Effects of Potamogeton crispus growth on phosphorus fractions in lake sediments at two nutrient levels

This study explored the regulatory effects of Potamogeton crispus (P. crispus) on phosphorus fractions in lake sediments under two nutrient conditions, using a rhizosphere–non-rhizosphere partitioning approach. Sediments from Tangxun Lake (mesotrophic) and Nan Lake (eutrophic), Wuhan, China, were used in a controlled microcosm experiment. The dynamics of seven phosphorus fractions (Ca₂-P, Al-P, Org-P, Fe-P, O-Al-P, O-Fe-P, and Ca₁₀-P) were analyzed across different growth stages. Results showed: (1) In mesotrophic sediments, P. crispus significantly reduced labile phosphorus (Ca₂-P and Fe-P) in the rhizosphere, indicating enhanced uptake and stabilization; (2) In eutrophic sediments, phosphorus fractions including Org-P and Ca₁₀-P accumulated in the rhizosphere, reflecting active turnover and long-term retention; (3) O-Fe-P was consistently lower in rhizosphere sediments across both lakes, likely due to rhizosphere-induced redox suppression. These findings highlight the dual role of P. crispus in activating and stabilizing phosphorus in sediments and provide theoretical guidance for plant-based lake restoration strategies.