Biogeochemical Cycles – The Cycles of Life

Biogeochemical cycles are the processes that move chemical elements through the Earth’s different systems, from the environment to living organisms, through food webs, and back again. These cycles ensure balance and sustain life on Earth.

Major Biogeochemical Cycles:

• The Carbon Cycle: Carbon enters the cycle as CO2 through the process of photosynthesis by plants. CO2 levels in the atmosphere are rising due to industrial, agricultural, and deforestation activities, leading to the greenhouse effect and global warming.

• The Nitrogen Cycle: Nitrogen makes up 79% of the atmosphere by volume and is an inert gas. Plants absorb nitrogen in the form of NH4+ and NO3-. Nitrogen salts are formed through chemical, physical, and biological processes, primarily through biological pathways.

• The Water Cycle: Water is the molecule that constitutes the majority of the mass of living organisms. Continuous water exchange occurs between living organisms and the environment. Water returns to the atmosphere as water vapor through transpiration from leaves and evaporation from the soil. Water plays a crucial role in global ecosystems.

Biosphere: The Global Natural System

The biosphere encompasses all living organisms in the Earth’s land, water, and air. It is approximately 20 kilometers thick and consists of the following layers:

• The Soil Layer: A few tens of meters thick, belonging to the geosphere.

• The Air Layer: 6-7 kilometers thick, belonging to the atmosphere.

• The Ocean Layer: 10-11 kilometers thick, belonging to the hydrosphere.

Within the biosphere, living organisms and abiotic factors are closely interconnected through biogeochemical cycles, forming a natural system on a global scale.