Influences of the macrophyte (<i>Scirpus mariqueter</i>) on phosphorous geochemical properties in the intertidal marsh of the Yangtze Estuary

Abstract

The role of the marsh plant ( Scirpus mariqueter ) in phosphorus (P) biogeochemical cycling was investigated in the present study. The marsh plant had a significant influence on P adsorption, benthic fluxes and P speciation in the intertidal system. The adsorption capacities of P were significantly higher in the rhizosphere sediments (54.38–77.12 mg kg −1 ) than in the bare sediments (43.91–54.81 mg kg −1 ). Lower half saturation concentration constants also appeared in the rhizosphere sediments. Similar adsorption kinetic patterns were found for the bare and vegetated habitats, which showed an initial fast P adsorption reaction, followed by a slow adsorption process. However, compared with the unvegetated sediments, the relatively higher adsorption rate appeared in the rhizosphere sediments during the fast adsorption stage. Also, soluble inorganic P was effluxed into the overlying water in the unvegetated habitat. In contrast, soluble inorganic P was transported from the overlying water into the vegetated sediments during the growth season of S. mariqueter . The comparative analysis of P speciation in both bare and vegetated habitats revealed that S. mariqueter could enhance the accumulation of Fe‐bound P, authigenic P and organic P in the rhizosphere sediments. The important role of S. mariqueter in P removal and storage has significant implications for the conservation and management of the Yangtze estuarine and intertidal marsh.