OUR ENDANGERED

WATERS

Any physical, biological, or chemical change in water

quality that makes it unfit for its desired purpose can be

considered water pollution. The amount of oxygen in the water is a good indicator of water quality

as it determines if water can support various life forms.

There are two ways to monitor water quality:• Biological oxygen

demand (BOD)• Dissolved oxygen content

(DOC)

Presence of Infectious

Agents

A serious water pollutant is disease-causing organisms. These pathogens

may bring cholera, typhoid fever, hepatitis, bacterial and amoebic

dysentery, polio, and schistosomiasis.

Vectors are organisms that carry or transmit disease-

causing organisms. Malaria, yellow fever, and filariasis are examples of

illnesses carried by animal vectors.

Eutrophication

The transparency of water is affected by the presence of

sediments, nutrients, chemicals, and population of planktons.

Freshwater environments, that are clear but with low biological

productivity are said to be oligotrophic.

Waters that are “nutrient-rich” are called eutrophic waters.

Eutrophication may occur in freshwater or even in marine

ecosystems especially near the shore, enclosed bays, and

estuaries.

Toxic Inorganic Chemicals

The weathering of rocks may release small amounts of toxic inorganic

materials, which are then carried by runoff to other bodies of water. Heavy

metals, which rank as the highest among the persistent toxic inorganic substances, tend to accumulate in

food chains where humans are at the top. This process of bioaccumulation

is known as biological magnification.

Organic Chemicals

There are thousands of different synthetic and natural

chemicals that are used to manufacture pesticides,

plastics, drugs, and a wide array of other everyday materials. Many of these

chemicals re highly toxic and exposure to these substances

may cause birth defects, cancer, and other genetic

disorders.

Sedimentation and Siltation

Rivers have always carried loads of sediment into

bodies of water. Sometimes, sediments clog the tiny

holes of corals through a process called siltation.

Thermal Pollution

The increase or drop in “normal” water temperature can affect water

quality and aquatic life. Aquatic organisms need a fairly constant

temperature to survive. They poorly adapt to rapid temperature changes

and may perish when sudden temperature changes happen. A one-

degree decrease in temperature in tropical oceans may even be fatal to

some corals and other reef organisms.