Chapter 18 Human Impact on the Earth

Water Water Air Air Soil Soil

Our Water Resources The water cycle is the continuous movement of water above, on, and below the Earth’s surface. It includes: The water cycle is the continuous movement of water above, on, and below the Earth’s surface. It includes: Precipitation Precipitation RunoffRunoff EvaporationEvaporation CondensationCondensation

Our Water Resources Pollution is the introduction of harmful substances into the environment. Pollution is the introduction of harmful substances into the environment. Point-source pollution is pollution that comes from a single or easily traced point (such as a pipe). Point-source pollution is pollution that comes from a single or easily traced point (such as a pipe).

Our Water Resources Nonpoint-source pollution is pollution that comes from many places rather than a single point. Nonpoint-source pollution is pollution that comes from many places rather than a single point. It comes from places like yards, parks, farms, streets, and storm sewers and reaches bodies of water via runoff. It comes from places like yards, parks, farms, streets, and storm sewers and reaches bodies of water via runoff.

Our Water Resources 65% of the Earth is water – but only 3% of that water is drinkable. 65% of the Earth is water – but only 3% of that water is drinkable. Freshwater pollution comes from: Freshwater pollution comes from: Fertilizer runoffFertilizer runoff Bacteria from wasteBacteria from waste Waste from factoriesWaste from factories PesticidesPesticides

Our Water Resources The Clean Water Act had a goal to make all surface water in the US safe enough for swimming and fishing by The Clean Water Act had a goal to make all surface water in the US safe enough for swimming and fishing by We have made progress – but that goal has still not been met. We have made progress – but that goal has still not been met.

Our Water Resources Our oceans are also polluted, the most common sources being: Our oceans are also polluted, the most common sources being: TrashTrash Sludge dumpingSludge dumping Oil spillsOil spills The US spends more than $130 million a year to protect the ocean and beaches. The US spends more than $130 million a year to protect the ocean and beaches.

The Air We Breathe Primary pollutants are pollutants that are put directly into the air by human or natural activity. Primary pollutants are pollutants that are put directly into the air by human or natural activity. Exhaust, volcanic ash, smoke sootExhaust, volcanic ash, smoke soot Secondary pollutants form from chemical reactions. Secondary pollutants form from chemical reactions. SmogSmog

The Air We Breathe Acid rain is rain, sleet, or snow that is highly acidic because of the burning of fossil fuels. Acid rain is rain, sleet, or snow that is highly acidic because of the burning of fossil fuels. The ozone hole formed when some chemicals added to the air reacted with the ozone layer. The ozone hole formed when some chemicals added to the air reacted with the ozone layer.

The Air We Breathe The Clean Air Act allows the Environmental Protection Agency (EPA) to control the amount of pollutants that can be released from any source. The Clean Air Act allows the Environmental Protection Agency (EPA) to control the amount of pollutants that can be released from any source.

Saving Our Soil Erosion is the process by which wind and water move soil from one place to another. Erosion is the process by which wind and water move soil from one place to another. There are three types: There are three types: Sheet erosionSheet erosion Rill erosionRill erosion Gully erosionGully erosion

Saving Our Soil Human causes of erosion: Human causes of erosion: Deforestation or the process of clearing forests. Deforestation or the process of clearing forests. Overgrazing removes large areas of grassland. Overgrazing removes large areas of grassland. Farming breaks up the soil. Farming breaks up the soil.

Saving Our Soil Desertification is a process by which human activity makes the soil infertile in areas where plants could once grow. Desertification is a process by which human activity makes the soil infertile in areas where plants could once grow.

Saving Our Soil Soil conservation is the methods by which humans take care of the soil. Soil conservation is the methods by which humans take care of the soil. Some examples are: Some examples are: Contour farmingContour farming Strip farmingStrip farming WindbreaksWindbreaks