GEOCHEMICAL CYCLE

8/17/2019 GEOCHEMICAL CYCLE

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DEFINITIONS ( Geochemical Cycle)

▪ The chemistry of the composition and alterations of the solid matter of the earth or a celestial

body.

▪ The pathway that chemical elements take in the surface and crust of the Earth

▪ This encompasses the natural separation and concentration of elements and heat-assisted

recombination processes.

Geochemical Balance

▪ The proportional distribution, and the migration rate, in the global fractionation of elements,

minerals, or compound

▪ The balance between the weight of the chemical elements that entered the ocean during theweathering of igneous rock (proportional to its clarks) during the earth’s eistence and the weight

of chemical elements that make up sedimentary rocks (taking into account water and carbon

dioide) together with the weight of chemical elements conser!ed in the marine "one.

Geochemical Processes

▪ change in the chemical composition of rocks and minerals, as well as of melts and

solutions from which the rocks were formed.

▪ it leads to the migration of chemical elements (remo!al of some, introduction and

concentration of others), changes in their !alence states, and so on

▪ They may be subdi!ided into geologically prehistoric, enogenic, e!ogenic, and

metamorphogenic categories.

BIOGEOC"E#IC$% C&C%E

# - #$%&' - *+%'E

- T%'E

' - '*E

/ - /'0/'%10

0 - 01231%

https://en.wikipedia.org/wiki/Chemical_elements


https://en.wikipedia.org/wiki/Crust_of_the_Earth






P"OSP"O'S C&C%E

DEFINITIONS



▪ is the circulation of phosphorous among the rocks, soils, water, and plants and animals of the

earth.

▪ n nature, most phosphorus occurs in phosphate rock, which contains phosphate ions combined

with calcium, magnesium, chlorine, and fluorine.

▪ /hosphorus is most commonly found in rock formations and ocean sediments as phosphate

salts. /hosphates are also limiting factors for plant-growth in marine ecosystems, because they

are not !ery water-soluble.

"#$N I#P$CTS TO P"OSP"O'OS C&C%E

▪ umans mine 2$%E 4uantities of phosphate rock to use in commercial fertili"ers and

detergents. /hosphorous is 'T found as a gas, only as a solid in the earth’s crust. t takes

millions to hundreds of millions of years to replenish.

▪ /hosphorous is held in the tissue of the trees and !egetation, not in the soil and as we deforest

the land, we remo!e the ability for phosphorous to replenish globally in ecosystems.



▪ #ultural eutrophication 5 ad ecess phosphate to a4uatic ecosystems in runoff of animal wastes

from li!estock feedlots, runoff of commercial phosphate fertili"ers fro cropland, and discharge of

municipal sewage.

I#PO'T$NCE OF P"OSP"O'OS C&C%E

▪ /hosphorous is an essential nutrient of both plants and animals.

▪ t is part of +$ molecules which carry genetic information.

▪ t is part of $T/ and $+/) that store chemical energy for use by organisms in cellular

respiration.

▪3orms phospholipids in cell membranes of plants and animal cells.

▪3orms bones, teeth, and shells of animals as calcium phosphate compounds.

hat is s*l+*r

$tomic number6 78.

0ymbol6 0

ati!e form6 is a yellow crystalline (crystal like) solid.

n nature6 it can be found as the pure element, and as sulfide and sulfate minerals.

commercial uses6 fertili"ers, gunpowder, matches, insecticides, fungicides, !itamins, proteins and

hormones.

t is critical in the en!ironment, climate and the health of ecosystems.

%andom facts6 it can also be referred to as brimstone. it’s the tenth most abundant element in the

uni!erse



S%F' C&C%E



The Cycles-

▪ Erosion, weathering, deposition

▪ /redominately atmospheric cycle

▪ 9arine cycle

▪ 0oil-plant cycle

▪9inerali"ation of organic sulfur to the inorganic form hydrogen sulfide (:0).

▪'idation of sulfide and elemental sulfur (0) and related compounds to sulfate (0' ;).

▪ %eduction of sulfate to sulfide

▪ 9icrobial immobili"ation of the sulfur compounds and subse4uent incorporation into the

organic form of sulfur.

"#$N I#P$CTS TO S%F' C&C%E

$pproimately 7<= of all sulfur emitted into atmosphere comes from human acti!ities.

▪ &urning sulfur containing coal and oil to produce electric power (0' > acid deposition).

▪ %efining petroleum 5 (0' emissions)



▪ 0melting to con!ert sulfur compounds of metallic minerals into free metals (#u, /b, ?n)

▪ ndustrial processing.

I#PO'T$NCE OF S%F' C&C%E

▪ 0ulfur is a component of most proteins and some !itamins.

▪ 0ulfate ions (0'; :- ) dissol!ed in water are common in plant tissue. They are part of sulfur-

containing amino acids that are the building blocks for proteins.

▪0ulfur bonds gi!e the three dimensional structure of amino acids.

▪ 9any animals, including humans, depend on plants for sulfur-containing amino acids.

0'1%#E0 '3 E'#E9#$2 #*#2E

./) Decaying 0oy 1/) Volcano

2/) Elemental s*l+*r may also occ*r near 3/) Fossil +*els

hot springs an 4olcanic regions/



5.) 5/) Earth6s Cr*st

7/) Ocean seiments 8/) Celestial 0oies

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GEOCHEMICAL CYCLE