5.4.1. Causes

♤ Indiscriminate use of fertilizers, pesticides, insecticides and herbicides

♤ Dumping of large quantities of solid waste

♤ Deforestation and soil erosion.

♤ Pollution Due to Urbanisation

5.4.2. Source

i. Industrial Wastes:

♤ Industrial waste includes chemicals such as mercury, lead, copper, zinc, cadmium, cynides, thiocynates, chromates, acids, alkalies, organic substances etc.

ii. Pesticides:

♤ Pesticides are chemicals that include insecticides, fungicides, algicides, rodenticides, weedicides sprayed in order to improve productivity of agriculture, forestry and horticulture.

iii. Fertilizers and manures:

♤ Chemical fertilizers are added to the soil for increasing crop yield. Excessive use of chemical fertilizers reduces the population of soil borne organism and the crumb structure of the soil, productivity of the soil and increases salt content of the soil.

iv. Discarded materials:

♤ It includes concrete, asphalt, rungs, leather, cans, plastics, glass, discarded food, paper and carcasses.

v. Radioactive wastes:

♤ Radioactive elements from mining and nuclear power plants, find their way into water and then into the soil.

vi. Other pollutants:

♤ Many air pollutants (acid rain) and water pollutants ultimately become part of the soil and the soil also receives some toxic chemicals during weathering of certain rocks. [in box]