[Rhodes22-list] Expanding Dead Zone in the Gulf of Mexico

[DCLewis1 at aol.com]

JW,
 
Thanks for your reply.  I didn’t know any of that, it’s really good  info.
 
The problem in the Chesapeake Bay (well, one principal problem) is runoff  
from agriculture and sewage.  And there are other problems (invasive  species, 
loss of wet lands, you name it).  
 
Re the red tide: Seems strange to me that the population of alge that  causes 
the red tide could simply take off without a lot of some sort of  nutrient.  
Clearly, it takes more of something for the little buggers  to “bloom”, 
whatever the “it” is, let’s call it a nutrient.  But it may  well not be “man made
”.
 
Re freshwater inhibiting oxygen exchange to salt water, that’s news to  me.  
I had no idea there was any substantial difference between the oxygen  
carrying capabilities of fresh and salt water - I’d never thought about  it.   Your 
post prompted me to do a little checking, I see there’s  about a 20% between 
the solubility of oxygen in seawater and fresh water.   I’m still bothered that 
the freshwater on top has more oxygen, I don’t see how  that maps to less 
oxygen in the salt water at depth - its as if the fresh water  were scavenging 
oxygen from the salt water, as opposed to being a richer source  of oxygen at 
some depth than would otherwise be the case.  If it were the  inverted situation, 
(fresh water = less oxygen) I could understand how the  freshwater could act 
as a barrier for transfer of oxygen from the atmosphere to  depth. 
 
Clearly, you know this stuff - I’m impressed.  I hope someone is  trying to 
figure it all out and mitigate these large  “dead zones” and fish  kills.  It’
s bad for tourism and bad for fish and other critters that are  in, use, or 
eat products from, those waters.
 
Dave



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