L15 Sulfur Cycle and Acid Rain

Question 1

Sulfur Cycle

Answer 1

Sulfur (S) is predominately found in inorganic form,
either in pure form, or in conjunction with a metal,
e.g., iron sulfide (FeS) or calcium sulfate (CaSO4

Question 2

Sulfate SO₄²⁻

Answer 2

Formed as sulfuric acid by bacteriological oxidation
processes such as acid mine drainage and sewer corrosion or by fossil fuel combustion

Question 3

Sulfate Reduction

Answer 3

Sulfate may reprecipitate to form inorganic sulfur or
be reduced by bacterial activity to hydrogen sulfide (H2S)…..gas

Question 4

Biochemical Reactions

Answer 4

Sulfur is also a constituent of several biochemicals required by organisms, including amino acids

Question 5

What is Acid Rain?

Answer 5

• Sulfur from ancient organisms has became
  incorporated into fossil fuels
• With combustion, the sulfur in the fuels is oxidized to SO2, a gas which can be transported great distances in the atmosphere
• SO2 becomes H2SO4 when it dissolves in water

Question 6

How is Sulfur Related?

Answer 6

SO2 dissolves into rain and reacts to become sulfuric acid, a major constituent of acid rain:

2SO2 + 02 +2H2O –> 2H2SO4

H2SO4 travels through the hydrologic cycle and is eventually deposited on land and into surface
water

Question 7

Acid rain impact: Lake Acidification

Answer 7

• Decreased pH and
  alkalinity (buffering
  ability) due to sulfate
  deposition
• Results in animal and
  plant death and
  decreased
  biodiversity

Question 8

Acid rain impact: Forest Destruction

Answer 8

1) Direct:
- Killing trees and other plants

2) Indirect:
- Acidification of soil
- Stripping of soil nutrients
- Release of heavy metals

Question 9

Acid rain impact: Infrastructure

Answer 9

1) Corrosion: Acid rain corrodes metals and materials like limestone, sandstone, and mortar.

2) Damage to paint: Acid rain can dissolve paint and damage protective coatings.

3) Structural damage: Acid rain can weaken the structure of buildings, leading to serious structural failures.