How do dead zones form

But with industrial and agricultural activity throughout Gulf and Midwestern states only increasing—and Mother Nature not making the job any easier—the task force has an uphill battle on its hands to say the least. Send questions to: earthtalk emagazine. Subscribe : www.

Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Go Paperless with Digital. What Causes Dead Zones? Dead zones are caused by excessive nitrogen and phosphorous pollution from human activities, including: Agricultural runoff from farmland that carries nutrients from fertilizers and animal manure into rivers and streams, eventually flowing into the Chesapeake Bay.

Wastewater treatment plants that release treated water—often still containing large amounts of nutrients—into streams and rivers across the watershed that flow into the Chesapeake Bay. Air pollution from our cars, factories, gas-powered tools, and power plants that contribute nearly 30 percent of the total nitrogen pollution to the Bay's waterways.

Can Dead Zones Recover? Here are actions you can take to fix the dead zones in the Chesapeake Bay: Support our Bay-saving work. Make a donation to help CBF continue the fight to stop the pollution that causes dead zones. Join our action network and let your elected officials know you care about clean water Get the latest updates on local and federal actions you can take by signing up to receive our action alerts.

Calculate your Bay Footprint , then take action at home. Don't over-fertilize your lawn or don't fertilize at all! If you do fertilize, do so when your grass is actively growing and absorbing the fertilizer think spring and summer. Make changes that reduce the amount of pollution that runs off your property. Install a rain barrel, build a rain garden, use porous pavers or gravel in place of paved surfaces. Direct your rain spouts into a rain barrel, rain garden, gravel swale, or—at the very least—onto your lawn, instead of your driveway.

If you live near the water in Maryland or Virginia , become an oyster gardener. Support farms that practice regenerative agriculture. Learn more ways to get involved in saving the Bay. When these algae die and sink to the bottom, they provide a rich food source for bacteria, which in the act of decomposition consume dissolved oxygen from surrounding waters.

If stratification of the water column prevents the mixing or dissolution of atmospheric oxygen into these waters, they will remain oxygen poor. Stratification occurs frequently in the deeper waters of Chesapeake Bay during the summer doldrums, when calm conditions minimize physical mixing of the water column by surface waves.