• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Environmental sciences Lab-2(Stream Pollution)

Free essay example:

Evs lab-2

Stream Study

Aim: To test a river at different locations to assess pollution levels.

Focused aim: To investigate pollution level of the river using bio indicators in the form of insects & dissolved oxygen.


Control variable: Number of sites

Dependant variable:Amount of insects, Level of pollution

Independent variable: Temperature, pH level, dissolved oxygen & turbidity of the stream


  • Dissolved oxygen meter
  • Digital thermometer
  • Plastic Bowl
  • Small Plastic cups
  • Net
  • Plastic box
  • pH paper


  • Each site will have different Stream Pollution Index
  • Each site will have different dissolved oxygen levels
  • Temperature & pH levels for each site will remain constant

Risk assessment:

  • Since we were studying the pollution levels of the stream & using insects as an indicator, there was an added risk that Insects might have been harmful to the human body. Hence contact with insects is not recommended.
  • Since current levels are high, any footwear in the stream such as flip-flops is not recommended.
  • Stones are wet & slippery, therefore rubber boots are recommended.


  • First each site was marked in order to start the experiment.
  • Stream was divided into 5 sites in order to analyse the stream pollution index of the stream carefully & accurately.
  • For each site(1-5), Insects were searched & caught by a Net.
  • Insects were then placed in a bowl of water in order to identify the species.
  • Turbidity of the stream was discovered.
  • pH level of the stream was discovered
  • Temperature of the stream was discovered
  • Dissolved oxygen for each site was measured using a dissolved oxygen meter
  • Insects were inputted in a table according to their Sensitivity rating, weight factor, Tolerance level & Number of Insects.
  • Stream pollution Index of the stream was then calculated.

Data collection & processing:

  • Ph of water on each site :7.6
  • Temperature: 17.1
  • Turbidity: 0
  • Site 1:1 Larva
  • Site 2:1 water strider
  • Site 3:1 water strider

              1 fish tadpole

  • Site 4:1 Larva

              1 water strider

              1 Needle bug

  • Site 5: 2 dragonfly nymph





Bug Type

Sensitivity Rating

Number of bugs found

Weight Factor

Column A    X Column C

Tolerant Bugs

Water Stider





Dragonfly Nymph





Needle Bug





Very Tolerant Bugs









Stream Pollution Index: Total of column D

                                          Total of column C                                                                                    


                                           =3.4,which is fair.

Stream Pollution index for each site:


Site 1

Site 2

Site 3

Site 4

Site 5



(Water Strider)

(Water strider)

(Larva, Water strider, water scorpion)

(Dragonfly Nymph)

Stream Pollution Index (SPI)







  Dissolved oxygen level(mg/l)

Site 1

Site 2

Site 3

Site 4

Site 5






Average Dissolved oxygen: 2.96



Based on the data above, We can observe that the stream pollution index gives a value of 3.4 which is fair,however in some sites while quality of water was just reaching a good level while in some sites quality of water was poor. Average dissolved oxygen for the stream was 2.96 which is harmful to aquatic life.


From our research & findings on this experiment we have discovered that the Stream Quality rating was fair, However dissolved oxygen is not suitable to aquatic life, obviously where dissolved oxygen is less than 3 it is harmful to aquatic life and were only seeing bugs that live on top of the water like the water strider on sites were dissolved oxygen was less than 3 and not finding other fishes at various sites. However this experiment could have been performed more accurately if :

  • By widening our time scale, for instance if we could have performed the tests at 3 different points in the day. To see whether if different dissolved oxygen levels would have been obtained & to see if there were any movement in the aquatic life.
  • By increasing the size of the nets, more aquatic life could have been captured & it could have helped us determine the stream pollution index more accurately.
  • It would be interesting to come back & run the test again to see if the levels are getting worse, and determine rate of change in the Stream pollution index & Dissolved oxygen.

This student written piece of work is one of many that can be found in our International Baccalaureate Group 4 Projects section.

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Related International Baccalaureate Group 4 Projects Skills and Knowledge Essays

See our best essays

Related International Baccalaureate Group 4 Projects essays

  1. Why is alcohol considered to be a serious problem? As many 33,000 people ...

    Although many people know that these misconceptions are not true it will be hard to come across someone who doesn't know at least one misconception. Conclusion The research I have presented before you have shown the many dangers of alcohol.

  2. EVS-Lab quadrant study

    Data Collection and Processing Quadrant Area 1(Terrace) Terrace 1 * 80% of the area covering the quadrant was dry. * 20% of the area covering the quadrant was vegetated. Many observations were made while studying the vegetation at site 1. o 6 Twigs were present accompanied with an average height of 6.5 inches.

  1. age sex pyramids environmental

    The predicted populations change for the year 2050 shows a rapid and large increase in births as the younger population is the largest. The population changes for the older groups is also bigger than the predicted population change for the year 2020 1991 2000 2020 2050 Population 253,492,503 282,158,336 341,386,665

  2. ITGS Portfolio Assignment #1 Improvement and use of electric cars, and its affect on ...

    http://www.scientificamerican.com/article.cfm?id=earth-talk-the-coal-truth February 3rd, 2010 at 3:31 pm Dirty Electric Cars Powered by Dirty Coal in: Electric Cars One of the most common questions electric vehicle proponents are asked is,"Aren't you just moving the pollution from the tailpipe to the smokestack?", when it comes to using electricity generated from burning coal.

  1. Group 4 project

    wire and battery * the 2 common circuit elements that we use are resistors and light bulbs. * Resistors convert electrical potential energy into heat * Light bulbs convert electrical potential into light and heat * ALL circuit elements convert some energy to heat * Because a current flows through

  2. Research Report Time management strategies among HKU SPACE Community College students".

    For different planning methods, there were a tendency of decreasing percentage in following the plan greater than 75%. The highest percentage was students using timetable, 50% of the students selecting this method could follow over 75% of the plan. For students using schedule and list, the percentages dropped to 25% and 10% respectively.

  1. Determine the presence of reducing sugar, protein and starch in the food products by ...

    Copper sulphate solution (Biuret: 1% CuSO4) 6. Sodium hydroxide (NaOH 10%) 1. Substances 1. Protein 2. Starch 3. Glucose 4. Milk 5. Cereal 6. Bread 7. Juice 8. Cheese 9. Apple 10. Pasta 11. Lattice 12. Meat 13. Tomato 14.

  2. Designing a series of modern fashion accessories design collection with the theme of combining ...

    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work