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