The Blue PlanetThe Blue PlanetIndicators of Water Quality

Water quality refers to the chemical, physical, biological, and radiological characteristics of water.

• It is a measure of the condition of water relative to the requirements of one or more biotic species and or to any human need or purpose.

What is Water Quality?

Most dissolved substances found in water are measured in parts per million (ppm) or even smaller amounts. This

means that for every one million parts (units) of water there is a certain number of

parts of the substance.

PARTS PER MILLION

It is also expressed as milligrams per liter. There are 1000 milliliters in a liter and 1000 milligrams in a gram. For example, a dissolved oxygen reading of 8 ppm means there are 8 milligrams of oxygen for every 1000 milliliters of water.

8/1000 gram 1000 milliliters =

8/1,000,000 (8 parts per million)

• A measure of the degree to which water looses its transparency due to the presence of suspended particulates

• Ideal Level: 1 NTU• High Level: 5 NTU

and above

• Causes: – Increased levels of

phytoplankton– Algae growth– Urban Runoff

• Results: – Increases absorption

of sunlight makes water warmer

– Lowers levels of dissolved oxygen

– As the suspended particles settle, the benthic organisms are smothered.

Turbidity

• Turbid Water • Clear Water

Turbidity

• The acidity of the water (presence of the hydrogen ion [H+])– 07 is acidic– 7 is neutral– 714 is basic

• Surface freshwater: 6.0-9.0

• Swamps: as low as 4.3• Salt Water: 8.1 but as low

as 7.7

• Causes: – Natural conditions

(especially in swamps)– Dumping of waste

(batteries)– Farm runoff (lime)

• Results– A change in pH by 2 units

results in a water system having 100x a difference in acidity

– Most aquatic life can’t withstand water outside the optimum pH resulting in death

pH

pH Scale

Alkalinity refers to the water’s ability to neutralize acids.

• Alkalinity is produced by minerals such as limestone

• Limestone is a type of ocean sediment composed of calcium carbonate.

Alkalinity

Water with low alkalinity is usually acidic.

• Ammonia is produced by the decay of organic matter and animal waste.

• It is toxic to most aquatic life, especially at high pH.

• Bacteria readily convert ammonia to nitrate.

Ammonia

Ammonia is a form of nitrogen and part of the Nitrogen Cycle.

• Oxygen dissolved in the water

• Average Level: 9.0 ppm

• Warmer water = less oxygen– Must be 4-5 ppm to

support diverse population of fish

– Cold water rarely has more than 15 ppm. Summer is often a time of oxygen stress for aquatic organisms.

• Causes– Turbulent Actions

(waves, rapids)– Water depth– Plant growth

• Results– When DO drops too

low fish die– When DO is high,

water actually tastes better but can corrode water pipes

Dissolved Oxygen

Dissolved Oxygen

• Measure of average kinetic energy

• Low: cannot be tolerated below 32°F

• High: only rough fish can tolerate temperatures above 97°F

• Causes– Source of water– Time of year– Suspended sediment– Depth of water– Shade from shoreline

vegetation

• Results– Changes make aquatic life

susceptible to diseases– At extreme levels can

result in death

Temperature

Rapid temperate change and temperature extremes can stress aquatic organisms.

Temperature affects the oxygen-carrying capacity of water

Temperature

• 14 Dissolved Oxygen (ppm)

• 12

• 10

• 8

• 6

• 4• ____________________________________• Winter Summer

As the water warms, the amount of dissolved oxygen decreases

• Compound that contains the nitrogen based polyatomic ion NO3 (Ex. Sodium Nitrate)

• Nitrates are water soluble and can move easily from surface to groundwater.

• Drinking Water Max: – 10 mg/L

• Fish: – Below 90 mg/L seems to

have no effect on warm water fish

• Causes– Fertilizer runoff– Manure pits– Rain trapping car exhaust

• Results– Nitrates can increase the

plant production and algal blooms

– If algae increases due to nitrates, the DO levels can decrease, killing fish

– Convert to nitrites can kill children

Nitrates

• Under normal conditions, the nitrogen cycle keeps the amount of available nitrogen in balance with the demands. However, excessive use of fertilizers and nutrient rich sewage release have created a surplus of nitrate. The result is EUTROPHICATION from excess algae and bacteria with reduced dissolved oxygen.

Nitrates

Nitrates Eutrophication

• Phosphorus is a naturally occurring element.

• Phosphates enter waterways from human and animal waste, phosphorus rich bedrock, laundry, cleaning, industrial effluents, and fertilizer runoff. 

Phosphates

• High levels of phosphates can overstimulate the growth of aquatic plants and algae.

• This will cause high D.O. consumption and death to fish and other aquatic organisms.

Phosphates

• Animals found living in water that are sensitive to pollution

• High Variety healthy water source

• Low Variety Poor water source (high levels of pollution)

• Causes– Pollution results in

changes to pH, temperature, dissolved oxygen, or nitrate levels

• Results– Lack of varied animals

indicative of pollution

Bioindicators