The researchers studied phosphorus levels in Nanhu Lake, Wuhan, by analyzing water and sediment samples from different sites. They found that phosphorus concentrations in the water and sediments varied throughout the year, with the highest levels in November and the lowest in February and August. In sediments, inorganic phosphorus was the dominant form, and bio-available phosphorus decreased with depth. The study suggests that bio-available and auto-calcium bound phosphorus in sediments are the main sources of phosphorus released into the water.