, chemical and biological parameters were monitored for three consecutive months. Water samples in the influent and effluent of each experimental wetland were analyzed. At the end of the monitoring, Cyperus Papyrus had a better removal of total phosphorus (50%), ammoniacal nitrogen (69.69%), biochemical oxygen demand (69.87%), chemical oxygen demand (80.69%), total coliforms (98.08%) and fecal coliforms (95.61%). Meanwhile, Phragmites Australis eliminated total solids better (62.85%). These data may be useful for comparative purposes on domestic wastewater treatment using Phragmites Australis and Cyperus Papyrus planted in VSSFCW.

Plant science's next top models.

BACKGROUND: Model organisms are at the core of life science research. Notable examples include the mouse as a model for humans, baker's yeast for eukaryotic unicellular life and simple genetics, or the enterobacteria phage λ in virology. Plant research was an exception to this rule, with researchers relying on a variety of non-model plants until the eventual adoption of Arabidopsis thaliana as primary plant model in the 1980s. This proved to be an unprecedented success, and several secondary plant models have since been established. Currently, we are experiencing another wave of expansion in the set of plant models. SCOPE: Since the 2000s, new model plants have been established to study numerous aspects of plant biology, such as the evolution of land plants, grasses, invasive and parasitic plant life, adaptation to environmental challenges, and the development of morphological diversity. Concurrent with the establishment of new plant models, the advent of the 'omics' era in biology has led to a resurgence of the more complex non-model plants. With this review, we introduce some of the new and fascinating plant models, outline why they are interesting subjects to study, the questions they will help to answer, and the molecular tools that have been established and are available to researchers. CONCLUSIONS: Understanding the molecular mechanisms underlying all aspects of plant biology can only be achieved with the adoption of a comprehensive set of models, each of which allows the assessment of at least one aspect of plant life. The model plants described here represent a step forward towards our goal to explore and comprehend the diversity of plant form and function. Still, several questions remain unanswered, but the constant development of novel technologies in molecular biology and bioinformatics is already paving the way for the next generation of plant models.

Optimal conditions for chlorothalonil and dissolved organic carbon in horizontal subsurface flow constructed wetlands.

The most efficient system of horizontal subsurface flow constructed wetlands (HSSFCW) for removing dissolved organic carbon (DOC) in the presence of chlorothalonil pesticide (CLT) present in synthetic domestic wastewater was determined using the macrophyte Phragmites australis. Two concentrations of CLT (85 and 385 µg L-1) and one concentration of glucose (20 mg L-1) were evaluated in four pilot scale horizontal surface flow constructed wetlands coupled with two sizes of silica gravel, igneous gravel, fine chalky gravel (3.18-6.35 mm), coarse gravel (12.70-25.40 mm) and two water surface heights (20 and 40 cm). For a month, wetlands were acclimated with domestic wastewater. Some groups of bacteria were also identified in the biofilm attached to the gravel. In each treatment periodic samplings were conducted in the influent and effluent. Chlorothalonil was quantified by gas chromatography (GC-ECD m), DOC by an organic carbon analyzer and bacterial groups using conventional microbiology in accordance with Standard Methods. The largest removals of DOC (85.82%-85.31%) were found when using fine gravel (3.18-6.35 mm) and the lower layer of water (20 cm). The bacterial groups quantified in the biofilm were total heterotrophic, revivable heterotrophic, Pseudomonas and total coliforms. The results of this study indicate that fine grain gravel (3.18-6.35 mm) and both water levels (20 to 40 cm) can be used in the removal of organic matter and for the treatment of agricultural effluents contaminated with organo-chloride pesticides like CLT in HSSFCW.

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.

Phylogeographic analyses and genetic structure illustrate the complex evolutionary history of Phragmites australis in Mexico.

PREMISE OF THE STUDY: Genetic data suggest that three lineages of Phragmites australis are found in North America: the Native North American lineage, the Gulf Coast lineage, and the Invasive lineage. In Mexico, P. australis is a common species, but nothing is known about the distribution or ecology of these lineages. We examined the phylogeography of P. australis to analyze the current geographic distribution of genetic variation, demographic history, and dispersal patterns to better understand its evolutionary history in Mexico. METHODS: We sampled 427 individuals from 28 populations. We used two noncoding regions of chloroplast DNA to estimate the levels of genetic variation and identified the genetic groups across the species' geographical range in Mexico. We compared the genealogical relationships among haplotypes with those previously reported. A hypothesis of demographic expansion was also tested for the Mexican P. australis lineages. KEY RESULTS: We found 13 new haplotypes native to Mexico that might be undergoing an active process of expansion and diversification. Genealogical analyses provided evidence that two independent lineages of P. australis are present in Mexico. The invasive lineage was not detected with our sampling. Our estimates of population expansions in Mexico ranged from 0.202 to 0.726 mya. CONCLUSIONS: Phragmites australis is a native species that has been in Mexico for thousands of years. Genetic data suggest that climatic changes during the Pleistocene played an important role in the demographic expansion of the populations that constitute the different genetic groups of P. australis in Mexico.

Effects of porous media, macrophyte type and hydraulic retention time on the removal of organic load and micropollutants in constructed wetlands.

The performance of horizontal subsurface flow constructed wetlands in the removal of micropollutants from a wastewater treatment plant effluent was evaluated at mesocosm level. Fifteen mesocosms were studied following a modified Latin Square experimental design with six additional points. Three variables at three levels were studied: porous media -PM- (river gravel, fine volcanic gravel and coarse volcanic gravel), macrophyte type -M- (Thypa latiffolia, Phragmites australis, and Cyperus papyrus) and hydraulic retention time -HRT- (1, 3 and 5 days). As response variables the removal percentages of the total organic load of the effluent (BOD5) and the loads of several micropollutants (caffeine, galaxolide, tonalide, alkylphenols and their monoethoxylates and diethoxylates, methyl dihydrojasmonate, sunscreen UV-15 and parsol) were used. The results showed that the systems remove between 70% and 75% of the organic load and that all the micropollutants were degraded at different extents, from 55% to 99%. The HRT was the variable that showed major effects on the treatment process, while M and PM showed no statistically significant differences in the used experimental conditions.