Why are Nutrients Important?
Nutrients are essential to the development, health and diversity of plants and animals and come from both natural and human sources. However, excessive inputs of nutrients into streams have potential human-health, economic, and ecological consequences. Excess amounts of nutrients, primarily nitrogen (N) and phosphorus (P) have been shown to cause eutrophication in aquatic ecosystems, which has been linked to fish kills, shifts in species composition, drinking water problems, and blooms of harmful algae.
Inputs of nutrients can come from point sources—which includes wastewater treatment or industrial discharges—and non-point sources—which include fertilizer application along with confined and unconfined livestock. Nonpoint-source nutrient inputs are one of the leading and most widespread causes of stream degradation. Studies conducted by the U.S. Geological Survey (USGS) National Water Quality-Assessment (NAWQA) Program estimate that about 90 percent of nitrogen and 75 percent of phosphorus originates from nonpoint sources; the remaining percentages are from point sources.
Monitoring nutrients in surface water and shallow groundwater is essential to establish where drinking water problems are likely to be present and to determine how ecosystem impairments such as algal blooms in a lake are linked to water-quality problems in a contributing watershed. Nutrients occur in dissolved and particulate forms but the dissolved forms are the most readily used by plants and easily transported to streams and groundwater.
Nitrate is the primary form in streams and shallow groundwater because it readily dissolves and is easily transported in water. Organic nitrogen and phosphorus can be dissolved or occur in particulate form (bound in plant and animal tissue), and contribute substantially to total nitrogen and total phosphorus in streams. As these various forms of nutrients enter receiving water bodies such as the Gulf of Mexico, excessive plant and bacteria growth can cause drastic reductions in dissolved oxygen when the associated plants and bacteria die (see information related to hypoxia).
Other Common Questions
To gain a deeper understanding of nutrient issues, you can find additional information by clicking on the links below for some of the most common questions about nutrients:
- What is being done to protect human health, streams, and lakes from excess nutrients?
- What is the nutrient condition of Indiana streams?
- What are the effects of nutrients on algal biomass and biological communities?
Water Resource Professionals Focusing on Nutrients Research and Monitoring in Indiana
- Jennifer Tank (University of Notre Dame)
- Melody Bernot (Ball State University)
- Jane Frankenberger (Purdue University)
- Jeff Frey (U.S. Geological Survey)
- Todd Royer (Indiana University
Committee on Environment and Natural Resources, 2003. An Assessment of Coastal Hypoxia and Eutrophication in U.S. Waters. U.S. National Science and Technology Council: Washington, D.C., 82 pages: http://oceanservice.noaa.gov/outreach/pdfs/coastalhypoxia.pdf.
Dubrovsky, N.M., and Hamilton, P.A., 2010. Nutrients in the Nation’s streams and groundwater: National Findings and Implications. U.S. Geological Survey Fact Sheet 2010-3078, 6 pages: http://pubs.usgs.gov/fs/2010/3078/.
Martin J.D., Crawford, C.G., Frey, J.W., and Hodgkins, G.A., 1996. Water-quality assessment of the White River Basin, Indiana—Analysis of selected information on nutrients, 1980–92. U.S. Geological Survey Water-Resources Investigations Report 96–4192, 91 pages: http://pubs.er.usgs.gov/usgspubs/wri/wri964192.
Mullins, G., 2014. Phosphorus, agriculture and the environment. Virginia Cooperative Extension, Virginia Tech University Web article accessed November 5, 2014 at: http://pubs.ext.vt.edu/424/424-029/424-029_pdf.