Jefferson High School – EPA Project Week 7 – March 4, 2015
1. Learn to work in a shared environment on Google Drive
a. You’ll need a Google email address
b. Sign in and access the shared folder at: http://goo.gl/jeOVq0
c. Open the file named “Research Guide for Copper Experiment”
d. Before making any changes, go to File, make a copy, and save it with your
name at the start of the file name.
2. Learn about designing an experiment -- read and discuss page 1 of the document
“Experimental Design Worksheet” (page 1 handout, full document on the Google
drive.)
3. Read information on copper toxicity (below) and do additional research on the web
4. Design your own experiment to test the effects of copper on stream biota, taking
into consideration some of the different factors that affect copper’s toxicity to
organisms. Use your copy of the file “Research Guide for Copper Experiment”
COPPER
Why is copper important? Copper is a naturally occurring metal found in the earth's crust.
Copper is also generally present in surface waters, with cupric ion (Cu+2) as the primary
form in natural surface waters. In freshwater systems, naturally occurring concentrations
of copper range from 0.2 μg/L to 30 μg/L. At low concentrations, copper is an essential
element to virtually all plants and animals, including humans. Copper is a reddish colored
metal and is a good conductor of heat and electricity. It is used in a variety of products,
including electrical wiring, plumbing materials, cookware, automobile brake pads, and
coins.
How is copper released into the environment? Some examples of how copper may be
released into the environment are through copper mining activities, agricultural activities
(e.g., through its use as a mildewcide, fungicide, and/or algaecide), and manufacturing
activities (e.g., manufacturing of leather and leather products, fabricated metal products,
electrical equipment, and automobile brake pads). Copper may also enter the environment
through natural processes, such as volcanic eruptions, windblown dusts, decaying
vegetation, and forest fires. These examples are not an exhaustive list of all sources of
copper. Additionally, copper is found in most municipal effluents due to the corrosion of
copper plumbing.
Is copper toxic to freshwater aquatic organisms? Elevated levels of copper are toxic in
aquatic environments and may adversely affect fish, invertebrates, plants, and amphibians.
In fish, copper toxicity occurs due to disruptions of ion regulation in gill membranes. Acute
toxic effects may include mortality of organisms; chronic toxicity can result in reductions in
survival, reproduction, and growth.
What factors affect copper toxicity to aquatic organisms? The following water quality
parameters affect copper toxicity: temperature, pH, dissolved organic carbon (DOC),
calcium, magnesium, sodium, potassium, sulfate, chloride, and alkalinity. These parameters
What is hardness? The simple definition of water hardness is the amount of dissolved
calcium and magnesium in the water. Hard water is high in dissolved minerals, both
calcium and magnesium. You may have felt the effects of hard water, the last time you
washed your hands. Depending on the hardness of your water, after using soap to wash you
may have felt like there was a film of residue left on your hands. In hard water, soap reacts
with the calcium (which is relatively high in hard water) to form "soap scum". Hardness is
caused by compounds of calcium and magnesium, and by a variety of other metals. General
guidelines for classification of waters are: 0 to 60 mg/L (milligrams per liter) as calcium
carbonate is classified as soft; 61 to 120 mg/L as moderately hard; 121 to 180 mg/L as
hard; and more than 180 mg/L as very hard.
What is alkalinity? Alkalinity is a measure of the capacity of water to neutralize acids.
Alkaline compounds in the water such as bicarbonates (baking soda is one type),
carbonates, and hydroxides remove H+ ions and lower the acidity of the water (which
means increased pH). They usually do this by combining with the H+ ions to make new
compounds. Without this acid-neutralizing capacity, any acid added to a stream would
cause an immediate change in the pH. Measuring alkalinity is important in determining a
stream's ability to neutralize acidic pollution from rainfall or wastewater. It's one of the
best measures of the sensitivity of the stream to acid inputs. Alkalinity in streams is
influenced by rocks and soils, salts, certain plant activities, and certain industrial
wastewater discharges. Total alkalinity is measured by measuring the amount of acid (e.g.,
sulfuric acid) needed to bring the sample to a pH of 4.2. At this pH all the alkaline
compounds in the sample are "used up." The result is reported as milligrams per liter of
calcium carbonate (mg/L CaCO3).
How are hardness and alkalinity related? If the stream has a lot of calcium carbonate, then
it will have high hardness (because of the calcium) and high alkalinity (because of the
carbonate). However, if the stream has high sodium carbonate, the water may be soft
(because of low amounts of calcium and magnesium) but still have high alkalinity (because
of the carbonate).