Air pollution Flashcards
What are primary and secondary pollutants
Primary pollutants are directly emitted pollutants while secondary pollutants are products of reactions in the atmosphere
Which wavelength of light is absorbed by CO2
infrared and longer wavelength EM waves
What does ppm mean in relative concentration units
parts per million
What does ppmv mean in relative concentration units
parts per million volume. This is equivalent of saying 1m^3 of substance per 1x10^6m^3 of air
how would you convert g/m^3 into ppmv
first identify the gas that is being measured. Divide mass by mr to get moles so in this case you would get moles per m^3. Multiply this by 22.4x10^-3 as this is the volume in m^3 of one mole of any gas. Then multiply this by 1 million as it is parts per million
What are the two out of the four layers that experience more pollution
The first two troposphere, stratosphere
Why can CO2 absorb IR waves
The bonds have discrete potentials which equate to IR wavelengths. They absorb the IR photons to excite the electrons in the covalent bonds, lengthening the bonds
How is ozone produced in the stratosphere
The UV from sunlight produces oxygen free radicals from oxygen gas that reacts with oxygen gas to form ozone. This ozone is good as it protects us from UV
How is polluting ozone created and where is it formed
The ozone in the troposphere is formed from pollutants such as VOC (volatile organic compounds), nitrogen oxides and carbon monoxide forming oxygen free radicals from UV which then react with oxygen. This is bad because the ozone is toxic
What is UV C and UV B
Different wavelength of UV. UV C is less than 240nm and breaks oxygen gas into free radicals. UV B is around 280-300nm and breaks ozone down into oxygen and free radicals. The ozone strongly absorbs 230-290 nm radiation and the oxygen gas absorbs the shorter wavelength UV C which creates a cycle of forming and destroying ozone called the oxygen ozone cycle.
How does the ozone layer protect us from UV
The ozone absorbs UV and breaks down into oxygen gas and oxygen free radicals which can then recombine into ozone. The balance between the destruction and regeneration of ozone keeps the ozone layer intact
How does nitrogen dioxide act as a catalyst for ground level production of ozone
UV splits nitrogen dioxide into nitric oxide and oxygen free radical. The O free radical reacts with O2 to form ozone. Hydrocarbon free radicals then react with oxygen to form aldehydes/ketones and an oxygen free radical that then regenerates the nitrogen dioxide from the nitric oxide
What happens to oxygen free radicals when not used to form oxygen or ozone
Reacts with water to form hydroxyl radicals. These can react with hydrocarbons, sulfur/nitrogen oxides to form acids, ammonia to form nitrogen oxide etc
What are the health effects of particulates
Irritation of eye, nose or coughing, sneezing and long term there can be bronchitis, asthma, lung cancer etc
What are the sinks (removal) of atmospheric aerosols
wet or dry deposition such as acid rain
