Nutrient Sources, Flows & Sinks

  • Aerial shot of land plots beside the river
    Credit: Chuck Gallegos, with aerial support from LightHawk

Nutrient pollution, the key culprit behind massive algal blooms and low-oxygen “dead zones,” is damaging the health of bays and estuaries around the world. To keep excess nutrients like nitrogen and phosphorus from entering the water, scientists first need to trace them back to their sources and track how they flow through the watershed.

Agriculture is one of the largest sources of nutrient pollution. Fertilizers applied to farm fields and suburban lawns contain vast amounts to nitrogen and phosphorus that wash off in the rain. Other sources of nutrients include sewage, septic systems, power plants and even exhaust fumes from cars. Rainstorms carry these nutrients into streams, where they eventually find their way to coastal oceans. Impervious surfaces like driveways and paved roads make it easier for nutrients flow away, because these surfaces don’t absorb water.

But nutrient sources are sometimes balanced by nutrient sinks—landscape features that can absorb nutrients before they enter coastal waters. One of the best is a riparian buffer, a wetland or forest right next to a stream, which can filter out nutrient pollution from uphill farm fields, houses or roads. Rain gardens also can help absorb nutrients from residential and other developed areas.

In the following projects, SERC scientists are tracking the transfers of nutrients among sources, sinks and streams.  Their research helps uncover the best ways to keep nutrients on the land and out of the water.

(Top image by Chuck Gallegos, with aerial help from LightHawk)