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Beta diversity represents the spatial or temporal variation of species diversity among sampling sites and may be composed of two elements: turnover (Brepl, replacement of species assemblages) and nestedness (Brich, loss or gain of species assemblages). Knowledge of the mechanisms driving beta diversity contributes to an understanding of the variation in aquatic ecosystem community structures. We sampled zooplankton assemblages at 24 sites in 11 rivers in Shanghai City and conducted a nutrient addition experiment to elucidate the effects of various environmental variables on the community structure and beta diversity patterns of the zooplankton. The zooplankton assemblages in the rivers differed significantly at ammonia nitrogen (NH3-N) concentrations below (Group I) and above (Group II) 1.03 mg·L−1. The nutrient addition experiment further demonstrated that the composition of the zooplankton assemblages changed markedly along an ammonia concentration gradient (0.2 to 5.0 mg N·L−1). The total beta diversity of Group I was considerably higher than that of Group II, indicating that high nutrient (ammonia) pollution led to biotic homogeneity. Overall, turnover was the key factor determining the total beta diversity of the two groups, suggesting the key importance of replacement of zooplankton assemblages. Furthermore, we found a correlation between environmental factors (mainly nitrogen content) and the beta diversity of zooplankton, and beta diversity (Brepl and Btotal) decreased with increasing trophic state. These findings provide further insight into the changing characteristics of the beta diversity patterns of zooplankton in river networks and may help to guide managers dealing with conservation strategies for aquatic biodiversity preservation in urban river ecosystems.

Phytoplankton and bacterioplankton play a vital role in the structure and function of aquatic ecosystems, and their activity is closely linked to water eutrophication. However, few researchers have considered the temporal and spatial succession of phytoplankton and bacterioplankton, and their responses to environmental factors. The temporal and spatial succession of bacterioplankton and their ecological interaction with phytoplankton and water quality were analyzed using 16S rDNA high-throughput sequencing for their identification, and the functions of bacterioplankton were predicted. The results showed that the dominant classes of bacterioplankton in the Qingcaosha Reservoir were Gammaproteobacteria, Alphaproteobacteria, Actinomycetes, Acidimicrobiia, and Cyanobacteria. In addition, the Shannon diversity indexes were compared, and the results showed significant temporal differences based on monthly averaged value, although no significant spatial difference. The community structure was found to be mainly influenced by phytoplankton density and biomass, dissolved oxygen, and electrical conductivity. The presence of Pseudomonas and Legionella was positively correlated with that of Pseudanabaena sp., and Sphingomonas and Paragonimus with Melosira granulata. On the contrary, the presence of Planctomycetes was negatively correlated with Melosira granulata, as was Deinococcus-Thermus with Cyclotella sp. The relative abundance of denitrifying bacteria decreased from April to December, while the abundance of nitrogen-fixing bacteria increased. This study provides a scientific basis for understanding the ecological interactions between bacteria, algae, and water quality in reservoir ecosystems.

Water level fluctuation (WLF) has a significant effect on aquatic macrophytes, but few experimental studies have examined the effect of WLF on submerged community succession, especially from a large-scale perspective. In this study, field monitoring of WLF and submerged macrophytes was conducted in Yilong Lake (SE China) over two years, and the impacts of WLF on the growth characteristics and the community structure of submerged macrophytes were determined. The results show that the biomass of submerged macrophytes decreased significantly after the water level increased and submerged macrophytes could cope with the adverse environment by adjusting their growth posture, for example, increasing plant length and reducing branch number. However, different submerged plants have different regulatory abilities, which leads to a change in the community structure. Myriophyllum spicatum, Stuckenia pectinata, and Najas marina had better adaptation abilities to WLF than Najas minor and Utricularia vulgaris. Changes in water depth, dissolved oxygen, and transparency significantly contribute to the effect of WLF on submerged plant communities. Therefore, when determining the range of WLF, the above three critical factors and submerged plant species should be considered. WLF changed the spatial distribution of the aquatic plant community. When water levels rose, the density of the submerged macrophyte community in the original growth region reduced as the emergent plants migrated to shallower water, and the seed bank germination was aided by transparent water produced among emergent plants. This can be used as a pioneering measure to restore submerged plants in eutrophic lakes with low transparency. In addition, a suitable water depth created by WLF was conducive to activating the seed bank and improving the diversity of aquatic plants. Finally, a distribution map of aquatic plants in Yilong Lake is drawn.

Highlights • Ultrasound treatment reduces the lignin intensity in cell wall. • Ultrasound treatment reduced the relative hemicellulose content. • Ultrasound treatment increased the crystallinity. • Ultrasound-alkali treatment had more pronounced effects on cell wall., It is well-known that ultrasound has been studied for its cavitation, mechanical and thermal effects. As a pretreatment technology, ultrasonic alkali treatment has attracted much attention in the field of biomass biochemical transformation. In this study, the structural and dynamic changes of wood cell walls during ultrasound-water, alkali, and ultrasound-alkali treatments were investigated by stereoscopic microscopy, confocal Raman microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction. The results indicated that the ultrasound-water, alkali, and ultrasound-alkali treatments had the effect of removing extractives from conduits. The uniform self-shrinking samples with shrinkage conduits were obtained by the alkali and ultrasound-alkali treatments. All of the treatments affected the relative content, structure and distribution of the chemical components in the wood cell walls. Compared with water-immersion samples, the relative content of hemicellulose of the treated samples reduced from 32.31% to 7.02% for ultrasound-8% NaOH treated samples. For the signal intensity of lignin, ultrasound-water treated and ultrasound-alkali treated samples displayed a more significant reductions than the alkali treated samples in the cell wall region. The crystal zone and amorphous zone of cellulose coexisted before and after the treatment, for all of the treated samples, and particularly for the ultrasound-assisted treated samples, the crystallinity increased from 38.15% for water-immersion samples to 57.42% for ultrasound-8% NaOH treated samples.

High-efficiency desulfurization is key to the recovery and use of landfill gases. In this study, a nano‑iron oxide desulfurization agent modified from iron pentacarbonyl was prepared in n-decane (DE) and hexadecane (HE) by ultrasonic disruption without any supporting materials and its hydrogen sulfide removal ability and desulfurization mechanism were studied. The yield of the desulfurization agent was higher when HE was used as the solvent; however, the products generated by both solvents had the same crystal type and similar properties. The efficiency of the desulfurization agent was significantly improved at 150-200 °C, exceeding 90% at 150 °C with single sulfur production. The maximum sulfur adsorption capacity of the desulfurization agent produced after 3 h of DE ultrasonic treatment at 200 °C (DE3) was 492 mg/g (desulfurization efficiency = 97.33%), while that of the agent produced after 3 h of HE ultrasonic treatment at 250 °C (HE3) was 522 mg/g (desulfurization efficiency = 99.30%). The desulfurization reaction involved both chemical adsorption and catalytic decomposition and the catalytic decomposition reaction rate was lower than that of chemical adsorption. Therefore, the more Fe

In this study, (3-mercaptopropyl) triethoxysilane (MPTMS)-modified ordered mesoporous silica (OMS) materials were prepared using a post-grifting method, with MPTMS as the organic functionalized reagent. The OMS materials were analyzed by FT-IR spectra, N

In this study, (3-mercaptopropyl) triethoxysilane (MPTMS)-modified ordered mesoporous silica (OMS) materials were prepared using a post-grifting method, with MPTMS as the organic functionalized reagent. The OMS materials were analyzed by FT-IR spectra, N2 sorption, and small angle X-ray scattering to evaluate their potential for scavenging Cd2+ from water. Moreover, a (3-mercaptopropyl) triethoxysilane-functionalized ordered mesoporous silica modified polyvinylidene fluoride (MPTMS-OMS/PVDF) membrane was synthesized using the solvent phase inversion method to remediate wastewater containing heavy metal ions. The MPTMS-OMS was characterized by a maximum specific surface area of 422 m2/g, high surface hydrophilicity, and high pure water flux. The MPTMS-OMS/PVDF exhibited a dynamic adsorption capacity for Cd2+ in water. At an MPTMS-OMS content of 5 wt%, the Cd2+ removal efficiency was 90%, whereas the pure PVDF showed no Cd2+ adsorption capacity. These results highlight the potential of the MPTMS-OMS/PVDF membrane to eliminate Cd2+ during the decontamination of aqueous streams containing low-concentrations of contaminants.

To assess the response of Ottelia acuminata to a water-depth gradient, we investigated the plant growth and leaf photosynthesis by setting three water depths (0.5, 1.0, and 1.5 m) in situ in Yilong Lake, Yunnan Province, China. The results showed that the growth and photosynthetic fluorescent characteristics of O. acuminata exhibited different responses to the water-depth gradient. The plant height, fresh weight, root length, and leaf number of O. acuminata, varied significantly with changes in the water depth. With regard to the photosynthetic fluorescent characteristics of leaves, the maximum quantum yield half-saturation light intensity and fluorescence parameter of photosystem II markedly improved with increasing water depth. The increase of photosynthetically active radiation resulted in a decreased photochemical quenching coefficient (qP). In contrast, the nonphotochemical quenching coefficient was relatively high in the leaves of O. acuminata in shallow water under high photosynthetically active radiation. The chlorophyll content of the leaves varied significantly with changes in the water depth. Higher chlorophyll a, chlorophyll b, and carotenoid contents were detected in the leaves of O. acuminata at the water depth of 1.5 m. The results of the growth and photosynthetic fluorescent characteristics of O. acuminata indicate a better protection mechanism against high light in the leaves of O. acuminata in shallow water and a higher photosynthetic efficiency, as well as a greater photosynthetic potential, in the leaves of O. acuminata in deep water.

This study elucidates the mechanism of the influence of ultrasonic treatment on wood pyrolysis and the details of the thermal stability changes of samples treated with ultrasonic alkali are explained. Four groups of samples were designed to clarify this scientific question, including the control group, the ultrasonic water-treated group, the alkali-treated group and the ultrasonic alkali-treated group. The extractives contents (organic extractives and hot water extractives) were determined, the crystal region, the functional groups of chemical components, the distribution of chemical components, and the thermal stability of wood were investigated using X-ray diffraction, Fourier-transform infrared spectroscopy, confocal Raman microscopy, and thermogravimetric analysis, respectively. The results suggested that all the treatments reduced the extractives contents, increased the relative crystallinity, destroyed the structure of hemicellulose and lignin, and affected the thermal stability of wood, to different degrees. Ultrasonic time and alkali concentration were shown to be two important indexes. Ultrasound can enhance the treatment effects of low concentration alkali (0.1 %), but in a highly concentrated alkali environment, the auxiliary effect is not obvious. Ultrasonic treatment reduced the intensity of lignin in the whole cell wall region, while alkali treatment followed a more systematic process as the solvent permeated from the S layer to CCML. The initial degradation temperature T0 was not only related to the extractives content but also to the concentrations of hemicellulose and lignin in the sample. The hemicellulose degradation temperature T1 and cellulose degradation temperature T2 changed with changes in T0. A detailed understanding of the spatial and temporal variations of the major components in the rigid cell wall during the pretreatment process will help to develop more effective pretreatment strategies, which is crucial for the efficient optimization of the process.

The genus Populus L. has been divided into five sections based on morphological characters, but the phylogenetic relationships among sections remain uncertain. Topological discrepancies have been reported between trees obtained using nuclear and plastid sequences. We selected nine chloroplast genomes from all five sections, including two new sequenced species in this study for analyses of maternal phylogenetic relationships in the genus Populus at the sectional level. Phylogenetic analyses were performed using various subsets of data, coding sequences, noncoding sequences, and different districts of the genome, yielding contradictory outcomes for various subsets. According to our phylogenetic analyses, (1) a robust maternal phylogenetic relationship among sections based on complete chloroplast genomes was obtained; (2) Sect. Tacamahaca can be divided into two clades based on maternally inherited loci, i.e. cladeⅠ, distributed in North America and northeast China, and cladeⅡ, distributed in southwest China; (3) SSC-noncoding regions revealed an inconsistent topology compared with all other subsets; (4) this discrepancy may be resulted from incomplete lineage sorting between species of Populus . We tested multiple partitioning schemes to resolve deep-level phylogenetic relationships in Populus , and complete noncoding subset is most recommended.

Water eutrophication is one of the difficulties in urban landscape water. In the past period of time, people have been exploring the prevention and control of eutrophication of landscape water. At present, submerged plant restoration, chemical control of algae and physical equipment filtration technology are becoming more and more mature. Among them, submerged macrophyte restoration has become the mainstream technology, but the restoration of submerged macrophytes is faced with the problem of lack of transparency, which leads to the failure of engineering construction. Indigenous microbial activation(IMA) technology has become an effective method to solve this problem. The technology focuses on the water microbial community as the research object. By adding an activator with a suitable concentration gradient to the experimental landscape water, the indigenous microbial community is activated landscape water. The paper analyzed the current landscape water eutrophication technology, summarized the relationship between bacteria and algae, algae and submerged plants, and proposed IMA microbial activation technology. In addition, we share a project case to better illustrate this technology.In the case, IMA equipment was added to the experimental landscape water to study the water environment quality changes before and after the implementation of the project, so as to evaluate the feasibility and technical advantages of IMA technology, and provide technical ideas and data support for landscape water treatment.

During the ongoing revision of Populus Linnaeus (1753: 1034) for the Flora of Pan-Himalayas , the application of the name Populus wilsonii Schneider (1916: 16) has been considered a complicated problem. P. wilsonii was described by Schneider based on Wilson’s collections from western Hupeh and western Szech’uan. In the protologue, Schneider cited E . H . Wilson 706a , May 20 and August 1907, Hsing-shan Hsien as types, which belong to two gatherings ( cf. Art. 8.2 of the ICN, McNeill et al. 2012). Hao (1935) briefly reviewed Chinese Populus and cited E. H. Wilson no. 706a in Arnold Arboretum as the type of P . wilsonii , specifying in which herbarium the types were conserved, but not which of the two gatherings he designated as lectotype. We traced eight specimens of “ E. H. Wilson 706a ” in five herbaria: A, E, GH, K, US (Table 1). The two specimens kept in A (barcodes 00030875, 00030877) are labelled with Schneider’s handwriting “cotype, 20/5/07” and “type No. 8/07”, respectively, but both are composed of a flowering branch and a separated branch with mature leaves. These two specimens appear to be mixed gatherings, since most poplar flowers fade before the leaves unfold. Meanwhile, another specimen at K (barcode K000592058, image available at http://www.kew.org/herbcatimg/290165.jpg) labelled “ E . H . Wilson 706a , 5/07 + 8/07” provided additional evidence that one sheet of E . H . Wilson 706a could be composed of material from different gatherings. Although the collection date was not identical to the protologue (May 1907 vs. May 20 1907), the E specimen of “ E . H . Wilson 706a , 5/07” (barcode E00301557) was attached with an “Isotype” label and is supposed to be part of the gathering of E . H . Wilson 706a , May 20 1907. As a result, there are three gatherings under the same collection number: flowering female branches collected on May 20 1907, branches with mature leaves collected in August 1907, and flowering female branches with primary leaves collected in May 1907.