Biogeochemical Cycle

The process by which chemical elements are recycled through the Earth's systems, including the atmosphere, hydrosphere, lithosphere, biosphere, and pedosphere.

Carbon Cycle

Carbon: A fundamental building block of life, found in organic molecules, and continuously cycles through the atmosphere, biosphere, hydrosphere, and geosphere.

Key Processes in Carbon Cycle

• Photosynthesis: The process where carbon is fixed into organic matter.

• Respiration: The process which releases CO2 back into the atmosphere.

• Decomposition

• Combustion of Fossil Fuels

Human activities, particularly deforestation and burning fossil fuels, have significantly elevated CO2 levels in the atmosphere, contributing to global climate change.

Nitrogen Cycle

Nitrogen: is crucial for the synthesis of amino acids and nucleic acids and cycles through the atmosphere, soil, and living organisms.

Main Steps in Nitrogen Cycle

• Nitrogen Fixation: conversion of atmospheric nitrogen into ammonia

• Nitrification: conversion of ammonia to nitrates

• Denitrification: conversion of nitrates back into nitrogen gas

Excess nitrogen, often from fertilizers, can cause water pollution and eutrophication, leading to imbalances in aquatic ecosystems.

Water Cycle (Hydrologic Cycle)

Water Cycle: refers to the continuous movement of water on Earth through processes such as evaporation, condensation, precipitation, and runoff.

• This cycle is essential for regulating climate, sustaining ecosystems, and ensuring the availability of freshwater for human use.

• Human activities, like urbanization and deforestation, can disrupt natural water flows, leading to problems like flooding and water scarcity.

Phosphorus Cycle

Phosphorus: is critical for the formation of DNA, RNA, and ATP, and it primarily cycles through rocks, soil, water, and living organisms.

• Unlike other biogeochemical cycles, phosphorus does not have a gaseous phase. It is released from rocks through weathering and absorbed by plants.

• Excess phosphorus, typically from agricultural runoff, can lead to harmful algal blooms and degrade water quality in aquatic environments.

Sulfur Cycle

Sulfur: plays a vital role in the structure of proteins and vitamins and cycles through the atmosphere, lithosphere, and biosphere.

Key Processes

• Release of sulfur dioxide (SO2) from volcanic eruptions

• Human activities, which is then converted to sulfate ions in the atmosphere

The resulting acid rain, caused by sulfur emissions, can damage ecosystems and infrastructure.

Oxygen Cycle

Oxygen: essential for cellular respiration and is primarily produced by plants and phytoplankton through photosynthesis.

• The oxygen cycle involves the exchange of oxygen between the atmosphere, biosphere, and hydrosphere, with processes like respiration and decomposition releasing CO2. 

Human-induced changes, such as deforestation, can disrupt oxygen production and affect the carbon balance in ecosystems.

Rock Cycle

Rock Cycle: describes the ongoing transformation of rocks through processes like weathering, erosion, sedimentation, and metamorphism.

• It links geological processes to biogeochemical cycles, as rocks provide critical minerals and nutrients that support ecosystems.

• Studying the rock cycle is important for understanding soil formation, nutrient availability, and how geological events impact the environment.