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Tracking phosphorus sources in the Chesapeake Bay

Fertilizers are just one reason for high phosphorus levels in the Chesapeake Bay. Through a study of phosphorus pollution in Chesapeake Bay sediments over the last 75 years, researchers at the University of Delaware (UD) are learning that multiple sources may contribute to the bay's phosphorus content.

Relying on specialized instrumentation to recognize the distinctive isotope "signatures" of each source, Deb Jaisi of UD and his students are creating a "fingerprint" of each phosphorus source in Chesapeake Bay sediment cores. Their equipment enables them to assess the presence and levels of the different forms, or isotopes, of phosphorus.

Phosphorus in the Chesapeake Bay comes from three primary sources: land, ocean and sediments. In the case of sediments, buried phosphorus moves into the bay when it remobilizes and enters the water column. The relative contributions of these three major sources have varied since colonial times.

Currently, researchers point to fertilizer runoff as the primary culprit in the overenrichment of phosphorus in the Chesapeake Bay. A more detailed picture that includes other sources, such as the ocean and the remobilization of phosphorus buried in sediments, could help resource managers pinpoint the best ways to control the bay's phosphorus loads.

Images (1 of )

  • the thomas point shoal lighthouse in the chesapeake bay
  • researchers examine a sediment core in the lab
The Chesapeake Bay's Thomas Point Shoal Lighthouse
U.S. Coast Guard
Researchers examine a sediment core.
Kathy F. Atkinson, University of Delaware

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