• Home
• Section I: Tools and Skills
  • Chapter 1.2: Critiquing The Statistics You Encounter
  • Chapter 1.3: Experimental Design and Sampling
  • Chapter 1.4: Describing and Visualizing Data
  • Chapter 1.5: Examining Relationships: Correlations
  • Chapter 1.6: Testing for Differences Between Means: t-tests and ANOVA`s
  • Chapter 1.7: Making Predictions: Regression Analyses
  • Chapter 1.8: Chi-square (ᵡ2) Test
  • Chapter 1.9: Carbon Footprints
  • Chapter 1.10: Ecological Footprints
  • Chapter 1.11: Cost Benefit Analyses
  • Chapter 1.12: Environmental Risk Assessments
  • Chapter 1.13: Life Cycle Assessments
  • Chapter 1.14: Geospatial Analyses
  • Chapter 1.15: Communicating Like a Professional
• Section II: Global Water Resources Case Studies
  • Case Study 2.2: The Everglades: Changing Hydrology
  • Case Study 2.3: Mediterranean Sea: One System, Many Stressors
  • Case Study 2.4: Gulf of Mexico: Dead Zone
  • Case Study 2.5: Restoration: A Tale of Two Rivers
  • Case Study 2.6: Ocean Acidification
  • Case Study 2.7: Ground Water: What Lies Beneath
  • Case Study 2.8: China`s Three Gorges Dam (TGD): Costs vs. Benefits
• Section III: Air Quality and Atmospheric Science Case Studies
  • Chapter 3.2: Ozone Depletion
  • Chapter 3.3: Persistent Organic Pollutants (POPs)
  • Chapter 3.4: Particulate Matter Pollution (PM)
  • Chapter 3.5: Industrial Smokestack Pollution
  • Chapter 3.6: Household Air Pollution (HAP)
  • Chapter 3.7: Climate Change
• Section IV: Human Impacts on the Global Landscape Case Studies
  • Chapter 4.2: Bark Beetle Infestation
  • Chapter 4.3: Alberta`s Tar Sands
  • Chapter 4.4: Desertification
  • Chapter 4.5: The Amazon Rain Forests
  • Chapter 4.6: Electronic Waste (e-waste)
  • Chapter 4.7: Genetically Modified Organisms (GMOs)
• Section V: Looking Ahead
• Buy Now!

Case Study 2.4: Gulf of Mexico: Dead Zone



This case study examines a recurring problem that’s been plaguing the Gulf of Mexico (GOM): the annual formation of the Dead Zone, an area characterized by hypoxia, low dissolved oxygen (DO) levels in the water column that threaten Gulf marine life. While there are many scientific aspects to consider, we’ll focus on three of the most important: (1) the behavior of the key nutrient nitrogen (N) in Mississippi River watershed soils; (2) the transport of nitrates through the Mississippi River to the Gulf; and (3) the impacts of elevated nitrate levels on the GOM ecosystem.

We’ll conclude by looking at some options for reducing nitrate levels in the Mississippi. Along the way, we’ll look in depth at research being done on various aspects of this recurring problem.
Before you start, review some of the Background Materials on the Gulf of Mexico and its infamous Dead Zone presented here.

Background Materials:

Two good sites for background on the GOM are http://www.epa.gov/gmpo/about/facts.html
and http://www.gulfbase.org/facts.php. Both contain links to other useful web sites.

Also visit http://www.treehugger.com/natural-sciences/48-facts-you-should-know-about-the-gulf-of-mexico-from-sunken-ships-to-ancient-corals.html for some fascinating tidbits on the Gulf.  For instance, did you know that there are 29 species marine mammals found in the Gulf?  How many can you name?

Dead Zone Background: A good review of hypoxia (Dead Zone formation) and its causes is available from the Louisiana Universities Marine Consortium at http://www.gulfhypoxia.net/Overview/.

A US EPA web site (http://water.epa.gov/type/watersheds/named/msbasin/zone.cfm) gives
an update on the GOM Dead Zone formation in recent years and also contains some good
graphics and links to related web sites.

GOM Research:  Visit http://www.gulfhypoxia.net/Research/Shelfwide Cruises/2015/ to check out the latest “Shelfwide Cruise” which is taken each summer to determine the extent of annual Dead Zone formation.

Nitrogen in the Mississippi River Watershed: Web sites that provide useful information on the issue of nitrogen include US EPA’s  http://water.epa.gov/type/rsl/monitoring/upload/EPA-MARB-Fact-Sheet-112911_508.pdf    
and http://www.msrivercollab.org/focus-areas/nitrogen-phosphorus-pollution/. This site from the Mississippi River Collaborative includes useful information on some of the federal regulations that are being used to attempt to control inputs of nitrogen within the basin.

Textbook References and Links:

Innovative Solutions:
 
The Iowa Initiative wetland restoration program:  http://www.ewg.org/news/testimony-official-correspondence/dead-zone-action-needed-ewg-remarks-hypoxia-task-force

The USDA’s Natural Resources Conservation Service’s Mississippi River Basin Healthy Watersheds Initiative: http://www.nrcs.usda.gov/wps/portal/nrcs/detail/ga/programs/?cid=nrcs142p2_020764    OR
http://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/national/home/?cid=STELPRDB1048200

Dr. Nancy Rabalais is one of the leading members of the research community working on the
GOM Dead Zone. Visit https://www.youtube.com/watch?v=AVxF074FpqU to see a video
featuring some of her early work on the Dead Zone.

 

Downloadable data and files:

Exercise 2:  GOM case study data EX2.txt

Exercise 3:  GOM case study data EX3.txt

Exercise 5:  GOM case study data EX5.txt
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