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Abstract Pilot-scale three-stage surface flow constructed wetlands (SFCWs) planted with Myriophyllum aquaticum were constructed to study the organics removal performance from lagoon-pretreated swine wastewater. The removal performance of organics in the SFCWs was evaluated using deterministic and probabilistic methods and the results were consistent. The SFCWs achieved a relatively high removal efficiency (79.0–82.7%) for a wide influent COD concentration range (456–1010 mg L−1). No significant difference (p > 0.05) of COD removal efficiency and first-order removal rate constant among the various strengths of influent suggested that the present loading rates (2.74–6.06 g m−2 d−1) have not yet reached the maximum removal capacity of the SFCWs. The mean emission fluxes of methane from the SFCW units fed with different strengths of wastewater were 25–1210 mg m−2 d−1. A significantly positive correlation (p < 0.01) between methane emission fluxes and COD loading rates indicated that the anaerobic digestion of organics was an important process for organics removal in the SFCWs. No significant organics accumulation in the sediment over time suggested that plant harvest could be in favor of reducing the organics accumulation in the substrate and should be considered important during management of constructed wetlands. Graphical abstract Image 1 Highlights • Pilot-scale three-stage CWs can remove organics from swine wastewater effectively. • Probabilistic approach was used to evaluate variability of organics removal. • Organics removal was little affected by influent loading rates and seasons. • Organics accumulation slowed down in the substrate under plant multiple harvesting. [ABSTRACT FROM AUTHOR]

Disturbance has been considered to exert positive, neutral or negative effects on the invasion of exotic plants. Disturbance may enhance the invasion success of alien invasive species by both increasing their performance and alleviating the harmful effects caused by disturbance via tolerance and resistance, especially in the late phases of the invasion process. However, the tolerance and resistance of invasive plant clonal populations to disturbance has been mostly neglected. In the present study, we explored the phenotypic responses of clonal populations of the invasive plant Alternanthera philoxeroides and three co-occurring non-invasive clonal species, i.e., Alternanthera sessilis , Myriophyllum aquaticum and Jussiaea repens , to different levels of fluctuating flood disturbances using a mesocosm experiment. Different functional traits related to morphology, biomass allocation and physiology were used to evaluate plant performance. We found that A. philoxeroides coped with fluctuating flooding by performing phenotypic maintenance that affected ramet number, stolon length, specific leaf area, leaf mass ratio, chlorophyll content, nitrogen content and non-structural carbohydrate content; additionally, the plant experienced variations in stolon diameter, stolon mass ratio, root mass allocation and maximum fluorescence. In addition, Alternanthera philoxeroides demonstrated several similarities with the three non-invasive species in terms of the observed phenotypic responses to different disturbance statuses. Furthermore, Alternanthera philoxeroides showed respective advantages in tolerance compared to A. sessilis , photosynthetic capacity compared to M. aquaticum and especially J. repens , and resistance to submergence compared to all three non-invasive species. Overall, tolerance and resistance facilitated the successful invasion of A. philoxeroides in disturbed habitats. Furthermore, the native constructive species J. repens was severely harmed by fluctuating flooding; thus, fluctuating flooding could create an empty niche that promotes the expansion of the clonal populations of A. philoxeroides . [ABSTRACT FROM AUTHOR]

A series of three-stage pilot-scale surface flow constructed wetlands (CWs) planted with Myriophyllum aquaticum were fed with three strengths of lagoon-pretreated swine wastewater to study nitrogen (N) removal and recovery under sustainable plant harvesting management. The CWs had mean removal efficiency of 87.7–97.9% for NH 4 + -N and 85.4–96.1% for total N (TN). The recovered TN mass via multiple harvests of M. aquaticum was greatest (120–222 g N m −2  yr −1 ) when TN concentrations were 21.8–282 mg L −1 . The harvested TN mass accounted for 0.85–100% of the total removal in the different CW units. Based on mass balance estimation, plant uptake, sediment storage, and microbial removal accounted for 13.0–55.0%, 4.9–8.0%, and 33.0–67.5% of TN loading mass, respectively. The results of this study confirm that M. aquaticum is appropriate for the removal and recovery of nutrients in CW systems designed for treating swine wastewater in conjunction with sustainable plant harvesting strategies. [ABSTRACT FROM AUTHOR]

Although constructed wetlands (CWs) are used as one relatively low-cost technology for livestock wastewater treatment, the improvement of phosphorus removal in CWs is urgently needed. In this study, a three-stage pilot-scale CW system consisting of three surface flow CWs (SFCWs; CW1, CW2, and CW3) in series from inlet to outlet was constructed to treat swine wastewater (SW) from a lagoon. The CWs were planted with Myriophyllum aquaticum . Considering different inlet loading rates, three strengths of swine wastewater (low: 33% SW, medium: 66% SW, and high: 100% SW) were fed to the CW system to determine total phosphorus (TP) removal efficiency and clarify the important role of plant harvest. Results from the period 2014–2016 indicate that the three-stage CW system had mean TP cumulative removal efficiencies and removal rates of 78.2–89.8% and 0.412–0.779 g m − 2 d − 1 respectively, under different inlet loading rates. The TP removal efficiency and removal rate constant had temporal variations, which depended on temperature condition and the annual growth pattern of M . aquaticum . The harvested phosphorus mass was 15.1–40.9 g m − 2 yr − 1 in the CWs except for CW1 with high strength SW, and contributed 22.5–59.6% of TP mass removal rate by the SFCWs. The TP removal was mainly by adsorption and precipitation in the substrate in CW1 but by uptake and multiple harvests of M . aquaticum in CW2 and CW3. The results suggest the three-stage CW system planted with M . aquaticum is suited for removing high TP concentrations from swine wastewater with a high removal efficiency. However, TP removal in high strength SW amounted to 70.1 ± 23.3%, and the outflow concentration of 17.0 ± 14.9 mg L − 1 was still high. Optimal loading rates for high strength SW still need to be investigated for the CW system presented here. [ABSTRACT FROM AUTHOR]

Octadecaoctaenal is a psittacofulvin pigment associated with the bright red coloration of parrots. It consists of a linear polyene chain terminated by an aldehyde group and therefore provides an opportunity to examine the fundamental factors controlling the excited state ordering and dynamics of polyenals. Steady-state and ultrafast time-resolved spectroscopy were performed on octadecaoctaenal and a derivative in which the aldehyde group was converted to a methylenehydroxyl group. It was found that for octadecaoctaenal, solvent proticity was more important than polarity in determining its excited state lifetime. Theoretical computations were carried out to reveal the origin of the effect. [ABSTRACT FROM AUTHOR]

To evaluate the Myriophyllum aquaticum and Potamogeton pusillus macrophytes as indicator organisms of heavy metal pollution in biomonitoring studies of the aquatic ecosystem, the aim of this study was to determine the Co, Cu, Fe, Mn, Ni, Pb and Zn accumulation in leaves of the those species and the possible relationship to water pollution by these metals. Surface water, sediment and plants were collected at 10 sampling sites of the Ctalamochita river (Argentina). Cooper and Pb concentrations exceeded the limits established for the protection of aquatic life defined by Argentina Legislation (Cu: 2.0 μgL − 1 , Pb: 2.0 μgL − 1 ) and international norms (Cu: 1.6 μgL − 1 , Pb: 2.5 μgL − 1 ) in surface water, while Cu and Zn exceeded the limit for ecological screening levels (Cu: 31.6 mgkg − 1 , Zn: 121.0 mgkg − 1 ) in sediment. Heavy metal concentrations were found to be higher downstream of Río Tercero city in water and sediments samples, probably related to the contribution of pollutants from the effluent discharge of the city. Both species revealed a high capacity to accumulate heavy metals in its tissues, in areas of the river with higher heavy metals values in the abiotic compartments. Particularly, high accumulation of Co, Cu, Ni and Zn in P. pusillus correlated with their concentrations in sediments and Co, Cu, Mn and Zn accumulation in M. aquaticum correlated with the concentrations of these metals in water. These macrophytes reflect spatial variations of metals in water and sediments of the Ctalamochita river; therefore they are of potential use as heavy metal bioindicators of river pollution. [ABSTRACT FROM AUTHOR]

A recent study shows that most aquatic alien plants in temperate cold climate are of tropical and subtropical origins and only those that can withstand cold climates become invasive. This suggests that a changing climate that becomes warmer may result in currently non-invasive alien plants becoming invasive in the future. To facilitate pre-emptive actions when controlling invasive aquatic plants in South Africa under climate change, we reconstructed predictive models for the five most damaging aquatic alien plants of freshwater systems in the country. We found evidence of contrasting shifts in species distribution ranges: the ranges of Myriophyllum aquaticum and Pistia stratiotes will contract, while Azolla filiculoides , Eichhornia crassipes , and Salvinia molesta will increase their future ranges with most suitable habitats found in the Western Cape province and along coastal areas. In addition, the predicted range contraction and expansion would result in some dams currently vulnerable to invasion becoming resilient while others that are currently resilient may become vulnerable due to climate change. These results can be used to develop future monitoring programs for aquatic ecosystems, prioritize control efforts, and raise public awareness on risks posed by these aquatic invasive plants, especially under future climate scenarios. [ABSTRACT FROM AUTHOR]

In order to study the accumulation of nickel, lead and zinc for their use in the phytoremediation of aquatic environments, the aquatic plants Myriophyllum aquaticum and Egeria densa were exposed to increase the concentrations of these metals (Ni: 0.05–10 mg L −1 , Pb: 0.05–15 mg L −1 , Zn: 0.15–20 mg L −1 ) for 7 days. The accumulation of Ni, Pb and Zn in plants was determined and their effects on physiological parameters (chlorophyll a concentration and degradation, lipid peroxidation measured as malondialdehyde) were evaluated in the leaves for both species. M. aquaticum showed a higher accumulation capacity of Pb and Zn than E. densa , particularly at the highest concentrations of exposure to these metals. Nevertheless, the physiological changes observed in these species, especially in M. aquaticum , at high metal concentrations and accumulations, did not represent a risk in relation to their survival during the study period. Therefore, taking into account their accumulation capacity and tolerance to heavy metals, M. aquaticum is more suitable for phytoremediation in aquatic environmental contaminated with Ni, Pb or Zn than E. densa . [ABSTRACT FROM AUTHOR]

Highlights: [•] We studied the impact of light, temperature and carbon on growth of submerged Myriophyllum aquaticum. [•] CO2 acts as the major trigger for plant growth, rather than light and temperature. [•] M. aquaticum responded to changes in CO2 with both morphological and physiological acclimations. [ABSTRACT FROM AUTHOR]

Abstract: The success of invasive species is due to their ability to displace other species by direct competition. Our hypothesis is that the strategy of the invasive L. grandiflora differs according to the growth form of this plant (submerged/emergent) and to its density, and the presence and the density of neighbouring species, during the first step of introduction phase. Moreover, we also suppose that the invasive species L. grandiflora affects the European native aquatic macrophyte and that invasive species can facilitate the establishment, growth and spread of exotic species coming from the same biogeographical area (the “Invasional Meltdown Hypothesis”). We studied the relationships between three exotic species coming from South America (Ludwigia grandiflora, Egeria densa and Myriophyllum aquaticum) and two European macrophyte species (Ceratophyllum demersum, Mentha aquatica) in monocultures and in mixed cultures. The experiments were carried out in containers placed in a greenhouse for one month in spring 2011. We measured six morphological traits to test the intraspecific and interspecific interferences. In accordance with our hypothesis, the strategy of L. grandiflora differed between its emergent growth form and its submerged growth form, whereas the establishment and the growth of L. grandiflora did not seem to be facilitated by other exotic species (i.e. E. densa and M. aquaticum). The interspecific effect between C. demersum or E. densa on submerged L. grandiflora was stronger in inhibiting plant growth than the intraspecific interferences of L. grandiflora on itself. Mutual inhibition of root production and growth was observed between L. grandiflora and M. aquatica. However, L. grandiflora seemed to have little impact on native species, which may coexist with L. grandiflora during the early stages of L. grandiflora establishment in the introduction area. L. grandiflora stimulated the growth and the vegetative reproduction of E. densa. L. grandiflora facilitated the establishment of E.densa in accordance with the “Invasional Meltdown Hypothesis”. L. grandiflora stimulated the root production and the growth of M. aquaticum at low densities and inhibited it at high densities. L. grandiflora, the first introduced plant in France, could slightly facilitate the growth of E. densa. However, spatial heterogeneity or differential use of resources could explain the coexistence of L. grandiflora and M. aquaticum in the same environment. [Copyright &y& Elsevier]

Abstract: The aim of the present study was to assess the temporal variation of the heavy metal content (Co, Cu, Fe, Mn, Ni, Pb, and Zn) in surface water and sediments in relation to agricultural practices in the Xanaes River (Córdoba, Argentina). A second objective was to analyze possible relationships between the input of heavy metals on surface water and sediment, heavy metal accumulation and physiological changes in the aquatic plant Myriophyllum aquaticum. Samples were taken from the river at two contrasting sites (between April 2010 and August 2010): (1) a pristine area (mountain site), and (2) an area with intensive agricultural activity located at 60km down river (agricultural site). The total concentration of heavy metals in surface water was higher in samples collected at the agricultural site but in sediments only the Mn concentration was higher than at the mountain site. The Fe and Mn concentrations in surface water at the agricultural site exceeded the recommended values for Argentinean Legislation of 300μgL−1 for Fe and 100μgL−1 for Mn. The accumulations of Zn and Mn in M. aquaticum were higher at the agricultural site and more elevated than the Zn and Mn concentrations in sediments at the same sites and sampling times. At the agricultural site, temporal variations of Cu, Fe and Zn were relatively similar for plants and water column, but the levels of the metals in plants were displaced over time. These results suggest that the levels of pollutants in the river came in pulses from the riverbank. These results show the potential use of M. aquaticum as a suitable accumulation biomonitor at the early stages of heavy metal pollution in rivers. [Copyright &y& Elsevier]

Abstract: Seasonal biomass and starch allocation patterns were determined from natural populations of Myriophyllum aquaticum that were sampled monthly from January 2006 to December 2007 in Mississippi. Water temperature, water depth, light irradiance, light transmittance, pH, and conductivity were also recorded during biomass harvests. Overall, few significant relationships were observed between the environmental factors tested and seasonal biomass. Submersed shoot biomass was negatively related (p <0.01) with water temperature. Stolons accounted for 40–95% of total biomass followed by emergent shoot, submersed shoot, and root biomass. Percent starch in plant tissues was positively related to water temperature. Starch allocation was greatest in stolons where up to 16.3% of total starch was stored. Submersed shoots stored 0.6–11.0% of total starch followed by emergent shoots (0.4–7%). The roots of M. aquaticum stored less than 3.8% of total starch throughout the study period. Reduced biomass and starch storage occurred from October to March in both 2006 and 2007. Management strategies for this species could utilize an integrated approach to exploit times of low energy reserves (fall and winter), or to remove emergent shoots to gain access to the stolons and other submersed tissues. [Copyright &y& Elsevier]

Crude plant extract solutions (spinach and parrotfeather) were prepared and spiked with 2,4,6-trinitrotoluene (TNT) (20 mg l−1). 90-h TNT removal by these solutions was compared to controls. Spinach and parrotfeather extract solutions removed 99% and 50% of the initial TNT, respectively; TNT was not eliminated in the controls or in extract solutions where removal activity was deactivated by boiling. A first-order removal constant of 0.052 h−1 was estimated for spinach extract solutions treating 20 mg l−1 TNT concentrations, which compared favorably to intact plant removal. Concentration variation was described by Michaelis–Menton kinetics. Detectable TNT degradation products represented only a fraction of the total TNT transformed, and the transformation favored the formation of 4-aminodinitrotoluene. The results indicated that crude plant extracts transform TNT, without the presence of the live plant. [Copyright &y& Elsevier]