Environmental Chemistry: Green House Effect and Global Warming (For CBSE, ICSE, IAS, NET, NRA 2022)

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Acid Rain

  • When the PH of rain goes below 5.6 it is term as acid rain.
  • Both and nitrogen oxides are converted into acids and when they combine with oxygen and water vapour in the atmosphere as per the following photo chemical reactions.

Effects of Acid Rain

  • Excessive acid concentrations are phytotoxic (toxic to plants) . There have been widespread death of trees in forests due to acid rain.
  • Sea waters are rich in minerals and have great buffering capacity. But buffering capacity of freshwater bodies is low and acid deposits have a toxic effect on the fresh water ecosystems.
  • Mature (capable of reproduction) fish survives in acid rain fed water bodies but fails to reproduce. So, there are no young fish in such waters.

Green House Effect and Global Warming

The literal meaning and function of green house is to trap the heat. You must have seen delicate plants being grown in a glass chamber which is comparatively warmer inside than outside. Glass permits solar radiations to come in but restricts the outward movement of heat. The radiations get trapped inside the glass chamber and raises the temperature.

Green House Effect and Global Warming

Global Warming

Global warming is defined as the increase in the average global temperature of the atmosphere near earth՚s surface.

Depletion of Ozone Layer

Ozone shield depletion is primarily caused due to the following reasons:

  • Chlorofluorocarbons (CFCs) are the heat transfer agents used in refrigerators and air conditioners, and foaming agents in foam cups and cartons.
  • Halons or halocarbons are anti fire agents used in fire extinguishers.

It is believed that one molecule of CFC is capable of destroying 1,00, 000 ozone molecules in the stratosphere. The area where the ozone is completely destroyed is known as ozone hole.

Effects of Ozone Depletion

Ozone layer depletion will allow more UV rays to enter the troposphere and will cause a series of harmful effects such as:

  • Plants and animals living on the surface will start dying.
  • UV radiation will fasten the formation of smog.
  • Temperature of the earth will increase leading to rise in sea level and flooding of low-lying areas.
  • More UV rays will directly fall on the skin of humans causing skin cancer.
  • Leaves of plants will show chlorosis (loss of chlorophyll and yellowing.

Water Pollution

Water pollutants refer to the substances which are capable of making any physical, chemical or biological change in the water body.

Fresh water pollution may be classified into two types:

Surface Water Pollution

When pollutants enter a stream, river or lake these gives rise to surface water pollution. The surface water pollution has a number of sources.

These can categorized as:

  • Point and Non-point Sources
  • Natural and Anthropogenic Sources

Point and Non-Point Sources

  • The well-defined sources that emits pollutants or effluents directly into different water bodies of fresh water are called point sources. Domestic and industrial waste are examples of this type.
  • On the other hand, the non-point sources of water pollution are scattered or spread over large areas. This type of sources deliver pollutants indirectly through environmental changes and account for majority of the contaminants in streams and lakes. For example, the contaminated water that runs off from agriculture farms, construction sites, abandoned mines, enters streams and lakes.

Natural and Anthropogenic Sources

  • As mentioned earlier, an increase in the concentration of naturally occurring substances is also termed pollution. The sources of such an increase are called natural sources. It is a common natural phenomenon, which occurs in most water bodies.
  • On the other hand, the human activities that result into the pollution of water are called anthropogenic or manmade sources of water pollution. For example, domestic , industrial and agricultural wastes that goes into the rivers, lakes, streams and seas are anthropogenic sources.
Natural and Anthropogenic Sources

Ground Water Pollution

When the polluted water seeps into the ground and enters an aquifer, it results into ground water pollution. The most of our villages and many townships, ground water is the only source of drinking water. Therefore, pollution of groundwater is a matter of serious concern. Groundwater gets polluted in a number of ways. The dumping of raw sewage on soil, seepage pits and septic tanks cause pollution of groundwater.

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