Researchers study agricultural impact on Mississippi River

According to a study published in Nature by researchers at LSU and Yale University, farming has significantly changed the hydrology and chemistry of the Mississippi River, injecting more carbon dioxide into the river and raising river discharge during the past 50 years.

LSU Professor R. Eugene Turner and graduate student Whitney Broussard, along with their colleagues at Yale, tracked changes in the discharge of water and the concentration of bicarbonate, which forms when carbon dioxide in soil water dissolves rock minerals. Bicarbonate in rivers plays an important, long-term role in absorbing atmospheric carbon dioxide, a greenhouse gas. Oceans then absorb this carbon dioxide, but become more acidic in the process, making it more difficult for organisms to form hard shells – a necessary function in coral reefs, for example.

Researchers concluded that liming and farming practices, such as changes in tile drainage, tillage practices and crop type, are most likely responsible for the majority of the increase in water and carbon in the Mississippi River, North America’s largest river.

“It’s like the discovery of a new large river being piped out of the corn belt,” said Pete Raymond, lead author of the study and associate professor of ecosystem ecology at the Yale School of Forestry & Environmental Studies.

The research team analyzed 100-year-old data on the Mississippi River warehoused at two New Orleans water treatment plants, and combined it with data on precipitation and water export.

“The water quality information we used has been sitting idle for over 50 years in an attic in New Orleans, waiting to be discovered,” said Broussard, who is pursuing a doctoral degree in coastal ecology at LSU. “I felt like a treasure-hunter when we opened those boxes in that 100-plus degree attic to find those data logs. You never know where your research will take you if you’re open to suggestion and serendipity.” Turner, distinguished professor of coastal ecology, added, “and [where it will take you] if you have the benefits of long-term collaborations of trusting and high-quality academic research groups.”

The research team used the data to demonstrate the effects of this excess water on the carbon content of the river, and argue that the additional water in the river is altering the chemistry of the Gulf of Mexico as by increasing the amount of nutrients and pollution the river transports to the Gulf.

“We’re learning more and more about the far-reaching effects of American agriculture on rivers and lakes. This also means that the agricultural community has an incredible opportunity to influence the natural environment in a positive way, more than any other contemporary enterprise,” said Broussard. “If we want to clean the water, we have to steward the land with right agriculture.”

Source: Louisiana State University

Related stories:

OSU Scientist Uses Fiber Optics to Measure Water and Air
Scientists at Oregon State University are using fiber optics to study the temperature of water, the flow of air, and the dynamics of snow melt.
Did a Significant Cool Spell Mark the Demise of Megafauna?
The end of the Pleistocene Epoch was marked with steadily warmer temperatures and the great ice age glaciers that covered vast areas of North America were in retreat.
Researchers view microorganisms from space
What is the smallest thing you can see from space? From a standard shuttle orbit of 217 kilometers above the Earth’s surface, it is suggested that you can see the Great Wall of China. With the aid of binoculars, you can also see clearly the pyramids of Giza, large ships and even major roads.
Nanoscience will change the way we think about the world
The ubiquity of mineral nanoparticles in natural waters, the atmosphere, and in soils and their intriguing properties provide Earth scientists with another dimension in which to understand our planet.
Studying rivers for clues to global carbon cycle
In the science world, in the media, and recently, in our daily lives, the debate continues over how carbon in the atmosphere is affecting global climate change. Studying just how carbon cycles throughout the Earth is an enormous challenge, but one Northwestern University professor is doing his part by studying one important segment -- rivers.
Waterborne carbon increases threat of environmental mercury
Mercury is a potent neurotoxin and a worrisome environmental contaminant, but the severity of its threat appears to depend on what else is in the water.
New, rare and threatened species discovered in Ghana
Scientists exploring one of the largest remaining blocks of tropical forest in Western Africa discovered significant populations of new, rare and threatened species underscoring the area’s high biological diversity and value.
Where does stored nuclear waste go?
Millions of gallons of hazardous waste resulting from the nation’s nuclear weapons program lie in a remote location in southeastern Washington state called Hanford. Beneath this desert landscape about two million curies of radioactivity and hundreds of thousands of tons of chemicals are captured within the stratified vadose zone below which gives rise to complex subsurface flow paths.

News discussion:

Space & Earth science news