THE CHEMISTRY OF WATER
We use it every day. We drink it, we bathe in it, we wash our hands every time we go to the bathroom (RIGHT?). But do we ever wonder what is hidden in it?
Some of you may have heard of microplastics. Scientists discovered that microscopic particles of plastics can be found in most bodies of water. We also know some water tastes bad when you drink. And (hopefully) we remember that water is also made of two atoms of Hydrogen and one atom of Oxygen (H2O).
Some of you may have heard of microplastics. Scientists discovered that microscopic particles of plastics can be found in most bodies of water. We also know some water tastes bad when you drink. And (hopefully) we remember that water is also made of two atoms of Hydrogen and one atom of Oxygen (H2O).
We normally don't think about where it comes from, or what is in it besides H2O. All water we come in contact with has more than this molecule (with the exception of precisely distilled water). All of these are chemicals, including H2O!
But some chemicals are harmful when you drink them. What's more, many chemicals cause conditions in the waters of rivers and oceans that make life very difficult, and sometimes impossible.
But some chemicals are harmful when you drink them. What's more, many chemicals cause conditions in the waters of rivers and oceans that make life very difficult, and sometimes impossible.
Around the world, species become extinct due to pollution coming from many different sources. Industrial runnoff, sewage, trash, oil and other environmental dangers are frequently dumped in rivers around the world. This is what happened to the Yangtze river in China, for instance. The Yangtze is the third longest river in the world, and it is known for being extremely polluted.
It was also the home to the Yangtze river dolphin, an ancient species that had developed to be almost blind. With so much pollution and a radically decreased fish population, this dolphin is now considered extinct, and no confirmed sightings have been made for the past ten years.
|
This should be a warning for everyone who lives near rivers and has seen orcas, eagle and hawk in BC; maybe even a bear or two.
|
All these animals rely on the health of the rivers around us. We have a well-tracked population of resident Orcas, who rely almost exclusively on salmon for survival. In recent years, there has been a decrease in the orca population of some pods. If the river is not healthy, this breaks the natural balance and everything falls together in succession.
Climate change also plays a part in the health of a river. The temperature of different bodies of water around the world has changed in recent years. This could have catastrophic consequences for wildlife, such as slowing down ocean currents and making some areas uninhabitable by some species of fish. Drought can also cause entire populations of salmon to die as they try to spawn in the rivers they were born. The recent heat dome event of 2021 is estimated to have killed over a billion animals which were simply cooked to death in BC.
THE PROJECT - HOW HEALTHY IS OUR RIVER?
We all love the Fraser River. It's a frequent sight for many of us. But how are we showing our love for the river?
In theory, we understand that civilization causes an impact on the natural world around it. But in practice, the river seems fine; people are fishing in it, so there is still fish. How can we measure the impact of humans on the river?
In theory, we understand that civilization causes an impact on the natural world around it. But in practice, the river seems fine; people are fishing in it, so there is still fish. How can we measure the impact of humans on the river?
Play the Powerpoint from Water Rangers!
Measurements and Data
We need to split into 5 groups. I used a random group generator to separate everyone as shown below.
Every group will need to select:
- One student that writes everything down
- One student responsible for testing the conductivity
- One student responsible for strip testing
- One student responsible for checking the data, as well as comparing data in the end with other groups
- One student responsible for clearing up the materials and making sure everything is accounted for before returning to teacher
We will also need AS A CLASS:
- 2 students responsible for sampling (dropping the sampler and bringing it up)
What you will receive:
- An organization sheet
- A conductivity meter
- A box of strips (please try to use only one or two)
- A cup for your group's sample
Qualitative Observations
What do you see? How is the weather today? How was it yesterday? Do you see anything floating on the water? How is the flow? Colour? Level?
Talk to your group, and write it all down!
Talk to your group, and write it all down!
Temperature of Air
Use the black thermometer to measure the air temperature.
Try not to have it out in the Sun. Hold it by the loop on a shaded spot and wait until the temperature equalizes.
Try not to have it out in the Sun. Hold it by the loop on a shaded spot and wait until the temperature equalizes.
Water Flow
Testing for Visibility
Testing for depth visibility is an important part of testing the health of a river. The furthest the light can penetrate, the better it is for aquatic plants and organisms that rely on light for photosyntesis.
To do this test, we will hook the secchi disk (black and white disk) to the measurement wheel, and pay close attention to when the black and white disappear in the water. Then, write down the measurement -- this is your depth visibility, or water transparency.
To do this test, we will hook the secchi disk (black and white disk) to the measurement wheel, and pay close attention to when the black and white disappear in the water. Then, write down the measurement -- this is your depth visibility, or water transparency.
Taking the Sample
Samples should be taken from at least 15 cm deep, or deeper.
When we take the sample from the river, we will need to rinse the container used three times. Then, with the fourth water pull, we will rinse everything that will come in contact with the water, also 3 times. Then we will pull water again, and finally use that for our testing.
When we take the sample from the river, we will need to rinse the container used three times. Then, with the fourth water pull, we will rinse everything that will come in contact with the water, also 3 times. Then we will pull water again, and finally use that for our testing.
Temperature of Water
Do this quickly so that the water doesn't have a chance to warm up. You can use the same thermometer as above. Place thermometer in the cup and record your results when the temperature stabilizes.
Testing for Dissolved Oxygen
This test is very neat, but difficult to do. If you are not comfortable breaking glass with your hands, don't try it! We can have one person per group try to do this, in order to save on the ampoules.
Step 1: Pour sample on the small cup provided.
Step 2: Place an ampoule, thin side down, inside the small cup.
Step 3: Place the tip of the ampoule on one of the grooves inside the cup.
Step 4: Apply pressure until the tip breaks off.
Step 5: The ampoule will immediately fill with water. MAGIC TRICK!!
Step 6: Immediately, remove the ampoule from the sample and flip it upside down and back again, so that the bubble inside the ampoule moved up and down twice.
Step 7: Place the ampoule between two of the control colours. Try to find the best match.
Step 8: Write down the results.
Step 2: Place an ampoule, thin side down, inside the small cup.
Step 3: Place the tip of the ampoule on one of the grooves inside the cup.
Step 4: Apply pressure until the tip breaks off.
Step 5: The ampoule will immediately fill with water. MAGIC TRICK!!
Step 6: Immediately, remove the ampoule from the sample and flip it upside down and back again, so that the bubble inside the ampoule moved up and down twice.
Step 7: Place the ampoule between two of the control colours. Try to find the best match.
Step 8: Write down the results.
Testing for Conductivity
Conductivity measures the ability of water to pass an electrical current. This is influenced by a number of different chemicals, like calcium, bicarbonate, nitrogen, sulphur and other compounds. Sometimes, a spike in conductivity indicates pollution, but this is not always true. Some places have naturally high conductivity due to the geology around it.
How to test:
Press the top button. Place conductivity meter in the water immediately after water surfaces. Read the values. The top will give you the conductivity in microsiemens per cm. If it doesn't, we can change it easily.
How to test:
Press the top button. Place conductivity meter in the water immediately after water surfaces. Read the values. The top will give you the conductivity in microsiemens per cm. If it doesn't, we can change it easily.
Salinity
We only have two salinity meters, as they are more expensive. When you are ready, please come and borrow the salinity meter. Write down the number when it has stabilized.
Test Strips
These measure all sorts of different things. The rule is, in for 2 seconds, out for 20 seconds, then do the comparison.
Please do not shake water off strip. Handle with care so they don't cross-contaminate.
Please do not shake water off strip. Handle with care so they don't cross-contaminate.
