Confronting the ghosts of nutrients past, present and future in water quality management
On this page:
Abstract: Nutrient inputs to the landscape often move beyond their intended human uses in agricultural or urban systems, unintentionally being released to air, deeper soils, wetlands, groundwater, streams, rivers, lakes, and coastal areas. Added nitrogen or phosphorus may remain in the watershed for years, requiring recognition of these prior nutrient ghosts in the management of current and future nutrient issues. Ghosts can also include prior changes to the structure and function of watersheds as well as the spectre of climate change.
Understanding the role, impacts and fate of nutrient inputs to the landscape is critical for air and water quality management. US National Rivers and Streams Assessment (NRSA) surveys conducted by the States and EPA Fifty-eight percent (706,754 miles) of the nation’s rivers and streams were rated poor for phosphorus relative to the least-disturbed reference distribution, and 43% (522,796 miles) were rated poor for nitrogen. Nitrogen deposition is the largest source of nitrogen in 46% of stream length across the US, followed closely by agricultural non-point sources with 34% of the length. Excess nutrients are largely a nonpoint source issue and no single entity has complete jurisdiction over the problem, requiring partnerships to address.
By illustrating the value of combining datasets on nutrient inputs, climate variations, watershed characteristics and stream chemistry, we hope to provide science that the watershed biogeochemistry community can use to support decision making and management.