Water Testing

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Water Testing
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Why?

• Water is one substance that makes our planet
  unique.
• All life depends on it.
• We use it to drink and bathe.
• Animals and plants that live in water cant take
  high levels of pollution.

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Water Temperature

• Select a calm spot in the water.
• Totally submerse the thermometer in water for
  15-20 minutes. Before taking reading.
• If water is rushing, tie rope to thermometer
• Make sure to retrieve before leaving.

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Alkalinity
What is Alkalinity? Alkalinity is the
measurement of a body of waters resistance to
the lowering of pH when acids are added to the
water. Alkalinity Water acquires alkalinity
from dissolving rocks (e.g., carbonates)
Alkalinity influences pH, and thus affects the
kinds of aquatic life that will survive in
water. Alkalinity is measured in ppm (mg/L) as
CaCO3.
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Alkalinity (cont)
Typical Values Fresh water typically has
alkalinity of 20 - 200 ppm as CaCO3. Well-buffer
ed waters have alkalinity greater than 100 ppm.
The pH should be relatively stable. Sea water
has alkalinity of 100 - 125 ppm as CaCO3.
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Alkalinity (cont)
Sample collection and reporting Rinse sample
bottle 3 times with sample water Take sample
near location of water temperature
measurement Follow kit instructions. Repeat 3
times. Alkalinity values should agree within
the precision of the kit (typically ? 1 drop of
titrant).
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Dissolved Oxygen
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Scientists want Dissolved Oxygen data to

• Determine the mixing of air and water at the
  waters surface
• Determine what animals can live in the water

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Dissolved Oxygen

• Oxygen accounts for one of every five molecules
  in the air on the other hand, in water, roughly
  five of every million molecules are dissolved
  oxygen, mg/L (ppm by mass)
• Test will measure the amount of free oxygen gas
  dissolved in your water sample in mg/L (ppm)
• Dissolved oxygen levels of at least 5 - 6 ppm
  (mg/L) are usually required for growth.
• Dissolved oxygen levels of below 3 ppm are
  stressful to most aquatic organisms.

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The amount of oxygen that water can hold
decreases with

• Temperature increases
• Elevation increases (due to decreasing
  atmospheric pressure)
• Increasing amounts of dissolved substances (e.g.,
  salts)

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Taking a Sample and testing

• Rinse sampling bottle 3 times with sample water
• Submerge bottle in water and allow to fill.
• Tap bottle to release air bubbles
• While bottle is submerged, replace cap
• If there are air bubbles in the bottle, empty and
  repeat
• Preserve sample immediately. Test within 2 hours.
• Repeat 3 times. Take the average to see if all
  values are within the precision of the kit.
  Discard outliers.

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Sample Preservation and Sample Testing

• Dissolved Oxygen test kits involve two overall
  parts sample preservation and sample testing.
• Preservation
• 1st - addition of a chemical that precipitates in
  the presence of dissolved oxygen
• 2nd - addition of a chemical that causes the
  solids to dissolve and produce a colored
  solution. This should be done in the field.
• Sample Testing
• Titration of preserved sample. This can be done
  in the lab.

Most DO test kits are based on the Winkler
titration method.
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Nitrates
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• Nitrate is a limiting nutrient for aquatic plant
  growth. It is often depleted.
• Nitrate sources include atmospheric deposition,
  organic matter decomposition, excretion by
  organisms, urban and agricultural run off.

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Significant Levels

• In most kits the amount of nitrate in a water
  sample is reported as nitrate nitrogen (NO3-N).
  This means the amount of nitrogen that exists in
  the sample in the form of nitrates.
• Natural waters usually have NO3-N levels lower
  than 1 mg/L.
• In the United States, fresh water with NO3-N
  levels above 10 mg/L is considered unsafe for
  human consumption.

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To Measure Nitrates

• Nitrate can not be measured directly. It is first
  reduced to nitrite, in the presence of cadmium,
  and the amount of nitrite produced is then
  determined by color.

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Method

• Collect sample
• Follow directions on kit
• Add reagent (e.g., cadmium) that reduces NO3- to
  NO2-
• Add reagent that reacts with NO2- to form color
• Determine concentration by comparing the color of
  the sample with a color indicator in the test kit
• This method is time sensitive
• If DO values are low, perform steps 2 and 3 on a
  fresh sample of water to determine the background
  NO2- levels
• Repeat 3 times. Values should agree within
  precision of kit. If not, discard outlier(s).

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pH
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pH of Common Solutions
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Understanding pH

• pH tells us how acid or basic a solution is
• pH is the measure of the hydrogen ion
  concentration of water or a solution
• pH is measured using a logarithmic scale

?
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The pH scale is logarithmic

• Each pH unit is 10 times as large as the previous
  one
• A change of 2 pH units means 100 times more basic
  or acidic

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pH and Plant Health
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pH and the Environment
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Location
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Using a GPS Unit

• There are 24 GPS satellites orbiting Earth right
  now.
• The more of them that your GPS will lock onto the
  more accurately your position can be determined.

NASA/JPL
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• By collecting the information from several
  satellites, a GPS unit can determine your exact
  location on Earth.

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What to look for and record
Elevation
Satellites
Latitude
Longitude
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Using A Compass

• The red point of the arrow is pointing north.
  Turn your body until the red arrow is pointing to
  N on the compass. You are now facing north.

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Latitude/Longitude

• A way to describe our location on the earth
• Tells how far north/south and east/west
• These are called coordinates

N
E
W
S
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Mapping
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What is a transect?
A transect is a straight line placed on the
ground along which ecological measurements are
taken.
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Transect Mapping a Water Sampling Site

• Determine Site Location

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Transect Mapping a Water Sampling Site

• Measure a line 15 meters either side of the
  sampling site.

X
Sampling Site
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Transect Mapping a Water Sampling Site

• Reference the transect to a permanent object such
  as a tree or boulder.

X
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Transect Mapping a Water Sampling Site

• Mark the transect with flags every two meters.

X
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Transect Mapping a Water Sampling Site

• Draw the transect line on your grid.

X
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Transect Mapping a Water Sampling Site

• Measure from each flag to the edge of the water.

X
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Transect Mapping a Water Sampling Site

• Plot these points on your grid sheet.

X
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Transect Mapping a Water Sampling Site

• Connect the plot points with a line.

X
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Transect Mapping a Water Sampling Site

• Draw other significant details.

X
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Transect Mapping a Water Sampling Site

• Note sampling location, directions, and reference
  points.

X
X
N
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• You are now ready to test the water!