door Klintersaas » di 21 aug 2007, 15:51
Hier is alles te vinden over de hypoxiezone in de Golf van Mexico.
Dit onderdeel geeft goed weer wat de oorzaken zijn:
The hypoxic zone in the Gulf of Mexico results from two sets of circumstances occuring simultaneously. The first occurs where the freshwater of the Mississippi River flows into the salty waters of the Gulf of Mexico. The freshwater, being lighter than saltwater, floats on the surface. Normally, winds churn the waters and mix the layers. However, during the summer months, the weather is warm and the Gulf is especially calm. Fresh and salt water remain separated in layersa condition called stratification. When stratification occurs, the lower saltwater layer becomes cut off from the resupply of oxygen from fresh surface waters.
The second key to hypoxia is the rich nutrient content of the Mississippi River water. Mineral nutrients, especially dissolved inorganic nitrogen, encourage the growth of algae. Some of the algae die; others are consumed by aquatic organisms that generate large amounts of fecal matter. This abundance of organic waste sinks to the saltier depths where it decomposes, using what remains of the available oxygen and creating a hypoxic zone. This condition persists until autumn winds sometimes in the form of tropical storms and hurricanes return to stir the waters of the Gulf.
[url=http://www.ncat.org/nutrients/map.html]Hier[/url] is alles te vinden over de hypoxiezone in de Golf van Mexico.
[url=http://www.ncat.org/nutrients/hypoxia/hypoxia1.htm]Dit onderdeel[/url] geeft goed weer wat de oorzaken zijn:
[quote]The hypoxic zone in the Gulf of Mexico results from two sets of circumstances occuring simultaneously. The first occurs where the freshwater of the Mississippi River flows into the salty waters of the Gulf of Mexico. [b]The freshwater, being lighter than saltwater, floats on the surface.[/b] Normally, winds churn the waters and mix the layers. However, during the summer months, the weather is warm and the Gulf is especially calm. Fresh and salt water remain separated in layersa condition called stratification. When stratification occurs, the lower saltwater layer becomes cut off from the resupply of oxygen from fresh surface waters.
The second key to hypoxia is the rich nutrient content of the Mississippi River water. [b]Mineral nutrients, especially dissolved inorganic nitrogen, encourage the growth of algae. Some of the algae die; others are consumed by aquatic organisms that generate large amounts of fecal matter. This abundance of organic waste sinks to the saltier depths where it decomposes, using what remains of the available oxygen and creating a hypoxic zone.[/b] This condition persists until autumn winds sometimes in the form of tropical storms and hurricanes return to stir the waters of the Gulf.[/quote]
[img]http://www.globalchange.umich.edu/gctext/Inquiries/Inquiries_by_Unit/Unit_10_files/image017.jpg[/img]
