Featured Research

from universities, journals, and other organizations

Phosphorus Found To Be Another Culprit In Gulf Of Mexico's 'Dead Zone'

Date:
November 15, 2006
Source:
National Science Foundation
Summary:
Nitrogen is flowing down the Mississippi River and into the Gulf of Mexico faster than it can be consumed by floating microscopic plants called phytoplankton, increasing the size of the "dead zone" off the Louisiana coast. The findings, based on analysis of data gathered in 2001, are published online this week in the journal Environmental Science and Technology.

A research boat gathers seawater samples in the Gulf of Mexico to test for nutrient levels.
Credit: Quay Dortch

Nitrogen is flowing down the Mississippi River and into the Gulf of Mexico faster than it can be consumed by floating microscopic plants called phytoplankton, increasing the size of the "dead zone" off the Louisiana coast. The findings, based on analysis of data gathered in 2001, are published online this week in the journal Environmental Science and Technology.

Related Articles


Because of the increased nitrogen levels, phytoplankton blooms are growing, and the Gulf's hypoxia zone -- an area lacking enough oxygen to sustain most life -- is getting bigger.

"In a pristine system, nutrients would flow down the river and into the Gulf, and there would be limited phytoplankton growth and no hypoxia," said James Ammerman, co-author of the paper and a biological oceanographer at Rutgers. "Heavy use of fertilizers containing nitrogen and phosphorus in the agriculture of the Mississippi Valley has thrown the system out of balance."

According to Ammerman, phytoplankton need both nitrogen and phosphorus to grow. Because they require a 16-to-1 ratio of nitrogen to phosphorus, phytoplankton usually run out of nitrogen first; most coastal surface waters have ratios lower than 16-to-1.

"There is now so much nitrogen in the Gulf that even though phytoplankton consume it faster than they consume phosphorus, they can't get rid of it fast enough, and it's the phosphorus, instead of nitrogen, that runs out first and becomes the limiting nutrient," Ammerman said.

This research shows the complex interactions of "nitrogen and phosphorus, river water inputs and timing, and coastal circulation and salinity as they interact to fuel biological productivity in the Gulf of Mexico," said Philip Taylor, Director of the National Science Foundation's (NSF) Biological Oceanography Program. "Multiple nutrients are implicated in the problems in the Gulf, and need to be considered in solving those problems."

The research was funded by NSF and the National Oceanic and Atmospheric Administration (NOAA).

Scientists have been measuring the flow of nutrients down the river since the 1950s, and the "dead zone," first noticed as a seasonally recurring feature in the late 1980s, has since doubled in size to an area larger than New Jersey.

"There are models that suggest hypoxia wasn't a problem there before the 1970s," Ammerman said." Data indicates occasional hypoxic events going back to the 19th century, but only in years of extremely high freshwater flow."

Jason Sylvan of the Rutgers University Institute of Marine and Coastal Sciences in New Brunswick, N.J., is the lead author of the paper. He and Ammerman are joined as co-authors by Quay Dortch, of the Louisiana Universities Marine Consortium and NOAA; Wendy Morrison, also of the Louisiana Universities Marine Consortium; Alisa Maier Brown of Louisiana State University; and David Nelson of Oregon State University.


Story Source:

The above story is based on materials provided by National Science Foundation. Note: Materials may be edited for content and length.


Cite This Page:

National Science Foundation. "Phosphorus Found To Be Another Culprit In Gulf Of Mexico's 'Dead Zone'." ScienceDaily. ScienceDaily, 15 November 2006. <www.sciencedaily.com/releases/2006/11/061115053913.htm>.
National Science Foundation. (2006, November 15). Phosphorus Found To Be Another Culprit In Gulf Of Mexico's 'Dead Zone'. ScienceDaily. Retrieved October 31, 2014 from www.sciencedaily.com/releases/2006/11/061115053913.htm
National Science Foundation. "Phosphorus Found To Be Another Culprit In Gulf Of Mexico's 'Dead Zone'." ScienceDaily. www.sciencedaily.com/releases/2006/11/061115053913.htm (accessed October 31, 2014).

Share This



More Earth & Climate News

Friday, October 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How A Chorus Led Scientists To A New Frog Species

How A Chorus Led Scientists To A New Frog Species

Newsy (Oct. 30, 2014) A frog noticed by a conservationist on New York's Staten Island has been confirmed as a new species after extensive study and genetic testing. Video provided by Newsy
Powered by NewsLook.com
Raw: Hawaii Lava Approaching Village Road

Raw: Hawaii Lava Approaching Village Road

AP (Oct. 30, 2014) The lava flow on the Big Island of Hawaii was 225 yards from Pahoa Village Road on Wednesday night. The lava is slowing down but still approaching the village. (Oct. 30) Video provided by AP
Powered by NewsLook.com
Endangered Carpathian Ponies Are Making a Comeback in Poland

Endangered Carpathian Ponies Are Making a Comeback in Poland

AFP (Oct. 29, 2014) At the foot of the rugged Carpathian mountains near the Polish-Ukrainian border, ranchers and scientists are trying to protect the Carpathian pony, known as the Hucul in Polish. Duration: 02:17 Video provided by AFP
Powered by NewsLook.com
Deadly Mudslide in Sri Lanka Buries Houses

Deadly Mudslide in Sri Lanka Buries Houses

AP (Oct. 29, 2014) A mudslide triggered by monsoon rains buried scores of workers' houses at a tea plantation in central Sri Lanka on Wednesday, killing at least 10 people and leaving more than 250 missing, an official said. (Oct. 29) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins