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• Effect of vermiculite on Vallisneria spiralis and sediment microenvironment. • A certain amount vermiculite accelerate the growth of Vallisneria spiralis. • Diversity and richness of microbial communities in vermiculite group were increased. • PCA demonstrated 5% and 10% group improved the sediment conditions. • Vermiculite can be applied to ecological restoration projects in eutrophic lakes. Ecological restoration is one of the hot technologies for the reconstruction of eutrophic lake ecosystems in which the restoration and propagation of submerged plants is the key and difficult step. In this paper, the effect of vermiculite on the growth process of Vallisneria spiralis and sediment microenvironment were investigated, aiming to provide a theoretical basis for the application of vermiculite in aquatic ecological restoration. Results of growth indexes demonstrated that 5% and 10% vermiculite treatment groups statistically promote the growth of Vallisneria spiralis compared to the control. Meanwhile, the results of ecophysiological indexes showed that photosynthetic pigment, soluble sugar content, superoxide dismutase (SOD), and catalase (CAT) activity of 5% and 10% group were increased compared with the control while the malondialdehyde (MDA) content exhibited the opposite result (p < 0.05), which illustrated that vermiculite can improve the resistance of plants and delay the aging process of Vallisneria spiralis. In addition, result of PCA (Principal Component Analysis) demonstrated 5% and 10% group has improved the sediment physical conditions and create more ecological niche for microorganisms directly, and then promoted the growth of plants. The dissolution results showed that vermiculite can dissolve the constant and trace elements needed for plant growth. Furthermore, the addition of vermiculite increased the diversity of microorganisms in the sediments, and promoted the increase of plant growth-promoting bacteria and phosphorus-degrading bacteria. This study could provide a technique reference for the further application of vermiculite in the field of ecological restoration. [Display omitted] [ABSTRACT FROM AUTHOR]

The diffusive gradients in thin films (DGT) technique was applied to determine the mechanism by which bentonite improves the eutrophic lake sediment microenvironment and enhances submerged plant growth. The migration dynamics of N, P, S, and other nutrient elements were established for each sediment layer and the remediation effects of bentonite and submerged plants on sediments were evaluated. Submerged plant growth in the bentonite group was superior to that of the Control. At harvest time, the growth of Vallisneria spiralis and Hydrilla verticillata was optimal on a substrate consisting of five parts eutrophic lake sediment to one part modified bentonite (MB5/1). Bentonite addition to the sediment was conducive to rhizosphere microorganism proliferation. Microbial abundance was highest under the MB5/1 treatment whilst microbial diversity was highest under the RB1/1 (equal parts raw bentonite and eutrophic lake sediment) treatment. Bentonite addition to the sediment may facilitate the transformation of nutrients to bioavailable states. The TP content of the bentonite treatment was 22.47%–46.70% lower than that of the Control. Nevertheless, the bentonite treatment had higher bioavailable phosphorus (BIP) content than the control. The results of this study provide theoretical and empirical references for the use of a combination of modified bentonite and submerged plants to remediate eutrophic lake sediment microenvironments. [Display omitted] • DGT technique was applied to reveal the combined remediation mechanism. • Remediation effects of bentonite and submerged plants on sediments were evaluated. • Bentonite and submerged plants improved eutrophic lake sediment microenvironment. • Bentonite was conducive to rhizosphere microorganism proliferation. • Bentonite enhanced submerged plant nutrient bioavailability in lake sediment. [ABSTRACT FROM AUTHOR]

A biomass-derived carbon aerogel (CA) was prepared and employed as an efficient metal-free and green carbon-based catalyst for peroxymonosulfate (PMS) activation to degrade tetracycline (TC). The surface functional groups, morphology, and other properties of the CA were characterized using various methods. Different carbonization temperatures were used to produce CA samples to control the oxygen-containing functional group content and defect degree, both of which play important roles in PMS activation. The carbonization temperature showed a clear negative correlation with the oxygen-containing functional group content on the CA surface, while exhibiting a positive correlation with the degree of defects in the CA. The optimal temperature for producing the CA was 300 ℃ owing to the high oxygen-containing functional group content and low loss rate. Neutral and weakly alkaline conditions were conducive to TC removal. Under optimal conditions, 93% removal of TC could be achieved within 90 min. The results of reactive oxygen species (ROS) quenching experiments and electron paramagnetic resonance (EPR) spectroscopy indicated that both non-radical species (1O 2 and electrons) and radical species (•OH and SO 4 •−) resulted in the removal of TC. 1O 2 was identified as the main activated ROS. This study deepens our understanding of the preparation of biomass-derived carbon aerogels and control of the oxygen-containing functional group content and defect degree for improving the pollutant removal efficiency. [Display omitted] • Biomass-derived carbon aerogel (CA) catalyst is produced at a low temperature. • The CA is used for peroxymonosulfate (PMS) activation to degrade tetracycline (TC). • Oxygen functional groups and defects play important roles in PMS activation. • The PMS/CA system facilitates 93% removal of TC within 90 min. • Both non-radical and radical species contribute to TC removal. [ABSTRACT FROM AUTHOR]