Ambient Air Pollution

Question 1

What is Acid Rain?

Answer 1

Precipitation that is significantly more acidic than natural rain.

Question 2

Why does it drive acidity?

Answer 2

Presence of dissolved atmospheric CO2, forming carbonic acid, H2CO3, which ionises releasing a H+, reducing the pH of the system

Question 3

What are the two dominant acids in acid rain?

Answer 3

Sulfur Dioxide and Nitrogen Oxides as primary pollutants and Sulfuric acid and nitric acid as secondary.

Question 4

How do both of these form?

Answer 4

Secondary pollutants through reactions with O2, travelling downwind from their source.

Question 5

What is the pathway of sulfuric acid from SO2?

Answer 5

Emission from coal/oil combustion in power plants, SO2 reacts with O2 and H2O forming sulfuric acid, this reacts with other aerosols which then precipitates

Question 6

What is the reaction of SO2-H2SO4?

Answer 6

SO2 oxidised to sulfur trioxide(SO3) by O2, (2SO2 + O2 –> 2SO3, which then reacts with water vapor forming sulfuric acid.

Question 7

What is the pathway of nitric acid formation from Nox?

Answer 7

Emission from combustion, NO2 oxidation to NO3 then reaction with water vapor forming HNO3, reaction with acidic aerosols, then precipitation…

Question 8

What does the impact of acid rain on biota largely depend on?

Answer 8

Composition of surrounding soil and bedrock.

Question 9

What are examples?

Answer 9

f bedrock is limestone/chalk, acid can be neutralised by CaCO3, a base reacting with acid, forming bicarbonate ions, dissolving the rock.

Question 10

What soil properties determine acid rain impact?

Answer 10

Buffering capacity, Ca availability, nutrient availability, and metal mobilization.

Question 11

How does acid rain impact plant-life?

Answer 11

Through lowering of pH, cations like K, Ca and Mg exchange with H+ and the ions are leached.

Question 12

How does acid rain leach nutrients?

Answer 12

Reacts with cations like Ca2, Mg2 and K2, dissolving from soil matrix, depleting the soil.

Question 13

What is a study demonstrating this acid rain leaching nutrients?

Answer 13

Ibrahim et al., 2024

Question 14

How does it exacerbate aluminium toxicity?

Answer 14

Mobilizes Al, which is toxic to plant roots, impairing water/nutrient assimilation capacity.

Question 15

How can this impact water bodies?

Answer 15

Lakes relying on land-runoff for calcium may become threatened if dependent on calcium, thus impacting species composition and ecosystem function.

Question 16

Why is calcium important for organisms?

Answer 16

Roles in vital physiological functions, essential for CACO3 in shells, skeletons, and eggshells

Question 17

What is the concept of critical load?

Answer 17

Recognition that different levels of risk from acid rain are faced in different regions.

Question 18

How can acidification reduce plants ability to grow?

Answer 18

Decreased productivity in lakes and streams means amount of DOC has declined.

Question 19

What effects does declining DOC have?

Answer 19

Absorbs UV, thus allowing more UV penetration into lower layers of the lake.

Question 20

Why does UV scattering changes impact organisms?

Answer 20

Positively by reducing DNA damage and impaired photosynthesis risk, or negatively by loss of contro of algal blooms and regulation of abundance/composition of phytoplankton communities.

Question 21

What are the direct effects of acid rain?

Answer 21

Reduced growth, cuticle weathering, cation leaf leaching, seed germination, seedling growth, and flower/seed formation.

Question 22

What is the major source of impacts of acid rain?

Answer 22

Increased levels of aluminium ions.

Question 23

How are they released by acid rain? -

Answer 23

Leaching from rocks.

Question 24

Why are fish populations affected by acidification?

Answer 24

Their reproduction is drastically lowered when pH drops below 5.

Question 25

What is the mechanism of its impacts on reproduction?

Answer 25

Toxicity to eggs and larvae, mobilising Al from soils/sediments,

Question 26

How does Al impact fish reproduction?

Answer 26

Interference with ion regulation in fish, disruption in gill function, and impairment of respiratory and metabolic processes.

Question 27

What is a study showing the impact of Al on fish reproduction?

Answer 27

(Taslima et al., 2022)

Question 28

What’s an example of how fish have been affected?

Answer 28

30% of salmon rivers in Nova Scotia are too acidic for Atlantic salmon to survive.

Question 29

What is the economic damage of air pollution to crops in North America?

Answer 29

About 3 billion a year.

Question 30

How does Al impact plants?

Answer 30

Root damage, nutrient uptake inteterfence, cell function disruption…

Question 31

How are roots damaged by Al?

Answer 31

Inhibition of cell division of root meristem, limiting ability to explore soil for nutrients, as well as interference of biosynthesis of cellulose and lignin, and other cell wall components.

Question 32

How is photosynthesis negatively impacted by SO2 and NO2?

Answer 32

H+ gradient across thylakoid membrane is disrupted, and disruption of activity of pH sensitive calvin cycle enzymes.

Question 33

What is the extent of growth inhibition?

Answer 33

7.5-25% by SO2, and up to 55% by Nox.

Question 34

What consequences can indoor air pollutants have on forests?

Answer 34

In tandem with droughts and temperature stress, O3 and acid rain stress trees.

Question 35

How has air pollution impacted crops?

Answer 35

North American crops like Alfalfa and white beans in Canada, totalling to 3 billion a year.

Question 36

How are pollution impacts on health determined?

Answer 36

Collective information across an area, measuring spatial changes in pollutant concentration and relationship to human health.

Question 37

What has this elucidated?

Answer 37

Linking Carbon Monoxide to congestive heart failure among the elderly

Question 38

How does air quality relate to industrial development?

Answer 38

Proportional until a level of affluence is reached.

Question 39

What does air pollution most impact?

Answer 39

Majorly in and through the lungs, like O3 link to causing asthma.

Question 40

What is an example of increasing death rates by soot-and-SO2 smog?

Answer 40

London in 1952, 4000 people died a few days following a smog.

Question 41

What’s an example of deaths by SO2?

Answer 41

In Athens, death increased by 12% when SO2 exceeded 10 ug/m

Question 42

What exacerbates these issues in the modern day?

Answer 42

Diesel-powered engines and coal burning.

Question 43

Why does SO2 and O3 concentrations correlate diseases?

Answer 43

With lung dysfunction, like wheezing and bronchitis, with decrease in colon and breast cancer, as they scatted UV-B which is required for vitamin-d deficiency.

Question 44

What is the most important type of smog today?

Answer 44

Photochemical produced by nitrous oxides.

Question 45

How has this affected mortality rates?

Answer 45

Day to day mortality fluctuations correlate with air pollutant concentrations: a study shows in the US, high O3 concentrations increased daily cardiovascular and respiratory mortality by 0.5% per 10-ppb.

Question 46

What study shows photochemical smog effects on mortality rate?

Answer 46

Zanobetti and Schwartz, 2008)

Question 47

What is an anticipated impact of O3 exposure?

Answer 47

Decreased disease resistance due to lung tissue destruction.

Question 48

Why are inhaled particles so damaging to human health?

Answer 48

Their ability to carry organic matter and metal ions into lungs, and release them there.

Question 49

Why are coarse particles less impactful to human health?

Answer 49

Settle out quickly, with efficienct filtering by the nose and throat, thus not travelling as far to the lungs, with smaller change of transport due to smaller ratio of surface are to volume.