Upstream Drought Shrinks Gulf Dead Zone - "Only" Rhode Island-Sized

[hatrack]

NEW ORLEANS -- The dead zone off the coasts of Louisiana and Texas should be considerably smaller than usual this year -- about the size of Rhode Island, rather than larger than Jamaica, researchers say. That's because the Mississippi and Atchafalaya rivers are carrying much less nitrogen and other nutrients than usual into the Gulf of Mexico, according to scientists from the National Oceanic and Atmospheric Administration.

Nancy Rabalais, head of the Louisiana Universities Marine Consortium in Cocodrie, and other researchers will head out Saturday on a week-long research trip to measure the dead zone's summer peak. NOAA is predicting that about 1,500 square miles of Gulf of Mexico waterbottom are likely to be without oxygen this year. That's less than one-third the 4,900-square-mile average (Jamaica is 4,250 square miles) and less than one-fifth the record.

The NOAA forecast is based on the nutrients which feed algae, which eventually die and fall to the ocean floor. When still weather allows the lighter fresh water pouring in from the rivers to remain above the saltier water of the Gulf, the algae's decay uses up oxygen faster than it can be replenished from the surface. Eventually, the lower layer holds too little oxygen for fish and other aquatic life.

The low "nutrient loads" probably were caused by lower-than-normal snow and rainfall across much of the Mississippi River Basin, according to NOAA. In addition, tropical storms and hurricanes have kept the Gulf of Mexico stirred up lately, noted Nancy Rabalais, head of the Louisiana Universities Marine Consortium."

EDIT

http://www.latimes.com/news/science/wire/sns-ap-dead-zone,1,2054885.story?coll=sns-ap-science-headlines

[kestrel91316]

1. I guess the "dead zone" is now what we used to call ..................

the Mississippi?

[Nihil]

2. Ummm

Am I just missing something here?
To my mind, this simply means that there was insufficient rainfall to
wash the nitrates into the "dead zone", not that the nitrates weren't
produced or distributed. This, in turn, means that the nitrates (and
phosphates and ...) are accumulating in the ground so that when the
next rainy season actually arrives, there will be a serious boost in
the dead zone.

Shouldn't the NOAA be banging the drum warning about the next phase
rather than breathing a sigh of relief that "it's not too bad this year"?

[dcfirefighter]

3. Dwell time

if the Nitrates etc. sit in soil long enough, microbes etc. (if they haven't been killed by pesticides) as well as plants will process and/or take up those nutrients. Near-surface groundwater flows are pretty efficient at cleaning up water.

IOW that stuff isn't just sitting there waiting for the next rainy season.

[BeFree]

4. Following that logic...

...one would have to say it's not the pollution that is causing the dead zones - it is too much rainfall.

Damn that rain. If it would just leave the pollution where it falls, we wouldn't be a problem. :sarcasm:

[dcfirefighter]

5. not quite

but almost.

if people wouldn't use more fertilizer than they need to, and would leave riparian buffers (greenspace near rivers and streams), it wouldn't be such a problem.