Download - Chemistry in the Environment: Atmosphere
Chemistry in the Environment: Atmosphere
Earth’s atmosphere as seen from spacePhoto: NASA
What are the natural components of our atmosphere?
78 % Nitrogen
21 % Oxygen 1 % Argon
and other trace gases
Composition of the Atmosphere
Troposphere◦ Most of our weather
occurs in this layer closest to the Earth’s surface
Stratosphere◦ Where ozone (O3)
absorbs harmful UV radiation from the Sun and prevents it from reaching Earth’s surface
Layers of the Atmosphere
Atmosphere contains the air we breathe Protects us from the Sun’s radiation Keeps Earth balanced traps and releases
heat
Atmospheres of other planets are different◦ Mars very thin atmosphere made of mostly CO2◦ Venus denser and hotter than Earth’s
atmosphere◦ Jupiter large, turbulent atmosphere made of H
and He
Why do we need an atmosphere?
What are ways that human activity has negatively
affected the atmosphere?
Fossil fuels are fuels formed by natural resources such as anaerobic decomposition of buried dead organisms.
Fossil fuels are non-renewable resources because they take millions of years to form, and reserves are being depleted much faster than new ones are being made.
Fossil Fuels
We burn fossil fuels to produce useful energy
This fuel provides gas for our cars, electricity for our homes, and runs factories and powerplants
Why do we burn fossil fuels?
The burning of fossil fuels produces around 21.3 billion tons (21.3 gigatons) of carbon dioxide (CO2) per year
Burning of Fossil Fuels
What are ways that human activity has contributed to the pollution that causes
smog and acid rain?
A type of air pollution that comes from internal combustion engines and industrial fumes that react with sunlight to form photochemical smog
The word ‘smog’ comes from a combination of smoke and fog
Mixture of air pollutants, including gases and particles that are too small to see
Smog is also caused by large amounts of coal burning in an area caused by a mixture of smoke and sulfur dioxide
What is smog?
Type: Particulate Matter - or PM. This is the name given to microscopic particles that pollute the air. They vary in size and chemical make-up.Sources: Industrial and vehicle emissions, road dust, agriculture, construction and wood burning.
Type: Ground-level Ozone. This gas is the result of a chemical reaction when certain pollutants are combined in the presence of sunlight. Ground-level ozone shouldn't be confused with the ozone layer in the sky, which protects us from ultraviolet radiation.Sources: Ground-level ozone comes mostly from burning fossil fuels for transportation and industry. Ozone levels peak between noon and 6 p.m. during the summer months.
What types of air pollution cause smog?
Type: Sulfur dioxideSources: Coal-fired power plants and non-iron ore smelters
Type: Carbon monoxideSources: Mostly from burning carbon fuels (e.g. motor vehicle exhaust)
Air Pollution Continued…
Smog in Major US Cities
Smog in Major International Cities
Acid rain is a rain or any other form of precipitation that is unusually acidic (has a low pH)
Acid rain is caused by emissions of sulfur dioxide and nitrogen oxides which react with the water molecules in the atmosphere to produce acids
Acid Rain
What are some effects of smog and acid rain on the
environment?
Asthma Lung Cancer
Can cause coughing, chest pains, throat irritation
Colds and pneumonia
Side Effects of Exposure to Smog
Can damage buildings and historic monuments, especially those made of rocks such as limestone and marble containing large amounts of calcium carbonate
Soil biology and chemistry can be damaged because microbes cannot tolerate changes in pH
As lakes and river become more acidic, biodiversity is reduced◦ Because of low pH, fish eggs may not hatch and some
adult fish are killed◦ Eliminates insect life and some fish species (brook
trout)
Adverse Effects of Acid Rain
Effect of acid rain on a forest in Jizera Mountains, Czech Republic
What has been done or is being done to reduce the
pollution that causes smog and acid rain?
Founded in 1990 by US Environmental Protection Agency (EPA)
Goal is to reduce overall atmospheric levels of sulfur dioxide and nitrogen oxides, which cause acid rain.
The program is an implementation of emissions trading that targets coal-burning plants, allowing them to buy and sell emission permits.
Acid Rain Program
There are several options for reducing SO2 emissions, including using coal containing less sulfur, washing the coal, and using devices called “scrubbers” to chemically remove the SO2 from the gases leaving the smokestack
Powerplants can use different fuels burn natural gas instead of coal
Clean up smoke stacks and exhaust pipes
Nuclear power Hydropower Wind energy Geothermal energy Solar energy
Use alternate energy sources
Takes many years for ecosystems to recover from acid rain even after emissions are reduced and rain pH is back to normal
“Liming” = a process in which limestone or lime is added to acidic lakes to cancel out the acidity ◦ Disadvantage: expensive and short-term solution
Restore a damaged environment
Reducing and controlling the emissions from powerplants and cars
Implement cost-effective mechanisms to reduce emissions
Look to the future
Turn off lights, computers, and other appliances when you're not using them.
Use energy-efficient appliances: lighting, air conditioners, heaters, refrigerators, washing machines, etc. For more information, see EPA’s ENERGY STAR Program.
Only use electric appliances when you need them. Keep your thermostat at 68°F in the winter and 72°F in the
summer. You can turn it even lower in the winter and higher in the summer when you are away from home.
Insulate your home as best you can. Carpool, use public transportation, or better yet, walk or bicycle
whenever possible Buy vehicles with low NOx emissions, and properly maintain your
vehicle. Be well informed.
Take action as individuals
What are ways that human activity has
affected the balance of greenhouse gases in the
atmosphere?
Gases which absorb and emit radiation Greenhouse Gases (GHG):
◦ Water Vapor◦ Carbon Dioxide◦ Methane◦ Nitrous Oxide ◦ Ozone◦ Chlorofluorocarbons (CFCs)
Greenhouse Gases
The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions
The greenhouse effect keeps our planet warm
If we had no atmosphere, our Earth would be 32°C colder than it is today
Greenhouse Effect
Greenhouse Effect
Global anthropogenic greenhouse gas emissions for the year 2000
Household activities which produce Greenhouse Gases
What are some effects of increased greenhouse gas
concentrations on the environment?
Increasing CO2 Concentrations
Plants need CO2 to survive, and plants exposed to more CO2 could grow up to 50% faster than normal
Increased global temperature due to greenhouse effect
What does increased CO2 concentrations mean for the Earth?
Average Global Temperatures
What has been done or is being done to reduce the
concentration of greenhouse gases in the
atmosphere?
What’s wrong with this picture?
What are ways that human activity has contributed to the
reduction of the ozone layer?
What are some effects of the reduced ozone layer on
the environment?
What has been done or is being done to repair the
ozone layer?
Treaty signed in which banned the use of CFCs and HFCs
Montreal Protocol