Distribution of Phosphorus in Sediments of Onshore Reed Areas of Lake Taihu

To reveal additional effects of aquatic macrophytes on biogeochemical properties of onshore lake phosphorus and to investigate the ecological response of reed communities to this phosphorus, sediments from the Meiliangwan onshore reed area of Lake Taihu were sampled by using a columnar sampler (D=8 cm) on September 18, October 17 and December 3, 2003. The samples were compared with those from macrophyte-free areas. The collected samples were dried naturally at room temperature, ground and screened with a 100 mesh sieve. The HClO4-H2SO4 digesting and H2SO4-H2O2 heating digesting methods were used to analyze the total amount of phosphorus (TP) contained in sediments of the reed area and in tissues of reed roots and stems. The result shows: 1) the level of TP, from both the reed area sediment and the reference samples, is highest during the vigorous growing stage and lowest during the slow growing stage. The difference between the two levels is statistically significant (p < 0.01); 2) the top layer (0–2 cm) of the sediment from the area without higher aquatic macrophytes and the sediment (4–7 cm) in the central reed area show peak values of phosphorus enrichment; 3) the phosphorus enrichment of different parts of reed tissues is in decreasing order: firous root > rhizome > stem. All are smaller in the level of phosphorous than that in rhizosphere sediments (0–2 cm).