Water Review 2

The ocean is an integral component of the world's climate due to its capacity to collect, drive and mix water, heat, and carbon dioxide

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8.E.1.3 Predict the safety and potability of water supplies in North Carolina based on physical and biological factors, including:

• Temperature

• Dissolved Oxygen

• pH

• Nitrates and phosphates

• Turbidity

• Bio-indicators

Temperature and dissolved oxygen

Aquatic organisms have preferred water temperature ranges within which they will live and thrive. Warm water dissolves more of a solid substance as it gets warmer, but it also dissolves less of important gases like oxygen and carbon dioxide. Very warm water may not contain enough dissolved oxygen for aquatic life to survive. Measuring dissolved oxygen is an important factor in determining water quality

pH

pH is a measure of how acidic or basic water is. pH is measured on a scale that ranges from 0 to 14, with 7 considered neutral. Values of pH less than 7 are acidic, while values higher than 7 are basic. In pure water the pH measures exactly 7. Change in pH is an indicator of a change in the chemical structure of the water.

Nitrates and Phosphates

Nitrogen and phosphorous are essential plant nutrients. These nitrates and phosphates pose possible health risks to humans if their presence in drinking water is not controlled and can lead to eutrophication. The major sources of nitrates in surface water include runoff contaminated with fertilizers, septic tank leakage, sewage, and erosion of natural deposits. Phosphates usually enter waterways from human and animal waste, laundry, cleaning, and industries.

Multiple Choice

If a lake has excess levels of phosphates and nitrates in its water, what will most likely result?

• The temperature of the lake water will decrease

• The turbidity levels of the lake will decrease.

• The dissolved-oxygen levels in the lake will increase

• The growth of algae in the lake will increase

Turbidity

Turbidity is a measure of how clear water is. The more suspended solids there are in a water sample, the less transparent it is. Turbidity is considered a good measure of water quality. In surface bodies of water, high turbidity can lead to increased water temperatures, low dissolved oxygen, and even physical impairment of aquatic organisms

Bio-indicators

The quality of a body of water can also be assessed by using bioindicators. The presence, condition, and numbers of the types of fish, insects, algae, plants and other aquatic life provide accurate information about the health of freshwater and marine waters. Because many bioindicators are sensitive to pollution in water, they are a good indicator of whether or not a body of water is livable. Good water quality is indicated by a variety of bioindicators.

8.E.1.4 Conclude that the good health of humans requires:

• Monitoring of the hydrosphere

• Water quality standards

• Methods of water treatment

• Maintaining safe water quality

• Stewardship

The health of a water system is determined by the balance between physical, chemical and biological variables

Physical variables include temperature, turbidity, and water movement. Chemical variables include dissolved oxygen and other gases, pH, nitrates, and salinity. Freshwater systems are of particular concern because they are the source of most of the potable water consumed by humans. Testing for the occurrence of chemicals and other factors that can influence water quality, such as nutrients and pesticides in water resources is a normal part of public health maintenance and stewardship of freshwater resources. Water that is safe to drink is called potable water. In the United States, the Environmental Protection Agency sets maximum levels for the 90 most commonly occurring contaminants.

Maintaining water quality

Water quality standards outline the water quality pollution control program that is mandated and regulated by local, regional and federal agencies. Standards outline the goals for a body of water by identifying its uses, establishing how to protect those uses and establishing regulations to protect and preserve the water bodies in the long term. Point and non-point environmental stressors such as urban and/or agricultural runoff, industrial inputs and over-fishing can impact a variety of aquatic and land-based populations. Because the water quality of a given water body is so closely linked to the surrounding environment and land use, monitoring and regulation at local, regional, and national levels is important.