The oldest body of seawater ever identified is buried under the Chesapeake Bay.
According to the U.S. Geological Survey (USGS), this recently discovered body of water dates back to the Early Cretaceous period, when wet and dry seasons controlled the climate, tropical jungles dominated the landscape and dinosaurs were becoming more plentiful.
Image courtesy Nicolle Rager-Fuller/National Science Foundation
The water is buried beneath a large meteorite that struck the earth 35 million years ago, throwing debris into the atmosphere and spawning a train of tsunamis that probably reached as far as the Blue Ridge Mountains. The so-called “Chesapeake Bay impact crater” is the largest crater discovered in the United States and helped determine the current shape of the Bay.
Because the water is trapped in place, USGS scientists have been able to estimate its age—100 to 145 million years old—and its salinity—twice as salty as modern seawater.
Acting USGS Associate Director for Water Jerad Bales said in a media release that before this discovery was made, no one realized that the saltier-than-normal groundwater found deep in the Atlantic Coastal Plain “was North Atlantic ocean water that has essentially been in place for 100 million years.”
“We are working directly with seawater that dates far back in earth’s history,” Bales said.
Slow-moving groundwater on the Delmarva Peninsula could push excess nutrients into the Chesapeake Bay even after we have lowered the amount of nitrogen and phosphorous we put onto the land.
Image courtesy yorgak/Flickr
According to new research from the U.S. Geological Survey (USGS), most of Delmarva is affected by the slow movement of nutrients from the land into the water. A USGS model developed to track the movement of nitrogen through the region showed that groundwater—and the pollutants it can contain—takes an average of 20 to 40 years to flow through the peninsula’s porous aquifers into rivers and streams. In some parts of Delmarva, the groundwater that is now flowing into local waterways contains nitrogen linked to fertilizer used three decades ago.
The slow flow of nitrogen-laden groundwater into the Bay could affect efforts to restore the watershed, lengthening the “lag-time” between the adoption of a conservation practice and the effect of that practice on a particular waterway. In other words, it could take days or even decades for today's management actions to produce positive water quality results.
“This new understanding of how groundwater affects water-quality restoration in the Chesapeake Bay will help sharpen our focus as many agencies, organizations and individuals work together to improve conditions for fish and wildlife,” said Lori Caramanian, Department of the Interior Deputy Assistant Secretary for Water and Science, in a media release.
While these findings seem to contradict the value of our restoration work, the study in fact indicates that pollution-reducing practices put in place over the past decade have begun to work. The study also confirms that rigorous steps taken to reduce nutrients on the land will lower the amount of nitrogen loading into streams in the future.