Transcript Biogeochemical Cycle: Sulfur

Biogeochemical Cycle:
Sulfur
By Jeff Roberge
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”)
Introduction

Flow of a chemical through certain
subdivisions
– Atmosphere
– Lithosphere
– Hydrosphere
– Biosphere

Usually of Elements
(Institute)
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
(“Sulfur”)
 Can dissolve in water
 With metals in water, forms metal sulfides;sulfates
in air
Sulfur Cycle
(“Part IV”)
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, (“Oxygen”)
rock, ocean, somewhat in air
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
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
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)
(“A Black Smoker”)
– Plant uptake, microbes
(Desulfovibrio sp. or
Desulfotomaculum sp.)
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= .00562
http://www.soils.wisc.edu/soils/courses/451/20b.%20
Global%20S%20cycle.ppt
(“Sulfur Cycle”)
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 .000314 percent
– 90-95% SO2 from power plants and factories
Human Effect
When mine ores, sulfur/sulfides released
into
(“Arial”)
soil
 Combustion
of fossil
(“Sulfur
Mining”)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
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

Works Cited
“A Black Smoker Venting.” NOAA. 17 Nov. 2008 <http://whyfiles.org/coolimages/index.html%3Fid=1016732011.html>.
“Arial Photograph of Eggborough Power Station.” June 2005. 17 Nov. 2008
<http://www.webbaviation.co.uk/industrial/eggborough-power-station.htm>.
Institute for Computational Earth System Science. 1 March 2005. University of California. 17 Nov. 2008
<http://www.icess.ucsb.edu/>.
“Introduction to Biogeochemical Cycles Chapter 4.” 26 Jan. 1998. University of Colorado at Boulder. 17 Nov. 2008
<http://www.colorado.edu/GeolSci/courses/GEOL1070/chap04/chapter4.html>.
“Oxygen Family.” 2008. Advameg Inc. 17 Nov. 2008 <http://www.scienceclarified.com/Oi-Ph/Oxygen-Family.html>.
“Part IV of "Matter cycles": The sulfur cycle.” 2006. Lenntech Water Treatment and Air Purification. 17 Nov. 2008
<http://www.lenntech.com/sulfur-cycle.htm>.
“Sulfur.” AK Collectibles. 17 Nov. 2008 <http://www.akcollectables.com/store/index.php?page=2&act=viewCat&catId=2>.
“Sulfur Cycle.” University of Wisconsin: Department of Soil Science. 17 Nov. 2008
<http://64.233.169.132/search?q=cache:wQIjeBetZEJ:www.soils.wisc.edu/soils/courses/451/20b.%2520Global%2520S%2520cycle.ppt+human+effect+on+sulfur+cycle&hl=e
n&ct=clnk&cd=2&gl=us>.
“Sulfur Mining.” 2008. Microsoft. 17 Nov. 2008 <http://encarta.msn.com/media_461536436_761568357_1_1/sulfur_mining.html>.