SOURCE: Yale e360

DATE: March 14, 2019

SNIP: With global sea levels steadily rising — already up 8 inches in the past century and now increasing at an average of 1.3 inches per decade — the incidence of high-tide “sunny day” or “blue sky” flooding is on the rise, especially along the U.S. East Coast. Those flooding events now routinely wash over sections of cities, and when the waters recede they take with them an excess of nutrients and a toxic mix of pollutants that flows into rivers, bays, and oceans.

As high-tide flooding worsened in Norfolk, Virginia in recent years, Margaret Mulholland, a biological oceanographer at Old Dominion University, started to think about the debris she saw in the waters that flowed back into Chesapeake Bay. Tipped-over garbage cans. Tossed-away hamburgers. Oil. Dirty diapers. Pet waste.

[S]he decided to sample those waters.

Until Mulholland… few if any researchers had examined exactly how much pollution this sunny day flooding was creating. And what Mulholland found shocked her. Analysis of water samples indicates that one morning of tidal flooding along the Lafayette River in Norfolk poured nearly the entire annual U.S. Environmental Protection Agency allocation of nitrogen runoff for the river — 1,941 pounds — into Chesapeake Bay.

Mulholland is focused on measuring nitrogen, including ammonium, because of its effect on algae blooms, which create oxygen-depleted dead zones in bay waters. She said that other pollutants — including oil, gasoline, and trace metals — are also washing into waterways, as evidenced by the petroleum sheens visible on the water during high-tide flooding. “We can see it, and it would be great if we could measure it in the future,” she says. “But we don’t have the analytical chops to measure it so far.”