7.4 Atmospheric CO2 and Particulates

Introduction

Carbon dioxide (CO2) is a greenhouse gas that is released into the atmosphere through natural processes and human activities such as the burning of fossil fuels, deforestation and agriculture. When CO2 is present in the atmosphere, it traps heat from the sun and warms the Earth's surface, a phenomenon known as the greenhouse effect. High concentrations of CO2 in the atmosphere can lead to an increase in the Earth's average temperature, which is known as global warming.

Particulate matter (PM) refers to tiny particles suspended in the air, such as dust, dirt, soot, and smoke. These particles can come from both natural and human-made sources, such as wildfires, dust storms, construction and industrial activities, and the burning of fossil fuels. Particulate matter can have serious health effects, particularly for people with respiratory conditions, such as asthma, and cardiovascular disease.

Atmospheric CO2 and particulate matter are linked in several ways:

• CO2 emissions from burning fossil fuels can also release particulate matter into the atmosphere, which can contribute to air pollution and health problems.
• Climate change caused by high levels of CO2 in the atmosphere can lead to an increase in the frequency and severity of wildfires, which can release large amounts of particulate matter into the air.
• Climate change can also lead to an increase in the frequency and intensity of dust storms, which can release large amounts of particulate matter into the air.

Natural Sources of Air Pollutants

General Examples

Natural sources of air pollutants include:

1. Volcanic eruptions: volcanic eruptions can release large amounts of ash, sulfur dioxide, and other pollutants into the air.
2. Wildfires: wildfires can release large amounts of particulate matter, carbon monoxide, and other pollutants into the air.
3. Dust storms: dust storms can release large amounts of dust, sand, and other particulate matter into the air.
4. Sea spray: sea spray can release salt particles and other pollutants into the air.
5. Biological processes: certain biological processes, such as the release of methane from wetlands, can contribute to air pollution.
6. Natural radioactivity: certain types of rocks and minerals, such as uranium and radon, release radioactive particles that can contribute to air pollution.

Lightning Strikes

Lightning strikes are a natural source of air pollution in the form of nitrogen oxides (NOx) and volatile organic compounds (VOCs). When lightning strikes, it generates high temperatures that can cause the rapid oxidation of nitrogen and oxygen in the air, producing nitrogen oxides. Nitrogen oxides are a group of gases that can contribute to the formation of smog and acid rain, and can have negative impacts on human health and the environment.

VOCs are also produced when lightning strikes, as the intense heat and energy from the lightning can cause the rapid vaporization of volatile compounds present in the air. VOCs are a diverse group of chemicals that can have negative impacts on human health and the environment. They are also precursors of tropospheric ozone, a harmful air pollutant that can aggravate respiratory conditions and damage crops and other vegetation.

Forest Fires

Forest fires are a natural source of air pollution that can have significant impacts on air quality, both locally and regionally. When a forest fire occurs, it releases a variety of pollutants into the air, including:

• Particulate matter (PM): Forest fires release large amounts of particulate matter into the air, including smoke and ash. These particles can be inhaled and can have negative impacts on human health, particularly for people with respiratory conditions such as asthma.
• Carbon monoxide (CO): Forest fires release large amounts of carbon monoxide, a colorless and odorless gas that can reduce the amount of oxygen that the body can absorb, leading to headaches, nausea, and even death in severe cases.
• Volatile organic compounds (VOCs): Forest fires release large amounts of volatile organic compounds into the air, which can contribute to the formation of smog and ozone, and can have negative impacts on human health and the environment.
• Greenhouse gases: Forest fires also release large amounts of greenhouse gases, such as carbon dioxide (CO2) and methane, which can contribute to global warming and climate change.
• Toxins: Forest fires can also release toxins such as dioxins, furans, and polycyclic aromatic hydrocarbons (PAHs) which are harmful to human health and the environment.

Plants

Plants are a natural source of air pollution through the process of photosynthesis, the process by which plants convert sunlight, CO2 and water into energy and oxygen. During photosynthesis, plants release volatile organic compounds (VOCs) into the air. VOCs are a diverse group of chemicals that can have negative impacts on air quality and human health.

Some examples of VOCs that are released by plants include isoprene, terpenes and methanol. These compounds can react with other pollutants in the air, such as nitrogen oxides and sunlight, to form ground level ozone, a harmful air pollutant that can aggravate respiratory conditions and damage crops and other vegetation.

Volcanos

Volcanoes are a natural source of air pollution, releasing a variety of pollutants into the atmosphere, including:

• Ash: Volcanic eruptions release large amounts of ash and other volcanic debris into the air. Ash can be inhaled and can have negative impacts on human health, particularly for people with respiratory conditions such as asthma. Ash can also damage buildings, vehicles and other infrastructure.
• Sulfur dioxide (SO2): Volcanic eruptions release large amounts of sulfur dioxide, a gas that can contribute to the formation of acid rain and can have negative impacts on human health.
• Carbon dioxide (CO2): Volcanic eruptions also release large amounts of carbon dioxide, a greenhouse gas that contributes to global warming and climate change.
• Other gases: Volcanic eruptions also release other gases such as methane, hydrogen sulfide, and chlorine. These gases can have negative impacts on human health and the environment.
• Volcanic dust and particulate matter: volcanic eruptions can also release dust and particulate matter that can affect air quality and visibility for miles around the volcano.
• Volcanic ash can also have an effect on air travel, as it can cause damage to aircraft engines and can affect visibility for pilots. This can lead to flight cancellations and disruptions.

Natural Sources of CO2

General Examples

Natural sources of CO2 include:

• Volcanic eruptions: volcanic eruptions can release large amounts of CO2, typically dissolved in magma, into the atmosphere.
• Natural respiration: all living organisms release CO2 as a byproduct of respiration, which is the process of converting energy from food into energy the organism can use. This process is responsible for a large natural source of CO2.

Respiration

Respiration is a natural process by which living organisms convert energy from food into energy they can use. During respiration, organisms release carbon dioxide (CO2) as a byproduct. Therefore, respiration is a natural source of CO2.

Plants, animals, and microorganisms all respire and release CO2 into the atmosphere. Respiration is an important natural process that helps to maintain the balance of gases in the atmosphere and contributes to the global carbon cycle.

Natural PM Sources

Particulate matter (PM) refers to tiny particles suspended in the air, such as dust, dirt, soot, and smoke. Here are some natural sources of PM:

• Dust storms: Dust storms are a natural source of PM, as they can release large amounts of dust and sand into the air. Dust storms can occur in dry regions, such as deserts and semi-arid areas, and can travel long distances, affecting air quality over a large area.
• Volcanic eruptions: Volcanic eruptions can release large amounts of ash and other volcanic debris into the air, which can contribute to PM levels. Volcanic ash can also damage buildings, vehicles and other infrastructure.
• Wildfires: Wildfires can release large amounts of PM into the air, including smoke and ash. Wildfires can occur naturally due to lightning strikes or human-caused such as negligence or arson.
• Sea spray: Sea spray can release salt particles and other pollutants into the air, particularly in coastal areas.
• Biological processes: Certain biological processes, such as the release of spores from certain plants, can contribute to PM levels in the air.
• Natural radioactive processes: Certain types of rocks and minerals, such as uranium and radon, can release radioactive particles that can contribute to PM levels.

Aerobic Decomposition relation to CO2

Aerobic decomposition is the process by which microorganisms, such as bacteria and fungi, break down organic matter in the presence of oxygen. During this process, the microorganisms release carbon dioxide (CO2) as a byproduct. This means that aerobic decomposition is a natural source of CO2.

Aerobic decomposition is an important part of the global carbon cycle, as it helps to recycle the carbon in organic matter back into the atmosphere. This process helps to maintain the balance of CO2 in the atmosphere. In natural environments such as forests, wetlands, soils, and oceans, aerobic decomposition is a vital process that allows for the recycling of nutrients and the maintenance of biodiversity.

However, human activities such as deforestation, land use changes and urbanization can disrupt the natural process of aerobic decomposition. This can lead to the accumulation of organic matter in the soil, increasing the amount of CO2 released in the atmosphere.

In addition, human-caused activities such as burning fossil fuels, deforestation, and agriculture have greatly increased the amount of CO2 in the atmosphere, leading to global warming and climate change. Therefore, it is important to consider the impacts of human activities on the natural processes of aerobic decomposition in order to maintain the balance of CO2 in the atmosphere and mitigate the negative effects of climate change.

Anaerobic Decomposition relation to CO2

Anaerobic decomposition is the process by which microorganisms, such as bacteria and archaea, break down organic matter in the absence of oxygen. During this process, the microorganisms produce methane (CH4) and carbon dioxide (CO2) as byproducts. This means that anaerobic decomposition is a natural source of both methane and CO2.

Anaerobic decomposition is an important process in natural environments such as wetlands, bogs, rice paddies, and some soils. It also occurs in human-made environments such as landfills, wastewater treatment plants, and industrial systems where organic matter is broken down in the absence of oxygen. In these environments, anaerobic decomposition is responsible for the production of methane and CO2.

Methane is a potent greenhouse gas, which is about 25 times more effective at trapping heat than CO2 over a 100-year time frame. Therefore, the release of methane from anaerobic decomposition is a significant contributor to global warming.

Anaerobic decomposition is also a natural source of CO2, however, the amount of CO2 produced is usually smaller than the amount of methane produced. Additionally, CO2 produced by anaerobic decomposition is not considered as a direct contributor to global warming as it is part of the natural carbon cycle and it is not a greenhouse gas.

Human activities such as land use change, agriculture, and urbanization can disrupt the natural process of anaerobic decomposition and increase the amount of methane and CO2 released into the atmosphere. Therefore, it is important to consider the impacts of human activities on anaerobic decomposition to mitigate the negative effects of climate change.