DNA and RNA also contain phosphate groups. Phosphate groups contain phosphorus and oxygen atoms. The Phosphate Cycle. The picture below shows the phosphate cycle. Inorganic phosphate can come from weathering of rocks or it can be added in the form of fertilizer.
Plants use the phosphates to grow, and animals that eat plants consume the phosphates in the plants.
You may have noticed that many laundry detergents advertise that they are phosphate free . Well in fact, when high concentrations of phosphates are added to river water, this can lead to an algal bloom. Algae is important since it is food for fish and algae produce oxygen during photosynthesis. However, when there is a lot of algae in the water there can be very negative effects on the quality of the river water. Thick layers of algae can block the sunlight from reaching the bed of the creek.