Oceanic Dead Zones: How Bad?

Following Hatrack’s post, I’d like to poll the Energy/Environment readers about the meaning and possible peril of the recent appearance of oceanic “Dead Zones”.

Well, exactly how bad are they?

--p!

I guess I'm just a cockeyed optimist, to borrow a phrase from Rodgers & Hammerstein. ;-)

I expect they would all clear themselves up pretty quickly, if we ever curtailed the massive flows of fertilizer from our rivers. The worrisome part is that nobody is making any serious attempt to curtail anything, so we can expect them to continue getting worse.

Personally, I'm more frightened of global climate change. All the indications are that it would continue for decades, even if we magically quit dumping CO2 into the atmosphere tomorrow. To say nothing of what we're actually doing, which is steadily increasing the rate of our dumping.

from 1992 to 1995 (5 research cruises - 3 publications).

There are a lot of things going on out there that haven't been investigated.

The so-called Dead Zone may be a "hot spot" for nitrous oxide emissions (a greenhouse gas that also destroys stratospheric ozone).

A lot of the fertilizer-derived nitrogen discharged from the Mississippi River is rapidly transformed to ammonium in the Gulf of Mexico.

This ammonium is oxidized to nitrate by nitrifying bacteria (which also consume a lot of oxygen in the process).

Under low oxygen (hypoxic) conditions, up to 10% of the nitrogen processed by nitrifying bacteria is transformed into nitrous oxide (which may be out-gassed to the atmosphere).

Nitrification rates in the Mississippi River plume are the highest measured in any marine system - but we really don't know what they are in the hypoxic waters, and we know even less (nothing actually) about nitrous oxide production.

And...we don't really know how fast recovery would be if nitrogen inputs to the Gulf of Mexico were curtailed - there may be enough nitrogen accumulated on the Louisiana Shelf to sustain the formation of hypoxic bottom water for a long time to come.

Valley of the Sun (maybe more appropriately named "The Phoenix super-sprawl").

A couple weeks ago, every fish in that "lake" up and died. It was algae, that attached to the gills and suffocated the fish. Every damned fish. 33 thousand pounds of it. Boom, dead.

I hadn't heard this, but the algae got into this lake from the Saguaro Reservoir. Where all the fish also died recently.

That sort of makes ya think.