Evolving atmosphere and air pollution Flashcards
What does the Earth’s atmosphere consist of?
- 78% nitrogen
- 21% oxygen
- Small amounts of other gases (e.g. noble gases, carbon dioxide and water vapour)
Why is oxygen important?
- Oxygen is a reactant in respiration - a chemical reaction that takes place in all living cells.
- As humans, we breathe oxygen into our lungs. From here, it diffuses into our blood and is carried to all the cells in our body
Why is nitrogen important?
Nitrogen is a key component of proteins, which are essential for growth.
Whilst it is abundant in the atmosphere, the producers found at the base of food chains are not able to exploit this source. Instead, they must absorb nitrogen in the form of soluble nitrates from the soil.
What type of gas are carbon dioxide and water vapour?
They are greenhouse gases.
What do greenhouse gases do?
They absorb and the re-radiate heat energy that is reflected off the Earth’s surface. This is known as the greenhouse effect. If the greenhouse effect is too strong, it can lead to global warming.
What was the Earth’s early atmosphere like?
The Earth was formed roughly 4.6 billion years ago.
Age of the volcanoes
- Highly active volcanoes were littered across the Earth’s surface for the first billion years of its existence.
- The frequent eruptions of these volcanoes resulted in the release of lots of carbon dioxide (as well as smaller amounts of gases such as water vapour, methane, ammonia and nitrogen).
- Scientists think carbon dioxide dominated the early atmosphere in a similar way to modern-day Mars.
Reduction of carbon dioxide levels
- Levels of atmospheric nitrogen accumulated steadily.
- The oceans were formed as a result of the water vapour condensing.
- The formation of the oceans caused a significant reduction in carbon dioxide levels in the atmosphere.
- Carbonate precipitates were produced by reactions between the dissolved carbon dioxide and seawater. These precipitates were deposited as sediment.
What increased the atmospheric concentration of oxygen?
Photosynthesis: the process in which light energy is used to produce oxygen from carbon dioxide and water.
What are the 3 main factors that influenced the decrease in atmospheric carbon dioxide>
- Evolution
- Evolution of marine animals
- Formation of the oceans
What is the process of the greenhouse effect?
- The Sun emits short wavelength infrared radiation that enters the atmosphere and travels towards the Earth.
- The Earth absorbs a portion of this radiation, but longer wavelength radiation is reflected back into the atmosphere.
- Greenhouse gases can’t absorb the short wavelength radiation emitted by the Sun, but they can absorb the reflected radiation.
- The gases re-radiate this as heat energy. some of which heads back to Earth.
- This increases the temperature at the Earth’s surface.
What human activities cause the atmospheric concentrations of greenhouse gases to increase?
AGRICULTURE
- Farm animals release methane during digestion
- As the global population continues to rise, the scale of agriculture is increasing. This means that more methane is being release into the atmosphere by livestock.
DEFORESTATION
- As we cut down more and more trees, the global rate of photosynthesis will decrease.
- Given that carbon dioxide is a reactant in the equation for photosynthesis, this means that less carbon dioxide will be removed from the atmosphere by this process.
LANDFILL SITES
- The number and size of landfill sites is increasing
- This means that more mounds of waste are decomposing.
- This process of decomposition releases methane, which is a greenhouse gas.
BURNING FOSSIL FUELS
- Burning fossil fuels releases carbon, in the form of carbon dioxide. This carbon dioxide had been stored away for millions of years previously.
What will lead to global climate change?
Increased greenhouse gas emissions caused by changes to human activity.
What are the potential consequences of climate change?
MELTING OF POLAR ICE CAPS
- The melting of polar ice caps would cause:
Sea levels to rise, leading to flooding and erosion of our coastlines.
- Some species to be less successful hunters (e.g. the polar bear).
METEOROLOGICAL EVENTS
- Extreme meteorological events, such as storms, heatwaves and droughts, could increase in frequency and intensity.
CHANGES IN WATER AVAILABILITY
Changes in water availability could affect how species are distributed.
CHANGES IN PRECIPITATION
- The quantity, timing and distribution of precipitation could change. This would result in some regions receiving much less or much more rainfall than they previously did.
FOOD SHORTAGES
- A combination of some or all of these factors could hinder a region’s ability to produce food. This could lead to potential famines.
Why is Carbon monoxide so toxic?
- Carbon monoxide binds to haemoglobin in the blood.
- This restricts the blood’s ability to transport oxygen throughout the body.
- Carbon monoxide is odourless and colourless.
This means that it is difficult to detect in the air.
If exposed to too much carbon monoxide, symptoms can range from fainting to fatality.
Why are particulates toxic?
- Inhaling particulates can cause respiratory issues.
- Particulates reflect incoming radiation out into space.
- This leads to global dimming, which decreases the levels of sunlight available for photosynthesis. This can have knock-on effects for rainfall patterns.
Why is sulfur dioxide toxic?
- Inhaling sulfur dioxide can cause respiratory issues.
Sulfur dioxide can react with water to form sulfuric acid. - Sulfuric acid is a major part of acid rain, which can cause:
-> The corrosion of steel.
-> The weathering of buildings, monuments and statues.
->The death of insects, plants, and aquatic organisms.
