There are three main biogeochemical cycles - the hydrologic, gaseous, and sedimentary cycles. The sedimentary cycle involves mineral elements being obtained initially from inorganic sources in the soil and occurring as dissolved salts. The phosphorus cycle begins with phosphorus contained in sedimentary rocks in the form of apatite, which weathers into the soil where plants uptake it. Phosphorus then moves through the food chain and sometimes aquatic systems before settling in sediments or being lost to leaching. The sulfur cycle involves sulfur being found in rocks underground and ocean sediments, moving between organic and inorganic forms through microbial processes, and cycling through the lithosphere, hydrosphere and biosphere.

2. NEARLY 30 Y0 40 ELEMENTS REQUIRED
FOR PROPER GROWTH AND DEVELOPMENT
OF LIVING ORGANISM ,
MOST IMPORTANT OF THESE ARE C, H, O,
P, K, N, S, Ca, Fe, Mg, B, Zn, Cl, Mo, Co, I,
AND F.
THESE ELEMENTS FLOW FROM ABIOTIC TO
BIOTIC COMPONENTS AND BACK TO THE
NON LIVING COMPONENT AGAIN IN A MORE
OR LESS CYCLIC MANNER. THIS IS KNOWN
AS NUTRIENT CYCLES.

3. THERE ARE THREE TYPE OF BIOGEOCHEMICAL
CYCLE
1.HYDROLOGIC CYCLE OR WATER CYCLE
2.GASEOUS CYCLE
3.SEDIMENTARY CYCLE

4. SEDIMENTARY CYCLE
MINERAL ELEMENTS REQUIRED BY LIVING
ORGANISMS ARE OBTAINED INITIALLY FROM
INORGANIC SOURCES. AVAILABLE FORMS
OCCUR AS SALTS DISSOLVED IN SOIL
WATER.
MINERAL CYCLES ESSENTIALLY CONSIST
OF TWO PHASE
1.THE SALT SOLUTION PHASE
2.ROCK PHASE

6. PHOSPHORUS IS A MAJOR CONSTITUENT OF
BIOLOGICAL MEMBRANES, ENERGY RICH
COMPOUNDS AND NUCLIE ACIDS. IN
ADDITION MANY ANIMALS ALSO NEED
LARGE QUATITIES OF THIS ELEMENT TO
MAKE SHELLS, BONES, AND TEETH.

7. • PLANTS AND ANIMALS OBTAIN
PHOSPHORUS FROM THE ENVIRONMENT.
PHOSPHORUS IS A COMPONENT OF
NUCLEIC ACID, PHOSPHOLIPDS
• IT OCCURS IN THE SOIL AS ROCK
PHOSPHATE, CALCIUM PHOSPHITE,
FLUROPATITE (Ca10Fe2(PO4)6), IRON
PHOSPHATE, ALUMINIUM PHOSPHATE.

8. PHOSPHORUS OCCUR IN THE SOIL IN FIVE
FORMS :
 P1 (STABLE ORGANIC)
 P2 (LABILE ORGANIC)
 P3 (LABILE INORGANIC)
 P4 (SOLUBLE)
 P5 (MINERAL FORM

9. THE CYCLE STARTS
WITH THE ROCKS,
THE SEDIMENTARY
ONES. THEY HAVE
THE PHOSPHORUS
IN A FORM CALLED
APATITE
Ca5(PO4)3OH.

10. THE SEDIMENTARY ROCKS MERELY ADD
PHOSPHORUS TO THE CYCLE , THEY ARE
NOT ACTUALLY PART OF THE CYCLE

11. THE SEDIMENTARY ROCKS WILL THEN
WEATHER DOWN FROM STORMS AND
SUCH WHICH MOVE THE APATITE INTO THE
SOIL

12. THE PLANTS THEN USE THE PHOSPHORUS
IN THEIR REPRODUCTIVE STRUCTURE,
SUCH AS DNA AND RNA.

13. AND THE PHOSPHORUS GOES THROUGH
THE FOOD CHAIN

14. SOMETIMES DUE TO RUN OF THE
PHOSPHORUS ENTERS AREA OF
WATER.
IT IS GOES THROUGH THE MARINE FOOD
CHAIN

15. PHOSPHORUS ALONG WITH MANY
OTHER MINERAL ELEMENTS REACHES
THE OCEAN AND SETTLE DOWN AS
SEDIMENT. A GOOD PROPOTION OF
PHOSPHORUS LEACHES DOWN TO DEEP
LAYERS OF SOIL. IN THIS WAY, MAJOR
PROPOTION OF PHOSPHATE BECOME
LOST TO THIS CYCLE BY PHYSICAL
PROCESS, SUCH AS SEDIMENTATION
AND LEACHING.
BIOLOGICAL PROCESS SUCH AS
FORMATION OF TEETH AND BONES
ALSO KEEP PHOSPHORUS LOCKED UP
FOR SOME TIME

19. SULFUR IS ONE OF THE ESSENTIAL
ELEMENT OF LIFE SYSTEM AND ITS
MAJOR RESERVOIR LIES IN THE
EARTH’S CRUST TOGETHER WITH
OCEANIC SEDIMENT. IT ACTS AS A
COMPONENT OF SEVERAL
COMPOUND LIKE AMINO ACID,
PROTIEN,ENZYME etc. NATURAL
FUEL LIKE COAL AND OILS ALSO
HAVE SOME SULFUR (1-30%)

21. WHERE IS SULFUR FOUND ??
• IN ROCKS UNDERGROUND
• IN SULFUR SALTS AT THE BOTTOM OF
THE OCEAN

23. MINERALISATION OF ORGANIC SULFUR TO
THE INORGANIC FORM HYDROGEN SULFIDE
(H2S).
OXIDATION OF SULFIDE AND ELEMENTAL
SULFUR AND RELATED COMPOUNDS TO
SULFATE (SO4).
REDUCTION OF SULFATE TO SULFIDE
MICROBIAL IMMOBILIZATION OF THE
SULFUR
COMPOUNDS AND SUBSEQUENT
INCORPORATION INTO THE ORGANIC FORM
OF SULFUR

24. WEATHERING OF ROCKS RELEASE
STORED SULFUR
SULFUR COMES INTO CONTACT WITH AIR
AND IS CONVERTED INTO SULFATE IONS
THE SULFATE IS TAKEN UP BY PLANTS
AND MICROORGANISM, CONVERTED INTO
ORGANIC FORMS

25. ANIMALS CONSUME ORGANIC
MOLECULES CONTAINING SULFUR, SULFUR
MOVES THROUGH THE FOOD CHAIN
THE DEATH AND DECOMPOSITION OF
ORGANISMS RELEASE SULFUR ONCE
AGAIN IN SULFATE FORM AND SOME OF IT
BECOME PART OF THE BIOMASS OF
MICROORGANISM

27. VOLCANIC ERUPTIONS, BREAKDOWN OF
ORGANIC MATTER IN SWAMPS AND TIDAL
FLATS, AND THE EVAPORATION OF WATER,
ESPECIALLY SEAWATER, RELEASE SULFUR
DIRECTLY INTO THE ATMOSPHERE
SULFUR EVENTUALLY SETTLES TO EARTH
OR COMES DOWN WITH RAINFALL

28. Human Activities
The burning of fossil fuels and processing
of metals releases huge quantities of
sulfur into the atmosphere
Human activities are responsible for onethird of all sulfur emissions and 90% of
all sulfur dioxide emissions
Sulfur dioxide emissions lead to acid rain
as sulfur dioxide and sulfur trioxide
reacts with water to form H2SO4