chapter 9 Water Quality and Environmental Health

Comprehensive vocabulary flashcards covering hydrological concepts, water treatment methodologies, waterborne infectious agents, chemical disinfection by-products, and regulatory frameworks from Chapter 9 Water Quality.

Hydrology

The field of water science that studies the occurrence, distribution, movement, and properties of water on earth and its relationship with the environment.

Hydrological (Water) Cycle

The natural water cycle, driven by the sun, in which water evaporates from oceans and other water bodies, accumulates as water vapor in clouds, and returns to oceans and land as precipitation.

Aquifer

A layer or section of earth or rock that contains freshwater, known as groundwater (any water stored naturally underground or flowing through rock or soil, supplying springs and wells).

Surface Water

All water open to the atmosphere on the surface of the earth (such as lakes, rivers, reservoirs, ponds, streams, and oceans), as distinguished from subsurface or groundwater.

Groundwater

Freshwater that is stored naturally underground and contained in the interconnected pore spaces of an aquifer.

Finished Water

Water (such as drinking water) delivered to a distribution system after undergoing treatment, if any.

Source Water

Untreated water (i.e., raw water) utilized to produce residential drinking water.

Nonrenewable Water

Water in aquifers and natural reservoirs that is not replenished by the hydrological cycle or recharges so slowly over centuries that human extraction causes depletion (e.g., fossil aquifers).

Renewable Water

Freshwater that is continuously replenished by the hydrological cycle within reasonable time limits, such as water in rivers, lakes, or reservoirs filled by precipitation or runoff.

Water Scarcity

A condition occurring when a country's annual supply of renewable freshwater drops below $1,000\,\text{m}^3$ ($35,000\,\text{ft}^3$) per person, causing chronic shortages that hinder economic development.

Water Stress

A condition occurring when a country's annual supply of renewable freshwater is between $1,000\,\text{m}^3$ and $1,700\,\text{m}^3$ ($35,000\,\text{ft}^3$ and $60,000\,\text{ft}^3$) per person, leading to temporary or limited water shortages.

Water Withdrawal

The removal of freshwater for human use from any natural source or reservoir, such as a lake, river, or aquifer.

Wetlands

Ecosystems saturated or covered by water including swamps, bogs, marshes, mires, lagoons, and floodplains, covering an estimated total global area of approximately $2,900,000\,\text{km}^2$.

Coagulation

The first major step of drinking water treatment where a chemical coagulating agent, usually aluminum sulfate, is added to untreated water to aggregate and remove suspended material.

Sedimentation

The water treatment stage following coagulation where water rests in tanks to allow heavy aggregated particles to settle to the bottom for physical removal.

Filtration

The drinking water treatment stage where water passes through progressively finer layers of sand and a layer of activated charcoal to capture smaller residual particles and impurities.

Disinfection

The final stage of drinking water treatment where antimicrobial agents such as chlorine are added to eliminate pathogenic microorganisms prior to distribution.

Water Treatment Process

The four-step sequence utilized by municipal treatment plants to purify water for residential consumption: coagulation, sedimentation, filtration, and disinfection.

Water Fluoridation

The controlled addition of fluoride to public drinking water supplies to an optimal level of $0.7$ to $1.2\,\text{ppm}$ to prevent dental caries (tooth decay) while minimizing fluorosis.

Dr. Frederick McKay

The early 20th-century dentist who investigated 'mottled enamel' ('Colorado brown stain') and established that naturally occurring fluoride in drinking water prevents dental caries.

Groundwater under the Direct Influence of Surface Water

Any water beneath the surface defined by the US EPA as containing insects, macroorganisms, algae, large-diameter pathogens (e.g., Giardia, Cryptosporidium), or rapid shifts in turbidity, temperature, pH, or conductivity matching surface water.

Oocyst

A hardy, thick-walled environmental survival structure formed by certain parasitic protozoa that exhibits high resistance to environmental factors and standard water chlorination.

Sporozoite

The infectious life cycle stage of a protozoan parasite released from excysted oocysts in the host organism to penetrate epithelial cells and reproduce.

Cryptosporidiosis

A waterborne diarrheal illness caused by the protozoal parasite Cryptosporidium parvum, transmitted via chlorination-resistant oocysts and causing watery diarrhea, abdominal cramping, and fever.

Amebiasis

A waterborne disease caused by the protozoan Entamoeba histolytica, transmitted by fecal-oral cyst ingestion, which can produce dysentery, colitis, and extraintestinal liver or lung abscesses.

Giardiasis

A waterborne gastrointestinal infection caused by the flagellated protozoan Giardia lamblia, whose cysts persist in cold water and cause acute or chronic diarrhea.

Cyclosporiasis

A waterborne diarrheal disease caused by the protozoan Cyclospora cayetanensis, contracted by ingesting food or water contaminated with sporulated oocysts.

Typhoid Fever

An acute bacterial infection caused by Salmonella enterica serogroup Typhi, transmitted through fecally contaminated water and food, characterized by high fever, chills, abdominal pain, and a 'rose spots' rash.

Escherichia coli O157:H7

A pathogenic strain of E. coli found in animal and human intestines that causes severe, often bloody diarrhea and abdominal cramps, historically linked to unchlorinated municipal water supplies.

Cholera

An acute bacterial waterborne disease caused by Vibrio cholerae that causes profuse watery diarrhea and vomiting, carrying a case fatality rate up to $50\%$ when untreated.

Norovirus

A highly resilient viral pathogen transmitted through contaminated food, water, or person-to-person contact that causes viral gastroenteritis lasting $24$ to $72\,\text{hours}$.

Viral Hepatitis (Hepatitis A and E)

Liver-infecting viral conditions spread via the fecal-oral route and the ingestion of contaminated drinking water, ice, or uncooked produce in areas with inadequate sanitation.

Guinea Worm Disease (Dracunculiasis)

A disease caused by the nematode Dracunculus medinensis, contracted by drinking unfiltered water with infected copepods, wherein female worms ($2$ to $3\,\text{feet}$ long) emerge through painful foot blisters.

Legionellosis

A bacterial infection caused by Legionella pneumophila, transmitted by inhaling aerosolized contaminated water from air conditioning cooling towers, whirlpool spas, or domestic plumbing, presenting as Legionnaires' disease or Pontiac fever.

Pontiac Fever

A milder, non-pneumonic clinical form of legionellosis caused by Legionella pneumophila.

Disinfection By-Products (DBPs)

Unintended secondary chemical contaminants that form in treated drinking water when chemical disinfectants like chlorine react with naturally occurring organic matter.

Trihalomethanes (THMs)

A prevalent group of disinfection by-products formed when chlorine interacts with organic materials in water, consisting of a central carbon atom bound to one hydrogen and three halogen atoms.

Sewage Epidemiology

The scientific surveillance of excreted substances—such as pathogens, pharmaceuticals, illicit drugs, and chemical biomarkers—in municipal sewage to evaluate community health status and exposure.

Clean Water Act (1972)

A landmark United States environmental law passed in 1972 establishing the legal framework for regulating pollutant discharges into waters of the United States and enforcing surface water quality standards.

Safe Drinking Water Act (1974)

United States federal legislation enacted in 1974 that authorizes the EPA to establish enforceable health-based water quality standards to protect public drinking water supplies from natural and anthropogenic contaminants.

Exxon Valdez Oil Spill

A massive environmental catastrophe occurring on March 24, 1989, when an oil tanker ran aground on Bligh Reef in Prince William Sound, Alaska, discharging approximately $10.9\,\text{million gallons}$ of crude oil.

Deepwater Horizon Oil Spill

The largest accidental marine oil spill in history, initiated on April 20, 2010, by an explosion and sinking of an offshore drilling platform in the Gulf of Mexico, releasing an estimated $4.2\,\text{million barrels}$ of crude oil.