ESS Topic 6 Atmospheric systems and societies

The atmosphere

…is a dynamic system that has undergone changes throughout geological time

atmosphere composition

nitrogen, oxygen, carbon dioxide, argon, water vapour and other trace gases

Nitrogen Gas (N2)

About 79%

Oxygen Gas (O2)

About 20%

Carbon Dioxide Gas (CO2)

Was 350 parts per million (ppm) in late 1980s; in 2016 in reached 400 ppm (0.04%)

Human activities are altering gases

artificial ozone, carbon dioxide, water vapour, methane

troposphere

first layer (nearest Earch) of atmosphere where weather happens (0-10 km)

stratosphere

second layer (above troposphere) where "good" ozone exists protecting us from sun's ultraviolet radiation

albedo

the relectiveness of a surface. White is higher and reflects more solar radiation.

Greenhouse effect

a natural phenomenon of the atmosphere, trapping solar radiation in the troposphere and keeping the Earth at a livable temperature for living systems.

Stratospheric ozone

03 protects living systems from the negative effects of ultraviolet radiation from the sun

Stratospheric Ozone formation

UV breaks apart O2 molecules and these oxygen atoms react with O2 to form O3. The O3 molecules are also broken apart by UV but then reform in a dynamic equilibrium

Ozone depleting substances (ODSs)

halogenated organic gases such as chlorofluorocarbons (CFCs) are used in aerosols, gas-blown plastics, pesticides, flame redardants and refrigerants (e.g. in air conditioning units)

ODSs function

halogen atoms (such as chlorine) increase destruction of ozone in a repetitive cycle, allowing more UV radiation to reach the Earth

effects UV radiation on humans

damages human living tissues, increasing the incidence of cataracts, mutation during cell division, skin cancer and other subsequent effects on health

UV radiation on biological productivity

damages photosynthetic organisms, especially phytoplankton, which form the basis of aquatic food webs.

Pollution management strategy for ODS - altering human activity

recycling refrigerants and changing consumer behaviour

Pollution management strategy for ODS - controlling release

developing alternatives to gas blown plastics, halogenated pesticides, propellants and aerosols; international legislations such as Montreal Protocol and Kigali Amendment; developing non-propellant alternatives

Pollution management strategy for ODS - Clean up and restoration

Only time will renew the ozone layer once ODS eventually break down.

halogenated gases

compounds which contain atoms from Group VII of the periodic table such as chlorine, fluorine or bromine.

Primary pollutants from combustion of fossil fuels

carbon monoxide (CO), carbon dioxide (CO2), black carbon / soot (C), unburned hydrocarbons, oxides of nitrogen (NOx), oxides of sulphur (usually SO2)

Photochemical reaction

These are reactions sped up by the solar energy of sunlight (UV radiation) and in the case of air pollution, create secondary pollutants from the primary pollutants formed by the combustion of fossil fuels

Tropospheric ozone (bad)

is a secondary pollutant formed when oxygen molecules react with oxygen atoms that are released from NOx in the presence of sunlight

tropospheric ozone impacts

plant damage (crops and forests), irritates eyes, creates respiratory illnesses, damage to fabrics and rubber materials.

smog

is a complex mixture of primary and secondary pollutants of which tropospheric ozone is the main pollutant. Generally caused by burning of fossil fuels (transportation and industry) but also by deforestation and burning e.g. in North India or Indonesia.

Frequency and severity of smog

depends on the local topography, climate, population density and fossil fuel use

thermal inversions

occur due to a lack of air movement when a layer of dense cool air is trapped beneath a layer of less dense, warm air. This causes concentrations of air pollutants to build up near the ground instead of being dissipated by "normal" air movements

Pollution management strategy - air pollution - altering human behaviour

consume less fossil fuels e.g. purchase of energy efficient technologies, use of public transport, walking or cycling

Pollution management strategy - air pollution - controlling release of pollutant

regulating and reducing pollutants at point of emission through government regulation or taxation; use of catalytic converters, regulating fuel quality by governments; pedestrian zones and charging for driving in city centres

Pollution management strategy - air pollution - clean up and restoration

reforestation, regreening and conservation areas to sequester carbon dioxide; cloud seeding to wash pollution out of atmosphere.

Primary pollutants leading to Acid Deposition

Sulphur dioxide (SO2) and Nitrous oxides (NOx)

Secondary pollutants of acid deposition

sulphuric acid (H2SO4) and Nitric Acid (HNO3) formed from primary pollutants by reaction with water

Dry deposition

ash and dry particles of acids

Wet deposition

rain and snow of acids

Direct effect of acid deposition

intolerance of aquatic organisms to changes in pH; coniferous forests drop needles and have reduced immunity to pests and diseases

Indirect effect of acid deposition

increases solubility of metals such as aluminium which cause white froth to form in fish gills leading to suffocation

Indirect nutrient effect of acid deposition

leaching of plant nutrients so soil has decreased fertility, mobilisation of aluminum ions that can damage plant root systems

The decrease in soil pH also releases aluminium ions which are then leached into the aquatic system. Fish exposed to aluminium ions secrete excess mucus around the gills, preventing oxygen uptake and leading to death.

Pollution management strategy - acid deposition - altering human activity

reducing use, or using alternatives to, fossil fuels; lobbying results in international agreements and national governments to reduce pollutant (SO2 & NOx) production.

Pollution management strategy - acid deposition - controlling release

regulating and monitoring release of pollutants, e.g. through use of scrubbers or catalytic converters that may remove sulfur dioxide and oxides of nitrogen from coal burning powerplants and cars

Pollution management strategy - acid deposition - cleap up and restoration

spreading limestone in acidified lakes or recolonisation of damaged systems but the scope of these measures is limited; repair and restoration of damaged limestone buildings