6.4 - Human influences on the environment
Air pollution
● Various waste gases pass into air, causing pollution
● Most polluting gases come from industrial processes\burning of fossil fuels (e.g.:
coal/oil) in factories/power stations/domestic homes/motor vehicles
● Sulphur dioxide (SO2)
○ Mainly produced from burning of fossil fuels (especially coal/oil) {sulphur as
impurity}
○ Dissolves in water in atmosphere, forming sulphuric acid
■ SO2 + H2O → H2SO3 (sulphurous acid)
■ SO2 + 2H2O → H2 + H2SO4 (sulphuric acid)
■ ⇒ 2SO2 + 2H2O + O2 → 2H2SO4 (sulphuric acid)
○ Sulphuric acid (in solution) then falls as acid rain
■ pH of freshwater lakes ↓ (i.e.: high acidity), reduced fish
population\/of aquatic life
● Acid rain ALSO causes fish to produce lots of sticky mucus
on their gills, making gas exchange difficult → die
■ Acidified lakes - loss of microscopic algae/suspended plant material
→ affects (balances in) food webs
■ Direct damage to plant life - low pH in soil interferes with ability of
roots taking in mineral ions
■ Damage buildings made of limestone/marble (both containing CaCO3)
● Carbon monoxide (CO)
○ Mainly comes from waste gases in exhaust from motor vehicles (as result of
incomplete combustion of petrol)
○ ***Poisonous to humans - displaces oxygen from (oxy)haemoglobin → blood
oxygen levels ↓
Greenhouse gases and the greenhouse effect
● ***Greenhouse gases in atmosphere traps radiation
1
, 2
Air pollution
● Various waste gases pass into air, causing pollution
● Most polluting gases come from industrial processes\burning of fossil fuels (e.g.:
coal/oil) in factories/power stations/domestic homes/motor vehicles
● Sulphur dioxide (SO2)
○ Mainly produced from burning of fossil fuels (especially coal/oil) {sulphur as
impurity}
○ Dissolves in water in atmosphere, forming sulphuric acid
■ SO2 + H2O → H2SO3 (sulphurous acid)
■ SO2 + 2H2O → H2 + H2SO4 (sulphuric acid)
■ ⇒ 2SO2 + 2H2O + O2 → 2H2SO4 (sulphuric acid)
○ Sulphuric acid (in solution) then falls as acid rain
■ pH of freshwater lakes ↓ (i.e.: high acidity), reduced fish
population\/of aquatic life
● Acid rain ALSO causes fish to produce lots of sticky mucus
on their gills, making gas exchange difficult → die
■ Acidified lakes - loss of microscopic algae/suspended plant material
→ affects (balances in) food webs
■ Direct damage to plant life - low pH in soil interferes with ability of
roots taking in mineral ions
■ Damage buildings made of limestone/marble (both containing CaCO3)
● Carbon monoxide (CO)
○ Mainly comes from waste gases in exhaust from motor vehicles (as result of
incomplete combustion of petrol)
○ ***Poisonous to humans - displaces oxygen from (oxy)haemoglobin → blood
oxygen levels ↓
Greenhouse gases and the greenhouse effect
● ***Greenhouse gases in atmosphere traps radiation
1
, 2
