Bio-Geo Chemical Cycle in an Eco-System

Bio-Geo Chemical Cycle

Nutrients Cycle

It describes the nutrients movement from the physical environment to the living organisms and recycles back to the same physical environment. To maintain the sustainable ecosystem and to balance the nutrient cycle, this movement of nutrients from the environment into organisms & again back to the environment is necessary.

1.Gaseous Cycles

a). Water Cycle

Hydro Cycle

The continuous circulation of water in the atmosphere & earth systems which is driven by solar energy. Water on our planet is stored in reservoirs like atmosphere, oceans, rivers, lakes, dams, glaciers, groundwater etc. Water moves from one reservoir to another by the processes of evaporation, condensation, transpiration, deposition, running infiltration and flowing water.

b). Carbon Cycle

Carbon Cycle

Carbon exists in the atmosphere mainly in the form of carbon compound like CO₂, CO etc. Carbon cycle involves a continuous exchange of carbon between atmosphere and organisms. Carbon used in the photosynthesis from atmosphere by the plants & then moves to animals. By the process of respiration & decomposition of dead organic matter, it returns backs to the atmosphere.

Fossils fuels such as coals, oil, natural gas are organic component that were buried before decomposition & were transformed by time & geological process into fossil fuels. When they are burned, carbon stored in them released back into the atmosphere as carbon dioxide.

c). Nitrogen Cycle

Nitrogen Cycle

Nitrogen exists in the atmosphere is abundant. The largest constituent of air by volume, also the most essential constituents of protein and is a basic building block of all the living organism.

Nitrogen as an elemental form can’t be used directly. It is used to be fixed i.e. converted to nitrogen compound (nitrites or nitrates, ammonia) before it can be taken up by plants.

Nitrogen fixation takes place by:

I. By micro-organisms (bacteria & blue green algae)

Certain micro-organisms are capable of fixing atmospheric nitrogen into ammonium ions. These include free living nutrifying bacteria (e.g. Aerobic azotobacterial & Anerobic Clostridium) and symbiotic nutrifying bacteria living in association with leguminous plants symbiotic bacteria living in non-leguminous root module plants (e.g. Rhizobium) as well as blue-green-algae (e.g. Anabaena Spirulina).

Plant's Root: host to nitrogen fixation bacteria

Certain quantity of soil nitrates, being highly soluble in water, is lost to the system by being transported away by surface run-off (or) ground-water. The special denitrifying bacteria which converts the nitrates/nitrites to elemental nitrogen. This nitrogen escapes into the atmosphere, this forms the nitrogen cycle.

II. By using industrial process (Fertilizers)

In modern day, farmers have started using industrial processed fertilizers which can turn ammonia into nitrates just like those produced by soil bacteria. Plants can use these nitrates directly, and human industry can produce them in large quantity.

III. By atmospheric phenomenon (Lightening & Thunderstorm)

The production of nitrogen oxides NO₂ by lightening flashes has been computed from a model of gaseous molecular reaction occurring as heated lightening- channel air cools by mixing surrounding ambient air. The effect of ozone on the production of nitrogen, is that ozone gas oxidizes NO to NO₂ mainly at the end of the cooling process.

2. Sedimentary Cycle

The element involved in the sedimentary cycle normally does not the cycle through the atmosphere but follows a basic pattern of flow through erosion, sedimentation, mountain building volcanic activity & biological transport through excreta of the marine bird.

a). Phosphorus Cycle

Phosphorus occurs in large amounts as a mineral in phosphate rocks and enters the cycle from the means of erosion and mining. The nutrients considered to be the main cause of excessive growth of rooted & free-floating microscopic plant in lakes. Phosphorus found in the form of phosphates on land. These phosphorous deposited in the in the continental shelf of the oceans, after millions of years the crustal plates rise from the sea floor & expose the phosphate on land. Later weathering will release them from rock and the cycles geochemical phase begin again.

b). Sulphur Cycle

Sulphur Cycle

The Sulphur reservoir is in the soil & sediments where it is locked in organic (coal, oil) and inorganic deposits (Pyrite Rocks, Sulphides and Organic Sulphur). It is released by weathering of rocks, erosional runoff & decomposition of organic matter & is carried to terrestrial & aquatic ecosystem in salt solution.

Almost all the sulphur cycle are sedimentary except Hydrogen Sulphides(H₂S) and Sulphur Dioxide (SO₂) add a gaseous component to its normal sedimentary cycle.

Activities like volcanic eruptions, combustion, of fossil fuels from surface of ocean and gases released by decomposition enable sulphur to enter in the atmosphere. Atmospheric Hydrogen Sulphides also gets oxidised into sulphur dioxide. Atmospheric sulphur dioxide is carried back to the earth after being dissolved in rainwater as weak sulphuric acid.

Plants takes sulphur in the form of sulphates & incorporated in the autotrophs as protein. This sulphur carried back to the soil through the excretion of decomposition of dead organic material.