WATER QUALITY

WATER QUALITYWater quality is a term used to describe the chemical, physical, and biological characteristics of water.

Factors that affect water quality are broken down into two categories: biotic and abiotic.

WATER QUALITYBiotic Factors: Living factors affecting water quality

Abiotic Factors: Non-living factors affecting water quality

WATER QUALITYWater quality is also described in

terms of the water’s intended use.Water that is drinkable is called

potable.Water than can be used for

swimming or bathing is referred to as safe.

WATER QUALITYWater quality standards outline

the water pollution control program that is mandated by local, state and federal government agencies.Primary among these is the

Environmental Protection Agency (EPA)

WATER QUALITYEnvironmental Protection Agency

(EPA)Acts as a Steward of the

environmentSets maximum levels for the 90

most common water contaminants

WATER QUALITY Water quality standards are based on the

following questions: What is the intended use of the body of water? How can we protect that use? What long term dangers might the body of water

face?

ABIOTIC FACTORS

Temperature – the temperature of water in rivers and lakes determine the kinds of organisms that can survive there. Certain species have preferred water

temperature ranges. The temperature of water affects what solids and

gasses are dissolved within it. Warm Water = Less Oxygen Colder Water = More Oxygen

ABIOTIC FACTORS

Dissolved Oxygen – (DO) Oxygen that is dissolved in water. DO is a measure of the amount of oxygen in

water that is available for chemical reactions and for use by aquatic organisms.

DO is vital for the survival of micro-organisms, and higher organisms such as zooplankton and fish.

Dissolved Oxygen gets into the water through diffusion with the air (the higher concentration of oxygen in the air causes oxygen to move from the air to the water) and as a by-product of photosynthesis by water plants.

High DO levels in potable water make it taste better

MAJOR AFFECTS THAT ADJUST DO

Water temperature increases and DO goes down.

Increased eutrophication. Eutrophication: Decreased amount of DO in a

body of water due to increased algae and plant growth.

ABIOTIC FACTORS

pH A measure of how acidic or basic the water is On a scale of 0 to 14 – 7 is neutral, below 7 is

acidic, above 7 is basic The pH of pure water is 7 Water that is too acidic may cause other

elements that are always present to become toxic to organisms living there

ABIOTIC FACTORS

Turbidity – A measure of how clear water is Higher turbidity in potable can mean pathogens

are present Higher turbidity in lakes and rivers can lead to

increased temperatures, lower DO, and bad conditions for aquatic organisms

ABIOTIC FACTORS

Phosphates and Nitrates If these levels are too high they pose a risk to

humans in potable water. The major sources of phosphates are: humans

and animal waste, detergents, cleaning and industrial waste.

The major sources of nitrates: runoff contaminated with fertilizers, animals waste and septic waste.

BIOTIC FACTORS

Bioindicators – living things whose presence, condition, and numbers are indicators of the health of a body of water

THINKING QUESTION

On the left hand side of your notes: What are some connections between water quality factors?

Right hand side: Look back in your notes and try to find as many connects between the abiotic factors just discussed.