Input, Storage, and Output of Plant Nutrients *

All water contributing to the surface runoff in a river basin is the solvent and vehicle for transporting varying amounts of the elements that are essential nutrients for aquatic plant and animal growth. The concentration of these elements in runoff waters and eventually in river waters depends on the types of soils and agricultural operations occurring in the drainage area, plus amounts of domestic sewage and industrial effluents that may also be discharged within this area. ^{1 – 9}