Phosphate, PO43−, while naturally present in water, can be detrimental in excess amounts. Phosphate is an important atom in DNA. Animals will absorb phosphates from plants, which in turn absorb phosphates from the soil that are aided by fertilizer and other natural phosphates that can be introduced to a river through erosion. If the soil contains enough natural phosphates, then the river’s ecosystem can be negatively impacted. Rivers that have a high concentration of phosphates are often subject to eutrophication, which is an algea bloom characterized by excess plant growth. Plant growth in an aquatic ecosystem can be detrimental to animals that rely on the oxygen in the water. When the plant eventually dies, bacteria will congregate to decompose the plant. This leads to a high demand for oxygen, for oxygen is consumed by the bacteria as the plant decomposes. Therefore, high phosphate levels can create a higher biological oxygen demand (BOD) reading.