Fen plant growth in peat contaminated with groundwater discharges of oil sands process water (OSPW) was assessed in a greenhouse over two growing seasons. Three treatments (non-diluted OSPW, diluted OSPW and rainwater) were tested on five vascular plants and four mosses. All vascular plants tested can grow in salinity and naphthenic acids levels currently produced by oil sands activity in northwestern Canada. No stress sign was observed after both seasons. Because of plant characteristics, Carex species (C. atherodes and C. utriculata) and Triglochin maritima would be more useful for rapidly restoring vegetation and creating a new peat-accumulating system. Groundwater discharge of OSPW proved detrimental to mosses under dry conditions and ensuring adequate water levels would be crucial in fen creation following oil sands exploitation. Campylium stellatum would be the best choice to grow in contaminated areas and Bryum pseudotriquetrum might be interesting as it has spontaneously regenerated in all treatments.

Nitrogen (N) deposition may alter physiological process of plants in grassland ecosystem. However, little is known about the response mechanism of individual plants in alpine regions to N deposition. We conducted a field experiment, and three treatments including 0 kg Nha⁻¹year⁻¹ (CK), 8 kgNha⁻¹year⁻¹ (Low N), and 72 kg N ha⁻¹ year⁻¹ (High N) were established to simulate N deposition in alpine meadow of Qinghai-Tibetan plateau. Our objectives were to determine the influence of N deposition on photosynthesis of different functional types of herbage species in alpine meadow, and finally characterize the links of plant productivity and photosynthesis with soil nutrients. The results showed that responses of alpine plants were species-specific under N deposition. Compared with grass species Agropyron cristatum and forb species Thalictrum aquilegifolium, the sedge species Carex melanantha was much more sensitive to N deposition; a lower N load (8 kgNha⁻¹year⁻¹) can cause a negative effect on its photosynthesis and productivity. Additionally, N deposition can promote plant N uptake and significantly decreased the C (carbon)/N (nitrogen) ratio. Compared with CK and low N deposition, high N deposition inhibited the photosynthesis and growth of the forb species Thalictrum aquilegifolium and sedge species Carex melanantha. In all three functional types of herbage species, the grass species A. cristatum tended to show a much higher photosynthetic capacity and better growth potential; thus, suggesting that grass species A. cristatum will be a more adaptative alpine plants under N deposition. Our findings suggested that plant photosynthetic responses to N deposition were species-specific, low N deposition was not beneficial for all the herbage species, and N deposition may change plant composition by the differential photosynthetic responses among species in alpine grassland. Plant composition shift to grass-dorminant in alpine regions might be attributed to a much higher photosynthetic potential and N use efficiency of grass species.

Ozone and atmospheric nitrogen are co-occurring pollutants with adverse effects on natural grassland vegetation. Plants of the rhizomatous sedge Carex arenaria were exposed to four ozone regimes representing increasing background concentrations (background-peak): 10–30, 35–55, 60–80 and 85–105 ppb ozone at two nitrogen levels: 12 and 100 kg N ha−1 yr−1. Ozone increased the number and proportion of senesced leaves, but not overall leaf number. There was a clear nitrogen × ozone interaction with high nitrogen reducing proportional senescence in each treatment and increasing the ozone dose (AOT40) at which enhanced senescence occurred. Ozone reduced total biomass due to significant effects on root biomass. There were no interactive effects on shoot:root ratio. Rhizome tissue N content was increased by both nitrogen and ozone. Results suggest that nitrogen mediates above-ground impacts of ozone but not impacts on below-ground resource translocation. This may lead to complex interactive effects between the two pollutants on natural vegetation. Nitrogen alters threshold of ozone-induced senescence, but not below-ground resource allocation.

Dissolved organic carbon (DOC) plays diverse roles in carbon biogeochemical cycles. Here, we explored the link between DOC and pCO2 using high-performance size-exclusion chromatography (HPSEC) with UV254 detection and excitation emission matrix (EEM) fluorescence spectroscopy to determine the molecular weight distribution (MW) and the spectral characteristics of DOC, respectively. The relationship between DOC and pCO2 was investigated in the Poyang Lake wetlands and their adjacent aquatic systems. The results indicated significant spatial variation in the DOC concentrations, MW distributions, and pCO2. The DOC concentration was higher in the wetlands than in the rivers and lakes. pCO2 was high in wetlands in which the dominant vegetation was Phragmites australis, whereas it was low in wetlands in which Carex tristachya was the dominant species. DOC was divided into five fractions according to MW, as follows: super-low MW (SLMW, <1 kDa); low MW (LMW, 1–2.5 kDa); intermediate MW (IMW, 2.5–3.5 kDa); high MW (HMW, 3.5–6 kDa); and super-high MW (SMW, > 40 kDa). Rivers contained high proportions of HMW and extremely low amounts of SLMW, whereas wetlands had relatively high proportions of SLMW. The proportion of SMW (SMWp) was particularly high in wetlands. We found that pCO2 significantly positively correlated with the proportion of IMW, and significantly negatively correlated with SMWp. These data improve our understanding of the MW of bioavailable DOC and its conversion to CO2. The present results demonstrate that both the content and characteristics of DOC significantly affect pCO2. pCO2 and DOC must be studied further to help understanding the role of the wetland on the regional CO2 budget.

To understand spatial and temporal variations of nitrous oxide (N₂O) fluxes, we chose to measure N₂O emissions from three plant stands (Kobresia tibetica, Carex muliensis, and Eleocharis valleculosa stands) in an open fen on the northeastern Qinghai–Tibetan plateau during the growing seasons from 2005 to 2007. The overall mean N₂O emission rate was about 0.018 ± 0.056 mg N m⁻² h⁻¹ during the growing seasons from 2005 to 2007, with highly spatiotemporal variations. The hummock (K. tibetica stand) emitted N₂O at the highest rate about 0.025 ± 0.051 mg N m⁻² h⁻¹, followed by the hollow stands: the E. valleculosa stand about 0.012 ± 0.046 mg N m⁻² h⁻¹ and the C. muliensis stand about 0.017 ± 0.068 mg N m⁻² h⁻¹. Within each stand, we also noted significant variations of N₂O emission. We also observed the significant seasonal and inter-annual variation of N₂O fluxes during the study period. The highest N₂O emission rate was all recorded in July or August in each year from 2005 to 2007. Compared with the mean value of 2005, we found the drought of 2006 significantly increased N₂O emissions by 104 times in the E. valleculosa stand, 45 times in K. tibetica stand, and 18 times in the C. muliensis stand. Though there was no significant relation between standing water depths and N₂O emissions, we still considered it related to the spatiotemporal dynamics of soil water regime under climate change.

Currently, the use of nanotechnologies is in rapid expansion, which entails increasing risks of environmental contamination by nanoparticles. Many studies describe the toxic effects on human cells, but little is known about the possible adverse effects on plants. Currently, various nanoparticles are often detected in streams, wastewater, and sewage due to widespread nanoparticle uses. We studied the accumulation and the effect of metal oxide nanoparticles together with their bulk counter particles and soluble metal salts on the growth of a wetland plant species true fox-sedge (Carex vulpina L.). The concentration 100 mg/l of copper nanoparticles significantly affected the growth of the plants, roots characteristics, and content of the photosynthetic pigments in leaves, while the same concentration of iron nanoparticles did not reduced any of the measured items. Using the bulk materials, the effect was very similar.

In this study, we aimed at determining greenhouse gas (GHG) (CO₂, CH₄, and N₂O) fluxes exchange between the soil collected from sites dominated by different vegetation types (Calamagrostis epigeios, Phragmites australis, and Carex schnimdtii) in nitrogenous loaded riparian wetland and the atmosphere. The intact soil columns collected from the wetland were incubated in laboratory and continuously treated with [Formula: see text]-enriched water simulating downward surface water percolating through the soil to become groundwater in a natural system. This study revealed that the soil collected from the site dominated by C. epigeios was net CO₂ and N₂O sources, whereas the soil from P. australis and C. schnimdtii were net sinks of CO₂ and N₂O, respectively. The soil from the site dominated by C. schnimdtii had the highest climate impact, as it had the highest global warming potential (GWP) compared with the other sites. Our study indicates that total organic carbon and [Formula: see text] concentration in the soil water has great influence on GHG fluxes. Carbon dioxide (CO₂) and N₂O fluxes were accelerated by the availability of higher [Formula: see text] concentration in soil water. On the other hand, higher [Formula: see text] concentration in soil water favors CH₄ oxidation, hence the low CH₄ production. Temporally, CO₂ fluxes were relatively higher in the first 15 days and reduced gradually likely due to a decline in organic carbon. The finding of this study implies that higher [Formula: see text] concentration in wetland soil, caused by human activities, could increase N₂O and CO₂ emissions from the soil. This therefore stresses the importance of controls of [Formula: see text] leaching in the mitigation of anthropogenic N₂O and CO₂ emissions.

Carwashes are highly water-consuming processes that require wastewater treatment before discharge into a sewer system due to the complex composition of leachate. Anionic surfactants (AS) are the main constituents of this wastewater because of their cleaning and solubilization properties; they can be potentially dangerous for the environment if not adequately treated. Constructed wetlands (CWs) are low-cost systems increasingly used to treat different types of wastewater; however, there are few studies on their use for the treatment of carwash wastewater. In this study, an innovative constructed wetland arranged in a “cascade” to simulate a wall system (WCCW) was experimented in 2010 and 2011 to treat AS. Three plant species were tested at different AS inlet concentrations (10, 50, and 100 mg L⁻¹) with two hydraulic retention times (HRTs; 3 and 6 days): ribbon grass (Typhoides arundinacea (L.) Moench (syn. Phalaris arundinacea L.) var. picta; Ta), water mint (Mentha aquatica L.; Ma), and divided sedge (Carex divisa Hudson; Cd). All plant species grew constantly over the experimental period, showing a capacity to tolerate even the highest AS concentration. Using the HRT of 6 days, raising the inlet concentration increased the AS outlet concentration, with similar values for the treatments (median values of 0.13–0.15, 0.47–0.78, and 1.19–1.46 mg L⁻¹ at inlet concentrations in the order 10, 50, and 100 mg L⁻¹). The shorter HRT led to significant differences among treatments in the reduction of outlet concentration, the best result being given by the tanks vegetated with Ma (A = 97.7 % with outlet concentration 0.35 mg L⁻¹). After treatments of the WCCW, the AS content was reduced almost completely, with removal in the ranges 0.07–10.2 g m⁻² day⁻¹ for tanks planted with Ta, 0.10–9.1 g m⁻² day⁻¹ for Ma tanks, and 0.11–9.5 g m⁻² day⁻¹ for Cd tanks depending on the inlet concentration.

Colony formation in Microcystis aeruginosa played important roles in blooms formation. To study the effects of plant allelopathy on colony formation in M. aruginosa, unicellular M. aeruginosa was cultivated under laboratory conditions treated with various extract concentration of Carex cinerascens. The growth of M. aeruginosa in the treatments with 0.05 and 0.1 mg L⁻¹ extract of C. cinerascens was promoted but the growth in the treatments with 1.5, 3.0, and 6.0 mg L⁻¹ C. cinerascens extract was inhibited. Obvious colony formation in M. aeruginosa was observed in all treatments while no colony formation was detected in the control. The cell number per colony at the first day was the largest and decreased along with culture time. The cell number per colony in the control ranged from 3.0 to 4.0 during the experiment. However, the values in the five treatments at the first day were 33, 80, 58, 41, and 30, respectively. A positive exponential relationship between cell number per colony of M. aeruginosa and extracellular polysaccharides (EPS) content was found as well. Compared the fold-increase in cell number per colony and the fold-increase in total biomass of M. aeruginosa at various day, it was found that colony formation induced by extract of C. cinerascens was primarily dependent on promotion of cell adhesion during the first 2 days. The cell number per colony decreased afterward was due to the increasing proportion of single cells in the culture because single cells had a great higher growth rate than M. aeruginosa colonies under culture condition. Our results suggested that plant allelopathy be one of the major factor contributing to colony formation in M. aeruginosa.

Pig manure is a complex mixture with excessive nutrients such as ammonium, microbial pathogens and may contain contaminants such as antibiotics. Conventional pig manure management practices caused water contamination. Sludge treatment wetland has been evaluated to determine its potential use under Mediterranean climate aiming at a parsimonious use of water and preventing water contamination, two major steps to preserve water resources in the Mediterranean Basin. Preliminary NH₄-N degradation was tested using aeration process and/or addition of commercial bacterial products. Aeration alone appeared to be sufficient to ensure nitrogen transformation of the pig manure at lab small-scale (10 L) and medium-scale (300 L). Selected plant species e.g., Carex hispida for use in the integrated constructed wetland tolerated the nitrogen content after aeration enabling their use in a treatment vertical bed.