Sunday, 4 September 2011

Air Pollution Effects On Other Living Things

Air Pollution Effects on Animals

We don’t know a lot about air pollution effects on animals.
  • Probably one of the best examples here is that of acid rain and how it affects freshwater animal life.
pollution effects, rain, lake
Hope this rain is not acidic
Photo: Heather Dietz
Sulfur dioxide and nitrogen dioxide are transformed in the atmosphere to produce acid compounds – sulfuric and nitric acids. These compounds then fall back on to the ground as particulates or raindrops – in other words, acid rain.
So acid rain also falls on streams and lakes, acidifies them and destroys fish life in these freshwater ecosystems. (58)
For example, in Sweden acid rain made over 18,000 lakes so acidic that all the fish died out. (59) Salmon species appear to be particularly sensitive to acidity. (60)
Some other populations of animals in Europe and North America that have also been declining due to acid rain are brown trout, mayfly larvae, beetle larvae, mollusks, and aquatic bird species (ex., the dipper). (61)
  • Pollution may also affect animals through plants on which they feed.
For example, pea aphids feed on pea plants exposed to sulfur dioxide in the air. High exposure to sulfur dioxide negatively affects the health of the pea plants, and therefore, the health of the aphids as well. (62)
Some other examples of air pollution effects on animals:
  • Excessive ultraviolet radiation coming from the sun through the ozone layer in the upper atmosphere which is eroded by some air pollutants, may cause skin cancer in wildlife (63)
  • Tropospheric ozone may damage lung tissues of animals (64)

It is also probably logical to assume that many higher order animals (especially those closely related to humans, ex. mountain gorillas) experience air pollution effects similar to those experienced by humans.

Air Pollution Effects on Forests, Trees & Plants

Air pollution can have both long-term and short-term effects on plants.
  • Physical injury to leaves is the immediate effect of air pollution on plants. Here is how leaves are affected by different air pollutants (65):
    • Ozone produces a speckle of brown spots, which appear on the flat areas of leaf between the veins
    • Sulfur dioxide: larger bleached-looking areas
    • Nitrogen dioxide: irregular brown or white collapsed lesions on intercostal tissue and near the leaf edge
    • Ammonia: unnatural green appearance with tissue drying out
    pollution effects, sulfur pollution, trees Trees Damaged by Sulfur Emissions Czech Republic  Photo: Wikimedia Commons
  • Of all main air pollutants, sulfur dioxide often comes up as the one that most negatively affects plants & trees.
    Here is a very illustrative example of how destructive sulfur dioxide can be to vegetation.
    The development of ore deposits in Canada in the middle of the 20 th century was a major source of sulfur dioxide emissions in high concentrations.
    Sulfur emissions of one specific iron smelting plant in Wawa, Ontario, caused the destruction of large tracts of native boreal forest (spruce, cedar, larch and pine), in a belt stretching some 30 km from the smelter. (66)
    Another good example is that of the Black Triangle – the area where the borders of Germany, Poland and the Czech Republic meet, with significant brown coal deposits.
    Industrial activity in this area led to high sulfur emissions which resulted in devastation of many square kilometers of forest (incl. the Norway spruce forest), particularly above an altitude of 750 m. (67)
However, it has been noted that sulfur dioxide concentrations in the atmosphere have recently been significantly reduced almost throughout the world (68) and do not carry such dramatic effects as they used to during the 20th century.
Lichens are considered to be most sensitive to sulfur dioxide. During the period of high levels of sulfur pollution, large parts of Europe lost many species of lichen and became known as “lichen deserts”. But as sulfur pollution levels dropped, many lichen species re-appeared. (69)
Sulfur dioxide may also affect higher plants, including wild species, crops and trees (though some species may develop sulfur dioxide tolerant populations in response to long-term exposure).
These effects may be (70):
      • Cell metabolism disruption (membrane damage, respiration and photosynthetic effects)
      • Leaf injury and loss
      • Reduced growth and reproduction
      • Increase in susceptibility of plants to attacks by insect herbivores
  • Nitrogen dioxide , another air pollutant, may act in synergy with sulfur dioxide to produce a negative effect on plants’ photosynthesis. (71)
  • Tropospheric ozone can prevent plant respiration by blocking stomata and negatively affecting plants’ photosynthesis rates which will stunt plant growth; ozone can also decay plant cells directly by entering stomata. (72)
  • Particles, just like ozone, often affect plants & trees via blocking of leaf stomata through which plants undertake the gas exchange necessary for photosynthesis and respiration. (73)
Andrew Farmer notes that:
“In sufficient quantities, dusts [i.e. particles] may form a smothering layer on leaves, reducing light and hence lowering photosynthetic rates.
pollution effects, trees, cement
Trees in a Cement Factory, Brazil 
Photo: Darlan Cunha
Many dusts are inert and so only act by shading.
However, some dusts are also chemically active.
Thus cement dust will also dissolve leaf tissue, resulting in additional injury.
Coal dust may also contain toxic compounds.
Dusts may also affect ecosystems through their action on soil. Thus the alkaline chemistry of limestone dusts can raise the soil pH of acid and neutral habitats, resulting in the loss of plant and animal species.” (74)
So, particulate air pollution effects on plants & trees may be as follows (75):
  • Blocked stomata
  • Increased leaf temperature
  • Reduced photosynthesis
  • Reduced fruit set, leaf growth, pollen growth
  • Reduced tree growth
  • Leaf necrosis and chlorosis, bark peeling
  • Acid rain (a product of air pollution) severely affects trees and plants as well.
It can kill trees, destroy the leaves of plants, can infiltrate soil by making it unsuitable for purposes of nutrition and habitation. (76)
It is also associated with the reduction in forest and agricultural yields. (77)

Air Pollution Effects on Wider Environment

The effects of acid rain have been known for a long time.
Though experts admit that the problem of acid rain is generally under control, it’s still worth reiterating the effects brought on by acid rain on the wider environment.
Acid rain has adverse effects on (78):
  • Forests & other vegetation
  • Freshwater lakes & streams destroying aquatic life
  • Soil
  • Buildings & materials

Air pollution also has a negative impact on visibility. (79)


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