GI Flashcards
What is primary data
Collected by investigator himself/herself for a specific purpose
What is secondary data
Gathered and recorded by someone else prior to and for a purpose other than the current project
Advantage of using primary data
More reliable/relevant as the data collected is by the one who is investigating the issue
Disadvantage of using primary data
More time consuming to collect the data
Advantage of using secondary data
Involves less time, effort and money to collect data.
Sometimes more accurate that primary data in some cases
Disadvantages of using secondary data
May be outdated
May not be as relevant/useful to the issue compared to primary data
What is turbidity
Amount of cloudiness in water
Murkiness can give clues as to what is in the water. It could be dissolved solids or bacteria but it need not always mean that there is pollution
How to conduct turbidity test
Fill the container with the water from the river and compare the Secchi disks with the icons on the chart
Record results in JTU
This will give a rough estimate of water turbidity level of water using JTU (Jackson Turbidity Unit)
Precautions needed to be taken to ensure accuracy of results for turbidity
Sun’s glare off the surface of the water makes it more difficult to see the Secchi disk so a solution is to view the water under the shade
Wearing sunglasses reduces the surface glare but decreases the Secchi Disk measurements
What is dissolved oxygen
Amount of dissolved oxygen in a body of water such as lakes, rivers or stream. The level of dissolved oxygen in water can be an indicator to see how polluted water is and how well the water can support aquatic plant and animal life
How to conduct dissolved oxygen test
Carefully fill the small vial brim-full with sampled water
Drop 2 dissolved oxygen tablets into the vial
Cover the vial with care to ensure that no air is introduced into the vial
Mix the sample by inverting several times. Continue this until the water changes colour
Compare the colour of the sampled water with the one on the coloured chart. That should give a rough estimate on the dissolved oxygen in the sampled water
Record the results in ppm (parts per million) dissolved
Precautions must be taken to ensure accuracy of readings for dissolved oxygen test
Vial must be completely filled with water (no air is left to skew the results)
Sample should be measured immediately after collecting
What is pH level
Refers to the amount of hydrogen ions found in a substance
pH level of a substance refers to how acidic the water is. pH level of pure water is 7
Water with a pH level lower than 7 is acidic and water with pH level higher than 7 is alkaline
Normal range of pH for surface water systems is 6.5 to 8.5
Knowing level of pH is important as it tells us the potential contamination
How to conduct pH test
Carefully fill the larger tube with sampled water.
Drop a pH tablet into the tube
Mix the sample several times by inverting it. continue until the sample changes colour
By comparing the colour of sampled water with the pH scale chart, roughly showing the pH level which can be obtained
Record the results in pH
Precautions must be taken to ensure accuracy of readings for pH
Always place the tube against a white background when comparing water to the given chart
Other attributes that affect water quality
Colour of water (Colourless? Light blue?)
Debris in water (Twigs? Leaves? Soil?)
Temperature of water (Record in degree Celsius)
Smell of water (smell of chlorine)
