humans and their effects on the environment

Question 1

what does rapid growth in the human population and an increase in the standard of living mean for the environment

Answer 1

more waste is produced and unless waste is properly handled, more pollution will be caused

Question 2

what may waste pollute

Answer 2

-water -air -land -sewage and fertilisers may cause eutrophication

Question 3

how may waste pollute water

Answer 3

with sewage, fertiliser or toxic chemicals

Question 4

how may waste pollute air

Answer 4

with smoke and gases such as sulfur dioxide, which contributes to acid rain

Question 5

how may waste pollute land

Answer 5

with toxic chemicals such as pesticides and herbicides, which may be washed from land into water

Question 6

what is eutrophication

Answer 6

-an increase in the concentration of mineral ions in the water stimulates the growth of algae and/or plants -eventually the growth of the algae and/or plants results in some of these being unable to receive sufficient light for photosynthesis and these organisms die -there is a large increase in the population of microorganisms that feed on these dead organisms -the respiration of the microorganisms depletes the oxygen concentration in the water, leading to the death of aerobic organisms

Question 7

how do humans reduce the amount of land available for other animals and plants

Answer 7

by building, quarrying, farming and dumping waste

Question 8

why has large-scale deforestation in tropical areas occurred

Answer 8

so that: -there can be increases in cattle and in rice fields to provide more food. -crops can be grown from which biofuels, based on ethanol, can be produced

Question 9

what effect has an increase in cattle caused

Answer 9

these organisms produce methane and this has led to increases in methane in the atmosphere

Question 10

what does loss of forest lead to

Answer 10

loss of forest leads to reduction in biodiversity

Question 11

what does the destruction of peat bogs, and other areas of peat do

Answer 11

it releases carbon dioxide into the atmosphere

Question 12

why are gardeners and other users of peat composts encouraged to find a more sustainable alternative

Answer 12

Burning the peat releases its stored carbon back into the atmosphere as carbon dioxide. Similarly, as peat is mixed in with soil it is exposed to aerobic conditions and begins to decompose - which again causes the release of its trapped carbon as carbon dioxide. This is in addition to the carbon dioxide released in extracting the peat. Therefore, the destruction of peat bogs contributes to global warming as well as destroying important habitats.

Question 13

what is peat

Answer 13

Peat is formed in waterlogged, acidic fens and bogs over thousands of years by the growth of mosses and other plants, which absorb and ‘lock away’ carbon dioxide during photosynthesis. When the moss dies, the waterlogged bog provides anaerobic conditions which, together with the acidity of the bog, prevent the total decomposition of the moss. It accumulates in the bogs in a partially-decomposed state, forming peat.

Question 14

what are peat’s uses

Answer 14

Peat can be dried and burnt as a fuel due to the amount of biomass it contains, making it an important energy source in some countries. Peat also has valuable properties when mixed in with soil - including improved soil structure, mineral retention, water retention and acidity - making it valuable in agriculture and gardening.

Question 15

what may an increase in the earth’s temperature of only a few degrees cause

Answer 15

-big changes in the earth’s climate -a rise in sea level -changes in migration patterns, eg in birds resulting in changes in the distribution of species

Question 16

where can carbon dioxide be sequestered

Answer 16

The oceans, lakes and ponds of planet Earth are important as they absorb and ‘lock away’ (sequester) over a quarter of the carbon dioxide that humans emit into the atmosphere.

Question 17

why does the sequestration of carbon dioxide occur

Answer 17

This occurs due to: -carbon dioxide being soluble and dissolving directly in the water. -phytoplankton performing photosynthesis which absorbs carbon dioxide, trapping the carbon within their biomass.

Question 18

why is the sequestration of carbon dioxide important

Answer 18

This sequestering plays an important role in removing carbon dioxide from the atmosphere. As carbon dioxide levels in the atmosphere rise, it is likely that more would be sequestered in the oceans, rivers and ponds. Many organisations and companies are also looking at how more carbon dioxide can be sequestered by enhancing natural sequestration (eg getting the phytoplankton to do more photosynthesis) or by using artificial sequestration.