biogeochemical cycle

M.Sc 2nd semster

1. BIOGEOCHEMICAL CYCLE SUBMITTED BY BHIMSEN M.S c 2 nd Semester ROLL NO. 11

2. The term biogeochemical tells us that Biological , Geological & Chemical factors are involved . In earth science, a biogeochemical cycle is a pathway by which a chemical substances moves through both Biotic(Biosphere ) & Abiotic (Lithosphere, Atmosphere & Hydrosphere ) compartments of earth. A cycle is a series of change which comes back to the starting point & which can be repeated. INTRODUCTION

3. – “ More or less circular pathways, through which the chemical elements , including all the essential elements of the protoplasm, circulate in the biosphere from environment to organisms and back to the environment, are known as the Biogeochemical cycle”. Biogeochemical cycles always involve Hot equilibrium states : A balance in the cycling of the elements between compartments . As biogeochemical cycles describe the movements of substances on the entire globe , the study of these is inherently multidisciplinary. DEFINATION

4. Macronutrients : required in relatively large amounts “ Big six": Carbon , Hydrogen , Oxygen , Nitrogen, Phosphorous . other Macronutrients: Sulfur , Potassium , Calcium , Iron , Magnesium Micronutrients : required in very small amounts, (but still necessary) Boron Copper Molybdenum CYCLING ELEMENTS

5. TYPE OF BIOGEOCHEMICAL CYCLE Biogeochemical cycles can be classed as; GASEOUS CYCLE – The term gaseous cycle refers to the transformation of gases between various biogeochemical reservoirs; Hydrosphere, Atmosphere & Biosphere Important gaseous cycles are; a ) NITROGEN CYCLE b ) OXYGEN CYCLE c ) CARBON CYCLE d ) WATER CYCLE

6. Sedimentary cycles include the leaching of minerals & salt’s from the earth’s crust, which the settle as sediment or rock before the cycle repeats. Sedimentary cycle includes ; a ) PHOSPHORUS CYCLE b ) SULFUR CYCLE c ) IRON CYCLE d ) CALCIUM CYCLE Sedimentary cycles vary from one elements to another, but each cycle consist fundamentally of a solution phase & a sediment phase . SEDIMENTARY CYCLE LITHOSPHERE

7. The majority of earth’s atmosphere is Nitrogen(78 %). However , Atmospheric N2 has limited availability for biological use, and this form is relatively nonreactive and unusable by plants. Nitrogen availability can affect the rate of key ecosystem processes including primary production and decomposition The Nitrogen(N2) cycle is the process by which N2 is converted between its various chemical forms. This transformation can be carried out through both biological & physical processes. NITROGEN CYCLE

8. The nitrogen cycle processes The processes involved in a complete nitrogen cycle are : Nitrogen fixation : Atmospheric nitrogen is converted into the usable form by lightning strikes or symbiotic bacteria which are known as Diazotrophs . These bacteria consist of a nitrogenase enzyme which has the capability to combine gaseous nitrogen with hydrogen to form ammonia.

9. Ammonification When plants or animal die organic nitrogen is again released back into the soil. Bacteria or fungi present in the soil convert them back into ammonium. This process is also called as mineralization. Assimilation Primary producers take in this gas from the soil with the help of their roots in the form of amino acids, nitrite ions, nitrate ions or ammonium ions. This way it enters the food cycle when the consumers eat the  plants .

10. Nitrification

11. In this process, the ammonia is converted into nitrate by the presence of bacteria in the soil. Ammonia is oxidized to form nitrites by bacteria such as Nitrosomonas species. Nitrates are converted into nitrates by Nitrobacter . This conversion is very important as ammonia gas is toxic for plants. Nitrification

12. Denitrification In order to complete the nitrogen cycle, the nitrites are reduced back to inert nitrogen gas in this process. This is done by bacterial species such as Clostridium and Pseudomonas in the absence of oxygen. To learn more about the nitrogen cycle, visit BYJU’S.

13. The phosphorus cycle is the slowest Biogeochemical cycle that describes the movements of phosphorus( P) through the Lithosphere , Hydrosphere & Biosphere . Unlike many other biogeochemical cycles, the atmosphere does not play a significant role in the movements of phosphorus. It is an essential nutrient for plants and animals. It is a part of DNA-molecules and RNA-molecules , molecules that store energy (ATP and ADP) It is also a building block of certain parts of the human and animal body, such as the bones and teeth. Phosphorus Cycle

14. Ecological Function Phosphorus is an essential nutrient for plants and animals. Limiting nutrient for aquatic organisms . Forms parts of important lifesustaining molecules that are very common in the biosphere.

15. Biological Function The primary biological importance of phosphates is as a component of nucleotides, which serve as energy storage within cells (ATP ) or when linked together, form the nucleic acids DNA and RNA..

16. Ecology and Environment – P. D. SHARMA Biogeochemical cycle – Wikipedia, the free encyclopedia . REFERENCE