Water Purity and Pollution

Water Purity and Pollution 2016-03-02T16:33:56+00:00

Water Purity

  • Difficult to define
  • Means different things to different people
  • Water is a solvent
    • Takes into solution some of almost everything it touches
  • Water is most pure when it evaporates, but
    • Picks up matter from the atmosphere when falling to the ground
    • On the ground, dissolves and carries some of almost everything it touches
    • Naturally occurring impurities may give it bad taste, color, or odor, or cloudy appearance (turbidity)
  • Surface water
    • Contains more suspended solids, but less mineral and iron than groundwater
      • makes surface water softer than groundwater
    • Easily contaminated, but relatively easy to purify
  • Groundwater
    • Can be contaminated from surface water
    • Cleaning can be difficult and time consuming
    • Pollutants introduced by people include pathogens (bacteria and viruses), heavy metals, pesticides (mostly organic), and other organic chemicals from manufacturing, industry, and agriculture
    • In Alabama,
      • Bacteria and nitrates are the greatest pollution threat to rural groundwater
      • Eroded sediments and animal wastes are the major sources of agricultural pollution, particularly from poultry farms
      • Most common source of pollution in urban areas are chemicals leaking from pipelines and tanks, concentrated chemical spills, and leaching waters from landfills and buried wastes.

Scope of Water Pollution

  • Pollution
    • Occurs when the natural quality of water is degraded through the activity of people
    • Most occurs when the natural capacity of water to purify itself to a certain standard in reference to a particular pollutant and particular use is exceeded
  • Sources of pollution
    • Point source
      • Enters water from a specific point through a pipe, ditch, or culvert
      • Common sources are factories and municipal sewage treatment plants
    • Nonpoint Source
      • A major problem (at least half of all pollution)
      • Difficult to quantify and control
      • Generally regarded as runoff and sedimentation
      • Common sources
        • Urban stormwater runoff
        • Manufacturing and industrial sites
        • Streets and parking areas
        • Construction runoff
        • Mines
        • Logging and timber cutting
        • Leaching water from septic tanks, landfills, or waste disposal areas
        • Leaking chemical storage tanks and pipelines
      • Major types
        • Sediment
        • Plant nutrients
        • Toxic chemicals
        • Animal wastes or organic materials
      • Factors influencing NPS
        • Rainfall
        • Vegetation
        • Soil erodibility
        • Topography
        • Human alteration of physical features

Source: Water Quality and Pollution Handbook, Circular ANR-970, Alabama Cooperative Extension Service, Auburn University, Alabama