Water Pollution and Quality Measurement

Water Pollution

• Water is the only molecule present in all states of matter on Earth.
• The Hydrologic cycle describes water movement between reservoirs locally and globally.
• Evaporation, Condensation, Precipitation, Infiltration, Groundwater flow, Transpiration, and Overland flow are key processes in the Hydrologic cycle.
• Earth's water is mostly ocean water (97%), with only 3% freshwater.
• Most freshwater is stored in ice caps and glaciers.
• 1.2 Billion people lack access to clean drinking water.
• Water pollution leads to premature deaths, with 5 million deaths annually from waterborne diseases, including 1.5 million from diarrhea.
• 1.6 million people in North America experience illness from infectious agents in food and water.

Water Quality Measurement

• Physical Parameters: Temperature, Suspended solids, Odor
• Chemical Parameters: pH, Nutrients, Metals, Pesticides, Herbicides
• Biological Parameters: Fish, Bacteria, Algae

Dissolved Oxygen

• Important for aquatic ecosystems, fish survival, and odor control.
• Low dissolved oxygen can lead to reduced fish reproduction, suffocation, and death.
• Bacterial degradation of organic matter consumes dissolved oxygen.
• Biochemical Oxygen Demand (BOD): Measures oxygen required to oxidize organic matter.
• BOD levels indicate water pollution:
  • 1-2 ppm: Very good
  • 3-5 ppm: Moderately clean
  • 6-9 ppm: Somewhat polluted
  • 100+ ppm: Contains organic waste

Salinity

• Measures salt content in soil or water.
• High salinity affects agriculture, infrastructure, the economy, and environment through:
  • Machinery corrosion
  • Vegetation health

Water Pollutants

• Infectious Agents (Pathogens): Bacteria, Parasites, Human waste
• Oxygen Demanding Wastes: Plant debris, Sewage
• Plant Nutrients: Nitrate, Sewage and animal wastes
• Organic Chemicals: Oil, Gasoline, Industry, Farms
• Inorganic Chemicals: Acids, Bases, Salts, Industry
• Sediments: Soil, Land erosion from farms and urban streets
• Heavy Metals: Lead, Unlined landfills
• Thermal: Excessive heat, electric power plants

Major Sources of Water Pollution

• Agriculture
• Industries
• Mining

Point Sources of Water Pollution

• Discharge pollutants at specific locations
• Easy to identify, monitor, and regulate

Nonpoint Sources of Water Pollution

• Broad, diffuse areas
• Pollutants are washed into surface waters by rainfall or snowmelt

Pollution of Freshwater Streams

• Streams and rivers can cleanse themselves of biodegradable pollutants if not overloaded.
• Cleaning processes include dilution and bacterial biodegradation, which require time and can be overwhelmed.
• Oxygen sag curve illustrates the depletion and recovery of dissolved oxygen in a stream.

Steps toward Reduction of Stream Pollution

• Developed countries have significantly reduced point source pollution.
• Developing countries face a growing problem with untreated sewage and industrial waste discharge.
• Poverty and religious beliefs can hinder implementation of water pollution laws and treatment plants.

Pollution of Freshwater Lakes and Reservoirs

• More vulnerable to pollution than streams due to slower water exchange.
• Cultural Eutrophication: Excessive nutrient enrichment from human sources.
• Oligotrophic Lake: Low nutrients, clear water.
• Cultural Eutrophication: Increased nitrates and phosphates from human activities.
• Prevention of Cultural Eutrophication: Waste treatment, soil conservation, phosphate limitations.
• Lake cleanup methods include weed removal, herbicides, and aeration.

Great Lakes Restoration Initiative (GLRI)

• 1.3 billion investment to reduce Great Lakes pollution.
• Focus on reducing pollution and preventing further contamination.

Pollution of Groundwater

• Contaminated with various chemicals.
• Primary source of drinking and irrigation water.
• Common pollutants: Fertilizers, Gasoline, Organic Solvents, Fracking.

Groundwater Pollution Solutions

• Substitute toxic chemicals
• Prevent toxic chemical leaks
• Use leak detectors
• Ban hazardous waste disposal
• Store hazardous liquids aboveground