Hurricane keeps dead zone small - July 31, 2008
Posted on behalf of Amber Dance
The huge "dead zone" of oxygen-poor water in the Gulf of Mexico failed to reach record size this year. Scientists had predicted that this hypoxic zone would swell to 8,800 square miles (Reuters, 15 July) due to floodwaters that poured tonnes of fertilizer into the Mississippi River, which empties the Midwest’s agricultural runoff into the Gulf. But it ended up rating a mere 7,988 square miles (still nearly the size of Israel) and thus ranks as second-biggest since scientists started tracking it in the 1980s. 2002 keeps its place as the worst year, with an 8,500-square-mile dead zone (Washington Post).
Increased corn farming, for ethanol, meant farmers used lots of fertilizer this season. When the rains hit, they rinsed the fertilizer into the river. This spring 83,000 tons of phosphorus rode the Mississippi to the Gulf, 85% higher than average levels. Those nutrients, as they do every year, sparked an algal bloom. When the algae die and sink to the bottom, bacteria feast on their remains. With so many bacteria slurping so many dead algae, the bacteria suck all the dissolved oxygen out of the water faster than it can diffuse back in. Fish and crustaceans rush toward airier waters, including the coastline, in an underwater stampede some Louisiana seafood lovers call a “jubilee.”
But this year, Hurricane Dolly stirred the dead zone like a big pot of soup, aerating water that would otherwise have been oxygenless. Thus by the time scientists finished measuring it, the zone was smaller than predicted.
It should shrink further in the fall, with cooler weather, fewer algae and more storms mixing the waters.
Image (2004 data, for illustration purposes only): NOAA
Comments
Actually it's not just agricultural runoff that is aiding this. Lots of the fertilizer that flows into the Mississippi comes from average homeowners using its on their lawns, etc.
Plus there are plenty of high-phosphorous products on the market that people are still buying, like washing detergent. Electrasol tabs for example contain 8.7% phosphorous concentration. That's a LOT.
I'm part of a boycott to get them to make more environmentally-friendly products: http://www.thepoint.com/campaigns/save-the-environment-by-boycotting-electra-sol-dishwasher-detergent
But basically my point is that there is plenty the average consumer can do here to combat these "dead zones."
Posted by: Vadim | August 1, 2008 07:52 PM
Could the heated dead zones add fuel to hurricanes as they enter the gulf and near our coasts? Seems the algae would be darker and cause more solar heating, so more fuel for the hurricane.
Lawns are often not the problem with phosphorus and nitrogen, because the grass grows densely and holds runoff. By contrast, growing corn for ethanol is done with complete weed eradication with atrazine between rows, and plent of phsphorus and nitrogen added. The runoff from farm lands is massive when compared to lawns. Most of the land use along the ol Miss, is not residential, but in fact agricultural. Factory farms are culprits too, the intentionally overapply manure to nearby "farm fields" in order to get rid of the stuff. Factory farms regularly overload streams and rivers with organic phosphorus which is even more bio available to algae than inorganic phosphorus fertilizer.
Posted by: prime3end | September 10, 2008 11:28 PM