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

\