the effects of environmental features on severity of pollution

Question 1

define degradation

Answer 1

the breaking down of a substance

Question 2

list the features which can affect degradation of a pollutant

Answer 2

1) temperature
2) light levels
3) oxygen
4) PH
5) pollutant interactions

Question 3

outline the affects of temperature of the degradation of a pollutant

Answer 3

• higher temperatures increase the rate of breakdown

- for example pollution such as sewage will break down more rapidly at high temps

Question 4

what impact can high temperatures influencing degradation influence the environment

Answer 4

• high temps increase the speed of breakdown- rapid degradation can increase problems such as deoxygenation of water bodies as it increases the rate of decomposition which is an aerobic process so oxygen is taken and and carbon dioxide released

Question 5

outline the effects of light levels on degradation

Answer 5

• light can act as an activation energy which drives the chemical reactions involving pollutants
• for example photochemical smogs and the photodegradation of some pesticides

Question 6

outline the effects of oxygen on degradation

Answer 6

• oxygen is involved in many chemical and biological reactions involving pollution
• for example
  1) aerobic bacteria breakdown of sewage
  2) oxidation of sufides ores producing sulphur dioxide
• the oxidation sate affects the solubility of many metals

Question 7

how can the oxidation state of a metal increase the severity of a pollutant

Answer 7

the oxidation state affects the solubility of many metals- therefore allowing them to enter different pathways and become more mobile

Question 8

outline the effects of PH on the degradation of pollutants

Answer 8

• PH can affect the solubility of substances

- many heavy metals such as lead become more soluble and therefore mobile under acidic conditions

Question 9

outline the effects of pollution interactions on degradation

Answer 9

• the behavior of one pollutant may be affected by the presence of another
  for example
  1) interactions of nitrous oxides and hydrocarbons in photochemical smogs
  2) the combined affect of phosphates and nitrates in eutrophication

Question 10

explain the role of light in photochemical smogs

Answer 10

• causes the formation of secondary more toxic pollutants such as PANs
• UV light can split molecules such as nitrogen dioxide into monatomic oxygen in nitric oxide, the oxygen can then go on to form tropospheric ozone which goes to form a secondary pollutant PANS

Question 11

How can acidic PH be neutralised

Answer 11

by basic/alkaline rocks

Question 12

what factors affect the dispersal of pollutants

Answer 12

1) wind and water currents

2) temperature inversions

Question 13

outline how temp inversions increase the dispersal of pollutants

Answer 13

1) atmospheric temps in the troposphere normally decline with altitude
2) warm pollutant gases released at ground level are less dense so rise
3) the rising of the pollutant causes it to disperse and become diluted
4) as the pollutants rise they cool, however, the surrounding air is also cooler so they continue to rise and disperse

Question 14

outline how wind and water currents affect the distribution of pollutants

Answer 14

velocity and direction of air and water will affect how far a pollutant travels but also how much it is diluted

Question 15

outline how the presence of absorbent materials on pollutants

Answer 15

• pollutants may absorb onto materials such as clay particles in aquatic sediments and become immobilised which stops it causing problems
• other toxic metals may be absorbed such as lead or aluminium

Question 16

what factors allow for the formation of a temp inversion

Answer 16

1) valleys where cold dense air can collect
2) low wind velocity- so that air layers with different temps dont mix
3) cloudless skies- infrared radiation emittes from the ground faster causing increased cooling
4) mist or fog- water condenses at ground layer creating an albedo affect reflecting sunlight so the ground cools