These Can Be Stirred up by a Current Or Animal Walking

11.3 Testing Water Quality

Definitions:

Sediment :any small bits of solid matter that float or sink to the bottom of a body of water

- these can be stirred up by a current or animal walking

- used to measure the turbidity of water

- can be dirt, sand, silt (carbon from organic matter)

Turbid :the measure of unclear water that has sediment floating in it, related to light going into it due to “cloudiness”

- a disc is dropped down and the depth is measured where you can no longer see it

- the more sediment, the cloudier, the poorer the quality of the water

- plants use light for photosynthesis and the high turbidity may cause light to not go so deep

Thermal pollution :artificially raising the temperature of natural water (lakes, ponds)

- Can be done by letting more sun reach the water (cutting trees back) and industry dumping warm water used for cooling machine into lakes

- warm water has less dissolved oxygen than cold water and fish use this to breathe

Acidity :based on the pH scale (acidic is less than 7, basic is more than 7)

-this can happen by sulfuric and nitric acids cause this

-fish cannot reproduce in acidic conditions (eggs and sperm die)

-pH means “percent hydrogen”

Conductivity :how well electricity can go through a substance

- based on the salinity of the water (salt in it)

- water can let electricity pass through it

- the more salt in the water, the more the electricity can go through

- salt water can be undrinkable

- fresh water fish cannot live in fresh water with high salinity

pH scale :a scale used to determine the acidity or basic level of a liquid

- ranges from 1 (most acid), to 7(neutral), to 14 (most basic)

- pH means “percent hydrogen” or “power hydrogen”

Questions :

a)How do you test the turbidity of water?

Using a Secchi disk, drop it down into the water until you cannot see it any more. That tells you how bad (much) the sediments are.

b)How does the temperature of water affect its ability to hold oxygen? (warm vs cold)

The warmer the water, the less dissolved oxygen the water will have in it. This is bad for fish and underwater plants

c)What is a current human-made action that can result in thermal pollution?

Deforestation (cutting down trees) along shorelines can result in thermal pollution. Industrial water release does this as well

d)How do nuclear power plants contribute to thermal pollution.

They use water to cool their generators. This water absorbs the heat and then gets released into water, or lakes, around the power plant. This raises the water temperature.

e)What would be the pH values (above, at or below 7) of the following:

Battery acid : 1 Fresh water : between 6-8Milk : between 6-7

f)How does testing for conductivity help in assessing the salinity of water?

The more salt in the water, the brighter the light (electricity)

g)How do the following become dissolved in water :

i) chlorine – used to kill unwanted organisms (bacteria)

ii) nitrates – come from fertilizer on lawns, grass, golf courses

iii) iron and copper – comes from dissolved rocks and stone

iv) calcium and magnesium – comes from limestone (hard water)