So by now you should know how does these air pollutants will affect you and me on a personal level. Now, we are going to touch on the global effects!
The air pollutants that we have mentioned will have an indirect impact not only to our environment, but also economy and infrastructure. Some of the aftermaths due to these air pollutants that we are going to discuss here are
- Acid Rain
- Haze
ACID RAIN
Acid rain is the result of a chemical reaction of compounds such as SOx and NOx.
SULFUR
S(s) + O2 (g) -> SO2 (g)
Sulfur reacts with oxygen forming sulfur dioxide.
2 SO2 (g) + O2 (g) 2 SO3 (g)
Sulfur dioxide further reacts with oxygen forming sulfur trioxide.
SO2 (g) + H2O(l) H2SO3 (aq)
SO3 (g) + H2O(l) H2SO4 (aq)
Acid rain is thereby formed from these compounds reacting with water.
NITROGEN
4 NO2 (g) + 2 H2O(l) + O2 (g) -> 4 HNO3 (aq)
Nitrogen dioxide reacts with water and oxygen, producing nitric acid.
How do these pollutants come about?
Majority of sulfur dioxide and some of the nitrogen oxides released into the air are produced by the burning of fossil fuels, i.e. coal, by power plants in order to produce electricity.
China may further limit car purchases to curb pollution
Road vehicles also contributed to the releasing of SOx and NOx into the air, heightening chances of acid rain forming.
IMPLICATIONS ON SOCIETY: ACID RAIN
So how does Acid rain have an impact on our society?
- The Ecosystem
As acid rain flows through soil, aluminium from the soil could be leached away, flowing into nearby streams and lakes. This is especially the case for soils that are not rich in limestone or marble.
Limestone and marble are alkaline, hereby able to neutralise the acid rain since pH of both parties increases when dissolved in water.
Hence, the more acid being introduced into the ecosystem, the more aluminium is being released into nearby lakes, causing the deaths of some organisms.
Some organisms may be lost due to the intolerance of the acidity of their environment.
As seen from the picture, different organisms have different tolerance to the different pH of the environment. Most fishes are unable to hatch eggs at pH 5, any further would even result in the death of these fishes themselves.
The ecosystem, i.e. the predator-prey relationship, might also be disrupted. For example, even though frogs are able to withstand an environment of pH 4, their prey, mayflies, are only able to withstand a pH up to 5.5. This could lead to a decrease in population of the ecosystem.
(b) Plants and Trees
Ions of Calcium, Magnesium and other ions attached to clay are important source of nutrients for cell formation and photosynthesis. Acid rain however removes these important ions from clay via Cation-exchange.
H+ ions from acid rain displaces essential ions from the soil
H+ ions are more attractive than the essential ions, hence, the negatively charged ions from the soil would be attracted to the H+ ions instead, releasing the important ions instead, leading to the deaths of trees and plants due to insufficient nutrients.
(c) Buildings and infrastructure
Acid rain would be able to corrode buildings or infrastructures made up of limestone or marble. As mentioned, limestone and marble ( i.e.CaCO3) are alkaline, hence a neutralisation reaction when react with acid rain.
CaCO3 + H2SO4 –> CaSO4 + H2CO3
Limestone or marble reacts with acid rain to form calcium sulfate and carbonic acid
H2CO3 –> CO2 gas + H2O
Carbonic acid then decomposes into CO2 gas & H2O
Calcium sulfate is soluble in water, hence the limestone eventually dissolves and crumbles, corroding buildings and infrastructures in the process.
The Longmen Grottoesmost, one of the world`s most important sculptural sites, situated in China is experiencing instability due to acid rain corrosion over the years
HAZE
Haze includes an amount of smoke, dust, moisture, and vapour suspended in air. Very fine particles with a diameter of less than 10 mm made up majority of the haze.
SOURCES OF HAZE
Agriculture fire contributes to the haze. Farmers in certain countries are used to the slash-and-burn method to clear vegetation for palm oil, pulp and paper plantations. This method made lands even drier, hence, more susceptible to fire.
The forest fires are capable of releasing greenhouse gases i.e. CO2, CH4, CO gas, NOx, and fine and coarse particulate matter into the air.
IMPLICATIONS ON SOCIETY: HAZE
So how does haze has an impact on our society?
- The Economy
Due to the haze, countries may expect to see a decline in the amount of tourists and their productivity, leading to a decrease in their GDP.
In 2013, Singapore experience a $50 million loss to the economy overall due to the decline in tourism, retails, hotels etc. as a result of the haze.
(b) Wildlife
Photosynthesis is a process of using sunlight and carbon dioxide to provide nutrients for plants. However, as haze blocks sunlight, this leads to an increase in carbon dioxide and harmful chemicals in the air.
Just like humans, haze also causes health problems and a disruption to the lifestyle of wildlife animals.
Haze disrupts the singing behavior and communication of these gibbons, leading to reduced reproductive capacity in the long term.
Images References:
http://www.cyark.org/news/top-5-endangered-heritage-sites-acid-rain
https://www3.epa.gov/acidrain/education/site_students/whatcauses.html
http://www.todayonline.com/chinaindia/china/china-may-further-limit-car-purchases-curb-pollution
http://www.downtoearth.org.in/cartoon
Sources References:
http://www.wwf.org.my/media_and_information/updates__former_newsroom_main_/?uNewsID=20525
http://tunza.eco-generation.org/worldReportView.jsp?viewID=10330
http://www.straitstimes.com/business/economy/singapore-gdp-will-take-hit-from-haze-as-countries-issue-travel-warnings
http://www.bbc.com/news/world-asia-34265922
https://www.fs.fed.us/rm/pubs_other/rmrs_2009_urbanski_s001.pdf
https://www.epa.gov/acidrain/effects-acid-rain
http://www.air-quality.org.uk/16.php
http://chemistry.elmhurst.edu/vchembook/196buildings.html
http://chemistry.elmhurst.edu/vchembook/196soil.html