Atmospheric Pollution Flashcards
What was the aim of the Kyoto protocol?
1997
UN framework convention on climate change
committed to the reduction of greenhouse gasses namely carbon dioxide, methane, nitrous oxide and sulphur hexafluoride
What is a temperature inversion?
Normally warm air rises in the troposphere but a temperature inversion blocks upward movement of air. If no lateral movement of air possible then pollution is possible eg. LA basin and Glasgow
What are the 5 major sources of pollutants and how many millions of tonnes do they give off?
Automobiles - 86 m/t 6 Major industries - 23 m/t Electric power - 20 m/t Space heating - 8 m/t Refuse disposal - 5 m/t Total - 142 m/t
Main points on Carbon Dioxide
25% rise from 1900-1990 instead of predicted 2000
CO2 fluctuates seasonally due to photosynthesis
CO2 is a greenhouse gas - re-radiated heat from the Earth’s surface can not escape
US, N. and C. America, USSR, Europe and Oceania are biggest contributors
Main points on Carbon Monoxide
Highly toxic to animals, not plants
~ 100ppm serious danger to human health
Concentration on city streets can be up to about 90ppm
Most likely oxidised by CO2 or absorbed by oceans
Main points on Nitrogen Oxides
Contributors to acid rain effects
Some toxic in themselves but also significant in production of photochemical smog
Mainly from cars, electric power stations
NO2 seriously affects humans at exposure levels of 3.5ppm for 1 hour
NO is oxidised to NO2 which strongly absorbs UV radiation and is then split to NO and O, O combines with O2 to become O3
Main points about Ozone
Vital in upper atmosphere but toxic and serious pollutant in cities, reaching levels of 100 times normal concentration in lower atmosphere
A component of photochemical smog
Highly toxic to plants causing necrosis
Name a study that shows how Ozone affects plants
Foot et al (1997) - Experiment shows that exposure of Heather to ozone increases its susceptibility to frost damage
Main points about particulates
Heading covers a wide range of substances with a wide range of effects such as respiratory blockage, toxicity, carcinogenesis, radioactivity, scattering of sunlight and coating of surfaces
Examples include - soot, cement dust, China clay dust, DDT, radioactive fallout, asbestos, lead, nickel, chromium etc
Poisoning of cattle reported after ingestion of plants coated with fluoride dust
Lead from petrol has led to lead deposition in urban areas - lead is a neurotoxin
Blackening of tree trunks by soot - rise in industrial melanism in peppered moths
Killing of lichens by SO2
Main points about hydrocarbons
VOCs - organic chemicals that exist in gasses in the air
Plants major natural sources of VOCs - isoprene, methane etc
Numerous VOCs are produced by human activities and released into atmosphere - benzene, formaldehyde, phenols, CFCs etc
Some contribute to the formation of photochemical smog
Main points about Sulphur Dioxide
Product primarily of burning fossil fuels (peat, coal, oil)
Dry atmosphere remains unchanged and may be carried up high and dispersed long range
In damp atmosphere chemistry is more complex
How does SO2 react in damp conditions?
1
- SO2 dissolves in water droplets and is oxidised to SO3
- SO3 combines chemically with water and becomes H2SO4
- dissociates to H+ ions and SO4^2- ions - producing a mist of sulphuric acid, especially in the presence of particulates (smog)
2
- combines chemically with water forming H2SO3 (Sulphurous acid)
- dissociates to H+, HSO3- and SO3^2- ions
What are the potential environmental effects of SO2 release?
Acidification of soils and freshwaters
Increased leaching of soils by acidified groundwater
Sulphate deposition which may act as a plant nutrient or alternatively as a toxin
Deposition of strongly toxic sulphite and bisulphite ions
Mobilisation of toxic metals e.g. aluminium
Reduced solubility (& hence availability) of essential nutrients with reduction in pH
what plants are especially vulnerable to sulphite and bisulphite toxicity?
Species which remain metabolically active in the winter months
- evergreens, notably conifers
- mosses, liverworts
- lichens (not plants but vegetation)
Juniper populations are highest in areas with low SO2 in the air
What is contamination and pollution?
Contamination - release of substances into the air so that their subsequent concentrations are measurable
Pollution - situations where the substances concerned have measurable effects on living organisms
