PP

Chapter 20: Water Pollution

20.1 What Are the Causes and Effects of Water Pollution?

Water Pollution

  • Water pollution: Change in water quality that can harm organisms or make water unfit for human uses
    • Contamination with chemicals
    • Excessive heat
  • Nonpoint sources: Broad, diffuse areas. they are hard to identify and control as well as expensive to clean
    • Runoff
  • Point sources: Located at specific places. Easy to identify, monitor, and regulate
    • Sewage

Leading Causes of Water Pollution

  • Agriculture activities
    • Sediment eroded from the lands
    • Fertilizers and pesticides
    • Bacteria from livestock and food processing wastes
  • Industrial facilities
    • Release inorganic & organic chemicals
    • EX→ Coal ash (waste from burning coal) – stored in ponds (leak) & dumped into lakes & rivers
  • Mining
    • Surface mining disturbs the land-- creates soil erosion & runoff of toxic chemicals

Major Water Pollutants Have Harmful Effects

  • Infectious disease organisms: contaminated drinking water
  • The World Health Organization (WHO)
    • 1.6 million people die every year, mostly under the age of 5

Major Water Pollutants and Their Sources

  • Infectious agents (pathogens)
    • Effects→causes diseases
    • Examples→ bacteria, viruses, protozoa, parasites
    • Sources→ include human and animal wastes
  • Oxygen demanding wastes
    • Effects→ deplete dissolved oxygen needed by aquatic species
    • Examples→ biodegradable animal wastes and plant debris
    • Sources→ sewage, animal feedlots, food processing facilities, paper mills
  • Plant nutrients
    • Effects→ cause excessive growth of algae and other species
    • Examples→ Nitrates and phosphates
    • Sources→ sewage, animal wastes, inorganic fertilizers
  • Organic chemicals
    • Effects→ Add toxins to aquatic systems
    • Examples→ oil, gasoline, plastics, pesticides, fertilizers, cleaning solvents
    • Sources→ Industry, farms, households, mining sites, runoff from streets and parking lots
  • Inorganic chemicals
    • Effects→ Add toxins to aquatic systems
    • Examples→ acids, bases, salts, metal compounds
    • Sources→ Industry, households, mining sites, runoff from streets, and parking lots
  • Sediments
    • Effects→ disrupt photosynthesis, food webs, and other process
    • Examples→ soil, silt
    • Sources→ Land erosion from farms and construction and mining sites
  • Heavy metals
    • Effects→ cause cancer, disrupt immune and endocrine systems
    • Examples→ lead, mercury, arsenic
    • Sources→ unlined landfills, household chemicals, mining refuse, industrial discharge
  • Thermal
    • Effects→ make some species vulnerable to disease
    • Examples→ heat
    • Sources→ Electric power and industrial plants

Common Diseases Transmitted to Humans through Contaminated Drinking Water

  • Bacteria
    • Typhoid fever: diarrhea, severe vomiting, enlarged spleen, inflamed intestine; often fatal if untreated
    • Chlorea: diarrhea, severe vomiting, dehydration; often fatal if untreated
    • Bacterial dysentery: diarrhea, bleeding; rarely fatal except in infants without proper treatment
    • Enteritis: severe stomach pain, nausea, vomiting; rarely fatal
  • Viruses
    • Infectious hepatitis (type B): Fever, severe headache, loss of appetite, abdominal pain, jaundice, enlarged liver; rarely fatal but may cause permanent liver damage
    • Poliomyelitis: Fever diarrhea, backache, sore throat, aches in limbs; can infect the spinal cord and cause paralysis and muscle weakness
  • Parasitic protozoa
    • Amoebic dysentery: Severe diarrhea, headache, abdominal pain, chills, fever; if not treated can cause a liver abscess, bowel perforation, and death
    • Giardiasis: Diarrhea, abdominal cramps, flatulence, belching, fatigue
    • Cryptosporidium: Severe diarrhea, cramps for up to 3 weeks, and possible death for people with weakened immune systems
  • Parasitic worms
    • Schistosomiasis: Abdominal pain, skin rash, anemia, chronic fatigue, and chronic general ill health
    • Ancylostomiasis: Severe anemia and possible symptoms of bronchial infection

20.2 What Are the Major Water Pollution Problems in Streams and Lakes?

Stream Pollution in More Developed Countries

  • The 1970s→ Water pollution control laws
  • Successful water clean-up stories
    • Ohio Cuyahoga River, U.S.
    • Thames River, Great Britain
  • Contamination of toxic inorganic and organic chemicals by industries and mines

Too Little Mixing and Low Water Flow Makes Lakes Vulnerable to Water Pollution

  • Less effective at diluting pollutants than streams
    • Stratified layers: Little vertical mixing
    • Little to no water flow
    • Can take up to 100 years to change the water in a lake
    • Biological magnification of pollutants

Eutrophication

  • Eutrophication: Natural enrichment of a shallow lake, estuary, or slow-moving stream. Caused by runoff into the lake that contains nitrates and phosphates
  • Oligotrophic lake: Low nutrients, clear water
  • Cultural eutrophication: Nitrates and phosphates from human sources. Farms, feedlots, streets, parking lots. Fertilized lawns, mining sites, sewage plants

Revisiting Lake Washington and Puget Sound

  • Severe water pollution can be reversed
  • Citizen action combined with scientific research
  • Good solutions may not work forever
    • Wastewater treatment plant effluents sent into Puget Sound

20.3 Pollution Problems Affecting Groundwater, Other Water Sources

Ground Water Cannot Cleanse Itself Very Well

  • Common pollutants
    • Fertilizers and pesticides
    • Gasoline
    • Organic solvents
  • Pollutants dispersed in a widening plume
  • Slower chemical reactions in groundwater due to
    • Slow flow
    • contaminants not diluted
    • Less dissolved oxygen
    • Fewer decomposing bacteria
    • Low temperatures

Groundwater Pollution Is a Serious Hidden Threat in Some Areas

  • China→ 90% of urban aquifers are contaminated or overexploited
  • U.S.→ FDA reports of toxins found in many aquifers •
  • Threats
    • Gasoline, oil
    • Nitrate ions
    • Arsenic
  • Prevent contamination of groundwater
  • Cleanup can be very expensive and time-consuming
    • PUR: chlorine and iron sulfate powder

Using Laws to Protect Drinking Water Quality

  • 1974 U.S. Safe Drinking Water Act: Sets maximum contaminant levels for any pollutants that affect human health
  • Health scientists: strengthen the law
  • Water-polluting companies: weaken the law

20.4 What Are the Major Water Pollution Problems Affecting Oceans?

Ocean Pollution Is a Growing and Poorly Understood Problem

  • 2006→ State of the Marine Environment
    • 80% of marine pollution originates on land
    • Sewage
    • Coastal areas most affected
  • Deeper ocean waters
    • Dilution
    • Dispersion
    • Degradation
  • U.S. coastal waters
    • Raw sewage
    • Sewage and agricultural runoff: NO3 and PO4 3-
    • Harmful algal blooms
    • Oxygen-depleted zones
  • The huge mass of plastic in the North Pacific Ocean

Ocean Pollution from Oil

  • Crude and refined petroleum: Highly disruptive pollutants
  • The largest source of ocean oil pollution: Urban and industrial runoff from land
  • 1989: Exxon Valdez, oil tanker
  • 2010: BP explosion in the Gulf of Mexico
  • Volatile organic hydrocarbons: Kill many aquatic organisms
  • Tar-like globs on the ocean’s surface
    • Coat animals
  • Heavy oil components sink
    • Affect the bottom dwellers

20.5 How Can We Best Deal with Water Pollution?

Reducing Surface Water Pollution from Nonpoint Sources

  • Agriculture
    • Reduce erosion
    • Reduce the number of fertilizers
    • Plant buffer zones of vegetation
    • Use organic farming techniques
    • Use pesticides prudently
    • Control runoff
    • Tougher pollution regulations for livestock operations
    • Deal better with animal waste

Sewage Treatment Reduces Water Pollution

  • Wastewater or sewage treatment plants
    • Primary sewage treatment: Physical process
    • Secondary sewage treatment: Biological process with bacteria
    • Tertiary or advanced sewage treatment: Special filtering processes and bleaching, chlorination

We Can Improve Conventional Sewage Treatment

  • Peter Montague: environmental scientist
    • Remove toxic wastes before the water goes to the municipal sewage treatment plants
    • Reduce or eliminate the use and waste of toxic chemicals
    • Use composting toilet systems
    • Wetland-based sewage treatment systems

There Are Sustainable Ways to Reduce and Prevent Water Pollution

  • Developed countries: Bottom-up political pressure to pass laws
  • Developing countries: Little has been done to reduce water pollution

Solutions: Methods for Preventing and Reducing Water Pollution

  • Prevent groundwater contamination
  • Reduce nonpoint runoff
  • Reuse treated wastewater for drinking and irrigation
  • Find substitutes for toxic pollutants
  • Work with nature to treat sewage
  • Practice the three R’s of resource use
  • Reduce air pollution
  • Reduce poverty
  • Slow population growth

Reducing Water Pollution

  • Fertilize garden and yard plants with manure or compost instead of commercial inorganic fertilizer
  • Minimize your use of pesticides, especially near bodies of water
  • Prevent yard wastes from entering storm drains
  • Do not use water fresheners in the toilet
  • Do not flush unwanted medicines down the toilet
  • Do not pour pesticides, paints, solvents, oil, antifreeze, or other products containing harmful chemicals down the drain or onto the ground