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In the present study we investigated whether subsurface flow constructed wetlands (SSF-CWs) can remove nitrogen from saline waste water and whether salinity affects nitrogen removal during the cold season (mean water temperature<10°C). Eight Iris pseudacorus-planted SSF-CWs were fed with normal (salinity 1.3-1.5%; CWP) or saline (salinity 6.3-6.5%; CWP+) waste water; similarly, eight unplanted SSF-CWs were fed with normal (CWU) or saline waste water (CWU+). The systems were run continuously at a hydraulic loading rate of 187.5 mm day-1 and a hydraulic retention time of 4 days. Nitrogen removal efficiency, plant parameters and bacterial abundance and community composition were measured. In CWP, 80% of NH4 + -N and 52% of total nitrogen (TN) were removed. In contrast, the removal rates of NH4 + -N and TN in CWP+ were reduced by 27 and 37% respectively. In the presence of higher salinity, not only were there decreases in plant biomass (32.1%) and nitrogen uptake (50.1%), but the growth, activity and oxygen release of roots were also reduced (by 37.8, 68.0 and 62.9% respectively). Bacterial community composition also differed under conditions of elevated salinity. Elevated salinity is associated with lower nitrogen removal in SSF-CWs, which we speculate is a result of suppressed wetland macrophyte growth and activity, as well as changes in microbial community composition. [ABSTRACT FROM AUTHOR]

Although embankment reclamation is a recurring activity in the coastal wetlands of China, the effect of embankment construction on plant growth has attracted little attention. Leaf carbon, nitrogen and phosphorus stoichiometry (C-N-P stoichiometry) of a plant can be used to reflect plant adaptation to new environments created by reclamation. In the present study we investigated the biomass and leaf C-N-P stoichiometry of Spartina alterniflora Loisel., soil C-N-P stoichiometry and soil moisture, salinity, bulk density and pH in both embankment-reclaimed and natural S. alterniflora salt marshes in eastern China. Plant biomass, leaf P content, soil salinity and soil moisture were significantly lower in the reclaimed compared with natural marsh. The decrease in leaf P content is possibly attributed to changes in soil salinity, soil moisture and soil organic C and N content in the reclaimed marsh. The results of the present study indicate that the decreased aboveground biomass in the reclaimed marsh is likely to be correlated with an increase in the leaf N: P ratio, in accordance with the 'growth rate hypothesis'. However, previously published threshold values of the N: P ratio as indicators of N or P limitation of plant growth may not be applicable to S. alterniflora at our study site. [ABSTRACT FROM AUTHOR]

The decline of submerged plants resulting from low light and high ammonia nitrogen (ammonia-N) has become a serious problem worldwide. In the present study, three levels of ammonia-N concentrations (0, 3 and 6 mg L-1) and four levels of light intensity (control, 15, 2.5 and 0.75% underwater light) were designed to investigate the combined effects of low light and high ammonia-N stress on the submerged plant Vallisneria natans. The effects of low light and ammonia-N were examined by measuring the relative growth rate (RGR), chlorophyll content and superoxide dismutase (SOD) and peroxidase (POD) activity in response to the stressors. The decline in RGR and increase in SOD and POD activity in high ammonia-N water were more significant than under low light conditions, indicating that the stress imposed on submerged plants due to ammonia-N enrichment is stronger. Moreover, the combination of ammonia-N enrichment and low light had a greater effect on submerged plants. This study indicates that V. natans were tolerant to ammonia-N concentrations <6 mg L-1. Moreover, low light intensity (0.75% underwater light) amplified the toxic effects of ammonia-N, reducing ammonia-N tolerance from <6 to <3 mg L-1. [ABSTRACT FROM AUTHOR]

An understanding of trace metal pollution due to reclamation activities around Yancheng National Nature Reserve is important for the utilisation and management of the reserve and surrounding coastal and marine areas. In the present study, we evaluated the current state of Cu, Cd, Pb and Zn pollution (total concentrations and ecological risk), their potential hazard (availability index and desorption rate) and soil properties (cation exchange capacity, iron and manganese oxide content, soil organic matter, salinity and pH) in different land use types around this nature reserve. Although the current state of trace metal pollution was not severe, the potential hazards of these trace metals should not be ignored, especially for Cd because of its significantly higher availability index values in farmlands and aquaculture ponds than in natural habitats (by 33 and 32% of the total amount of Cd respectively). Thus, strict monitoring and environmentally responsible land reclamation management practices should be considered for these coastal areas. [ABSTRACT FROM AUTHOR]

Constructed floating wetlands (CFWs) are used to treat waste waters of various origins either alone or as part of waste water treatment trains. The aim of the present study was to determine the extent of nitrogen removal by CFWs planted with Oenanthe javanica (Blume) DC. at low temperatures (<10°C) and whether CFWs with vesuvianite as a substrate perform better than those without substrate. A batch model was used, with CFWs planted with O. javanica (Tc), CFWs without O. javanica (Ts), CFWs without substrate (Tp) and floating mats only (To) as a control. The average removal rates of NH4 + -N, NO3 - -N and total nitrogen were 78.3, 44.4 and 49.7% respectively in Tc; 72.0, 40.0 and 39.5% respectively in Ts; and 73.1, 33.7 and 44.0% respectively in Tp. In addition to a gradual increase in chemical oxygen demand during the experimental period, Tc had higher microbial richness and diversity, as well as a higher abundance of bacteria, archaea, anaerobic ammonium oxidation (Anammox) bacteria and key genes (ammonia mono-oxygenase, amoA, nitrous oxide reductase, nosZ, dissimilatory cd1-containing nitrite reductase, nirS, and dissimilatory copper-containing nitrite reductase, nirK) involved in nitrogen metabolism in the substrate than Ts. Further analysis of microbial community composition revealed a difference at multiple taxonomic levels among different systems. These results demonstrate the positive roles of O. javanica and vesuvianite in CFWs in nitrogen removal from waste water during the cold season (mean water temperature <10°C). [ABSTRACT FROM AUTHOR]

Juniperus sabina L. is an evergreen coniferous shrub, with a widespread distribution in Asia and Europe. It is one of the key species for restoration of the ecosystem in desertification areas. In the present study, we isolated and characterized eight microsatellite loci of this species. The number of alleles per locus ranged from two to 27, with observed heterozygosity values ranging from 0.256 to 0.744 and expected heterozygosity from 0.276 to 0.939. The markers developed in this study could be useful for population genetics studies of J. sabina. [ABSTRACT FROM AUTHOR]

Background. The decline of submerged plant populations due to high heavy metal (e.g., Cu) levels in sediments and ammonia nitrogen (ammonia-N) accumulation in the freshwater column has become a significant global problem. Previous studies have evaluated the effect of ammonia-N on submerged macrophytes, but few have focused on the influence of sediment Cu on submerged macrophytes and their combined effects. Methods. In this paper, we selected three levels of ammonia-N (0, 3, and 6 mg L(-1)) and sediment Cu (25.75 ± 6.02 as the control, 125.75 ± 6.02, and 225.75 ± 6.02 mg kg(-1)), to investigate the influence of sediment Cu and ammonia-N on submerged Vallisneria natans. We measured the relative growth rate (RGR), above- and below- ground biomass, chlorophyll, non-protein thiol (NP-SH), and free proline. Results and Discussion. The below-ground biomass of V. natans decreased with increasing Cu sediment levels, suggesting that excessive sediment Cu can result in significant damage to the root of V. natans. Similarly, the above-ground biomass significantly decreased with increasing ammonia-N concentrations, indicating that excessive water ammonia-N can cause significant toxicity to the leaf of V. natans. In addition, high ammonia-N levels place a greater stress on submerged plants than sediment Cu, which is indicated by the decline of RGR and chlorophyll, and the increase of (NP-SH) and free proline. Furthermore, high sediment Cu causes ammonia-N to impose greater injury on submerged plants, and higher sediment Cu levels (Cu ≥ 125.75 mg kg(-1)) led to the tolerant values of ammonia-N for V. natans decreasing from 6 to 3 mg L(-1). This study suggests that high sediment Cu restricts the growth of plants and intensifies ammonia-N damage to V. natans.