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.
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