Research Areas > Nutrients > Identification of Nutrient Sources > Background: Where Do Nutrients Come From?

Background: Where Do Nutrients Come From?

Virtually all individuals living and industries operating in a watershed, and even some beyond the watershed, contribute nutrients that eventually reach aquatic habitats. In general, nutrients from non-natural sources reach aquatic habitats in several ways: from pipes (point sources of pollution), surface and groundwater runoff, and deposition from the air (via rain or dust).

Point sources of pollution typically come from wastewater treatment plants and industrial facilities. These sources release treated water – often still containing large amounts of nutrients – into local streams and rivers, estuaries and coastal waters. Nutrients that collect in runoff from agricultural, urban, and suburban areas are usually related to fertilizers, septic systems, boat discharges and farm animal manure, among other sources. Air pollution from vehicles, industries, gas-powered lawn tools, and other emitting sources also contribute nutrients to aquatic habitats.
 

Natural sources of nutrients include soil, plant material, animal waste, and the atmosphere. In oceans, another natural source of nutrients to surface waters comes from a phenomenon known as “upwelling” — when cooler nutrient-rich bottom waters rise to the surface of the ocean.

Nutrient inputs from these sources, at naturally-occurring levels, are not a problem and support the critical biological cycles that we rely on for life on earth. As human activity begins to increase natural loading of nutrients into aquatic ecosystems, the balance tips toward overproduction of organic matter, which in turn may cause a cascade of other ecosystem problems.