Types of Water PollutionTypes of Water Pollution

Sewage

Disease-causing agents

Sediment pollution

Inorganic plant and algal nutrients

Organic compounds

Inorganic chemicals

Thermal pollution

Types of Water PollutionTypes of Water Pollution

o Water pollution• Any physical or chemical change in

water that adversely affects the health of humans and other organisms

• Varies in magnitude by locationo Major water pollution issues

globally• Lack of disease-free water

SewageSewageo The release of wastewater from drains

or sewers (toilets, washing machines, showers,…), Includes human wastes, soaps, and detergents

SewageSewageCauses 2 serious environmental problems:

oEnrichment• Fertilization of a body of water by high levels of

plant and algal nutrients (nitrogen & phosphorus)

oIncrease in Biological Oxygen Demand (BOD)

• Amount of oxygen needed by microorganisms to decompose biological wastes

• As BOD increases Dissolve Oxygen (DO) decreases

• Leads to eutrophication

SewageSewage

Inorganic Plant and Algal Inorganic Plant and Algal NutrientsNutrients

o Chemical fertilizers such as nitrogen and phosphorus that stimulate the growth of plants and algae• Harmful in large concentrations

o Sources:• Human and animal wastes, plant residues,

atmospheric deposition, and fertilizer runoff

o Causes:• Enrichment, eutrophication, bad odors, and a

high BOD

Water Pollution from AgricultureWater Pollution from Agriculture

o nitrates and

phosphates from animal wastes and plants residues

o High BOD for decomposition

o Almost all streams and rivers are polluted with agricultural pesticides

Agriculture is leading source of water pollution in US

Water Pollution from Water Pollution from AgricultureAgriculture

EutrophicationEutrophication Eutrophication: the natural nutrient

enrichment of a shallow lake, estuary or slow moving stream, mostly from runoff of plant nutrients from the surrounding land.

Cultural or Artificial Eutrophication: human activities accelerate the input of plant nutrients (mostly nitrate- and phosphate- containing effluents) to a lake.

EutrophicEutrophic Lake Lakeo Slow-flowing stream, lake or estuary

enriched by inorganic plant and algal nutrients such as phosphorus

o Often due to fertilizer or sewage runoff

OligotrophicOligotrophic Lake LakeUnenriched, clear water that supports small populations of aquatic organisms

Cause/Effect of Cause/Effect of EutrophicationEutrophication fertilizers, sewage runoff...get into water enrichment occurs due to increase of

nutrients, ex. nitrogen and phosphorous effect – high photosynthetic productivity

(huge increase in algae and plants) algae and plants die and settle to bottom aerobic bacteria decompose the plant

matter and increase BOD (aka use up the oxygen)

aquatic life suffers

Cultural EutrophicationCultural Eutrophication

Because this gets into our water supply from runoff, etc., and is something that is not normally in the water, it is considered pollution.

85% of large lakes near major population centers in the U.S. have some degree of cultural eutrophication.

POLLUTION OF FRESHWATER POLLUTION OF FRESHWATER STREAMSSTREAMS

Flowing streams can recover from a moderate level of degradable water pollutants if they are not overloaded and their flows are not reduced. In a flowing stream, the breakdown of

degradable wastes by bacteria depletes DO

and creates and oxygen sag curve. This reduces or eliminates populations of

organisms with high oxygen requirements within the oxygen sag curve.

POLLUTION OF FRESHWATER POLLUTION OF FRESHWATER STREAMSSTREAMS

Most developed countries have sharply reduced point-source pollution but toxic chemicals and pollution from nonpoint sources are still a problem.

Stream pollution from discharges of untreated sewage and industrial wastes is a major problem in developing countries.

Inorganic Plant and Algal Nutrient- Inorganic Plant and Algal Nutrient- The Dead ZoneThe Dead Zone

o Explain why untreated sewage may kill fish when it is added directly to a body of water.

o How do Midwestern farmers threaten the livelihood of fishermen in the Gulf of Mexico?