9: Chemistry of the Atmosphere Flashcards
what percentage of different gases are in air?
nitrogen - 78%; oxygen - 21%; argon - 0.9%; CO2 - 0.04%`
what was the main composition of the early earth’s atmosphere?
due to intense volcanic activity, large amounts of carbon dioxide and water vapour were released, and smaller amounts of nitrogen, hydrogen, ammonia, methane and other gases - little to no oxygen
how were oceans formed?
while surface of Earth was still v hot, water vapour was mainly gaseous; once conditions cooled sufficiently, water vapour condensed & fell to surface forming oceans
how did CO2 levels decrease in the early atmosphere?
large amounts of CO2 dissolved in the oceans; carbonate substances were precipitated during this process; marine life began to evolve sea creatures used up the carbonates to form shells and skeletons, later formed sediments; plants photosynthesising used it up; being trapped in fossil fuels and sedimentary rocks.
how did oxygen levels increase?
plants and algae evolved and began photosynthesizing which used up CO2 and released oxygen
describe the greenhouse effect.
shortwave radiation from the sun is absorbed by earth’s surface and is re-emitted from surface as infrared (longwave) radiation; this long wave radiation is absorbed by the greenhouse gas layer, keeping the earth warm
what are sources CO2 emissions (now)?
combustion of wood and fossil fuels; respiration of plants and animals; thermal decomposition of carbonate rocks and the effect of acids on carbonates
what are sources methane emissions (now)?
digestive processes of animals; decomposition of vegetation; bacterial action in swamps and in rice paddy fields
why is there uncertainty about models of the early atmosphere?
the methods used are not as precise as modern day techniques nor do they provide data which is representative on a global scale
what are the consequences of climate change on humanity?
changes in rainfall patterns may lead to uneven distribution of water, causing flooding in some regions and drought in others; may lead difficulties in obtaining fresh drinking water
what are the consequences of climate change on Earth’s natural systems and processes?
melting of the polar ice caps, flooding and flash fires = the destruction of ecosystems; changes in temperature will affect the distribution of wildlife
what is a carbon footprint?
the amount of carbon dioxide released into the atmosphere as a result of the activities of a particular individual, organization, or community
why is it difficult to get an exact carbon footprint?
there are so many different factors to consider - e.g. sources materials; manufacturing
how can we reduce our carbon footprint?
use renewable energy supplies; conserve (use less) energy; carbon capture and storage; carbon taxes and licences; carbon off-setting (planting more trees)
why are there difficulties when reducing ghg emissions?
expensive equipment for switching over to alternative energy resources; governments tend to be slow to act - fear a negative impact on their economies; a lack of investment schemes for companies to help them to modernize their facilities; still lots of research to be done on alternative technologies
