Biogeochemical Cycles: Types, Importance & Effect|UPSC Notes

Biogeochemical cycles are the routes through which the essential elements flow across the Earth’s atmosphere, lithosphere, biosphere, and hydrosphere. These cycles are the foundation of life on earth; they support and sustain the flows of carbon, nitrogen, oxygen, and phosphorus, among other essential elements. It is against this background that one can appreciate how ecosystems operate and how this delicate balance sustains life. Elements circulating in a biogeochemical cycle move between living organisms and the physical environment, often forming closed loops that provide a basis for sustainability.

• Biogeochemical cycles connect living organisms with the Earth’s soil, water, and air.
• They regulate crucial processes, such as nutrient cycling, within and among ecosystems.
• Carbon, nitrogen, phosphorus, and water are a few key biogeochemical cycles.
• These cycles retain nutrients from being lost from ecosystems, which support plants, animals, and people.
• Human activities disturb these cycles, impacting health in the environment.

GS Paper	GS Paper III
Topics for UPSC Prelims	Definition and importance of Biogeochemical Cycles, Types of cycles, Key elements involved, Effects on ecosystems and climate
Topics for UPSC Mains	Detailed analysis of each cycle, Role of biogeochemical cycles in ecosystem stability and biodiversity, Policies and global initiatives

What is the Biogeochemical Cycle?

The biogeochemical cycle is the continuous transfer of elements between living and nonliving parts of the Earth. It thus demonstrates interactions among biological, geological, and chemical processes. These cycles prevent crucial elements from scarce by their reuse within ecosystems. Understanding the above definition requires first that one recognizes the natural path each element has to follow within earth’s systems; otherwise, the biological components of earth’s systems would run out of necessary nutrients, making life unsustainable.

Types of Biogeochemical Cycles

Biogeochemical cycles can be broadly categorized into different types based on the elements they cycle. There are some major cycles listed below:

Carbon Cycle

The carbon cycle is the exchange of carbon between organisms and the environment. Plants assimilate carbon dioxide converting it into energy through photosynthesis. Animals eat these plants, taking in carbon. At the death of organisms, carbon is released back into the environment by decomposers, which continues the cycle.

Nitrogen Cycle

It is moving through the soil, atmosphere, and living organisms. Nitrogen exists as a key constituent of proteins and DNA. The nitrogen involved in all these processes is fixed, nitrified, and denitrified to serve to support both plant and animal life.

Phosphorus Cycle

The phosphorus cycle involves transferring phosphorus among the soil, water, and the living organisms. Unlike the rest of the circles, phosphorus does not exist in the atmosphere. Instead, it occurs in rock formations and soil where, through weathering, it becomes soluble for the plants and then moves up the food chain.

Water Cycle

The hydrologic cycle, or the water movement process in Earth’s atmosphere, oceans, and land, is another name for it. This continuous journey of water due to evaporation, condensation, and precipitation brings about the movement of water across different regions and provides essential moisture for life.

Importance of Biogeochemical Cycle

The role of biogeochemical cycle is important in sustaining ecosystems. These cycles ensure the recycling of nutrients such as carbon, nitrogen, and phosphorus, which are vital to all living organisms. Biogeochemical cycles are integral to the general health and resilience of our Earth. They ensure that elements are constantly replenished for living organisms to use and rely on. Here is why biogeochemical cycles are crucial:

• Continued Survival of Life: Nutrient recycling would break down and elements necessary for survival would become less available for living organisms.
• Ecosystem Balance: An optimal balance between nutrients is needed to maintain the productivity of the ecosystems.
• Nutrient-Rich Fertile Land for Agricultural Use: Healthy biogeochemical cycles are supposed to result in nutrient-rich soils, which ultimately serve agricultural purposes.
• Reduced Amount of Garbage: Without the accumulation of nutrients through biogeochemical cycles, the amount of waste and pollution significantly reduces.
• Earth’s Stability: The cycles help keep the earth at a stable temperature, moisture level, and atmospheric constitution, thereby resulting in a stable climate.

Water Cycle

All other biogeochemical cycles are, in fact, interacting with the water cycle. It includes evaporation, condensation, precipitation, and infiltration, allowing the water to circulate among the atmosphere, oceans, and land. This cycling distributes the necessary water for drinking, agriculture, and habitat stability.

The falling precipitation that recharges water resources on land is the condensed water vapor in cloud droplets. Since the water is absorbed by plants it is transferred through the food web. Water forms the cycle because it leaves the earth through transpiration or evaporation.

Anthropogenically induced climate change impacts the water cycle, which eventually goes on to influence the rainfall pattern and water availability. Climate change exemplifies the need for interaction among biogeochemical cycles towards environmental stability.

Effects of Human Activity on Biogeochemical Cycles

Human activities significantly affect biogeochemical cycles and often throw them out of balance. Some of the major effects include the following:

Disturbances in the Carbon Cycle

• The burning of fossil fuels increases carbon dioxide concentration leading to global warming.
• Reduction of carbon through forests means less carbon is absorbed into the atmosphere.

Disturbances in the Nitrogen Cycle

• Overuse of fertilizers distributes excess nitrogen in the soil and can contribute to water pollution through runoffs.
• Acid rain affects ecosystems due to industrial emissions.

Effects on the Phosphorus Cycle

• Excessive phosphorus levels, caused by phosphorus mining and fertilizer runoff, stimulate water harming algal blooms.
• Soil erosion depletes phosphorus; thus the soil becomes less fertile.

Changes to the Water Cycle

• The carbon dioxide that goes to the atmosphere influences the pattern of rainfall that increases the instances of drought and floods.
• The increasing industrial utilization of water and associated pollution alter freshwater availability.

Conclusion

Understanding biogeochemical cycles is the way to sustain life on Earth. This cycle ensures nutrient flow, and therefore, ensures life is living sustainably. Understanding what the biogeochemical cycle is will help one understand the relatedness of life and the environment. The culture of keeping such cycles in place will ensure long-term prevention of environmental degradation.

Biogeochemical UPSC Notes

1. Biogeochemical cycles describe the movement of elements like carbon, nitrogen, and phosphorus through living and non-living systems. 2. These cycles ensure essential nutrients are available in ecosystems, supporting plant growth and overall biodiversity. 3. The carbon cycle plays a crucial role in regulating Earth’s climate by managing carbon dioxide levels in the atmosphere. 4. Human activities like deforestation and fossil fuel burning disrupt the carbon cycle, contributing to global warming. 5. The nitrogen cycle, vital for proteins and DNA, involves nitrogen fixation, nitrification, and denitrification processes. 6. Phosphorus, essential for DNA and cellular energy, primarily cycles through soil and water without a gaseous phase. 7. Biogeochemical cycles connect terrestrial, aquatic, and atmospheric systems, making them integral to ecosystem balance. 8. Disruptions in these cycles can lead to ecological issues like soil depletion, eutrophication in water bodies, and climate change.

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