Dianchi Lake in China has become very polluted with phosphorus, leading to excessive plant growth. Scientists studied sediment samples from the lake to see how phosphorus moves around. They found that phosphorus levels in the sediment varied across the lake, with the highest levels near the surface in some areas. Certain types of phosphorus in the sediment can easily be released into the water, contributing to the pollution. The amount of phosphorus in the sediment is linked to the amount of phosphorus and algae in the water. The type of phosphorus in the sediment changes depending on how much oxygen is in the water and how much organic matter is present.