Water Exam Review Notes

Hydrologic Cycle

  • Earth’s Water

    • Abundance of water covering the planet.

    • Water covers approximately 71% of Earth's surface.

  • Hydrologic Cycle Processes

    • Evaporation: Water is transformed from liquid to vapor.

    • Condensation: Occurs when rising air cools and forms clouds.

    • Precipitation: When water falls from clouds to the surface, driven by rising air.

  • Relative Humidity

    • Percentage of water vapor in the air compared to the maximum amount the air can hold at that temperature.

    • What happens after reaching 100%?: Leads to condensation and precipitation.

  • Rainshadow Deserts

    • Areas that receive little rainfall due to geographical features blocking moisture from reaching them.

  • Definitions of Key Terms

    • Relative Humidity: Measure of moisture in the air.

    • Groundwater: Water located beneath the earth's surface.

    • Water Table: Upper surface of the saturated zone of groundwater.

    • Aquifers: Geological formations that can store and transmit groundwater.

    • Surface Water: Includes rivers, streams, lakes, and ponds.

  • Subtropical Deserts

    • Found between 25-35 degrees North and South latitude.

Water as a Resource and Water Stewardship

  • Water Usage

    • Largest use of water worldwide is for agriculture.

    • In homes, water is mainly used for toilets, showers, and cooking.

  • Global Water Issues

    • 20% of the world population lacks access to safe drinking water, leading to many diseases.

    • Groundwater demand is rising, causing depletion with negative impacts such as:

    • Falling water tables

    • Diminishing surface waters

    • Land subsidence

    • Saltwater intrusion

  • Environmental Impact

    • Death of the Aral Sea was caused by extensive irrigation.

    • Estuaries: Areas where freshwater meets saltwater; example is San Francisco Bay, which faces increasing salinity.

  • Water Usage Statistics

    • Average water use for a US resident is about 80-100 gallons/day.

    • Hydrogen Bonding: Water’s ability to bond contributes to its unique properties, including its high specific heat.

    • Hadley Cell: Atmospheric circulation pattern that creates deserts.

    • Examples of consumptive water use include agriculture and industrial processes.

    • Dams serve as reservoirs but can adversely impact wetlands.

Water Pollution, Wastewater Management, and Eutrophication

  • Dead Zones (Hypoxic Waters)

    • Areas with low oxygen levels, creating dead zones, which are increasing globally.

  • Definitions

    • Pollution as defined by EPA: Contaminants that cause harm to the environment.

    • Point Source vs. Non-Point Source Pollutants: Point sources are identifiable, while non-point sources are diffuse.

    • Pathogens: Microorganisms causing diseases, e.g. cholera.

    • Dissolved Oxygen: A critical measure for aquatic health; affected by waste decomposition by anaerobic bacteria.

    • Fecal Coliform Tests: Used to assess water quality through the presence of coliform bacteria.

  • Components of Raw Sewage

    • Water constitutes 99% of raw sewage.

    • Categories: debris, particulate organics, colloidal and dissolved organics.

  • Sewage Treatment Process

    • Preliminary Treatment: Removal of large debris.

    • Primary Treatment: About 50-60% of solids are removed.

    • Secondary (Biological) Treatment: Further breakdown of organic matter; nutrients like nitrogen and phosphorus remain.

    • Activated Sludge Treatment: Microorganisms metabolize organic matter.

    • Final Disinfection in the US: Often uses chlorine gas for pathogens elimination.

  • Eutrophication

    • Excess nutrients (nitrogen and phosphorus) lead to algal blooms and oxygen depletion.

    • Distinction between cultural eutrophication (human-induced) and natural eutrophication.

    • Turbidity: Cloudiness of water caused by particulate matter.

    • Oligotrophic Waters: Nutrient-poor, clear waters.

  • Safe Drinking Water Standards

    • Governed by the Safe Drinking Water Act, ensuring access to safe drinking water.

Laboratory Practical Activities

  • Activity 1: Understanding of laboratory equipment for testing water quality (microscope parts, Secchi disk usage).

  • Activity 2: Testing for sewage contamination through fecal streptococci/coliform tests.

  • Activity 3: Collecting apparatus, examples of organisms like zooplankton and nekton, understanding of trophic levels.

  • Activity 4: Chemical water analysis including nitrate, phosphate, and dissolved oxygen levels, alongside percent saturation using oxygen saturation tables.