What constitutes pollution? Any substance which doesn’t belong in the water and causes harm.
Sources of Pollution Pollution can come from a variety of sources. Point sources: A specific source of pollution which can be easily identified. Non-point Sources: A widely spread out source of pollution which cannot be easily identified.
Human Wastes Cities and urban areas produce huge amounts of waste materials. Most wastes are filtered and removed with water treatment plants. Serious flooding can cause drains to overflow and spill into surface water.
Industrial Wastes Many factories and industries produce large amounts of waste. Chemicals: Toxic wastes may leak into the soil and freshwater. Smoke and Exhaust: Smokestacks can release various pollutants into the atmosphere along with water and carbon dioxide. Heat Pollution: Water used to cool factory machinery can runoff into rivers and warm them.