6.3: Photochemical smog Flashcards
outline what is meant by primary pollutant and secondary pollutant?
PP- emmitted directly from a process. May be natural e.g volcanic erruption or anthropogenic e.g industry.
SP- formed when primary pollutants under go a viarity reactions with other chemicals in the atmosphere.
define pollution?
Addition of substance or agent to an enviroemtn by human activity at a rate greater than it can be rendered harmless and which has an applicable effect on the enviroment and the organisms within it.
list three examples of primary pollutants?
carbon manoxide from incolplete combustion
nitrogen oxides
sulphere dioxide
list three exmaples of secondary pollutants?
troposferic ozone
particulates produced from gaseous primary pollutants
PAN - peroxideyacetly nitrate
outline how phtotchemical reations can form secondary pollutants?
these are reactons is the presense of sunlight. primary pollutants undergo chemical reactions with chemicals in the atmosphere.
E.g tropospheric ozone is formed when oxegen moecules react oxegen atoms realeased from NO2.
with refrence to fossile fules use, discribe what is meant by incomplete combustion?
poor mixing of fules and air or due to low tempratures.
Fossil fules are only partially burned realseasing carbon manoxide as a by product.
using a simle dirgam, summarise the formation of tropospheric ozone from nitric oxide.
Hilighted in blue is hot girl atmosphere.
distinguish between stratospheric ozone and and tropospheric ozone. Include refrence to soyurce and depletion, as well as consequences.
STRATOSPHERIC OZONE
Source- natural when o2 splits in the presents of sunlight
deppletion effects- ODSs such as CFCs, filtering of harmful UV radiation.
TROPSOPHERIC OZONE-
source- CO, CO2 black carbon, oxides of nitrogen and sulfere.
depletion effects- pollutant toxic gas and oxidising agent, reudces crop yeilds,irritates eyes, breathing dificulty.
what are the potentional negative effects of tropospheric ozone?
OXADIZING- ozone is a toxic gas and a powrfull oxidizing agent.
DAMAGE TO PLANTS- interferes with the ability of sensative plants to produce and store food. Damages leaves, degrades clorofilo with reduced phtotsynthesis nd therefore productivity.
DAMAGE TO HUAMNS- can harm lung tissue, impair the bodies defence mechanis, increase repiratory trait infection and agrivate asma.
DAMAGE TO MATERIALS- High levles of ozone can damge fabrics and rubber materials. It bleaches fabrics and reduces rubber. This can decrease the life time of tyres.
state the conditions in which photochemical smog is likely to form or become more pronouned?
associated with certain climates- in patricular high air pressure systems. Winds are low so pollutants are not dispersed.
Associated with low lying areas due to thermal inversion.
Associated with large populations due to greater number of verchiles.
outline formation of photochemical smog?
Photochemical smog is mainly nitrogen doxide and ozone but is a complex mixture of about 100 primary and secondary pollutants.
It is formed when ozone, nitrogen oxides and gaseous hydro carbons (mainly from motor verchile extasion in cities) interact with strong sunlight.
complex reactions creat many chemicals in photochemical smog including VOCs, PANs, ozone, carbon manoxide and nitrogen oxides.
Highly recative VOCS oxidise nitrogen oxides into nitrogen dioxide with out beaking down ozone which leads to a build up of ozone which lead t a build up of ozone near ground levle and smog formation.
photochemical smog often peeks in the early afternoon, dispite the fact that primary pollutant realse at a maximum during peak rush hours (early morning and later afternoon).
Explain why this is?
even through the main primary pollutants reach a maximum concentration during the mroning and evening rush hours, the important smog causing reactions is a photochemical one so it reaches peak in the early afternoon sun as it it the most intesne.
outline the factrs that influence the exent of a photochemical smog?
LOCAL TOPOGRAPHY- urban areas located within vallys with surrounding high land areas tend to experiance low air circulation and so high levels of accumulation of pollutants.
CLIMATE- stable high pressure reduces winds which could disperse the pollunatnts. In monnsoonal areas smog only occurs in the dry season.
POPULATION DESNITY- the larger the population th emore verchiles in the area.
FOSSIL FULE USE- increased fossile fuel iuse increase the changes of troposperic ozone being produced.
draw a diagram to expain how a themal inversion can amplify the effect of a phtot chemical smog.
on hot gir atmosphere hilighted in yellow.
what are your three stratagies for to tackle photochemical smog?
altering human activities causing the pollutant (education)
regulatte and reduce at the point of emmison (legistation)
clean up and restore (Mitigation)
