August 11, 2016 — Nitrogen-rich agricultural runoff into the Chesapeake Bay presents an ongoing environmental and economic concern for the bay’s massive watershed. Pollution from fertilizer application feeds algal blooms that poison humans and marine life, and devastate fisheries.
Extreme rainfall cycles caused by increased climate variability flush larger amounts of nitrogen-containing nutrients from fertilizer and other sources into the Susquehanna River, which carries them into the Chesapeake Bay, according to a report in the journal Geophysical Research Letters. Moreover, a spike in rainfall can increase nitrogen levels in the bay even if the amount of fertilizer used on land remains the same.
These chemicals feed explosive algae growth that can produce toxins that harm people, fish, wildlife and drinking water. Decaying algae also suck oxygen from the surrounding water, creating a low-oxygen state known as hypoxia that results in “dead zones” that suffocate fish and other species important to the aquatic food chain.
The researchers constructed a model that they say provides the most complete picture to date of how nitrogen moves from place to place in the Chesapeake Bay watershed. It connects weather and pollution in places as far away as upstate New York to the water conditions in the bay.