evidence for increase in atmospheric... (1 Viewer)

[ButterflyFish]

I'm just trying to do some dot-point summaries for the trial exams (yuck)
and I've been looking through the textbook, chem contexts 2 and nowhere can I find any information that relates to the dot point:

"Assess the evidence which indicates increases in atmospheric concentration of oxides of sulfur and nitrogen"

Does anyone feel like sharing their summaries for this dot point or pointing me in the direction of somewhere that might have some good information (other than HSC online)?

Thanks

 

[pLuvia]

There has been evidence found in the Antarctic. Scientists extracted some samples of the air from air bubbles in the ice which date back to thousands of years, and compared it with recent measurements of sulfur and nitrogen concentrations and saw an increase.

And also since the industrial revolution there has been an increase since the burning of fossil fuels releases sulfur dioxide

Hope that helped

 

[Forbidden.]

Out of my thick head ...

Does acid rain give you any ideas ?

 

[Mountain.Dew]

i wont tell u the answer, but this is a guide to how to address this dot point:

- look at how the evidence is gathered: through sampling, perhaps atmospheric measurement, etc...
- what evidence is potentially there: pLuvia and f3nr15 have given us good examples: industrialisation, acid rain, burning foosil fuels, ice caps melting, etc...
- most importantly: is this evidence reliably measured or collected? express points for AND against.

 

[ButterflyFish]

Thanks
I'll look into it a bit more but what you said has been really helpful.

 

[ButterflyFish]

Im still confused, because this is what HSC online says:

assess the evidence which indicates increases in atmospheric concentration of oxides of sulfur and nitrogen<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>

• There is extensive evidence for an increase of over 25% in atmospheric carbon dioxide levels over the last two hundred years. The evidence comes from quantitative analysis of trapped air bubbles in Antarctic ice and measurement of carbon isotopes in old trees, grass seeds in museum collections and calcium carbonate in coral. <o></o>

• Finding evidence for increases in atmospheric sulfur oxides and nitrogen oxides is more difficult for the following reasons: <o></o>

1. Whereas atmospheric CO<SUB>2</SUB> concentrations are about 360 parts per million (ppm), the levels for SO<SUB>2</SUB> and NOx are only about 0.001 ppm in populated parts of the Earth. <o></o>
2. The chemical instruments able to measure very low concentrations, like those for SO<SUB>2</SUB>, have only been commercially available since the 1970s. <o></o>
3. CO<SUB>2</SUB> changes to carbonate ions when it dissolves in water and most carbonates are insoluble. Seashells and coral are made up of carbonates that came from atmospheric CO<SUB>2</SUB>. Isotope ratio measurements using mass spectrometers on shells and corals of different ages give clues as to past atmospheric CO<SUB>2</SUB> concentrations. <o></o>

On the other hand, SO<SUB>2</SUB> eventually forms sulfate ions and NO<SUB>2</SUB> forms nitrate ions. Most sulfates and all nitrates are water-soluble. Soluble sulfates and nitrates circulate in the hydrosphere and biosphere and are chemically changed while insoluble carbonates tend to stay in inert forms such as shells or coral.

What do you think?

 

[pLuvia]

The HSC online site is just a guide it wouldn't fulfil the syllabus requirements, look into your textbook it should have some information there

 

[Riviet]

HSC online has gone into some detail in explaining why it is hard to measure increases in atmospheric sulfur and nitrogen oxides. Also in the first point, sulfur and nitrogen dioxide levels can be measured using the "quantitative analysis of trapped air bubbles in Antarctic ice" used to measure concentrations of CO₂ gas.

 

[ButterflyFish]

Thanks

Another thing i find Chem Contexts 2 lacking in is buffers - I really dont know where to find info about them.

Can anyone refer me to a good textbook, an internet site... or a resource on BOS that has info?

(of course I wont mind if anyone wants to explain them to me )

Thanks again...
Im sorry to be such a pain i just have a teacher who is hopeless so im trying to teach the course to myself.

 

[ButterflyFish]

Sorry by buffers im refering to this dot point in "The acidic environment"

Qualitatively describe the effect of buffers with reference to a specific example in a natural system<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>

 

[tristambrown]

that dotpoint is on crack.
Levels have actually fallen in recent years

in the industrial age they rose sharply, but since the introduction of controls levels have fallen sharply


look at early industrial age in europe, the "pea soup fog's" and high incidence of DEATH from respiritory failure caused by high concentration of NOx

evidenced also by the damage done to limestone carvings (gargoyles etc) on buildings - more damage done in last 100 years than last 1000

the mass deaths over there led to the controls on NOx and SO emissions and as such the drop in their concentrations recently.