Presentation on theme: "Water Cycle Water Quality. About the Hydrologic Cycle Hydrology is the study of movements and characteristics of water.Hydrology is the study of movements."— Presentation transcript:
Water Cycle Water Quality
About the Hydrologic Cycle Hydrology is the study of movements and characteristics of water.Hydrology is the study of movements and characteristics of water. The hydrologic cycle has a profound effect upon climate prediction.The hydrologic cycle has a profound effect upon climate prediction. Water is vital for life so we must understand where to find water and how water supplies cycle through the Earth.Water is vital for life so we must understand where to find water and how water supplies cycle through the Earth.
FIGURE 11.2 The distribution of water on Earth. [Data from J. P. Peixoto and M. Ali Kettani, The Control of the Water Cycle. Scientific American (April 1973): 46; E. K. Berner and R. A. Berner, Global Environment. Upper Saddle River, N.J.: Prentice Hall, 1996, pp. 2–4.] Wheres the Water? 2.5% 1.7% 2.5% 0.77% 97.5%
The Water Cycle
Flows and Reservoirs Flows and Reservoirs Precipitation: water vapor condenses into tiny drops that form clouds, eventually fall as rain or snow Infiltration: when precipitation soaks into the ground through particles of soil or cracks Runoff: precipitation that doesnt infiltrate moves over the land surface, eventually collecting in streams and rivers Evaporation/Transpiration: liquid water transforming into gaseous water (water vapor) from surface water (evaporation) or plants (transpiration) Sublimation: solid water (ice) transforming directly into gaseous water (without becoming liquid)
Water Quality We will be going on a field trip to test water quality. What is Clean water? Why is water quality important? What impacts water quality?
Water Quality Tests Temperature pH Dissolved Oxygen (DO) Biochemical Oxygen Demand (BOD) Nitrates Total Dissolved Solids (TDS) and Salinity Turbidity Total Coliform Bacteria
Temperature Water temperature changes much more slowly than air temperature. How would water body size affect temperature? How about vegetation near the water? How about flowing vs. standing water? Why do we care about temperature? – Warm water holds less oxygen, but produces conditions that require more oxygen.
pH A relative measure of waters alkalinity/acidity. Chemically a measure of the number of hydrogen ions. pH scale is logarithmic, so substances at the far ends are extremely acidic or alkaline.
pH Natural factors that influence pH – Decomposing organic materials release carbon dioxide, creating carbonic acid. Human factors that influence pH – Releases of sulfur dioxide, nitrogen oxides and carbon dioxide all can form acid rain. Why should we care about pH? How does it influence water quality?
Dissolved Oxygen (DO) Water holds a reasonably large amount of dissolved oxygen, which is essential for life. Dissolved oxygen is influenced by salinity, agitation and turbulence, temperature, minerals, plant life, and organic wastes. – How do you think these factors influence DO?
Biochemical Oxygen Demand (BOD) Decomposing organic materials consume oxygen. High BOD indicates pollution. Low BOD suggests good water quality.
Nitrates Nitrogen is an abundant element. Nitrogen is considered a nutrient because it is essential for plant growth. How could plant growth impact water quality? Eutrophication is enrichment with nutrients. – Eutrophication can be both a natural and human- induced phenomenon.
Total Dissolved Solids (TDS) and Salinity Water is a universal solvent, so it may contain a wide range of substances. – Examples include calcium, sodium, phosphorus, iron, etc. Some solids in water are essential to maintaining health. High concentrations may lower water quality by increasing turbidity. Salinity is a measure of specific type of dissolved solid, namely, salts.
Turbidity Turbidity is a measure of how cloudy water appears. – It is a measure of how much light passes through the water caused by light scattering solid particles. Do you think that if turbidity is low (water is clearer) that it is automatically healthier?
Total Coliform Bacteria Coliform bacteria is generally nonpathogenic and lives throughout the environment. Fecal coliform lives in the intestines of warm blooded animals and helps to digest food. The presence of fecal coliform indicates that pathogenic bacteria is present also. Testing for specific pathogenic bacteria takes a lot of time and may be difficult. – How might we solve this problem?
Water Quality For many of the indicators we will be testing for there are national standards determined by the Environmental Protection Agency. Water quality standards are based on the use. – Drinking water, recreation, and fishing each have different standards. Do you think there is a magic formula that creates high quality water?