Effect of abiotic stressors (As, Cl and Pb) on rhizomicrobiome and nutrient removal in a floating Equisetum hyemale wetland

Floating Treatment Wetlands (FTW) are receiving growing interest as a phyto-technology which shows promising removal of nutrients and potentially toxic elements (PTEs) from contaminated water bodies. Still, there are major research gaps concerning the actual role of plant species as well as plant-microbiome interaction.In this study, the performance of high silicate content species Equisetum hyemale for nutrient uptake was examined in FTW microcosms under the influence of abiotic stressors such as As (3 mg/L) and Pb (3 mg/L) as well as Cl- (300 and 800 mg/L) in reference to control during short screening experiment (50 days, divided into 2 phases with replenishing of nutrients). High removal efficiencies of nutrients, up to 88% for TN and 93% for PO4-P was observed. However, PO4-P removal was inhibited in the As reactor and max equalled 11%. Pb and As were removed with high efficiency, reaching 98% and 79% respectively. In the same time only Pb was bound in root biomass in effective way (reaching up to 43.7%) indicating . Equisetum hyemale as Pb bioaccumulator. This effect was achieved most likely due to high silicate content in this species. The development and structure of microbiome in microcosms was analysed by means of 16S rRNA gene amplicon sequencing, proving that Pb was the most influential factor in terms of selection pressure on specified bacterial groups, As present stimulating effect on Serratia subpopulation, while Cl- treatment resulted in the rhizobiome composition most similar to control.The outcomes of this study indicate that Equisetum hyemale is a suitable species for FTW usage in Pb and As polluted water bodies with periodic chloride increases. The plant-microbiome analysis performed in FTW microcosms provides information on the main contribution of individual system constituents on Pb and As elimination, as well as bacterial biodiversity.