Though not the only source of pollution, there is concern that increased mandates for biofuels will increase corn production, and fertilizer runoff, thereby exacerbating the dead zone problem. Photo: Ricky via flickr
TreeHugger has covered the issue of ocean dead zones, in particular the annual 8,000 square mile one in the Gulf of Mexico, a number of times. Now, the US Geological Survey has released new maps which pinpoint the watersheds within the Mississippi River Basin which most contribute to the problem:The short version is that commercial fertilizer and animal manure in nine states—Illinois, Iowa, Indiana, Missouri, Arkansas, Kentucky, Tennessee, Ohio and Mississippi—causes 70% of the problem. But when you look at the maps the USGS has put out you can see that it's a bit more complicated than that. Those bright red areas show areas with the greatest contribution; it's really specific places within these states.
Ranking of total phosphorus yields delivered to the Gulf of Mexico. Source: USGS
Ranking of total nitrogen yields delivered to the Gulf of Mexico. Source: USGS
Commenting on the new data released, Michelle Perez, Senior Agriculture Analyst at the Environmental Working Group said,
Currently, federal Farm Bill conservation dollars are not targeted to where the pollution is generated. This new report should help states focus their pollution reduction efforts in the top ranked watersheds and on the most cost-effective practices.
The USGS points out that just because an area is listed on these maps as not having a great contribution to the nitrogen or phosphorus yields into the Gulf of Mexico that are causing the dead zone, it does not address the smaller-scale nutrient management needed to protect streams and reservoirs at the local level.
More: USGS National Water-Quality Assessment Program and Incorporating Uncertainty Into The Rankings of SPARROW Model Nutrient Yields From Mississippi/Atchafalaya River Basin Watersheds
Ocean Dead Zones
Crop Biodiversity A Cure For Ocean Dead Zones?
Tropical Dead Zones Set to Expand by 50 Percent Under Climate Change
A Primer on Global Warming-Caused Marine Dead Zones
Another Dire Global Warming Effect: 10 Times As Many Ocean Dead Zones