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Grade 7: Human Impact on the Environment (Human Impact on Land (Why is…
Grade 7: Human Impact on the Environment
Human Impact on Water
Why is water important?
Every living thing is made up of water.
Most life processes use water.
Access to clean water is important for good health.
How can human activities affect water?
Thermal pollution
Warm water (e.g. caused by cooling a power plant) has less oxygen for organisms that live in the water.
Chemical pollution
Pesticides, herbicides and fertilizers reach water supplies by seeping into groundwater.
Biological pollution
Wastewater may contain microbes that cause diseases, such as dysentery, typhoid or cholera.
Eutrophication
Wastewater and fertilizer can add extra nutrients to water which can cause an overgrowth of algae and reduce oxygen levels.
Human Impact on Land
Why is land important?
Fossil fuels can be burned to provide energy.
Minerals can be used for construction materials.
It provides nutrients for plants.
It provides hiding places for animals.
Why is soil important?
It provides a habitat for organisms, such as plants, earthworms, fungi and bacteria.
Plants get water and nutrients from the soil, and these plants form the base of food chains.
Healthy soil is important for agricultural land which supplies humans with food.
How can human activities affect land and soil?
Positive impact
Restore land to its natural state.
Increase the amount of fertile soil on the land.
Negative impact
Urban sprawl
Erosion
Nutrient depletion and land pollution
Desertification
Deforestation
Human Impact on the Atmosphere
Why is the atmosphere important?
It provides gases that organisms need to survive.
It absorbs harmful radiation.
It keeps Earth warm.
How can human activities affect the atmosphere?
Air pollution
Gas pollutants (e.g. carbon monoxide, sulfur dioxide, nitrogen oxide and ground-level ozone)
Particle pollutants (e.g. ash, dust, pollen, particulates from vehicle exhaust)
Pollution from vehicle exhausts
Ground-level ozone is produced when sunlight reacts with vehicle exhaust and oxygen in the air.
Smog is produced when ground-level ozone and vehicle exhaust react in the presence of sunlight.
Acid precipitation
Acid precipitation can cause soil and water to become more acidic than normal.
It contains sulfuric and nitric acid that form when sulfur dioxide and nitrogen oxide combine with water in the atmosphere.
Protecting Earth's Water, Land and Air
How can we preserve water resources?
Conserving water
Water stewardship
How can we preserve land resources?
Preservation
Reforestation
Reclamation
Reducing urban sprawl
Recycling
Soil conservation methods
How can we reduce air pollution?
Through energy conservation
Through technology
Through laws