Nutrients

Nutrients are transported in water either sediment-bound or dissolved. In water, sediment-bound nutrients can be transformed to dissolved nutrients or dissolved nutrient can transformed to sediment-bound nutrients. These transformations depend on the properties of the water, soils, and nutrients.

For water quality, the two most important nutrients are nitrogen and phosphorus. Nitrogen is the dominant component of the atmosphere and is chemically transformed by plants. The chemical form of nitrogen varies primarily between nitrogen gas, organically-bound nitrogen, ammonia or ammonium, and nitrate. Sediment-bound nitrogen usually is organically-bound nitrogen or ammonia or ammonium. Dissolved nitrogen is usually ammonia or ammonium or nitrate. Most water quality problems associated with nitrogen involve dissolved nitrates.

Phosphorus, along with nitrogen and potassium, is one of the three primarily plant nutrients. The chemical form of phosphorus is split between organically-bound phosphorus and inorganically-bound phosphorus, usually in the form of phosphate. Almost all phosphorus compounds are highly insoluble, resulting in most phosphorus in water being sediment-bound.

Excessive levels of nitrogen and phosphorus in waters can cause a number of different problems. The biggest problem is excessive plant and algae growth, called eutrophication.