C6.3 Interpreting and interacting with Earth Systems

Question 1

What is the atmosphere like today?

Answer 1

1) js 3 substances form 99.9% of Earth’s atmos today:
a) nitrogen - 78%
b) oxygen - 21%
c) carbon dioxide 0.04%
2) there are smaller %ages of many other gases, including CO2 & water vapour

Question 2

What was the atmosphere like in the past?

Answer 2

1) likely Earth’s early atmos came from substances released by volcanoes
-> but no1 around then to record events as they happened, so diff. to be certain this theory correct
2) Earth is 4.54By/o
a) great deal of volcanic activity in early yrs
b) volcanoes release huge vols of water vapour & CO2
c) as Earth cooled, water vapour condensed to form oceans
-> left atmos of mostly CO2
-> probs contained small amounts of other gases like ammonia & methane, but little or no oxygen
3) Earth’s early atmos probs like atmos of Venus & Mars today

Question 3

Why has the atmosphere changed over time?

Answer 3

1) theories to explain the changes to the Earth’s atmosphere must explain where the oxygen came from & where carbon dioxide went
2) plants & algae make own food by photosynthesis; absorb carbon dioxide from atmos & release oxygen:
-> carbon dioxide + water -> glucose + oxygen
3) when plants & algae appeared, photosynthesis reduced amount of CO2 in atmos; also released oxygen
4) at 1st, oxygen reacted w/ metals in rocks to prod. metal oxides (formed abt 3BYA)
5) later, as most of metals became oxidised, free oxygen began to accumulate in atmos
6) eventually, oxygen-rich atmos of today dev.d

Question 4

What are pollutants?

Answer 4

Substances released into the environment that may harm living things.
Atmospheric pollutants are released into the air; many of them released as result of burning fossil fuels, including carbon monoxide, particulates, oxides of nitrogen, & sulfur dioxide.

Question 6

Why does carbon monoxide cause problems?

Answer 6

1) carbon monoxide, CO, is prod.ed in incomplete combustion of carbon-containing fuels
-> can happen when coal, wood, or natural gas burn in poor supply of air
-> also happens in vehicle engines
2) CO = toxic gas, colourless & has no taste or smell
3) when breathed in, attaches to haemoglobin protein in RBCs
-> reduces amount of oxygen bloodstream can carry
4) CO poisoning causes drowsiness, diff.ty breathing & even death
-> why many homes has CO detectors which sound an alarm if faulty gas boilers or cookers prod. CO

Question 7

Why do particulates cause problems?

Answer 7

1) particulates are small particles
a) prod.ed in industrial processes like metal extraction (released in industrial smoke too)
b) like CO, also prod.ed in incomplete combustion & vehicle engines (from poorly maintained diesel engines)
2) smallest particles settle deep in lungs when breathed in
-> causes diseases like bronchitis & other breathing problems & increases chance of heart disease

Question 8

What are PM(subscript)10 particles?

Answer 8

1) particles 10 nanometres in diameter or less
2) there’s link between their conc. in air & health probems

Question 9

Why do acidic oxides cause problems?

Answer 9

1) nitrogen & oxygen, main gases in air, don’t normally react together
-> but do react at high temperatures in vehicle engines, forming nitrogen monoxide, NO
-> then oxidised in air to form nitrogen dioxide, NO2
-> these oxides of nitrogen are jointly called ‘NO(subscript)x)’
2) nitrogen dioxide dissolves in moisture in clouds, forming acidic solution which eventually falls as acid rain
3) acid rain erodes stronework & corrodes metals, can kill trees & living things in rivers & lakes
4) fossil fuels (coal, crude oil & natural gas) naturally contain small amounts of sulfur compounds
-> these impurities form sulfur dioxide when fuel is burnt
-> sulfur dioxide also causes acid rain & can cause breathing diff.es

Question 10

What are oxides of metal?

Answer 10

Basic.

Question 11

What are oxides of non-metals?

Answer 11

Acidic.

Question 12

Why is rainwater naturally weakly acidic?

Answer 12

It contains dissolved carbon dioxide from the atmosphere.

Question 13

What is the greenhouse effect?

Answer 13

1) greenhouse gases like carbon dioxide & methane absorb infrared radiation radiated by Earth’s surface
-> then emi it in all directions
-> this GE keeps Earth & its atmos warm enough for living things to exist

Question 14

Describe the greenhouse effect.

Answer 14

1) energy transferred by radiation from the Sun reaches the Earth’s surface
2) radiation warms up Earth’s surface
3) infrared radiation emitted by Earth’s surface
a) ~ goes directly into space
b) ~ absorbed by greenhouse gas molecules in atmos
4) greenhouse gas molecules emit infrared radiation in all directions, warming Earth’s surface & atmos

Question 15

What is the enhanced greenhouse effect?

Answer 15

1) CO2 released into atmos by combustion of fossil fuels
2) CH4 released into atmos from a) rice paddy fields, b) cattle, c) landfill waste sites & d) use of natural gas
3) release of +ional GHGs by human (anthropogenic) activities has potential to cause enhanced G3, increasing T of Earth’s atmos
-> this global warming leads to melting ice caps & rising sea levels & to Climate Change
4) Climate Change brings altered weather patterns, causing flooding, and problems w/ farming & disease control

Question 16

How can greenhouse gas emissions into atmosphere be reduced?

Answer 16

1) reducing consumption of fossil fuels, e.g. using biofuels
2) using renewable energy resources like wind & solar energy to gen electricity
3) stopping CO2 escaping when fuels are used by using carbon capture
-> such steps are expensive, but so are steps to protect v. effects of GW
-> these include: flood barriers, planting diff. crops & designing buildings to w/stand high winds

Question 17

What is the relative warming effect of carbon dioxide and methane?

Answer 17

1) relative warming effect of CO2 = 1
2) relative warming effect of CH4 = 24

Question 18

Where does drinking water come from?

Answer 18

1) tap water will have originally have come from water stored in:
a) lakes, reservoirs, or aquifers
b) may alsohave come from rivers or waste water
-> water from all these sources contains micoorganisms & many diff. substances:
a) insoluble materials like leaves & particles from rocks & soil
b) soluble substances, including salts & pollutants like pesticides & fertilisers
-> most of these must be removed at treatment works to make water safe to drink

Question 19

How is fresh water treated?

Answer 19

1) reservoir
2) as water enters water treatment works, passes thru screen
-> made from bars of metal placed close together to catch large objects like leaves & twigs
3) settlement tank: sand & soil settle out
4) aluminium sulfate & lime added to water; small particles of dirt clump together so they sink to bottom of water; sludge that collects like this dumpted in landfill site where it forms mud
5) water passed thru special filter made of fine sand
-> removes any remaining particles of mud or grit so water is clear
6) tho water now looks clean, may still contain harmful bacteria; small amount of chlorine added to water to kill bacteria
7) pH of water checked & corrected so it’s neutral; water than stored in large tanks & service reservoirs, ready to be pumped to homes, schools, offices & factories

Question 20

How is salt water treated?

Answer 20

1) seawater contains high conc.s dissolved salts
-> must be removed to make this water potable in process called desalination
2) for small scale desalination, ‘reverse osmosis’ using special ‘ultrafilters’ used to filter out salts
3) for large scale desalination, simple distillation used
4) desalination wouldn’t be worthwhile in countries like UK, but is where fresh water supplied limited or cost of energy resources low

Question 21

What is the purpose of chlorine?

Answer 21

To kill the bacteria in the water, not to clean it.