It's tough being green..... - DPChallenge Forums

11/07/2008 12:09:14 AM · #1

Oh the tortured path of logic we try to follow to be "green". That was the darnest article I believe I've ever read.

It reminds me of the local police force that was running nitrogen in their tires and were saying it made their ride smoother.

The dumbacres in this piece might want to remember we have about 21 percent oxygen in our air. As spillways increase the agitation of water, they'll also increase the oxygenation of water, generally something fish like. While I concede there could be some quirk I don't know about salmon that might make them seek out waters with slightly lower oxygen levels, I doubt that their survival depends on it. In any event the environmentalists want us to remove the dams anyway! So lets just tear down the damn dams! Jesus de Cristo!

11/07/2008 12:29:00 AM · #2

High nitrogen levels are toxic to fish. If it just increased the oxygen level it wouldn't be so bad (though levels CAN be too high of it, too) but it doesn't work that way.

Message edited by author 2008-11-07 00:30:27.

Pentax D-FA* 70-200mm f/2.8 ED DC AW

11/07/2008 12:40:33 AM · #3

Originally posted by BeeCee:

High nitrogen levels are toxic to fish. If it just increased the oxygen level it wouldn't be so bad (though levels CAN be too high of it, too) but it doesn't work that way.

But... common sense says it would have to be a ratio different than that found in air to be problematic.
The partial pressure of nitrogen and oxygen in oxygenated water doesn't change at shallow depths.
The only wild card I see would be interaction of nitrogen with waste products of animals in the water. But most of these processes tend to fix nitrogen, thus reducing the quantity. Oh, well. They just need to blowup the dams and build an interconnecting power network for the North American continent and we'll be ok. hehehehe

Edit: Come to think of it the dams are supposed to be what's dooming the salmon anyway. A lot of running water existed before the dams were built..... hehehehe

Message edited by author 2008-11-07 00:42:38.

K3Master

Pentax K-3

11/07/2008 12:42:52 AM · #4

What we really need is a drastic reduction in the number of human beings living on the earth.

Although the earth will do that for us one day, it's inevitable.

11/07/2008 12:49:28 AM · #5

Originally posted by K10DGuy:

What we really need is a drastic reduction in the number of human beings living on the earth.

Although the earth will do that for us one day, it's inevitable.

I agree with both statements. To read an interesting novel about your first statement try out Tom Clancy's "Rainbow Six". It will give you a quick insight on Clancy's feelings about environmentalists.

11/07/2008 01:28:54 AM · #6

I had to run an errand in the middle of my searching so lost the one gov't article I'd read and was going to cite, but I believe it said in water going over a spillway nitrogen levels can rise to 115% of atmospheric pressure.

Here's stats I found here;

"Eggs can tolerate a relatively high total gas pressure (110% to 115%), however as the eggs hatch they become very sensitive to elevated gas pressure. Fish moralities can be expected at gas (nitrogen) pressures above 105%. However at lower levels ranging from 102% to 105% moralities might also be expected. The low gas pressures may not cause moralities directly, however they will stress the fish and predispose them to infection and possibly long terms problems.
GAS PRESSURE AND DISEASE
Salmonids and most aquatic animals will tolerate up to 102% gas supersaturation with nitrogen. However long term damage may be inflicted on the organisms. For example in the case of juvenile salmon, exposure to low level gas pressure may damage the gill structure, bone formation, blood capillaries and the nervous system. These conditions will render the fish susceptible to a high rate of infection in the hatchery.
Symptoms
Recent evidence has shown that levels up to 102% can cause an increased incidence of myxobacteria gill infections, the fish also become sensitive to light and mass mortalities may be experienced shortly after feeding the fish. Mass mortalities may also be experienced during periods of low atmospheric air pressure or if water level in the tanks are reduced.
There is also some evidence which suggests that exposure of salmon to elevated gas pressures for a short period of time after egg hatch may reduce the ability of the smolt to osmoregulate when transferred to the sea. It may therefore be the case that exposure to elevated gas pressures at an early stage in the Atlantic Salmon life cycle could be a possible reason for 'Failed Smolt Syndrome, or it could predispose the fish to increased incidence of disease or other as yet un-recognized problems."

Now I'm about to hit my old college texts and see if any of the ones I kept are the right ones :)

11/07/2008 01:40:32 AM · #7

I realise the above comments relate to hatcheries and fish farming but the principles are basically the same.

From the abstract on Estimating adult Chinook salmon exposure to dissolved gas supersaturation downstream of hydroelectric dams using telemetry and hydrodynamic models;

Gas bubble disease (GBD) has been recognized as a potential problem for fishes in the Columbia River basin. GBD results from exposure to gas supersaturated water created by discharge over dam spillways. Spill creates a downstream plume of water with high total dissolved gas supersaturation (TDGS) that may be positioned along either shore or mid-channel, depending on dam operations. We obtained spatial data on fish migration paths and migration depths for adult spring and summer Chinook salmon, Oncorhynchus tshawytscha, during 2000. Migration paths were compared to output from a two-dimensional (2-dimensional) hydrodynamic and dissolved gas model to estimate the potential for GBD expression and to test for behavioural avoidance of the high TDGS plume. We observed salmon swam sufficiently deep in the water column to receive complete hydrostatic compensation 95.9% of the time spent in the Bonneville Dam tailrace and 88.1% of the time in the Ice Harbor Dam tailrace. The majority of depth uncompensated exposure occurred at TDGS levels >115%. Adult Chinook salmon tended to migrate near the shoreline and they tended to remain in relatively deep water. Adults moved into the high dissolved-gas plume as often as they moved out of it downstream of Bonneville Dam, providing no evidence that adults moved laterally to avoid areas with elevated dissolved gas levels. When water depths decreased due to reduced river discharge, adults tended to migrate in the deeper navigation channel downstream from Ice Harbor Dam. The strong influence of dam operations on the position of the high-TDGS plume and shoreline-orientation behaviours of adults suggest that exposure of adult salmonids to high-TDGS conditions may be minimized using operational conditions that direct the spilled water mid-channel. Our approach illustrates the potential for combined field and modelling efforts to estimate the fine-scale environmental conditions encountered by fishes in natural and regulated rivers. Published in 2007 by John Wiley & Sons, Ltd.

In other words, salmon can get "the bends" too :)

11/07/2008 06:39:33 AM · #8

Damn, I come in here and got edumacated. LOL Take out the dams and we're in business.