The researchers studied phosphorus levels in water from a river to the sea in the Beibu Gulf. They found that phosphorus concentrations were high in the river but decreased in coastal waters. Most phosphorus in the river was inorganic, while in coastal waters it was mostly organic. Dissolved phosphorus was more common than particulate phosphorus. Factors like river inputs and biological processes affected phosphorus levels. In the coastal water, biological uptake reduced inorganic phosphorus, while in the river, phosphorus was replenished. The Gulf was found to be limited in phosphorus, despite high levels in the river.