11.3 Water Pollution: Sources, Effects, and Control Measures

Water pollution is a major environmental issue with diverse sources and far-reaching impacts. From agricultural runoff to industrial discharges, pollutants enter our water bodies, causing ecological damage and health risks. Understanding these sources is crucial for developing effective control measures.

The effects of water pollution are wide-ranging, impacting both ecosystems and human health. Eutrophication, bioaccumulation, and waterborne diseases are just a few consequences. Regulations like the Clean Water Act and innovative technologies play key roles in addressing this complex problem.

Sources of Water Pollution

Point and Nonpoint Sources

Top images from around the web for Point and Nonpoint Sources

• 

  Nonpoint source pollution - Wikipedia View original

  Is this image relevant?

• 

  7.3 Water Pollution – Environmental Issues View original

  Is this image relevant?

• 

  sources of pollution View original

  Is this image relevant?

• 

  Nonpoint source pollution - Wikipedia View original

  Is this image relevant?

• 

  7.3 Water Pollution – Environmental Issues View original

  Is this image relevant?

1 of 3

Top images from around the web for Point and Nonpoint Sources

• 

  Nonpoint source pollution - Wikipedia View original

  Is this image relevant?

• 

  7.3 Water Pollution – Environmental Issues View original

  Is this image relevant?

• 

  sources of pollution View original

  Is this image relevant?

• 

  Nonpoint source pollution - Wikipedia View original

  Is this image relevant?

• 

  7.3 Water Pollution – Environmental Issues View original

  Is this image relevant?

1 of 3

• Point sources of water pollution are single, identifiable sources such as wastewater treatment plants, industrial facilities, or oil spills
• Nonpoint sources are diffuse and harder to identify, such as agricultural runoff or urban stormwater

Agricultural and Industrial Pollution

• Agricultural runoff can contain pesticides, fertilizers, and animal waste that contribute to water pollution
  • Eutrophication is the process by which excess nutrients from agricultural runoff lead to algal blooms and oxygen depletion in water bodies (Gulf of Mexico dead zone)
• Industrial discharges can contain toxic chemicals, heavy metals, and other pollutants that harm aquatic ecosystems and human health
  • Examples include mercury from coal-fired power plants and PCBs from electrical equipment (Hudson River PCB contamination)

Sewage, Stormwater, and Marine Debris

• Sewage and wastewater from households and businesses can contain pathogens, nutrients, and chemicals that pollute water bodies if not properly treated
  • Combined sewer overflows during heavy rainfall events can release untreated sewage into waterways (New York City combined sewer system)
• Urban stormwater runoff can pick up pollutants such as oil, grease, heavy metals, and litter from impervious surfaces and transport them to nearby water bodies
  • Stormwater management practices aim to reduce these impacts (bioretention systems, permeable pavement)
• Marine debris, particularly plastic waste, can harm aquatic life through ingestion or entanglement and can also accumulate toxic chemicals
  • Microplastics are small plastic particles that can enter the food chain and potentially impact human health (Great Pacific Garbage Patch)

Impacts of Water Pollution

Ecological Effects

• Eutrophication caused by excess nutrients can lead to algal blooms, oxygen depletion, and fish kills in aquatic ecosystems
  • Harmful algal blooms can also produce toxins that affect human health and wildlife (red tides, cyanobacteria blooms)
• Bioaccumulation is the process by which pollutants, such as mercury or PCBs, accumulate in the tissues of organisms and become more concentrated at higher trophic levels in the food chain
  • This can lead to health risks for humans and wildlife that consume contaminated fish or shellfish (Minamata disease from mercury poisoning)
• Endocrine-disrupting chemicals, such as certain pesticides and pharmaceuticals, can interfere with hormone systems in wildlife and potentially impact reproductive success and development
  • Examples include feminization of fish exposed to estrogenic compounds and reproductive disorders in alligators exposed to DDT

Human Health Impacts

• Waterborne pathogens, such as bacteria, viruses, and protozoa, can cause gastrointestinal illnesses in humans through exposure to contaminated drinking water or recreational waters
  • Examples include E. coli, Giardia, and Cryptosporidium outbreaks (Milwaukee Cryptosporidium outbreak)
• Heavy metals, such as lead and cadmium, can have neurotoxic effects on humans and wildlife, particularly in developing organisms
  • Exposure can occur through drinking water or the consumption of contaminated fish (Flint, Michigan lead water crisis)
• Persistent organic pollutants (POPs), such as PCBs and DDT, are long-lasting chemicals that can accumulate in the environment and have toxic effects on wildlife and human health, including cancer and reproductive disorders
  • Examples include increased cancer rates in communities near contaminated sites and reproductive failures in birds of prey exposed to DDT

Water Quality Regulations

U.S. Federal Laws

• The Clean Water Act (CWA) is the primary federal law in the United States that regulates water pollution
  • It establishes the basic structure for regulating discharges of pollutants into waters of the United States and setting water quality standards
  • The National Pollutant Discharge Elimination System (NPDES) permit program under the CWA controls point source discharges from industrial facilities and wastewater treatment plants
  • The CWA also requires states to establish water quality standards for water bodies and develop Total Maximum Daily Loads (TMDLs) for impaired waters to guide pollution reduction efforts
• The Safe Drinking Water Act (SDWA) is another key federal law that protects public drinking water supplies in the United States
  • It sets standards for drinking water quality and requires regular testing and monitoring of public water systems

International Frameworks and Initiatives

• The European Union's Water Framework Directive (WFD) is a comprehensive approach to water protection that aims to achieve good status for all water bodies in the EU
  • It requires member states to develop river basin management plans and implement measures to reduce pollution and improve water quality
• International treaties and agreements, such as the Stockholm Convention on Persistent Organic Pollutants and the Minamata Convention on Mercury, aim to reduce the global production, use, and release of certain pollutants that can impact water quality
• Voluntary programs and industry initiatives, such as the International Organization for Standardization (ISO) 14001 environmental management standard, can also play a role in promoting best practices for water pollution prevention and control

Water Pollution Control Technologies

Wastewater Treatment

• Wastewater treatment plants use a combination of physical, chemical, and biological processes to remove pollutants from sewage and industrial wastewater before discharge into receiving waters
  • Primary treatment involves physical processes such as screening and sedimentation to remove solid materials
  • Secondary treatment uses biological processes, such as activated sludge or trickling filters, to remove dissolved organic matter and nutrients
  • Advanced or tertiary treatment can include processes such as filtration, disinfection, or nutrient removal to further improve effluent quality (reverse osmosis, UV disinfection)

Stormwater Management and Natural Systems

• Green infrastructure and low impact development (LID) practices, such as permeable pavement, bioretention systems, and green roofs, can help manage urban stormwater runoff and reduce pollutant loads to water bodies
• Constructed wetlands and treatment wetlands can be designed to remove pollutants from wastewater, stormwater, or agricultural runoff through natural processes such as filtration, sedimentation, and biological uptake
  • Examples include the Arcata Marsh and Wildlife Sanctuary in California and the Wakodahatchee Wetlands in Florida
• Phytoremediation is the use of plants to remove, degrade, or contain pollutants in soil, groundwater, or surface water
  • Different plant species can be selected based on their ability to accumulate or degrade specific pollutants (sunflowers for extracting lead from soil)

Advanced Treatment Technologies

• Membrane filtration technologies, such as reverse osmosis and nanofiltration, can effectively remove a wide range of pollutants, including dissolved salts, metals, and organic compounds, from water sources
  • These technologies are commonly used in desalination plants and advanced water treatment facilities
• Advanced oxidation processes, such as ozonation and UV/hydrogen peroxide treatment, can degrade recalcitrant organic pollutants and disinfect water through the generation of highly reactive hydroxyl radicals
  • These processes are effective for treating contaminants such as pharmaceuticals, pesticides, and industrial chemicals
• The effectiveness of water pollution control technologies can be influenced by factors such as the type and concentration of pollutants, the design and operation of the treatment system, and the site-specific conditions
  • Regular monitoring and maintenance are important to ensure the long-term performance of these technologies