A Look at Dead Zones

By now, many people know that fertilizers and pesticides from industrial farms are coming into contact with bodies of water crucial to environmental equillibrium. But the directly-contaminated sloughs and ponds are only a fragment of the damage being done; these contaminants accumulate down the stream of major river systems and feed into the ocean, creating "dead zones."

SeaWiFS (NASA's Sea-photographing satellite) displaying three creeping dead zones stoked by industrial runoff


Natural food sources like crabs, shrimp, and fish are starved of oxygen as the fertilizer overfeeds phytoplankton and turns the ocean from blue to green (and when the nutrients run out, to brown) as can be seen in the SeaWiFS graphic above.

It's one thing to make sure that industries are properly dealing with the pollutants that they produce and utilize, but sometimes it isn't enough: hurricanes, floods, and other weather anomalies can take everything from animal waste pools to entire fields worth of fertilizer out to sea, sometimes completely overwhelming aqua-ecosystems in just a few weeks.
flooded sewage lagoon
A flooded animal waste lot in the aftermath of Hurricane Floyd, 1999

Despite the effects of weather, dead zone creep is not out of our control. By tightening regulations on disposal of agricultural waste and use of fertilizers and pesticides, we can make sure that food is produced with a minimal chance of ecological disaster. If we don't, we could gradually destroy natural food resources and culture the agro-industrial feedback loop that forces us to rely on heavily-polluting food production.


Sources:
http://disc.sci.gsfc.nasa.gov/education-and-outreach/additional/science-focus/ocean-color/dead_zones.shtml

http://serc.carleton.edu/microbelife/topics/deadzone/index.html

http://onlinelibrary.wiley.com/doi/10.1029/94EO01045/abstract

http://earthobservatory.nasa.gov/Features/FloydFear/

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