1. SULFUR CYCLE
Group 5
Rey D. Abelita
William Arcilla
Jesher Arsenio
Emma Fernandez
Issa Maslog

2. AN INTRODUCTION – WHAT SULFUR IS
• Sulfur (Sulphur in UK) is a member of Group VIA->
same as oxygen. Its name was derived from soufre, an
Old French word which means “to burn”.
• Antoine Lavoisier-> Helped convinced the Scientific
Comm. That Sulfur = an element not a compound.
• Oxygen unlike Sulfur, is in the second period, hence,
no d orbitals.
• The d orbitals allows additional electrons to be
accommodated = six bonds instead of Oxygen’s two
bonds.

3. AN INTRODUCTION – SULFUR AND ITS IMPORTANCE
• In humanity, it is produced most specially in industries where it is used as
solvent, catalyst and reactant to produce different organic compounds.
(H2SO4)
• In ecosystems as a whole, no matter what form (SO 2, H2SO4, H2S), Sulfur in
its soluble form ===>plants ==>series of metabolic processes. ( starts
photosynthesis) ---> Sulfur-bearing amino acids.
• Sulfur -> Helps retain cellular structure; provides chemical links that creates
collagen and keratin; Activator of minerals and vit.;
• Sulfur (in protein assembly and structure) bonds-> known as disulfide bonds-
> plays an important role.
• Sulfur is also an important component of diff. enzymes such as coenzyme
A, and of standard amino acids such as Cysteine.
• Producers -------> Consumers [Sulfur in Amino Acids]

4. Cysteine Coenzyme A

5. THE SULFUR CYCLE
• The sulfur cycle gaseous and sedimentary phases.
• As an introductory note -> The long term sedimentary phase, Sulfur is tied up
in organic and inorganic deposits, released by weathering and
decomposition.
• The gaseous phase permits the circulation on a global scale. [to be expound
later]
• Their main difference is in their exchange sites/ sites of occurrence.
Sedimentary phase is mainly on the Earth’s surface (i.e
rocks, sediments, etc.) while the gaseous form is on the atmosphere.
• Reservoir: Oceans (aerosol/SO 4) ===> (CH3)2S, Atmosphere (Sulfur
Dioxide, Hydrogen Sulfide and Sulfates) , Organic and Inorganic Deposits
(Sedimentary Rocks, Igneous Rocks such as pyrite or FeS 2.)
• Exchange Pools: Hot Springs, Geysers, Surfaces of the Ocean,, Fossil Fuel
Combustion, Volcanoes, Decomposing Matter

6. SEDIMENTARY AND GASEOUS

7. • Sedimentary cycle
• Weathering of rock and leaching of its
minerals, transport, deposition and burial.
• Gaseous Cycle
• A biogeochemical cycle with the main
reservoir or pool of nutrients in the
atmosphere and ocean

8. SULFUR ENTERS THE BIOSPHERE THROUGH
• Natural Activity
Carried through
Weathering of rocks
terrestrial environments
and decomposition in salt solution.
Consumers Plants

9. SULFUR ENTERS THE ATMOSPHERE THROUGH
• Natural Activity • Human Activity
Volcanic eruptions, Burning of fossil
gases released by fuels, acidic drainage
decomposition from mines
Enters atmosphere as
H2S and reacts with
oxygen to form SO2

10. SO2 is soluble in
Acid rain (H2SO4)
H2O
consumers plants

11. Death of Sulfur to the
consumers atmosphere
Ponds, lakes,
seas and oceans
soil

12. Different kinds of
bacteria process this
sulfur
Non-
photosynthetic
photosynthetic
Colorless sulfur
Purple bacteria
bacteria
Green bacteria

13. Sulfur
Iron
Ferrous sulfide
(FeS2)

14. Sulfur from the
oceans
Released in the atmosphere
as Dimethyl sulfide
((CH3)2S )
Go back to the atmosphere
by bacteria fixation, or sea
sprays

16. GLOBAL SULFUR
CYCLE

17.  Gaseous phase of sulfur cycle
circulates on a global scale.
 300 x 1012 grams/year

18. Each flux is shown in units of
1012 grams S/year

19. Atmosphere
 Sulfur dioxide (SO2)
 Hydrogen sulfide (H2S)
 Sulfate Particles

20.  Sulfate particles become part of dry
deposition. (DRYFALL)
 Gaseous forms combines with
moisture and are transported in
precipitation.(WETFALL)

21.  Oceans
 Large sources of aerosols that contain
sulfate(SO4)
 Most are redeposited in oceans as
precipitation and dryfall.
 Dimethylsulfide((CH3)2S) major gas
emitted from oceans
 Estimated 16 x1012 grams S/year is
emitted

22.  Freshwater wetlands and anoxic soils
 Hydrogen sulfide (H2S)
 Forest fires
 3 x 1012 grams/year
 Marine Plants
 130 x 1012 grams/year
 Volcanic activity
 10 x 1012 grams S/year

23. Eruption of
Mt. Pinatubo
(1991)
release on the
order of 5 to 10
x 1012 grams
Sulfur

24.  Adding all anaerobic
oxidation of organic
matter
 200 x 1012 grams/year

26. Since the Industrial Revolution, human
activities have contributed to the amount of
sulfur that enters the atmosphere, primarily
through the burning of fossil fuels and the
processing of metals.

27. What exactly are we doing?
 Burn sulfur-containing coal and oil to
produce electric power.
 Refine sulfur-containing petroleum to
make gasoline, heating oil, and other
useful products.
 Convert sulfur-containing metallic
mineral ores into free metals such as
copper, lead, and zinc.
 Mining  erosion (exposure of mineral
sulfides)

28.  Emissions from these, along with
nitrogen emissions, react with
chemicals in the atmosphere
 SULFATE SALTS  ACID RAIN
 Damage the natural environment
(affects both plants and animals) as
well as man-made environments
weathering/corrosion of buildings

29. Dry Deposition
 Gaseous sulfur dioxide component of
the sulfur cycle and the nitrogen oxides
of the nitrogen cycle mix in the
atmosphere. Some of this mixture
returns to the Earth as particulate matter
and airborne gases, known as dry
deposition

30. Effects
 For humans, it irritates the
respiratory tract, from the nose
then moves into the lungs and attacks
sensitive tissues.
 High concentrations have caused a
number of air-pollution disasters
characterized by higher than expected
death rates and increased incidences
of bronchial asthma.

31. Wet deposition
 Major portion of D.D. is transported away from the
source in a direction influenced by the atmospheric
circulation. During their transport, sulfur dioxide and
nitrogen dioxide and their oxidative products
participate in complex reactions involving
hydrogen chloride and other compounds, oxygen and
water vapor.
 These reactions dilute solutions of strong acids (nitric
and sulfuric acids). Eventually they come to earth in
acidic rain, snow and fog.
 Sulfur dioxide combines with atmospheric moisture to
form sulfuric acid which falls on land and water and
forms significant part of acid rain

32. Effects
 Causes major damage to vegetation in areas
surrounding the source of emission
 Injures or kills exposed plants
 Acidic aerosols present during periods of
fog, light rain and high relative humidity together
with moderate temperatures do the injury.
External surfaces of the
leaves absorb the aerosols.
When dry, leaves and needles take up sulfur
dioxide through the stomata. In the leaf, the
sulfur dioxide rapidly reacts with moisture
forming sulfuric acid.

33. Symptoms to sulfur damage are
a bleached look to deciduous
leaves and red-brown needs on
conifers, partial defoliation and
reduced growth.

36. Nutrient deficient soils
 Acid rain low pH level of soil
nutrient leaching  reduce solubility
and availability (macronutrients) and
high availability of micronutrients
(Al, Fe, Manganese toxicity)  inhibits
fungal and bacterial activity  reduce
humus production, mineralization and
fixation of nutrients

37. Low pH level Nutrient
Acid Rain
of soil leaching
Affects
activity of Low: Macro
High toxicity
microorganis High: Micro
ms
Reduced humus Nutrient
production,
mineralization and
nutrient fixation
deficient
soils


38. In water…
 Sulfate and nitrogen ions replace
bicarbonate ions, pH declines, and
the concentration of metallic ions,
especially aluminum, increases.
 Although adult fish and some aquatic
organisms can tolerate high acidity, a
combination of high acidity and high
level of aluminum can kill them.

39.  Eggs and larvae of frogs and
salamanders are sensitive to acidic
water. Cause decline in
amphibians/increased rate of
mortality.
 Acidic waters – toxic to invertebrates
either killing them directly or
interfering with calcium metabolism
(causing crustaceans to lose the
ability to recalcify their shells after
molting)

40. Corrosive