O ciclo do nitrogênio nas florestas brasileiras

Agência FAPESP

27 Jun 201402:07

Summary

TLDRThe script discusses the nitrogen cycle in nature, highlighting that the majority of atmospheric nitrogen is inert N2, not directly usable by ecosystems. It emphasizes the crucial role of nitrogen-fixing bacteria in converting N2 to ammonia, which is then utilized by plants and microbes on land or transformed into nitrate for aquatic systems. The process inadvertently releases nitrous oxide and nitric oxide, potent greenhouse gases. Human activities, particularly legume cultivation and fertilizer use, have significantly increased nitrogen fixation, leading to environmental challenges such as eutrophication and climate change.

Takeaways

🌍 The majority of nitrogen in the atmosphere is part of the Earth's large compartments, including the atmosphere, lithosphere, biosphere, and hydrosphere.
💨 Nitrogen makes up 78% of the air we breathe, primarily in the form of inert N2 molecules.
🌱 Nitrogen must be converted into ammonia before it can enter the ecosystem and be utilized by plants and microorganisms.
🌿 A small group of bacteria, known as nitrogen-fixing bacteria, are responsible for converting N2 into ammonia.
🔄 Ammonia can be transformed into nitrate, which is also usable by plants or can enter the aquatic system.
🌀 During the conversion of ammonia to nitrate, nitrogen oxides are released, which are significant in the nitrogen cycle.
🌱 Human activities, such as cultivating leguminous plants and using fertilizers, have increased the fixation of atmospheric nitrogen into ammonia.
🚫 Ammonia does not return 100% to N2, leading to its accumulation in aquatic environments or release back into the atmosphere as nitrogen oxides.
🌧️ Nitrogen oxides combine with water vapor to form acid rain or contribute to the greenhouse effect as nitrous oxide.
🌡️ Nitrous oxide is one of the greenhouse gases, contributing to global warming.
🔬 The nitrogen cycle is a complex process involving various transformations and interactions between the atmosphere, land, and water systems.

Q & A

What is the primary component of the Earth's atmosphere?
-The primary component of the Earth's atmosphere is nitrogen, which makes up about 78% of the air we breathe in the form of N2.
What is the role of nitrogen-fixing bacteria in the ecosystem?
-Nitrogen-fixing bacteria are essential as they convert atmospheric nitrogen (N2) into ammonia, making it available for plants and other organisms in the terrestrial system.
How is ammonia used in the ecosystem?
-Ammonia is utilized by plants and microorganisms in the terrestrial system or can be transformed into nitrate, which is also used by plants.
What are the environmental impacts of converting ammonia into nitrate?
-The conversion of ammonia to nitrate can release nitrous oxide and nitric oxide, which are significant greenhouse gases contributing to global warming.
How does human activity contribute to the fixation of atmospheric nitrogen?
-Humans contribute to nitrogen fixation through the cultivation of leguminous plants and the use of fertilizers, which convert atmospheric nitrogen into ammonia.
What is the issue with the conversion of ammonia back to N2 in the environment?
-The conversion of ammonia back to N2 is not 100% efficient, leading to the accumulation of ammonia in aquatic environments and contributing to eutrophication.
What is eutrophication and how does it relate to nitrogen compounds?
-Eutrophication is the over-enrichment of water bodies with nutrients, particularly nitrogen compounds, leading to excessive growth of algae and depletion of oxygen in the water.
How does nitric oxide combine with water vapor to form acid rain?
-Nitric oxide reacts with water vapor to form nitric acid, which then falls as acid rain, contributing to environmental pollution and damage to ecosystems.
What is the significance of nitrous oxide in the context of greenhouse gases?
-Nitrous oxide is a potent greenhouse gas, with a global warming potential significantly higher than carbon dioxide, contributing to climate change.
How can the nitrogen cycle be managed to minimize environmental impacts?
-The nitrogen cycle can be managed through sustainable agricultural practices, such as crop rotation, using organic fertilizers, and minimizing the use of synthetic fertilizers.
What are the implications of nitrogen fixation for the biosphere and hydrosphere?
-Nitrogen fixation has implications for both the biosphere and hydrosphere as it affects the availability of nitrogen for plant growth and can lead to water pollution and eutrophication when not properly managed.

Outlines

00:00

🌱 Nitrogen Cycle and its Transformation

This paragraph discusses the nitrogen's role in the atmosphere and its transformation process in the ecosystem. Nitrogen, making up 78% of the air we breathe in the form of N2, is inert and must be converted into ammonia by a group of bacteria known as nitrogen fixers. This ammonia is then utilized by plants and microorganisms on land or transformed into nitrate for plant uptake or aquatic systems. The conversion process releases nitrous oxide and nitric oxide, which contribute to greenhouse gas emissions. Human activities, such as growing legumes and using fertilizers, have increased the fixation of atmospheric nitrogen into ammonia, but not all of it returns to the atmosphere as N2, leading to potential eutrophication in aquatic systems or the formation of acid rain through the combination of nitric oxide with water vapor.

Mindmap

Keywords

💡Nitrogen

Nitrogen is a chemical element with the symbol N and atomic number 7. It is a colorless, odorless, tasteless, and mostly inert diatomic gas that makes up about 78% of the Earth's atmosphere. In the video's context, nitrogen is discussed as a major component of the atmosphere and its transformation into other forms, such as ammonia, is crucial for its role in the ecosystem.

💡Atmosphere

The atmosphere is a layer of gases surrounding a planet, and in the context of the video, it is identified as one of the four compartments where nitrogen resides. It is where nitrogen exists in its most abundant form, N2, and is essential for the nitrogen cycle that supports life on Earth.

💡Lithosphere

The lithosphere is the rigid outermost shell of a planet, consisting of the crust and upper mantle. In the script, it is mentioned as one of the four compartments, indicating the vastness of the nitrogen cycle and its interaction with different parts of the Earth system.

💡Biosphere

The biosphere encompasses all regions of the planet where life exists, including land, sea, and parts of the atmosphere. It is relevant in the video as the place where nitrogen is transformed into forms usable by plants and microorganisms, such as ammonia, through the action of nitrogen-fixing bacteria.

💡Hydrosphere

The hydrosphere refers to the total amount of water found on Earth, including oceans, lakes, rivers, and groundwater. It is mentioned in the script as another compartment where nitrogen can be transformed and utilized, or where it can end up as a pollutant, affecting aquatic ecosystems.

💡Nitrogen-fixing bacteria

Nitrogen-fixing bacteria are a group of microorganisms that can convert atmospheric nitrogen (N2) into ammonia (NH3), a form of nitrogen that can be used by plants. In the video, they play a key role in the nitrogen cycle by making nitrogen available to the ecosystem.

💡Ammonia

Ammonia is a compound of nitrogen and hydrogen (NH3). It is a crucial intermediate in the nitrogen cycle, as it is the form into which atmospheric nitrogen is converted by nitrogen-fixing bacteria and then used by plants and microorganisms.

💡Nitrate

Nitrate is a polyatomic ion with the chemical formula NO3−. It is another form of nitrogen that is used by plants and can be formed from ammonia through a process called nitrification. The script mentions nitrate as part of the nitrogen transformation process in the ecosystem.

💡Eutrophication

Eutrophication is the process where an excess of nutrients, particularly nitrogen and phosphorus, causes a dense growth of plant life in water bodies, leading to a depletion of oxygen and death of animal life. The script discusses how nitrogen, through its various forms, can contribute to eutrophication in aquatic systems.

💡Nitrous oxide

Nitrous oxide (N2O) is a potent greenhouse gas that has significant effects on the ozone layer. In the video, it is mentioned as a byproduct of the nitrogen transformation process, highlighting its role in climate change and the environmental impact of the nitrogen cycle.

💡Leguminous plants

Leguminous plants, such as beans and peas, are known for their ability to host nitrogen-fixing bacteria in root nodules, which allows them to convert atmospheric nitrogen into a form they can use for growth. The script mentions the cultivation of leguminous plants as a way humans have been fixing nitrogen from the atmosphere.

💡Fertilizer

Fertilizers are substances that provide essential nutrients to plants to enhance their growth. In the context of the video, fertilizers are used to fix nitrogen from the atmosphere and convert it into ammonia, but not all of it returns to the atmosphere as N2, contributing to environmental issues.

Highlights

The majority of nitrogen in the atmosphere is part of the large reservoirs of the Earth's system.

Nitrogen exists in the atmosphere primarily as inert N2 molecules, making up 78% of the air we breathe.

Nitrogen must be converted into ammonia to enter the ecosystem, a process facilitated by a small group of bacteria known as nitrogen fixers.

Plants and terrestrial microorganisms utilize ammonia or it can be transformed into nitrate for plant use.

The transformation of ammonia into nitrate can lead to the release of nitrous oxide and nitric oxide, significant greenhouse gases.

Human activities, such as cultivating legumes and using fertilizers, have increased nitrogen fixation from the atmosphere.

Ammonia from human activities does not always return to the atmosphere as N2, leading to environmental impacts.

Excess ammonia can contribute to eutrophication in aquatic systems, causing environmental harm.

Nitrous oxide and nitric oxide emissions from nitrogen transformation are a concern due to their role in the greenhouse effect.

Nitrous oxide can combine with water vapor to form acid rain, impacting the environment.

The nitrogen cycle is a critical process in the Earth's ecosystem, with human activities having significant impacts on its balance.

Understanding the nitrogen cycle is essential for managing agricultural practices and reducing environmental harm.

Efforts to reduce nitrogen emissions are crucial for mitigating climate change and protecting ecosystems.

The role of bacteria in the nitrogen cycle is vital for converting atmospheric nitrogen into a form usable by plants.

Leguminous plants play a key role in nitrogen fixation, making them valuable in sustainable agriculture.

Fertilizer use must be carefully managed to prevent excessive nitrogen runoff and its environmental consequences.

Technological advancements can aid in more efficient nitrogen use in agriculture, reducing waste and environmental impact.

The interplay between the nitrogen cycle and climate change is a complex issue requiring multifaceted solutions.