SOCIALSCIENCE

Digital text



STD VIII

Sherlychacko chan rollno:53 kucte kunnam

Content Water on earth 1.water is life 2.water cycle 3.sources of water 4.water pollution 5.summary and extended activities

Chapter 1

Water on eath Water is life Earth is only living planet in the

solar system. It is beluved that life

is orginated in water. 71% of earth

surface is covered with water, it

appears to be blue,a pale viewed

in space 97% of saline water

to the total water of

earth

Water cycle

The water cycle

shows the

continuous

movement of

water within the

Earth and

atmosphere. It is

a complex system

that includes

many different

processes. Liquid

water evaporates

into water vapor,

condenses to

form clouds, and

precipitates back

to earth in the

form of rain and

snow.

Sources of water Water is a valuable natural resource found in different forms in our environment. There are two primary sources of water – surface water and groundwater..

Ground water Groundwater is the water present beneath

Earth's surface in rock and soil pore spaces and

in the fractures of rock formations. Examples 1.well

2.pond

Surface water Surface water is water that collected at ground level and can be collected by

precipitation. The amount of available surface

water depends upon rain fall Example 1.River

2.oceans

Water and water resources is very important

for maintaining an adequate food supply and a

productive environment for the all living

organisms

Water pollution

Water pollution is the contamination

of water bodies, usually as a result of

human activities, so that it negatively

affects its uses. Water bodies include

lakes, rivers, oceans, aquifers,

reservoirs and groundwater. Water

pollution results when contaminants

mix with these water bodies

Causes of water pollution

Water pollution is the contamination of

water sources by substances which make the

water unusable for drinking, cooking,

cleaning, swimming, and other activities.

Pollutants include chemicals, trash, bacteria,

and parasites. All forms of pollution

eventually make their way to water.

The major reason for water pollution are 1.Industrial waste Industries and industrial

sites across the world

are a major contributor

to water pollution.

Many industrial sites

produce waste in the

form of toxic chemicals

and pollutants, and

though regulated, some

still do not have proper

waste management

systems in place.

2.Sewage and Wastewater Harmful chemicals, bacteria and pathogens can

be found in sewage and wastewater even when it’s been treated. Sewage and wastewater from each

household is released into the sea with fresh

water. The pathogens and bacteria found in that

wastewater breed disease, and therefore are a

cause of health-related issues in humans and

animals alike.

3.Agriculture In order to protect their

crops from bacteria

and insects, farmers

often use chemicals

and pesticides. When

these substances seep

into the groundwater,

they can harm animals,

plants and humans

Ways to Prevent Water Pollution Pick up litter and throw it away in a

garbage can. low or sweep fertilizer back

onto the grass if it gets onto paved areas.

Don't put fertilizer on the grass right before

it rains. The chemicals will wash istorm

drains and waterways.ulch or compost

grass or yard waste. Or, leave it in your

yard if you can't compost.

Summary

.water is the base for life on earth . 71% of surface area of the eath is

water . There are different sources of water . Water cycle regulates the availability of water on earth . Human intervention pollute water

source

Extended activities

Prepare and execute a plan to clean

and conserve a pollued fresh water