4d - human influences on the environment

Question 1

what do humans demand from the environment?

Answer 1

• food to sustain an ever-increasing population
• materials to build homes, schools, industries
  -fuel to heat homes and power vehicles,
• space in which to build homes, schools, factories, as well as for leisure facilities,
• space in which to dump our waste materials

Question 2

what is the definition of pollution?

Answer 2

the contamination of the environment by harmful substances that are produced by the activities of humans

Question 3

name some harmful gases which are in the air

Answer 3

sulfur dioxide, carbon dioxide, methane, carbon monoxide

Question 4

why has the amount of CO2 increased over the past 100 years by 30%?

Answer 4

burning of fossil fuels like coal and oil and natural gas, as well as petrol and diesel in vehicle engines. cutting down parts of the rainforest also contributes to this

Question 5

is the greenhouse effect normal?

Answer 5

yes, without it, earth would be 30 degrees cooler than it is today

Question 6

name some greenhouse gases

Answer 6

methane (CH4), water vapour (H2O), nitrous oxide (N2O), and chlorofluorocarbons (CFCs), Most occur naturally but some are only produced by human activities like CFCs

Question 7

describe a ‘normal’ greehouse effect.

Answer 7

some long-wavelength IR radiation from Earth escapes into space. But some short-length radiation also strikes the earth. When this happens, some energy is absorbed and the radiation is re-emitted as longer wave radiation.
Some other long wave IR radiation from earth is absorbed by greenhouse gases and is re-emitted back to earth

Question 8

what happens in the greenhouse effect due to greenhouse gases?

Answer 8

short length IR radiation from the sun reaches the earth. Some is absorbed by the Earth’s surface and emitted again as longer-wavelength IR radiation. The greenhouse gases absorb and then re-emit some of this long-wavelength IR radiation, which would otherwise escape into space. this often heats up earth’s surface. however, with more greenhouse gases, this effect is enhanced and causes a rise in Earth;s surface temperature.

Question 9

what happens if Earth’s temperature rises only a few degrees

Answer 9

• polar ice caps would melt and sea levels would rise
• a change in the major ocean currents would result in warm water flowing into previously cooler areas
• a change in global rainfall patterns could be caused and with a rise in temperature, more evaporation from the surface of the sea could lead to more rainfall in some areas. Other areas might have less rainfall - long-term climate change
• it could change the nature of many ecosystems. if a species can’t migrate quickly enough to an appropriate habitat or adapt to existing conditions it could go extinct
• pests will become more abundant, so a change in farming practices has to take place. higher temps. might allow some pests to complete their life cycle more quickly

Question 10

what is methane?

Answer 10

an organic gas that is produced when microorganisms ferment larger organic molecules to release energy. it is a greenhouse gas

Question 11

what are the most significant sources of methane?

Answer 11

• decomposition of waste buried in the ground (landfill sites) by microorganisms
• fermentation by microorganisms in the rumen (stomach) or cattle and other ruminants
• fermentation by bacteria in rice fields

Question 12

how is carbon monoxide produced?

Answer 12

when carbon is burned in a limited supply of oxygen, carbon monoxide is formed. this happens when petrol and diesel are burned in vehicle engines. Exhaust engines contain a significant amount of CO

Question 13

why is carbon monoxide so bad?

Answer 13

• it is colourless and odourless, tasteless, and can be fatal
• haemoglobin binds preferentially (more strongly) with carbon monoxide than with oxygen
• if a person inhales CO for a period of time, more and more haemoglobin binds with the CO, therefore less oxygen can bind with the haemoglobin
• due to lack of oxygen reaching the cells, the person can become unconscious and die because the organs, heart and brain stop working

Question 14

why is sulfur dioxide so bad? how is it formed?

Answer 14

it is formed when fossil fuels are burned and combined with water droplets in air. It can be carried hundreds of miles in the atmosphere and fall as acid rain.
- this can cause:
death of conifers, acidification of soil (leeching of some ions into lakes, kills fish; root hairs less effective at absorbing minerals so tree growth slowed, acidification of lakes can cause death of bacteria and algae; death of fish and amphibian effs; change in ecosystem

Question 15

what are lichens?

Answer 15

small moss-like organisms. Some are more tolerant to SO2 than others. this pattern can be used to measure the level of pollution by SO2. The different lichens are called INDICATOR SPECIES as they indicate diff levels of SO2 pollution

Question 16

what is deforestation a consequence of?

Answer 16

enormous growth of the human population (to provide wood for building, for farmland (space)

Question 17

how are most trees removed? why is it bad

Answer 17

the slash and burn technique where trees are just cut down and burned.
this adds to the CO2 in the atmosphere and contributes to global warming. it also removes trees that would otherwise be absorbing CO2 for photosynthesis.

Question 18

what are the other consequences of deforestation apart from global warming

Answer 18

• destruction of habitat and reduced biodiversity,
• reduced soil quality (with no trees and other plants to return minerals to the soil when they die, and no tree roots to hold the soil together. crops planted in deforested areas also rapidly use up minerals from soil and rain washes the minerals out)
• soil it exposed due to lack of tree cover and is blown or washed away (e.g., into rivers with can cause rising water levels and flooding in lowland areas)
• climate change (water cycle is affected because there are no leaves for transpiration)
• loss of medical drugs (probably undiscovered)

Question 19

what is sustainable timber production

Answer 19

replacing the trees that are removed and ensuring that there is no ecological damage to the environment

Question 20

what are 2 major pollutants of freshwater?

Answer 20

sewage, minerals form fertiliser

Question 21

what is sewage?

Answer 21

wet waste from houses, factories farms. it is usually treated before it enters other waterways (because they contain human urine, faeces, dissolved organic and inorganic chemicals like soap and detergent)

Question 22

what are some issues with untreated sewage getting into waterways?

Answer 22

• aerobic bacteria in the water polluted by sewage use up the dissolved oxygen in the water as they break down larger organic materials. this reduction of the level of oxygen kills larger animals like freshwater insects and fish.
• untreated sewage contains pathogenic bacteria which are a danger to human health

Question 23

what is the aim of sewage treatment?

Answer 23

to remove solid and suspended organic matter and pathogenic microorganisms so that cleaner waste can be discharged into waterways

Question 24

how can pollution in water be monitored?

Answer 24

using indicator species like bloodworm (heavy organic pollution), caddis-fly larva (some organic pollution), stone fly nymph (clean water)

Question 25

what are the main causes of acid rain?

Answer 25

internal combustion engines in cars, and power stations

Question 26

what is the main cause of carbon monoxide?

Answer 26

car emissions because fossil fuels are burnt without sufficient air supply

Question 27

where is nitrous oxide naturally produced?

Answer 27

by bacteria in soils and the ocean

Question 28

what are some natural sources of methane

Answer 28

rotting plants, marshland

Question 29

how are CFCs made?

Answer 29

they are man-made chemicals which were once use d in aerosol sprays like deodorant and in fridges. they are very powerful greenhouse gases.
they don’t produce them in many countries due to how much damage they do but old fridges can still leak CFCs so they are still being released