Earth Science 4.3 Water, Air, Land Resources

Key Concepts Why is fresh water a vital resource? Why is the chemical composition of the atmosphere important? What are Earth’s important land resources?

The Water Planet Water covers nearly 71% of Earth’s surface Most of this water is salt water, not fresh water While salt water oceans are important for our climate and are an important part of our ecosystem; fresh water is what we as humans need to live. Every day we use fresh water for drinking, cooking, bathing and growing food Less than 1% of the water on the planet is usable fresh water

Freshwater Pollution Contamination of our freshwater supply is an important issue. There are two types of water pollution Point Source Pollution Nonpoint Source Pollution

Point Source Pollution Point source pollution is pollution that comes from a known and specific location

Nonpoint Source Pollution Nonpoint source pollution does not have a specific point of origin. Runoff, the water that flows over the land rather than seeping into the ground, often carries nonpoint source pollution Runoff can carry waste oil from streets, sediment from construction sites, or pesticides from farm soils Water filtering through piles of waste rock can carry sulfuric acid into rivers and streams killing fish Pollutants from eating contaminated fish can damage our bodies major organs and systems, cause birth defects and cause certain types of cancers

Earth’s Blanket of Air Earth’s atmosphere is a blanket of nitrogen, oxygen, water vapor and other gases The chemical composition of the atmosphere helps maintain life on Earth First and foremost, people and animals need oxygen to breath The atmosphere is also part of other cycles

Earth’s Blanket of Air The carbon cycle of Earth’s atmosphere makes vital nutrients available to many life forms The atmosphere also makes life on land possible by shielding Earth from harmful solar radiation

Earth’s Blanket of Air Earth’s ozone layer high in the atmosphere helps protect us from solar radiation Ozone is a three-atom form of oxygen that protects Earth from 95% of the sun’s harmful ultraviolet radiation Certain greenhouse gases in the atmosphere help maintain a warm temperature near earth’s surface

Pollution in the Air Pollution can change the chemical composition of the atmosphere and disrupt it’s natural cycles and functions Fossil-fuel combustion is the major source of air pollution. Most of this pollution comes from motor vehicles and coal or oil burning power plants

Pollution in the Air Power plants release sulfur dioxide and nitrogen oxide. These pollutants combine with water vapor to create acid precipitation The burning of fossil fuels also produces carbon dioxide, an important greenhouse gas.

Pollution in the Air The amount of carbon dioxide in the atmosphere has increased dramatically in the past 100 years with the industrial revolution This increase has altered the carbon cycle and contributed to global warming. Global warming could lead to huge changes in the Earth’s climate such as the melting of polar ice caps.

Pollution in the Air Chlorofluorocarbons (CFCs) destroy ozone in the upper atmosphere. A significant loss of ozone has resulted in the increased risk of health problems related to too much UV radiation exposure such as skin cancer and cataracts. Because of a growing hole in the Earth’s ozone layer, we now are unable to spend time outdoors without being conscious of the affects of sun-damage to our skin

Pollution in the Air Air pollution is a major public health problem Long term health effects include asthma, bronchitis, emphysema, and lung cancer The US EPA estimates 200,000 deaths each year are associated with the outdoor air pollution

Land Resources Earth’s land provides soil and forests, as well as mineral and energy resources Removing and using resources from earth’s crust can take a heavy environmental toll.

Land Resources There are essentially 500,000 mines in the United States. While mines are essential to our economy and energy usage, mining tears up Earth’s surface and often destroys the landscape. Mining also causes soil erosion, creates pollution through runoff, and contaminates surrounding water supplies as well as destroys entire ecosystems

Affects of Agriculture Agriculture and farming have heavy affects on the land as well While many dry areas are now being farmed thanks to irrigation, this heavy pumping and water use is depleting groundwater supplies in areas Over time, irrigation causes salinization ( the buildup of salts) . Eventually the soil becomes useless for plant growth. With the loss of plant growth soil deteriorates and becomes a dust bowl.