NATURAL CYCLES

CARBON | NITROGEN CYCLES

THE CARBON CYCLE.

 

The carbon cycle is a natural process that describes the movement and exchange of carbon among different reservoirs on Earth, including the atmosphere, oceans, land, and living organisms. It involves various interconnected processes through which carbon is continuously cycled and transformed. Here is an overview of how the carbon cycle works:

 

Carbon in the Atmosphere: The atmosphere is the carbon cycle’s primary reservoir of carbon dioxide (CO2). CO2 is exchanged between the atmosphere and living organisms through processes such as respiration, combustion of fossil fuels, and volcanic activity. Human activities, including burning fossil fuels and deforestation, have increased the concentration of CO2 in the atmosphere.

 

Photosynthesis: Plants, algae, and some bacteria carry out photosynthesis, using sunlight, water, and CO2 to produce glucose and oxygen. During photosynthesis, plants absorb atmospheric CO2 and convert it into organic compounds, incorporating carbon into their tissues.

 

Plant Respiration: Plants, like other living organisms, undergo respiration, breaking down organic compounds to release energy for cellular activities. Plant respiration releases CO2 back into the atmosphere, partially offsetting the carbon uptake during photosynthesis.

 

Decomposition: When plants and other organisms die, their organic matter undergoes decomposition. Decomposers, such as bacteria and fungi, break down the organic material and release CO2 into the atmosphere as a byproduct. Decay also occurs in soils, where soil microbes break down organic matter, contributing to the carbon cycle.

 

Carbon Storage in Biomass: Carbon can be stored as living and dead biomass, such as trees, vegetation, and organic matter in soils. This carbon reservoir plays a vital role in mitigating climate change by sequestering atmospheric CO2 for long periods, preventing its immediate release back into the atmosphere.

 

Carbon Sequestration: Carbon sequestration refers to capturing and storing carbon from the atmosphere in vegetation, soils, and other long-term reservoirs. This process is essential for reducing greenhouse gas concentrations in the atmosphere and mitigating climate change. Carbon sequestration mechanisms are intimately related to sustainable land management practices.

 

The carbon cycle is a complex and dynamic process involving interactions between the atmosphere, land, oceans, and living organisms. It plays a crucial role in regulating Earth’s climate and supporting the functioning of ecosystems. Understanding and managing the carbon cycle is vital for addressing climate change and ensuring the sustainability of our planet.

 

 

 * Text generated by ChatGPT, developed by OpenAI (https://openai.com/) accessed on 06/10/2023.

 

 

THE NITROGEN CYCLE.

 

The nitrogen cycle is a vital biogeochemical process that describes the movement and transformation of nitrogen in various forms through the atmosphere, land, water, and living organisms. Nitrogen is essential for the growth and development of living organisms, including plants and animals. The nitrogen cycle consists of the following key steps:

 

Nitrogen Fixation: Nitrogen gas (N2) makes up about 78% of the Earth’s atmosphere, but most organisms cannot directly utilise it in this form. Nitrogen fixation is the process by which certain bacteria, called nitrogen-fixing bacteria, convert atmospheric nitrogen gas into ammonia (NH3) or ammonium (NH4+), which plants can utilise. Some nitrogen-fixing bacteria live freely in the soil, while others form symbiotic relationships with certain plants, such as legumes (e.g., beans, peas) or alders. Industrial processes like Haber-Bosch also fix nitrogen to produce synthetic fertilisers.

 

Nitrification: Nitrification is the conversion of ammonia or ammonium into nitrite (NO2-) and then into nitrate (NO3-) by nitrifying bacteria. The first step involves ammonia-oxidising bacteria, which convert ammonia into nitrite, and the second step involves nitrite-oxidising bacteria, which further convert nitrite into nitrate. Nitrate is the primary form of nitrogen that plants can readily absorb and utilise for growth.

 

Assimilation: In assimilation, plants take up nitrate or ammonium from the soil through their roots and use it to synthesise organic molecules, such as proteins, nucleic acids, and other nitrogen-containing compounds. Animals acquire nitrogen by consuming plants or other animals containing nitrogen compounds and incorporating it into their tissues.

 

Ammonification: Ammonification, or mineralisation, is the process in which organic nitrogen compounds, such as proteins and nucleic acids, are broken down and converted back into ammonia or ammonium. Bacteria and fungi carry out this process while decomposing organic matter, such as dead plants, animal waste, and dead organisms. The released ammonia or ammonium can then be used in subsequent nitrogen cycle steps.

 

Denitrification: Denitrification is the conversion of nitrate back into nitrogen gas (N2) by denitrifying bacteria. This process occurs in oxygen-depleted environments, such as saturated soils or aquatic systems. Denitrification completes the nitrogen cycle by returning nitrogen gas to the atmosphere, closing the loop.

 

Nitrogen Losses: Nitrogen can be lost from the system through various processes. Apart from denitrification, nitrogen can also be lost through leaching, where excess nitrate moves downward through the soil profile into groundwater, potentially polluting water bodies. Additionally, nitrogen can be lost through runoff, particularly in agricultural settings, when plants do not efficiently take up fertilisers and are washed away into rivers and streams.

 

The nitrogen cycle is a complex and interconnected process involving biological, chemical, and physical nitrogen transformations. It is crucial in maintaining soil fertility, supporting plant growth, and sustaining ecological balance. Human activities, such as agriculture, industrial processes, and the combustion of fossil fuels, can disrupt the natural nitrogen cycle and lead to environmental issues like water pollution and eutrophication. Therefore, managing nitrogen inputs, optimising fertiliser use, and promoting sustainable agricultural practices are essential for minimising the negative impacts associated with nitrogen cycling.

 

 

 * Text generated by ChatGPT, developed by OpenAI (https://openai.com/) accessed on 06/10/2023.

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