Tag: air pollution - effects and control

When the pH of raindrops down below 5.5 it is called acid rain. It occurs because of oxides of sulphur (SO₂) and nitrogen (NO) which on reacting with water in the atmosphere form sulphuric acid and nitric acid. These acids then come down on earth along with rain and thus, making the rain acidic. Hence, acid rain is the downpour of sulphur dioxide (SO2) and nitric oxide (NO).

the biggest cause of acid rain today is Sulfur dioxide and nitrogen oxides released into the air by fossil-fuel power plants, oil refineries, and vehicles, that react with rain water to form sulphuric acid and nitric acid respectively

Acid rain is a rain that is usually acidic (elevated levels of hydrogen ions) or low pH. It can have harmful effects on plants and aquatic animals. Acid rain is caused by emission of sulphur dioxides and nitrogen oxides which react with water molecule in the atmosphere to produce acids.

The ecological effects of acid rain are most clearly seen in the aquatic environments, such as streams, lakes, etc. Acid rain flows into streams, lakes and marshes after falling on forests, fields, building and roads. Acid rain water primarily decreases the pH of water sources from normal range (6 to 8 pH) Lakes and streams become acidic (i.e., pH values goes down), when water itself and its surrounding soil cannot buffer the acid rain water to neutralize it. In areas where buffering capacity is low, acid rain releases aluminium from soils into lakes and streams, aluminium is highly toxic to many species of aquatic organisms leading to their mortality. Therefore, limiting the survival of aquatic animals. So, the correct answer is 'Lowering of pH in ponds, limiting survival of aquatic organisms'.

Acid rain is acidic with a pH of below 5.6. Rain becomes acidic because of gases that dissolve in the rain. Approximately 70% of acid rain is a result of dissolved sulfur dioxide ($SO _2$), which forms sulphuric acid. The remaining 30% or so comes from various nitrogen oxides (mostly $NO _2$ and $NO _3$, which has collectedly called NOx). There are also a small percentage of hydrochloric acid and carbonic acid.