1. Biogeochemical Cycle: Sulfur
By Jeff Roberge

2. Introduction
Biogeochemical Cycle- the cycle of matter through the Earth since:
Earth is a closed system
All matter is conserved
All matter cycles (since none is destroyed)
Cycle consists mostly of macronutrients
C, H2O, O, N, P, S, K, Na, Fe, Mg
But also of Micronutrients (B, Cu, Mo)
(“Introduction”)

3. Introduction Flow of a chemical through certain subdivisions
Atmosphere
Lithosphere
Hydrosphere
Biosphere
Usually of Elements
(Institute)

4. Introduction Sulfur- S, it is an element Naturally found in earth
At room temp., it is a solid
Present in proteins, amino acids, vitamins, and enzymes, necessary for plants and animals
Often reacts with hydrogen creating hydrogen sulfide
Can dissolve in water
With metals in water, forms metal sulfides;sulfates in air
(“Sulfur”)

5. Sulfur Cycle
(“Part IV”)

6. Sulfur Cycle
In ground: most found in rocks, or salt in earth, or as sediment at bottom of ocean
Found as S, H2S, SO4-2, (NH4)2SO4
Enter ground: Plants absorb, or left by acid deposition (fog or precipitation)
As SO4-2, (NH4)2SO4, and then turn H2S by bacteria, decay, and plant use
Stored: Ground, rock, ocean, somewhat in air
(“Oxygen”)

7. Sulfur Cycle
Sulfur is transferred into biosphere then back into ground, or from ground to atmosphere
Microorganisms turn it into H2S (gas)
Oxidized in atmosphere to SO2, and then to H2SO4 (an acid) with water contact
Mined ores released to atmosphere in factories as H2S and SO2
Volcanoes and hot springs

8. Sulfur Cycle Deposited next in water
Through precipitation, dry deposition, leaching
Rainfall= deposited 73E12 grams sulfur in 1960
SO4-2 leaches from soil into ocean as sediment
H2SO4 falls into ocean
Dimethyl Sulfide, carbonyl sulfide (biogenic gases), released by plankton returns back into atmosphere (turns into SO2)
Either re-evaporated, left as sediment for long time, or deposited on land
20E12 grams of sulfur a year deposited on land by sea
When back on land, cycle repeats

9. Driving Force Driven by:
constant addition of sulfur to environment by earths interior (geosphere)
Human disturbance, addition of sulfur to atmosphere, (also dug up from environment)
Natural processes (incl. Biological, hydrological, due to sun’s energy)
Plant uptake, microbes (Desulfovibrio sp. or Desulfotomaculum sp.)
(“A Black Smoker”)

10. Percentages of Sulfur Common in ground as FeS2
Reservoirs (in 10E18 grams of sulfur):
Oceanic Rocks= 2375 (accurate to 820)
Sediment= 7800 (accurate to 1700)
Freshwater= .003 (accurate to .002)
Ice= .006 (accurate to .002)
Atmosphere= 3.6
Sea= 1280 (accurate to 55)
Organic=
(“Sulfur Cycle”)

11. Percentages of Sulfur Most sulfur in particulate form
Therefore it is a sedimentary cycle
Very short residence time in atmosphere (1-2 days)
Even in atmosphere, found as aerosols (<1 micrometer), not gas usually
In atmosphere, way less than 1%
Its around percent
90-95% SO2 from power plants and factories

12. Human Effect When mine ores, sulfur/sulfides released into soil
Combustion of fossil fuels
Release of SO2, causes acid rain, increases amount already present
28% of sulfur in rivers from pollution, mining, erosion, etc.
Help move cycle but also upset balance- too much S means acid rain
Hydrodesulphurization (refine hydrocarbons)- surplus of S in Alberta Canada
(“Arial”)
(“Sulfur Mining”)

13. Conclusion
Sulfur Cycle is important to biological and natural processes although human’s role impacts nature in a negative way
Driving force for life, supported first life

14. Works Cited
“A Black Smoker Venting.” NOAA. 17 Nov <
“Arial Photograph of Eggborough Power Station.” June Nov <
Institute for Computational Earth System Science. 1 March University of California. 17 Nov <
“Introduction to Biogeochemical Cycles Chapter 4.” 26 Jan University of Colorado at Boulder. 17 Nov <
“Oxygen Family.” Advameg Inc. 17 Nov <
“Part IV of "Matter cycles": The sulfur cycle.” Lenntech Water Treatment and Air Purification. 17 Nov <
“Sulfur.” AK Collectibles. 17 Nov <
“Sulfur Cycle.” University of Wisconsin: Department of Soil Science. 17 Nov <
“Sulfur Mining.” Microsoft. 17 Nov <