Acid rain scourge from the skies essay

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Acid rain scourge from the skies essay

December 8, NASA: Life with arsenic December 7, Last week, in a much publicized news conference, NASA announced the discovery of a bacterium that can use arsenic instead of phosphorus.

The news media covered it with a flourish -- and produced much nonsense. The paper was posted at the Science magazine web site, so we can look at what was really shown.

Acid rain scourge from the skies essay

Whatever the hype that the news media added, it is an interesting -- but incomplete -- story. The figure at left shows a key experiment; this is Figure 1B of the paper. The graph shows the growth of the bacteria under different conditions.

Number of cells on the y-axis log scale ; time on the x-axis. The three conditions are, from the top: Importantly, if there is no addition, the bacteria grow very little, if at all lower curve. Then, arsenic in the form of arsenate does indeed stimulate growth middle curve.

So does phosphate; in fact, it is better upper curve. The above experiment along with other measurements does seem to establish the basic point: But now let's look at some of the limitations of the story -- as we have it so far. First, the bug prefers P to As: You can see this in the graph above.

They explicitly do not claim that the bug requires or prefers As, merely that it can use it. Second and more importantly, the growth medium with no added P contains a trace level of P. This probably comes from low levels of P contaminating other chemicals they use.

It's not enough to support growth alone lower curve in the graphbut it does mean that when the bugs are growing on As, they also have a small amount of P available. In fact, analysis of the bacteria grown on As shows a weight ratio of about 7 As: On a mole basis, the ratio would be about half that.

Thus there still is considerable P in the bacteria. They cannot claim a total replacement of As for P. The paper recognizes this limitation, but some of the news coverage does not. This may be interesting, too. So, where is the As in the cell?

This becomes particularly important since the replacement is incomplete. And this is where the paper gets rather weak.

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They hand-wave that it is everywhere, but there is little specific information. Where did this bacterium come from? It was isolated from Mono Lake -- a highly alkaline lake in the Sierras of eastern Californiawith a high As level.

Thus it is likely that the starting bug was quite resistant to As. All the reported work was done under lab conditions. There has been an opportunity for both physiological and genetic adaptation.

Thus we do not know whether the bug uses As in nature. This does not minimize the importance of the work as a proof of principle. It is whatever it is, and it could exist naturally.

Did the "adaptation" to growing on As in the lab require genetic changes? There is not enough information given to tell. From what the paper said, the adaptation did not seem very difficult, so it is unlikely that extensive genetic changes were needed.A Dance With Dragons part 1: Dreams and Dust George R.R.

Martin $ The future of the Seven Kingdoms hangs in the balance. In the east, Daenerys, last scion of House Targaryen, her dragons grown to terrifying maturity, rules as queen of a city built on dust and death, beset by enemies.

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Essay on Acid Rain: Scourge From The Skies - Acid Rain: Scourge from the Skies “North Americans have been smelting ore and burning fossil fuels for generations. In the past, the gases went up ordinary chimneys or small smoke stacks, to descend upon near by areas and pollute them,” states author, Robert Collins.

The best opinions, comments and analysis from The Telegraph. Need writing analysis of acid rain essay? Use our custom writing services or get access to database of 18 free essays samples about analysis of acid rain. Essay on Acid Rain – Causes and Effects Free words essay on Acid Rain – Causes and Effects for school and college students.

Acid rain is a crude manifestation of the scourge of atmospheric pollution in form of precipitation that consists of high levels of nitric and sulphuric acid. A candle for Christmas December 20, Musings posts items of historical interest from time to time. This one is a book: a book about what happens when a candle burns, a book about chemistry -- premised on the observations of the candle.

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