I. Water Quality-I. Water Quality-OverviewOverview

D. Types of Water PollutionD. Types of Water Pollution

Objectives - students Objectives - students should:should:

Distinguish among major sources Distinguish among major sources and types of potential contaminants and types of potential contaminants of drinking and recreational waters.of drinking and recreational waters.

List and describe problems List and describe problems associated with contaminated associated with contaminated drinking water worldwide.drinking water worldwide.

Water Pollution:Water Pollution: Water pollutants can be divided into Water pollutants can be divided into

several categories:several categories:– Disease-causing microorganisms.Disease-causing microorganisms.– Oxygen-demanding wastes.Oxygen-demanding wastes.– Inorganic chemicals.Inorganic chemicals.– Organic chemicals.Organic chemicals.– Sediments.Sediments.– Alien speciesAlien species..

Disease-causing Disease-causing microorganisms:microorganisms:

A variety of microorganisms found in A variety of microorganisms found in water are capable of causing disease in water are capable of causing disease in humans (humans (pathogenspathogens to be discussed later) to be discussed later)– The primary source of these microorganisms The primary source of these microorganisms

is is animal and human fecal contamination animal and human fecal contamination (e.g., feedlot runoff, natural animal wastes, or (e.g., feedlot runoff, natural animal wastes, or sewage contamination, combined sewer sewage contamination, combined sewer overflow).overflow).

Combined Sewer Overflow

Oxygen-demanding Oxygen-demanding wastes:wastes:

Organic matter in water may be used as a Organic matter in water may be used as a nutrient source by nutrient source by aerobicaerobic microorganisms microorganisms and deplete oxygen in water. and deplete oxygen in water.– Biochemical Oxygen Demand (BOD) Biochemical Oxygen Demand (BOD) measures measures

changes in oxygen over time due to changes in oxygen over time due to microbesmicrobes..– Chemical Oxygen Demand (COD) Chemical Oxygen Demand (COD) measures measures

the oxidation of organic compounds by a the oxidation of organic compounds by a chemicalchemical oxidant. oxidant.

Inorganic chemicals:Inorganic chemicals: Inorganic chemicals like acids, salts, Inorganic chemicals like acids, salts,

and toxic metals can make water unfit and toxic metals can make water unfit for drinking, decrease crop production, for drinking, decrease crop production, or corrode metal machinery.or corrode metal machinery.

Inorganic plant nutrients like nitrates Inorganic plant nutrients like nitrates and phosphates can cause and phosphates can cause eutrophicationeutrophication, and oxygen depletion , and oxygen depletion of water (e.g., in lakes).of water (e.g., in lakes).

Organic chemicals:Organic chemicals: A variety of carbon-containing A variety of carbon-containing

chemicals can threaten human or chemicals can threaten human or aquatic life.aquatic life.– Volatile Organic Compounds Volatile Organic Compounds (VOC’s), (VOC’s),

like oil, gasoline, cleaning solvents, etc.like oil, gasoline, cleaning solvents, etc.– pesticides, plastics, other pesticides, plastics, other Synthetic Synthetic

Organic CompoundsOrganic Compounds (SOC’s), (SOC’s),

Sediments or suspended Sediments or suspended matter:matter:

Insoluble particles of soil and other solids Insoluble particles of soil and other solids become suspended in water become suspended in water (primarily due to erosion).(primarily due to erosion).– Suspended solids Suspended solids can reduce photosynthesis can reduce photosynthesis

in plants, and carry other contaminants, in plants, and carry other contaminants, – Settleable solids Settleable solids (sediment) can destroy (sediment) can destroy

feeding and spawning grounds of fish, and feeding and spawning grounds of fish, and clog lakes, harbors, streams, etc.clog lakes, harbors, streams, etc.

Alien species:Alien species:

Artificially introduced species (whether Artificially introduced species (whether accidentally or intentionally accidentally or intentionally introduced), can outcompete native introduced), can outcompete native species.species.

This reduces the This reduces the biodiversitybiodiversity of the of the aquatic system and can cause severe aquatic system and can cause severe economic losses.economic losses.

Types of water Types of water pollution:pollution:

Sources of pollution can be Sources of pollution can be pointpoint (PS) or (PS) or nonpointnonpoint (NPS). (NPS).– Point sources discharge pollutants at Point sources discharge pollutants at

specific locations and are specific locations and are easiereasier to to locate, regulate, and remediate.locate, regulate, and remediate.

– Nonpoint sources cannot be traced to a Nonpoint sources cannot be traced to a single discharge point, and are single discharge point, and are difficultdifficult to monitor, regulate, and remediate.to monitor, regulate, and remediate.

River and stream River and stream pollution:pollution:

Flowing water recovers relatively quickly Flowing water recovers relatively quickly from oxygen-demanding wastes due to from oxygen-demanding wastes due to microbial action, dilution, and aeration.microbial action, dilution, and aeration.

BOD rises quickly, but decreases BOD rises quickly, but decreases downstream from the discharge point.downstream from the discharge point.

Water quality in 60% of stream length in Water quality in 60% of stream length in the U.S. has never been measured.the U.S. has never been measured.

Lake pollution:Lake pollution: Lakes are more susceptible to contam-Lakes are more susceptible to contam-

ination because of slower flow rates.ination because of slower flow rates. StratificationStratification (layering) of lakes results (layering) of lakes results

in a lack of mixing.in a lack of mixing. Eutrophication.Eutrophication.– OligotrophicOligotrophic– MesotrophicMesotrophic– EutrophicEutrophic

Groundwater pollution:Groundwater pollution:

Groundwater flow generally slow & non-Groundwater flow generally slow & non-turbulent, so contaminants are not turbulent, so contaminants are not degraded quickly.degraded quickly.

50% of U.S. groundwater systems are 50% of U.S. groundwater systems are contaminated with organic chemicals.contaminated with organic chemicals.

25 to 75% of groundwater contaminated.25 to 75% of groundwater contaminated. There are an estimated 1 million leaking There are an estimated 1 million leaking

underground storage tanks in the U.S.underground storage tanks in the U.S.

Ocean pollution:Ocean pollution: Ocean is the ultimate sink for all water.Ocean is the ultimate sink for all water. Coastal Coastal estuarineestuarine areas (where rivers areas (where rivers

meet the sea) are especially vulnerable meet the sea) are especially vulnerable to runoff pollution.to runoff pollution.

The Chesapeake Bay is an example of The Chesapeake Bay is an example of how an estuarine area can be damaged how an estuarine area can be damaged by pollution from inland runoff.by pollution from inland runoff.

Contaminated drinking Contaminated drinking water:water:

The World Health Organization (WHO) estimates The World Health Organization (WHO) estimates that 1.5 billion people lack safe drinking water that 1.5 billion people lack safe drinking water supplies.supplies.

1.7 billion people lack adequate sanitation 1.7 billion people lack adequate sanitation facilities.facilities.

5 million people die each year from water- borne 5 million people die each year from water- borne disease, primarily transmitted by oral-fecal route.disease, primarily transmitted by oral-fecal route.

Most of the 13,700 people who die each day from Most of the 13,700 people who die each day from waterborne diseases prevent-able by proper waterborne diseases prevent-able by proper sanitation and clean drinking water are children sanitation and clean drinking water are children under age 5.under age 5.

Solutions to water Solutions to water pollution:pollution:

PreventionPrevention of contamination is a more of contamination is a more economical and sensible approach:economical and sensible approach:– Control disposal of hazardous waste.Control disposal of hazardous waste.– Limit application of pesticides, fertilizers.Limit application of pesticides, fertilizers.– Above-ground storage of chemicals, etc.Above-ground storage of chemicals, etc.

Physical, chemical, and biological Physical, chemical, and biological treatments treatments can reduce water pollution can reduce water pollution (e.g., in natural and municipal systems).(e.g., in natural and municipal systems).

Summary:Summary:

Sources of water pollution include Sources of water pollution include chemical, physical, and biological chemical, physical, and biological contaminants.contaminants.

Contaminated drinking and bathing Contaminated drinking and bathing waters may transmit infectious waters may transmit infectious diseases through diseases through pathogenspathogens. .