Housatonic River Unit
Water Quality Station – Bartholomew’s
Cobble
Focusing Question:
How suitable is the water
in the Housatonic
River for aquatic life?
Standards:
Life Science (Grades
6-8)
13.0: Give examples
of ways in which organisms interact and have different functions within an
ecosystem that enable the ecosystem to survive.
Length of Time Needed
to Complete:
Pre-field – One 1 hour
class period; In the Field – One 45 minute rotation during field trip.
Resources/Materials:
River journals, pH test
kit, dissolved oxygen test kit, buckets with long ropes, and containers with
lids for discarding water that contains test chemicals.
Procedure:
Pre-field: Introduce the terms pH and dissolved
oxygen. Explain that pH is a scale that
determines the level of acidity or alkalinity in a substance. Point out that there are many acids that they
are familiar with (vinegar, citric acids, battery acid) and that some are more
acidic, and would be more dangerous than others. There are also some bases or alkalines that
they are familiar with too, including bleach and many household cleaners, some
more dangerous than others. Draw a pH
scale with some common substances placed on it.
Explain that a neutral substance would be placed at number “7” and that
pH values below that would be acidic, and those above 7 would be basic. Tell students that most aquatic animals
require a pH between 5.0 and 8.5 to survive.
Next, ask students why
oxygen is important to animals, and ask how aquatic animals (such as fish) get
the oxygen that they need. Explain that
there is oxygen dissolved in the water, similar to Kool Aid dissolved in water,
or the carbon dioxide bubbles in soda, and aquatic animals use this to
survive. Tell students that most large
fish require a dissolved oxygen content of at least 5.0 milligrams/liter. Finally,
demonstrate for students how the tests are done on a water sample, and explain
that they will test water samples taken from two different points on the river.
In the Field: Collect water samples from two
different points on the river. Taking
samples both upriver and downriver of some farming, industry, or other site
that could impact the pH or dissolved oxygen of the water would be
beneficial. Have students recall what
tests they will be running and why, and what pH and dissolved oxygen levels are
in a healthy range for aquatic life. Run
the tests on the water from both sample buckets and have students record the
data in their river journals. Discuss
the results and whether they are in an acceptable range, and why the results
may have been different at the two sites.
Also discuss other things that the water could be tested for that were
not (specifically pollutants), and how they might affect the things that live
in the water.
Journal Assignment: Based on the water quality data we took of the Housatonic River at the Cobble, how suitable is the
water for aquatic life? How is it
different at the two sites? Support your
statements with qualitative and quantitative data/observations.
Assessment:
In their journals,
students will explain in their own words, using the data taken at the Water
Quality Station, whether they think that the water in the Housatonic River
at Bartholomew’s Cobble is suitable for aquatic life.