The researchers studied the different forms of phosphorus in the surface sediments of a shallow lake. They found that the sediments contained various types of phosphorus, with bio-available phosphorus being a significant contributor. The main forms of phosphorus in the sediments were metal oxides bound phosphorus, organic phosphorus, and calcium bound phosphorus. Additionally, there was a gradient of soluble reactive phosphorus at the sediment-water interface, suggesting that phosphorus could move from the sediment into the water, potentially promoting algae growth.