The Challenge of Blue Carbon
A year on from Hurricane Katrina, the small Louisiana town of Luling, about 25 miles west of New Orleans, embarked upon a modest experiment. Instead of discharging treated municipal wastewater through a canal and into a nearby lake, the town would pump its effluent into surrounding bayou swampland.
The change would be a small step in reversing the ecological damage of flood control along the Mississippi River, which for centuries had slowly separated America’s longest river system from its natural floodplain. Although it opened up more land for farming and habitation, flood control set the scene for the levee failures in New Orleans, where more than 1,000 people died in Katrina and its aftermath. Preventing natural seasonal flooding also deprives the Mississippi delta of sediments that renew it, contributing to the loss of 30 percent of its land in the past half-century.
A mangrove swamp might contain 25 times as much carbon as a similar patch of terrestrial forest.
In Luling, sediments that would have flowed directly into the lake would now be trapped in the town’s bayous. Nitrogen, phosphorous, and other chemicals in the cloudy wastewater would enhance the growth of native bald cypress and water tupelo
