Bio-geo Chemical Cycles In Nature


Biogeochemical Cycles represent the constant interaction between the biotic and abiotic components of the biosphere that make it dynamic yet stable system. During this interaction, there is a transfer of matter and energy between the different components of the biosphere.

The water-cycle

The water cycle describes the continuous movement of water on, above, and below the surface of the earth. Water changes states between liquid, vapour and ice at various stages in the water cycle. It is one of the most important cycles in nature, it is also known as the hydrologic cycle.

Water in its liquid form on the surface of the earth, like the water in oceans, gets heated in the presence of sun rays and becomes vapour in the air. All the air around us will have water vapour content. Solid state water like Ice and snow can sublimate directly into water vapour.

Rising air currents reach higher layers of the atmosphere, here cooler temperatures cause these vapours to condense into clouds.

Clouds are moved by the air currents; these clouds further collide, grow, and are seen as precipitation. Some precipitation falls as snow and forms ice caps and glaciers.

In some parts, this snow thaws and melts under heat and the melted water flows back to the land making it a cycle. This precipitation falls back into the oceans or land and flows over the ground as surface water. Some of this flowing water enters rivers in valleys in the landscape, with streamflow moving water towards the oceans. Runoff and groundwater are stored as freshwater in lakes. Water also gets soaked into the ground.

The nitrogen-cycle

The nitrogen cycle is the biogeochemical cycle that describes the transformations of nitrogen and nitrogen-containing compounds in nature.

Our Earth’s atmosphere is made up of almost 78% nitrogen, making it the largest cradle of nitrogen. Nitrogen is essential for many biological processes; hence very important for any life here on Earth. Nitrogen is in all amino acids, in proteins, and is present in the bases that make up nucleic acids, such as DNA and RNA. In plants, nitrogen is used in chlorophyll molecules which are essential for photosynthesis.

Nitrogen fixation is the process which converts gaseous nitrogen into usable forms.

Some fixation occurs when lightning strikes, but most fixation is done by free-living or symbiotic bacteria. These bacteria have the nitrogenase enzyme that combines gaseous nitrogen with hydrogen to produce ammonia, which is then further converted by the bacteria to make its own organic compounds. Some nitrogen-fixing bacteria, such as Rhizobium, live in the root nodules of legumes (such as peas or beans). Here they form a mutualistic relationship with the plant, producing ammonia in exchange for carbohydrates. Nutrient-poor soils can be planted with legumes to enrich them with nitrogen.

The carbon-cycle

The carbon cycle is the biogeochemical cycle in which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth.

The cycle can have four major pools of carbon, listed below which are interconnected and constantly in exchange.:

(I) The atmosphere.

(II) The terrestrial – includes freshwater systems and non-living organic material, such as soil carbon.

(III) The oceans, including dissolved inorganic carbon, living and non-living marine layers,

(IV) The fossil fuels.

The greenhouse effect

Have you ever closed all windows and left your car in hot weather outside and seen that when you come back it's unbearably hot?

This high heat inside the vehicle is due to gases trapped inside after windows are closed which absorb infrared radiation and radiate heat. This Phenomenon is called Green House effect.

Greenhouse gases, which include water vapour, carbon dioxide and methane, making the atmosphere warm by absorbing thermal infrared radiation emitted by the earth’s surface, by the atmosphere and clouds. The further atmosphere radiates this thermal infrared in all directions. Thus, greenhouse gases trap heat within the surface-troposphere system. The greenhouse effect is one of several factors that affect the temperature of the Earth.

The oxygen-cycle



The oxygen cycle is the biogeochemical cycle that describes the movement of oxygen between three reservoirs: the atmosphere (air), the biosphere (living things), and the lithosphere (earth’s crust). The main driving factor of the oxygen cycle is photosynthesis, which is responsible for the modern Earth's atmosphere and life.