Biogenic volatile organic compounds (BVOCs) significantly contribute to atmospheric chemistry at both regional and global scales. The composition and intensity of BVOC emissions vary significantly among different plant species. Previous studies have focused on BVOC emissions from tree species, but the results of research on BVOC emissions from wetland plants are still limited. Therefore, in this study, BVOCs emitted by three aquatic plants (Phragmites australis, Typha angustifolia, and Iris pseudacorus) were sampled and analyzed using a dynamic headspace technique combined with GC-MS at daily scales. The diurnal observation data showed that the total BVOC emission rates of the three plants peaked with the increase in environmental factors (temperature, PAR, and water temperature). P. australis was the only of the three plants that emitted isoprene with a high rate of 48.34 μg·g⁻¹Dw·h⁻¹. Moreover, the peak emission rates of total BVOC (78.45 μg·g⁻¹Dw·h⁻¹) in P. australis were higher than most tree species. The emissions rates of volatile organic compounds, including monoterpenes, oxygenated volatile organic compounds, alkanes, and other volatile organic compounds, were statistically correlated across all species. The emission rates of isoprene from P. australis had significant associations with intercellular CO₂ concentration (Ci) (0.58, p < 0.05) and transpiration rate (Tr) (−0.63, p < 0.01). The emission rates of monoterpenes from P. australis were found to have a significantly positive correlation with the net photosynthetic rate (Pn) (0.58, p < 0.05) while T. angustifolia (−0.59, p < 0.05) and I. pseudacorus (−0.47, p < 0.05) showed the opposite trend. Such findings hold significance for the refinement of localized emission inventories and the development of comprehensive emission process models in future research, as BVOC emissions from wetland plants were reported here for the first time.

Potamogeton crispus (P. crispus), with strong nitrogen uptake capacity, plays an important ecological role during winter and early spring when most aquatic plants are inactive. Its presence can also influence microbial denitrification in sediments by regulating oxygen levels and organic carbon availability. In this study, an indoor hydroponic simulation system was used to systematically evaluate the effects of P. crispus under different nitrogen-loading conditions on nitrogen removal from water, changes in sediment carbon and nitrogen fractions, microbial community structure, and greenhouse gas fluxes. The results showed that P. crispus effectively removed TN, NH₄⁺-N, NO₃⁻-N, and NO₂⁻-N, maintaining strong denitrification capacity even under high-nitrogen loading. Under all nitrogen conditions, TN removal exceeded 80%, while NH₄⁺-N and NO₃⁻-N removal efficiencies surpassed 90%, with effective suppression of NO₂⁻-N accumulation. Rhizosphere-mediated regulation by P. crispus enhanced the transformation and stabilization of DOC and NO₃⁻-N in sediments, while also mitigating nitrogen-induced disturbances to carbon–nitrogen balance. The plant also exhibited strong CO₂ uptake capacity, low CH₄ emissions with a slight increase under higher nitrogen loading, and N₂O fluxes that were significantly affected by nitrogen levels—showing negative values under low nitrogen and sharp increases under high-nitrogen conditions. Correlation analyses indicated that CO₂ and N₂O emissions were mainly regulated by microbial taxa involved in carbon and nitrogen transformation, while CH₄ emissions were primarily driven by methanogenic archaea and showed weaker correlations with environmental factors. These findings highlight the importance of water restoration during low-temperature seasons and provide a theoretical basis for integrated wetland management strategies aimed at coordinated pollution reduction and carbon mitigation.