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BIOACCUMULATION AND BIOMAGNIFICATION
Persistent organic pollutants (POPs) do not break down easily and last a long time in the environment.
There are a variety of POPs that were developed for use as pesticides, industrial solvents, and other
uses. One example is DDT, a pesticide that was commonly used in the 1900s not only by farmers, but
as household bug killers, public mosquito abatement and to kill lice.
Rachel Carson published a book, Silent Spring, in 1963 about the dangers of
industrial chemicals including pesticides such as DDT to wildlife. As a result of this
book, a modern environmental movement was born and helped propel the banning
of DDT in 1972.
One of the things that DDT does is to make bird shells’ weak, killing babies when
parents sit on the eggs.
EXPLORE
Go to this website:
http://virtualbiologylab.org/NetWebHTML_FilesJan2016/BiomagnificationModel.html
This simulation shows how DDT in the ocean makes its way to top predatory species including many
species of birds.
1. Move the blue bar at the bottom to show a medium amount
of DDT in the water such as 0.0006 ppm (parts per million). See
the arrow on the screenshot to show where the bar is.
2. Click the blue “GO” Button and let the simulation run for 500
ticks. You can see the number of ticks in the top left corner.
3. Record the data below after 500 ticks. Use the vertical
yellow boxes that say “Rolling Mean Concentration of DDT”
You can find the “ticks” in the upper left corner. Press “Go” again to pause at 500. (Its okay if its not
exactly 500)
Species DDT in ppm Species DDT in ppm
Pelicans Zooplankton
Salmon Phytoplankton
Smelt Water
Press “Go” to resume and record the data after 1000 or more ticks on the next page.
Data after 1000 or more ticks. Use the vertical yellow boxes that say “Rolling Mean Concentration of
DDT”
©StrategicScience
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Species DDT in ppm Species DDT in ppm
Pelicans Zooplankton
Salmon Phytoplankton
Smelt Water
Sketch your graph (not the chart) below:
EXPLAIN
1. What do you notice about the level of DDT in individual organisms? Is it increasing, decreasing,
or staying the same?
When toxins are stored in our fatty tissues and build up over time, it is called bioaccumulation.
2. What do you notice about the levels of DDT going from water, to phytoplankton and on up to
pelicans?
When toxins increase as you go up the food chain/food web, it is called biomagnification.
©StrategicScience
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Math Practice
3. Calculate the percent change from phytoplankton to smelt. Show your setup and answer.
4. Calculate the percent change from smelt to pelican. Show your setup and answer.
ELABORATE
While many species such as the bald eagle have made comebacks in recent years, DDT is still causing
problems.
Watch this video about DDT:
https://spectrumnews1.com/ca/la-west/la-times-today/2020/11/13/how-la-s-coast-was-once-a-ddt-
dumping-ground# OR read the article https://www.latimes.com/projects/la-coast-ddt-dumping-
ground/
1. Where and when does this story take place?
2. What are two ways DDT ended up in the ocean?
3. What are the human and mammal health problems with DDT?
4. How did the scientist find the barrels?
5. How many are estimated to be out there in the ocean around Catalina Island?
6. What is the reaction of the EPA?
©StrategicScience
