The government has been working with agriculture, environmentalists and scientists to come up with a way to reduce the size of a ‘dead zone’ in the Gulf of Mexico. The dead zone causes problems for the fisheries in the Gulf. It’s believed the dead zone is caused by excess nitrogen on farm fields in the Midwest that’s washed to the Mississippi River and then to the Gulf. A government task force has determined that if the flow of nitrogen into the Gulf can be cut by 30 percent, the size of the dead zone can be reduced. The Great Lakes Radio Consortium’s Lester Graham reports… a new study predicts a 30 percent reduction won’t be enough to make a difference:
The government has been working with agriculture, environmentalists and scientists to
come up with a way to reduce the size of a ‘dead zone’ in the Gulf of Mexico. The dead
zone causes problems for the fisheries in the Gulf. It’s believed the dead zone is caused
by excess nitrogen on farm fields in the Midwest that’s washed to the Mississippi River
and then to the Gulf. A government task force has determined that if the flow of nitrogen
into the Gulf can be cut by 30 percent, the size of the dead zone can be reduced. The
Great Lakes Radio Consortium’s Lester Graham reports… a new study predicts a 30
percent reduction won’t be enough to make a difference:
The idea that fertilizer used on a corn field in the Midwest can cause a ‘dead zone’ in the Gulf of Mexico
is hard to fathom. But when you realize that all or parts of 31 farm states drain into the
Mississippi basin, it becomes a little easier to understand. Excess nitrogen causes a huge algae
bloom in the Gulf. When the vegetation dies, it decays on the bottom and bacteria feed
on it. The huge expanse of bacteria depletes the oxygen.
Nancy Rabalais is a professor with the Louisiana Universities Marine Consortium. She
says most life under the water needs that oxygen to survive.
“The oxygen is depleted in the water column so that the fish and shrimp, anything that
can swim, leaves the area. All the indicators show that it’s gotten much worse since the
1950’s to present, and that’s consistent with the increase in nitrogen in the Mississippi
Since 1985, Rabalais has been measuring the size of the dead zone every year. The zone
ranges in size from about 2,000 square miles to about 10,000 square miles.
That’s about the size of Lake Erie.
Jerald Horst is a biologist with the Louisiana Sea Grant. He says it’s hard to know the
exact impact on life under the sea…
“Very difficult to say ‘Gee, this year the shrimp
production is down somewhat because of hypoxia,’ or whether the shrimp production is
down somewhat because of a host of other environmental factors.”
But the fear is the hypoxic zone could stop being a dead zone that shrinks and grows
– and one year disappeared altogether… and instead become a permanent dead zone where nothing would ever live. That’s happened in a few other places on the globe such
as the Black Sea. It’s not clear that the same kind of thing can happen in the Gulf, but
signs are ominous. Horst says upwellings of oxygen-starved water near the shore after a
storm used to be very, very rare. Lately, they’ve become more and more frequent. He
says it means the problem is getting worse.
There’s still a lot of debate about whether the dead zone in the Gulf is a serious problem.
But, at this point, most agricultural agencies and farm groups have stopped disputing the
science and whether their nitrogen is causing the problem. Now they’re trying to figure
out the best and cheapest way to deal with it.
The government task force that’s working on the problem has arrived at an Action Plan;
the task force has determined the amount of nitrogen getting into the Mississippi River
needs to be cut by 30 percent to reduce the Gulf zone by half in ten years.
Donald Scavia has been working on the problem. He was involved in the debate when he
was a senior scientist with the National Oceanic and Atmospheric Administration. He’s
retired from NOAA and now directs the Michigan Sea Grant. From his office at the
University of Michigan, Scavia explained how the task force arrived at the figure.
“We agreed to a 30 percent reduction because it was similar to what was done in other
places, probably acceptable to the community and will head us in the right direction.”
After arriving in Michigan, Scavia started research to determine if a 30 percent reduction
would do the job. Using three very different computer models, Scavia and his team
learned that they could actually predict the size of the dead zone from year to year…
“From that analysis, that not only looked at the size of the zone, but actually looked at
potential inter-annual variability caused by changes in climate, changes in weather say
that probably 35 to 45 percent nitrogen load reduction’s going to be needed to get to that
goal in most years.”
Scavia’s study was published in the journal Estuaries.
A 35 to 45 percent reduction is a much tougher goal than the 30 percent the task force is
recommending. As it is, states were planning massive artificial wetlands and extensive
drainage programs to soak up excess nitrogen before it got to the tributaries that fed the
Mississippi River. They also planned to get farmers to reduce the amount of nitrogen
they’re using. That’s a tough sell for a couple of reasons. First of all, it would have to be
voluntary because nitrogen use is nearly completely unregulated. Second, farmers
often use what they call an insurance application of nitrogen… they use a little more than
is actually needed to get a good crop, because nitrogen is relatively cheap. The excess
often ends up washed into ditches and streams and creeks and rivers… and finally to the
Mississippi and the Gulf of Mexico’s dead zone. So… cutting nitrogen flow into the
Mississippi by 30 percent was a huge task. Cutting nitrogen by as much as 45 percent… well… you can imagine…
For the Great Lakes Radio Consortium, this is Lester Graham.