Synergistic effect of vermiculite and submerged plants on lake sediments

Abstract

The synergistic effect of vermiculite and the submerged macrophytes Vallisneria spiralis and Hydrilla verticillata on lake sediment was studied using diffusive gradients in thin films (DGT) technology. The dynamics of phosphorus (P) fractions in sediment, the labile-P and labile-S in the water-sediment continuum, and the microbial community in the rhizosphere were studied. Vermiculite effectively promoted reproduction of microorganisms in the sediments Microbial abundance in treatments containing V. spiralis with sediments containing 10% added vermiculite, and H. verticillata containing 50% added vermiculite being 1.7 and 3.5 times higher than the controls which contained no added vermiculite. Acidobacteria and Proteobacteria populations, which are both beneficial for the sediment microenvironment, were higher in treatment groups containing vermiculite. The bioavailable-P in treatment groups containing added vermiculite was lower at the sediment-water interface, with a correlating decrease of TP by between 63% and 91% in the overlying water. This suggests that vermiculite can affect the release of labile P and facilitate the assimilation of nutrients by macrophyte roots. Additionally, vermiculite can improve the Oxidation-Reduction potential and further reduce sulfide toxicity to plants. These results provide theoretical guidance and technical support for the application of vermiculite combined with submerged plants for the remediation of eutrophic lakes.