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Good evening, welcome to New Orleans.
I don't know if you knew this,
but you are sitting within 15 minutes of one of the largest rivers in the world:
the Mississippi river.
Old Man River, Big Muddy.
And it goes as far north as the state of Minnesota,
as far east as the state of New York,
as far west as Montana.
And 100 miles from here, river miles,
it empties its fresh water and sediments into the Gulf of Mexico.
That's the end of Geography 101.
Now we're going to go to what is in that water.
Besides the sediment, there are dissolved molecules, nitrogen and phosphorus.
And those, through a biological process,
lead to the formation of areas called dead zones.
Now, dead zone is a quite ominous word
if you're a fish or a crab.
Even a little worm in the sediments.
Which means that there's not enough oxygen
for those animals to survive.
So, how does this happen?
The nitrogen and the phosphorus
stimulate the growth of microscopic plants called phytoplankton.
And small animals called zooplankton eat the phytoplankton,
small fish eat the zooplankton, large fish eat the small fish
and it goes on up into the food web.
The problem is that there's just too much nitrogen and phosphorus right now,
too much phytoplankton falling to the bottom
and decomposed by bacteria that use up the oxygen.
That's the biology.
Now, you can't see it from the surface of the water,
you can't see it in satellite images,
so how do we know it's there?
Well, a trawler can tell you,
when she puts her net over the side and drags for 20 minutes
and comes up empty,
that she knows she's in the dead zone.
And she has to go somewhere else.
But where else do you go if this area is 8,000 square miles big?
About the size of the state of New Jersey.
Well, you either make a decision to go further,
without much economic return,
or go back to the dock.
As a scientist, I have access to high-tech equipment
that we can put over the side of the research vessel,
and it measures oxygen and many more things.
We start at the Mississippi River,
we crisscross the Gulf of Mexico all the way to Texas,
and even I sneak into Texas every now and then and test their waters.
And you can tell by the bottom oxygen --
you can draw a map of everything that's less than two,
which is the magic number for when the fish start to leave the area.
I also dive in this dead zone.
We have oxygen meters that we have to deploy offshore
that tell us continuous measurements of low oxygen or high oxygen.
And when you get into the water, there's a lot of fish.
Tons of fish, all kinds of fish,
including my buddy here, the barracuda that I saw one day.
Everybody else swam this way and I went this way with my camera.
And then, down at 30 feet you start to see fewer fish.
And then you get to the bottom.
And you don't see any fish.
There's no life on the platform, there's no life swimming around.
And you know you're in the dead zone.
So, what's the connection between the middle of the United States
and the Gulf of Mexico?
Well, most of the watershed is farmland.
And in particular, corn-soybean rotation.
The nitrogen that is put in fertilizers and the phosphorus goes on the land
and drains off into the Mississippi River
and ends up in the Gulf of Mexico.
There's three times more nitrogen in the water
in the Mississippi now,
than there was in the 1950s.
Three times.
And phosphorus has doubled.
And what that means is more phytoplankton and more sinking sails and lower oxygen.
This is not a natural feature of the Gulf; it's been caused by human activities.
The landscape is not what it used to be.
It used to be prairies and forests and prairie potholes
and duck areas and all kinds of stuff.
But not anymore -- it's row crops.
And there are ways that we can address this type of agriculture
by using less fertilizer, maybe precision fertilizing.
And trying some sustainable agriculture
such as perennial wheatgrass, which has much longer roots
than the six inches of a corn plant,
that can keep the nitrogen on the soil and keep the soil from running off.
And how do we convince our neighbors to the north,
maybe 1,000 miles away or more,
that their activities are causing problems with water quality in the Gulf of Mexico?
First of all, we can take them to their own backyard.
If you want to go swimming in Wisconsin in the summer
in your favorite watering hole,
you might find something like this
which looks like spilled green paint and smells like it,
growing on the surface of the water.
This is a toxic blue-green algal bloom
and it is not good for you.
Similarly, in Lake Erie, couple of summers ago
there was hundreds of miles of this blue-green algae
and the city of Toledo, Ohio, couldn't use it for their drinking water
for several days on end.
And if you watch the news,
you know that lots of communities are having trouble with drinking water.
I'm a scientist.
I don't know if you could tell that.
And I do solid science, I publish my results,
my colleagues read them, I get citations of my work.
But I truly believe that, as a scientist,
using mostly federal funds to do the research,
I owe it to the public,
to agency heads and congressional people
to share my knowledge with them
so they can use it, hopefully to make better decisions
about our environmental policy.
Thank you.
One of the ways that I was able to do this is I brought in the media.
And Joby Warrick from the "Washington Post"
put this picture in an article
on the front page, Sunday morning, two inches above the fold.
That's a big deal.
And Senator John Breaux, from Louisiana,
said, "Oh my gosh, that's what they think the Gulf of Mexico looks like?"
And I said, "Well, you know, there's the proof."
And we've go to do something about it.
At the same time, Senator Olympia Snowe from Maine
was having trouble with harmful algal blooms in the Gulf of Maine.
They joined forces -- it was bipartisan --
And invited me to give congressional testimony,
and I said, "Oh, all I've done is chase crabs around south Texas,
I don't know how to do that."
But I did it.
And eventually, the bill passed.
And it was called -- yeah, yay!
It was called The Harmful Algal Bloom
and Hypoxia Research and Control Act of 1998.
Thank you.
Which is why we call it the Snowe-Breaux Bill.
The other thing is that we had a conference in 2001
that was put on by the National Academy of Sciences
that looked at fertilizers, nitrogen and poor water quality.
Our plenary speaker was the former governor
of the state of New Jersey.
And she ...
There was no thinking she wasn't serious when she peered at the audience,
and I thought, "Surely she's looking at me."
"You know, I'm really tired of this thing being called New Jersey.
Pick another state, any state, I just don't want to hear it anymore."
But she was able to move the action plan
across President George H.W. Bush's desk
so that we had environmental goals
and that we were working to solve them.
The Midwest does not feed the world.
It feeds a lot of chickens, hogs, cattle
and it generates ethanol
to put into our gasoline,
which is regulated by federal policy.
We can do better than this.
We need to make decisions
that make us less consumptive
and reduce our reliance on nitrogen.
It's like a carbon footprint.
But you can reduce your nitrogen footprint.
I do it by not eating much meat --
I still like a little every now and then --
not using corn oil,
driving a car that I can put nonethanol gas in
and get better gas mileage.
Just things like that that can make a difference.
So I'm challenging, not just you,
but I challenge a lot of people, especially in the Midwest --
think about how you're treating your land and how you can make a difference.
So my steps are very small steps.
To change the type of agriculture in the US
is going to be many big steps.
And it's going to take political and social will for that to happen.
But we can do it.
I strongly believe we can translate the science,
bridge it to policy and make a difference in our environment.
We all want a clean environment.
And we can work together to do this
so that we no longer have these dead zones in the Gulf of Mexico.
Thank you.


【TED】The "dead zone" of the Gulf of Mexico | Nancy Rabalais

552 タグ追加 保存
Zenn 2018 年 5 月 10 日 に公開


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