Search Results (7)

This study aims to select the most suitable submerged plants for the remediation and ecological rehabilitation of nutrient-enriched aquatic environments. The experiment selected Vallisneria natans, Myriophyllum verticillatum, and Elodea nuttallii as research objects. An artificial outdoor pot experiment was conducted with six different levels of ammonia nitrogen: 2, 4, 6, 8, 12, and 16 mg/L. The present study measured the physiological and growth parameters of submerged macrophytes under varying ammonia nitrogen concentrations. The response characteristics of plants to ammonia nitrogen stress were analyzed, and the tolerance thresholds of different submerged macrophyte species to ammonia nitrogen were determined. This enabled us to screen for ammonia nitrogen-tolerant pioneer species suitable for water ecological restoration in eutrophic water bodies. The experiment spanned 28 days. The results showed that the maximum suitable concentration and maximum tolerance concentration of ammonia nitrogen for Vallisneria natans, Myriophyllum verticillatum, and Elodea nuttallii were 2, 4, and 4 mg/L and 4, 12, and 8 mg/L. Submerged plants can grow normally within their maximum ammonia nitrogen tolerance concentration. When the concentration exceeds the maximum tolerance level, the growth of submerged plants is severely stressed by ammonia nitrogen. Low ammonia nitrogen concentrations promote the growth of submerged macrophyte biomass and chlorophyll content as well as the accumulation of dry matter in plants, while high ammonia nitrogen concentrations damage the antioxidant enzyme system and inhibit the growth of submerged plants. The tolerance of the three submerged macrophytes to ammonia nitrogen is as follows: Myriophyllum verticillatum > Elodea nuttallii > Vallisneria natans. Therefore, Myriophyllum verticillatum should be chosen as the ammonia nitrogen-tolerant pioneer species in the ecological restoration of eutrophic water bodies. The research results can provide a theoretical basis for the application of aquatic macrophytes in the treatment of eutrophic water bodies and ecological restoration. Full article

Transition metals and their oxide compounds exhibit excellent chemical reactivity; however, their easy agglomeration and high cost limit their catalysis applications. In this study, an interpolation structure of a Myriophyllum verticillatum L. biochar-supported Mn/Mg composite (Mn/Mg@MV) was prepared to degrade triphenyl phosphate (TPhP) from wastewater through the activating periodate (PI) process. Interestingly, the Mn/Mg@MV composite showed strong radical self-producing capacities. The Mn/Mg@MV system degraded 93.34% TPhP (pH 5, 10 μM) within 150 min. The experimental results confirmed that the predominant role of IO3· and the auxiliary ·OH jointly contributed to the TPhP degradation. In addition, the TPhP pollutants were degraded to various intermediates and subsequent Mg mineral phase mineralization via mechanisms like interfacial processes and radical oxidation. DFT theoretical calculations further indicated that the synergy between Mn and Mg induced the charge transfer of the carbon-based surface, leading to the formation of an ·OH radical-enriched surface and enhancing the multivariate interface process of ·OH, IO₃, and Mn(VII) to TPhP degradation, resulting in the further formation of Mg PO₄ mineralization. Full article

Reclaimed water produced via the advanced treatment of domestic wastewater has broad application prospects for reuse in urban rivers, while the nutrients in reclaimed water, especially nitrogen and phosphorus, lead to eutrophication or ecological impacts. Submerged plants are preferred as an enhanced technology used at reclaimed water recharge sites for both water quality improvement purposes and ecological conservation functions. In this study, which adopted the typical submerged plant Myriophyllum verticillatum (M. verticillatum) as its experimental object, experiments were carried out in an illumination incubator without a substrate and under hydrostatic conditions to investigate the water purification effects and mechanisms of action of M. verticillatum at different planting densities. The analysis showed that the group with a wet weight of 2.5 g L⁻¹ had the best growth status and the best overall performance with respect to improvements in water quality indicators, including COD, nitrogen, and phosphorus, as well as demonstrating excellent uptake and synergistic effects in the process of removing nitrogen and phosphorus. The contributions of natural effects, the uptake and enrichment by M. verticillatum itself, and the synergistic effects during the nitrogen and phosphorus removal process were quantified. Furthermore, 16S rRNA gene sequencing was used to determine the surface-attached bacterial colonies of M. verticillatum, to analyze their population diversity, and to identify environmental functional genera. In conclusion, an appropriate density of M. verticillatum can improve water quality and provide a suitable environment for the survival and growth of relevant environmentally functional microorganisms, effectively removing nitrogen and phosphorus through its own absorption and synergistic effects. Full article

The contribution discusses macrophyte communities in natural and man-made waterbodies located on the active floodplain along the Drava river (Slovenia). We presumed that these different types of wetlands host a great number of macrophyte species, but this diversity may be affected by the presence of alien invasive species Elodea canadensis and E. nuttallii. Presence, relative abundance, and growth forms of plant species along with selected environmental parameters were monitored. Correlation analyses and direct gradient analyses were performed to reveal the possible relations between the structure of macrophyte community and environmental parameters. Number of macrophytes in surveyed water bodies varied from 1 to 23. Besides numerous native species we also recorded Elodea canadensis and E. nuttallii, which were present in 19 out of 32 sample sites, with E. nuttallii prevailing. The less invasive E. canadensis was absent from ponds and oxbow lakes but relatively abundant in side-channels, while E. nuttallii was present in all types but dominant in ponds. The most abundant native species were Myriophyllum spicatum and M. verticillatum, Ceratophyllum demersum and Potamogeton natans. Correlation analyses showed no negative effect of the invasive alien Elodea species to the species richness and diversity of native flora. Positive correlation between the abundance of E. nuttallii and temperature of the water was obtained. Full article

Combined use of in situ passivation and macrophytes is a valuable technology that exerts remarkable effects on aquatic systems. However, the effectiveness and ecological functions of this combined technology for macrophytes-dominated eutrophic (MDE) lakes with organophosphorus-controlled internal phosphorus (P) loading were poorly understood. In this study, aquatic simulation experiments were performed to study the combination of La-modified materials (LMM; La-modified bentonite (LMB), and La/Al co-modified attapulgite (LAA)) with macrophytes (Myriophyllum verticillatum L. (MVL), Hydrilla verticillata (Linn. f.) royle (HVR), and Ceratophyllum demersum L. (CDL)) for the control of P mobility in the water column, and to investigate the passivator effects on the physiological characteristics of macrophytes. The mineralization of organophosphates (BD−Po, HCl−Po, and Res−Po) is an important factor for maintaining high internal P loadings and overlying water P concentrations in the experiments. Compared with individual treatment groups, the reduction of internal P release flux and porewater SRP concentrations was more obvious in the combined treatments. Moreover, the redox-sensitive P forms transformation is more pronounced in the surface sediments. In the LAA+M group, internal P release flux was reduced by 55% and 55% compared with individual passivators and macrophytes retreatment groups, respectively. In contrast, the LMB+M group decreased by 16% and 46%, respectively. Simultaneously, LMM had less effect on macrophytes traits compared with individual macrophytes group and enhanced the absorption of phosphate by macrophytes. The phosphate content of macrophytes in the LAA+M and LMB+M groups increased by 24% and 11%, respectively, in comparison with the individual macrophytes group. Results concluded that the combination of passivator and macrophytes enhanced the effect of ecological restoration and exerts a synergistic effect on internal P pollution with macrophytes. Full article

The road runoff after rainfall carries a lot of pollutants that could cause great harm to the water environment. A biochemical pool can be used as a treatment for the road runoff. In order to further improve the efficiency of road runoff treatment by biochemical pool and to evaluate the purification effect of the aquatic plants, two aquatic plants of Iris pseudacorus and Myriophyllum verticillatum were chosen in this research. The effect of different planting densities on the treatment of runoff pollutants and the planting mode by different aquatic plants were studied. The results show that both plants have the ability to remove the pollutants like chemical oxygen demand (COD), Zn, Cu, oil, and suspended solids (SS), and the ability is increased with the increase of planting density. The Iris pseudacorus is better than Myriophyllum verticillatum on the removal of Zn, while Myriophyllum verticillatum does better on the removal of Cu, oil, and SS. Combined planting mode can effectively improve the purification effect of COD and petroleum. Full article

We examined the food preference of Chinese mitten crabs, Eriocheir sinensis (H. Milne Edwards, 1853), under food shortage, habitat choice in the presence of predators, and cannibalistic behavior by comparing their response to the popular culture plant Elodea nuttallii and the structurally more complex Myriophyllum verticillatum L. in a series of mesocosm experiments. Mitten crabs were found to consume and thus reduce the biomass of Elodea, whereas no negative impact on Myriophyllum biomass was recorded. In the absence of adult crabs, juveniles preferred to settle in Elodea habitats (appearance frequency among the plants: 64.2 ± 5.9%) but selected for Myriophyllum instead when adult crabs were present (appearance frequency among the plants: 59.5 ± 4.9%). The mortality rate of mitten crabs in the absence of plant shelter was higher under food shortage, primarily due to cannibalism. The proportion of molting crabs dying in the structurally more complex Myriophyllum habitats was significantly lower than in the less complex Elodea habitats, indicating that Myriophyllum provides better protection from cannibalistic behavior, likely due to its structurally more complex canopy. Stable isotope analyses of crab samples revealed a trophic shift in both δ¹³C and δ¹⁵N (Δδ¹³C: 2.2–4.0‰; Δδ¹⁵N: 1.5–2.8‰) during the experimental period. Significant positive correlations between body mass and δ¹³C and δ¹⁵N were recorded, suggesting that cannibalistic feeding might further increase crab growth and lead to ontogenetic increases in trophic position with increasing size. Our study overall demonstrates that a combination of submerged aquatic vegetation functioning as a highly suitable food with other less palatable plant species acting as efficient refuges against predators may be the optimal method of plant stocking in mitten crab aquacultures to ensure both high crab growth and a high survival rate. Full article