The researchers studied sediment in the Three Gorges Reservoir after raising the water level. They found that the sediment had high levels of total phosphorus, which could lead to pollution. The main phosphorus fractions were calcium-bound and reductant-soluble phosphorus. Only a small percentage of the phosphorus was bioavailable. Increasing the water level did not significantly increase the phosphorus content in the sediment. Smaller sediment particles and changes in mineral content could affect phosphorus accumulation. Dry-wet cycles and mud resuspension near the dam could impact phosphorus availability in the sediment.