The correct options are (d).
When water bodies are nutrient enriched, then a dense growth of algae occurs. When these algae die, the decomposers decompose them by using a lot of oxygen. It results in decrease in concentration of oxygen in water resulting in death of aquatic organisms.
No, clear and transparent water is not always fit for drinking. Water which looks clean may still have disease carrying microorganisms and dissolved impurities. Therefore, it is essential to purify water before drinking.
Sulphur dioxide and nitrogen dioxide produced from the industries like rubber processing industry, Mathura oil refinery etc. located in and around Agra are responsible for the discolouring of white marble of Taj Mahal. Sulphur dioxide and nitrogen dioxide gases released from the industries, react with water vapour present in the air to form sulphuric acid and nitric acid, respectively. The acids drop down with rain, making rain acidic. Acid rain corrodes the marble of the Taj Mahal. The phenomenon is also known as ‘Marble Cancer’. Suspended particulate matters emitted by ‘Mathura oil refinery’ have also contributed towards the yellowing of the marble.
Gases like carbon dioxide, methane, water vapour etc. present in the atmosphere are called green house gases. These gases trap the heat from Sun and prevent it from escaping into the outer space. It helps in keeping earth warm and is essential for life on earth. But increase in the concentration of these gases leads to excessive increase in Earth’s temperature leading to global warming.
Sulphur dioxide and oxides of nitrogen are produced from various industries. These gases react with water vapour present in the air to form sulphuric acid and nitric acid, respectively. These acids come down with the rain water and this process is called acid rain.
Acid rain destroys plants and vegetation. The water of the rivers and the lakes becomes acidic and this causes the destruction of the aquatic life. Acid rain also destroys the ancient buildings, monuments and sculptures due to the continuous erosion of the marble.
As a member of the municipal body of my town, I would take certain necessary actions to ensure the supply of clean water.
Water gets contaminated by following ways:
Global warming is an increase in the average temperature of Earth’s atmosphere. It is caused due to increased levels of green house gases like carbon dioxide, oxides of nitrogen, water vapour, methane, etc. These gases absorb solar radiation and prevent it from escaping into the outer space thereby, increasing Earth’s average temperature.
This continuous warming has lead to an increase in the temperature of Earth’s surface by 0.6°C approx. in the last three decades. Due to a rise in the temperature, the polar ice is melting and is threatening the survival of the polar bears.
The melting of the polar ice causes a rise in the sea level. It harms the coastal life and vegetation.
Pure air |
Polluted air |
Pure air contains 78% nitrogen, 21% oxygen and 0.03% carbon dioxide. Water vapour and other gases are present in traces. |
Composition of air is altered by the presence of harmful substances such as oxides of nitrogen, sulphur dioxide, carbon monoxide, particulate matters, etc. |
It does not have any harmful substances. |
Increased level of harmful substances and poisonous gases are present. |
Pure air is fit for breathing and does not cause any respiratory problems. |
Polluted air is unfit for breathing and causes many respiratory problems like asthma. |
An individual can reduce air pollution by:
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