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
- 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