Nitrogen

proteins, the building blocks of life.

All organisms require nitrogen

to live and grow.

The majority (78%) of the Earth’s atmosphere is N2.

Nitrogen

is N2, most of the nitrogen in the atmosphere is

unavailable for use by organisms.
This is because the strong triple bond between the N atoms in N2 molecules makes it relatively inert (like a noble gas).

 NO3
Nitrite  NO2
Atmospheric Dinitrogen N2
Organic N

to be able to use nitrogen, N2 gas must first

be converted to more a chemically available form such as ammonium (NH4+) or nitrate (NO3-).

WE CAN’T!

But BACTERIA & … can…

which break the bond N2
Examples: lightning forest fires hot lava flows

fuels,
using synthetic nitrogen fertilizers,
and cultivation of legumes
all

fix nitrogen.

manure, etc.
Done by decomposers (bacteria, fungi, etc.)
During this

process, a significant amount of the nitrogen contained within the dead organism is converted to ammonium (NH4+).

add oxygen to nitrogen in two steps:
STEP 1: Bacteria take

in NH3 or NH4+ & make NO2- = nitrite

Step 2: Bacteria take in NO2- & make NO3- = nitrate

and converts it back to atmospheric N2.

+ 6 H20
Inhibited by O2
Not inhibited by ammonia
Microbial reaction
Nitrate is

the terminal electron acceptor

compound with the formula N2O.
At room temperature, it is a colorless, odorless non-flammable gas,

with a slightly sweet taste.
It is used in surgeryand dentistry for its anaesthetic and analgesic effects.
It is known as "laughing gas" due to the euphoric effects of inhaling it, a property that has led to its recreational use as a dissociative anaesthetic.
It is also used as an oxidizer in rocket propellants, and in motor racing to increase the power output of engines.
At elevated temperatures, nitrous oxide is a powerful oxidizer similar to molecular oxygen.

Nitrous oxide gives rise to nitric oxide (NO) on reaction with oxygen atoms, and this NO in turn reacts with ozone.
As a result, it is the main naturally occurring regulator of stratospheric ozone.

so that the blood remains appropriately oxygenated.
A mixture of 20%

nitrous oxide and 80% oxygen has the same analgesic equipotence as 15 mg of morphine.

oxide (often referred to as just "nitrous") allows the engine

to burn more fuel by providing more oxygen than air alone, resulting in a more powerful combustion. The gas itself is not flammable at a low pressure/temperature, but it delivers more oxygen than atmospheric air by breaking down at elevated temperatures. Therefore, it is often mixed with another fuel that is easier to deflagrate. 

as E942), specifically as an aerosol spray propellant. Its most common

uses in this context are in aerosol whipped cream canisters, cooking sprays, and as an inert gas used to displace oxygen, to inhibit bacterial growth, when filling packages of potato chips and other similar snack foods.

3.5 teragrams N2O–N per year.
 Nitrous oxide is produced naturally in the

soil during the microbial processes of nitrification, denitrification, nitrifier denitrification and others.

The production of adipic acid is the largest source to nitrous oxide. It specifically arises from the degradation of the nitrolic acid intermediate derived from nitration of cyclohexanone.

and cosmic radiation increases cloud production.

to increase
Increases are heterogeneous, plus hard to determine pre-industrial concentrations
Stratospheric

Ozone
Loss in Stratosphere leads to cooling (more loss of energy out to space)
However, loss of stratospheric ozone also leads to greater UV absorption (and heating) in troposphere
As ozone loss is reversed, some heating may occur

Aerosol



Indirect Effects of Aerosol

Aerosol
Aerosol particles of diameter 0.2 to 1 mm is very

efficient in scattering light
A significant fraction is scattered in the backwards direction, so this effectively increases planetary albedo
Increase in albedo leads to cooling

Notice how smoke from Star fire is whiter vs. forest background

aerosol constituents do not absorb significantly in the visible region

(where light is most prevalent)
A big exception is soot (elemental carbon emitted in inefficient combustion)
Soot clouds lead to atmospheric warming (even if cooling the surface over short-term)

Notice how smoke from Kuwait oil fires is black vs. desert background

http://www.lpi.usra.edu/publications/slidesets/humanimprints/slide_16.html

is through modification of cloud reflectivity
Clean Case:
fewer but larger droplets
Polluted

Case:
more but smaller droplets

droplets reflect light more poorly per g of cloud water
Polluted

clouds look whiter from space

Source: http//www-das.uwyo.edu/~geerts/cwx/notes/chap08/contrail.html

Ship tracks are indicative of localized pollution

Most apparent where: clouds are normally clean and with thin clouds (thick clouds have high albedos regardless)

particles reflect sunlight
Soot particles absorb sunlight


Outdoor Air Pollution Can Temporarily

Slow Atmospheric Warming

one component of the system may cause changes in other

components. Sometimes the changes in other components enhance the initial change, then we say that these changes have positive feedback to the system. If the changes result in the reduction of the original change, then they have negative feedback.

Both positive and negative feedback processes may exist in the climate system. In studying the global climatic change, we cannot make conclusions based on intuition, but have to take all such possible complicated effects into account. A good climate model would have treated all of them realistically.

due to the increase of CO2 in the atmosphere or

other unknown mechanisms), the ocean may also become warmer. A warmer ocean has lower solubility of CO2 and hence will release more CO2 into the atmosphere. This may cause the climate to become even warmer than before. Thus the dependence of solubility of CO2 on temperature has a positive feedback on the climate system.

ocean. Since there is no cloud, the sun shines on

the ocean surface, causing it to warm up. This makes this part of the ocean warmer than other parts and the air over it tends to rise (causing convection). Rising air expands and cools, causing clouds to form. The formation of clouds will block out the sun and the solar heating of the ocean surface will cease. The surface will start to cool down. Thus the cloud formation due to surface heating and convection is a negative feedback to the climate system.