What is Biogeochemical Cycle ? Nutrient Cycles Types, Explained

A biogeochemical cycle is defined as the movement or circulation of elements through organisms and the environment. The term consist of two parts — bio, meaning biological organisms like bacteria, plants, animals and geochemical involves geological and chemical processes such as the formation of molecule.

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Bio­chem­i­cal

Ele­ments with­in bio­geo­chem­i­cal cycles flows in var­i­ous forms from the non liv­ing (Abi­ot­ic) com­po­nents of the bios­phere to the liv­ing (biot­ic) com­po­nent and back. 

In order to sur­vive, all the chem­i­cals ele­ments need to be recy­cled con­tin­u­ous­ly to main­tain the sur­vival of liv­ing com­po­nents of ecosys­tem. The term was giv­en by Russ­ian geo­g­ra­ph­er named B. B poly­nov in 1937 . It is also referred as the study of exchange of mate­ri­als between liv­ing and non liv­ing com­po­nents of the Bios­phere. The rapid exchange of ele­ments occurs between the biot­ic and abi­ot­ic com­po­nents of an ecosystem. 

The biogeochemical cycles are of two types : gaseous and sedimentary. 

The clas­si­fi­ca­tion has been giv­en on the basis of pri­ma­ry source of nutri­ents input into the ecosystem. 

  • Gaseous - in these cycles the gaseous phase is dom­i­nant. The main pool of nutri­ents is atmos­phere and oceans. Cycling of car­bon, nitro­gen occurs as gaseous cycles. Gaseous cycles tend to move more rapid­ly than do sed­i­men­ta­ry ones and adjust to changes in the bios­phere because of the large atmos­pher­ic reservoir. 
  • Sed­i­men­ta­ry - in these cycles, the cir­cu­la­tion of var­i­ous ele­ments such as car­bon, nitro­gen, phos­pho­rous, sul­phur occurs. The nutri­ents are released from lithos­phere (main reser­voir) via weath­er­ing of rocks. The main pool of ele­ments is rocks, soil and min­er­als. Sed­i­men­ta­ry cycles get dis­rupt­ed by local dis­tur­bances as the mate­ri­als remains Immo­bi­lized in the earth­’s crust. 
  • Water also cir­cu­lates with­in the dif­fer­ent com­po­nents of the ecosys­tem. Water from the water bod­ies gets heat­ed up due to sun’s rays and evap­o­rates to reach the atmos­phere as vapour (gaseous form) . It gets con­densed to form which again send the water back to earth in the form of rain.

Sed­i­men­ta­ry cycles vary from one ele­ment to anoth­er . Each cycle con­sist of a solu­tion phase ( water relat­ed) and a rock phase (sed­i­ment) . In the solu­tion phase, wether­ing releas­es min­er­als from Earth­’s crust in the form of of salts. The min­er­als dis­solve in water, pass through a series of organ­isms and ulti­mate­ly reach the deep seas, where they get stored as reserve and moves out of cir­cu­la­tion. In the rock phase, salts deposit as sed­i­ment even­tu­al­ly that get weath­ered and recycled. 

Reser­voirs or pools of nutri­ents include atmos­phere or rocks. These are gen­er­al­ly large in size. The nutri­ents moves to dif­fer­ent areas/compartments dur­ing cycling. The effect of human activ­i­ties on nutri­ents cycles needs to be assessed. Dis­tur­bances such as glob­al warm­ing, wild­fires and storms seri­ous­ly affect the capac­i­ty for self adjust­ment. Accu­mu­la­tion of gas­es such as car­bon diox­ide (CO2) are dis­si­pat­ed by winds or tak­en up by plants 

bio­geo­chem­i­cal cycles are said to be per­fect or imper­fect. In per­fect cycles, nutri­ents get replaced with the same pace as they are used up. Most of the gaseous cycles are con­sid­ered to be per­fect in con­trasts, sed­i­men­ta­ry cycles are con­sid­ered to be imper­fect because some of the nutri­ents are lost into soil and sed­i­ments as reserves and is not avail­able for Recy­cling. Some parts of nutri­ent stag­na­tion occurs in lakes and oceans . 

Both the nutri­ent cycles involves the bio­log­i­cal, non bio­log­i­cal process­es and are dri­ven by flow of ener­gy through ecosys­tem. Water as the medi­um helps in the move­ment of ele­ments and oth­er mate­r­i­al through the ecosystem. 

plants and some ani­mals obtain nutri­ents present in var­i­ous com­po­nents of the envi­ron­ment. Ani­mals get the nutri­ents through the plants and ani­mals. After the death of an organ­isms, the ele­ments fixed in its body are returned to the envi­ron­ment through the action of decom­posers (decay organ­isms such as bac­te­ria, insects and fun­gi) and become avail­able to oth­er liv­ing organisms. 

Nutri­ent cycles

These cycles con­sist of two parts — the envi­ron­men­tal phase and the organ­isms phase in the envi­ron­men­tal phase, cycling of nutri­ents by dif­fer­ent com­po­nents of envi­ron­ment such as air, water, soil occurs where in organ­isms phase trans­fer of nutri­ents to plants, ani­mals and microor­gan­isms occurs. Many nutri­ent cycles oper­ate simul­ta­ne­ous­ly in bios­phere to ensure the availability/supply of chem­i­cal nutri­ents to all liv­ing organisms. 

There are dif­fer­ent types of cycle

  • Car­bon cycle
  • Nitro­gen cycle
  • phos­pho­rus cycle

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