No abstract

Acid Mine Drainage (AMD) has become an important issue due to its significant ecological pollution. In this paper, phytoremediation technology and mechanism for AMD were investigated by hydroponic experiments, using six wetland plants (Phragmites australis, Typha orientalis, Cyperus glomeratus, Scirpus validus, Iris wilsonii, Juncus effusus) as research objects. The results showed that (1) the removal of sulfate from AMD was highest for Juncus effusus (66.78%) and Iris wilsonii (40.74%) and the removal of Mn from AMD was highest for Typha orientalis (>99%) and Phragmites australis (>99%). In addition, considering the growth condition of the plants, Juncus effusus, Iris wilsonii, and Phragmites australis were finally selected as the dominant plants for the treatment of AMD. (2) The removal pathway of pollutants in AMD included two aspects: one part was absorbed by plants, and the other part was removed through hydrolysis and precipitation processes. Our findings provide a theoretical reference for phytoremediation technology for AMD.

The nonlinear effects associated with the vacuum polarization and magnetization in the propagation of ultra-intense linearly polarized laser pulse in electron-positron plasmas are investigated. Using the slowly varying envelope approximation, a modified nonlinear Schrödinger equation describing the evolution of the pulse envelope is derived based on the Maxwell equations which include the vacuum polarization and magnetization effects. The analytical and numerical analysis show that the number density of electron-positron plasmas can enhance the vacuum polarization and magnetization effects, and due to the vacuum polarization and magnetization nonlinearity, a one-dimensional laser pulse envelope soliton can be formed. The evolution of an initially Gaussian laser pulse is also discussed by numerical analysis.

No abstract

Increased nitrogen (N) from urban stormwater runoff aggravates the deterioration of aquatic ecosystems as urbanisation develops. In this study, the sources and transport of nitrate (NO3 -) in urban stormwater runoff were investigated by analysing different forms of N, water isotopes (δD-H2O and δ 18 O-H2O), and NO3isotopes (δ 15 N-NO3 -and δ 18 O-NO3 -) in urban stormwater runoff in a residential area in Hangzhou, China. The results showed that the concentrations of total N and nitrate N in road runoff were higher than those in roof runoff. Moreover, high concentrations of dissolved organic N and particulate N in road runoff led to significantly different TN concentrations in road runoff (mean: 3.76 mg/L) and roof runoff (mean: 1.23 mg/L). The high δ 18 O-NO3 -values (mean: 60±13.1‰) indicated that atmospheric deposition was the predominant NO3 -source in roof runoff, as confirmed by the Bayesian isotope mixing model (SIAR model), contributing 83.6-97.8% to NO3 -. The SIAR model results demonstrated that atmospheric deposition (34.2-91.9%) and chemical fertilisers (6.27-54.3%) were the main NO3 -sources for the road runoff. The proportional contributions from soil and organic N were smaller than other sources in both the road runoff and roof runoff. For the initial period, the NO3 -contributions from atmospheric deposition and chemical fertilisers were higher and lower, respectively, than those in the middle and late periods in road runoff during storm events 3 and 4, while an opposite trend of road runoff in storm event 7 highlighted the influence of short antecedent dry weather period. It was suggested that reducing impervious areas and more effective management of fertiliser application in urban green land areas were essential to minimize the presence of N in urban aquatic ecosystems.