Download Unit 2 Lesson 7a Bioaccumulation

Grade 9 Geography - Unit 2
Bioaccumulation - Definitions
Bioaccumulation
? The process by which chemical substances are ingested and retained by organisms, either
from the environment directly or through consumption of food containing the chemicals.
Bioconcentration
? The ability of an organism to selectively accumulate certain chemicals, elements, or
substances within its body or within certain cells.
? A process by which there is a net accumulation of a chemical into an organism.
Biomagnification
? The cumulative increase in the concentration of a substance in successively higher levels of
a food web.
Ecosystem
? A region in which a mix of organisms (biota) including humans and their physical
environment form an interacting unit. Ecosystems vary in size and composition and display
functional relationships within and between systems. In its broadest sense, an ecosystem
includes environmental, social, and economic elements. The root words of ecosystem are
eco, a derivative of the Greek term for house or home, and system, which addresses the
relationships and connections between the biological and physical parts.
Food Chain
? A food relationship in an ecosystem in which energy and nutrients are transferred through a
series of organisms by each stage feeding on the preceding one and providing food for the
succeeding stage. Each stage of a food chain is known as a trophic level. The first trophic
level consists of the green plants that can undertake photosynthesis, thereby obtaining their
energy from the sun.
Food Web
? A complex intermeshing of individual food chains in an ecosystem.
Trophic
? The processes of energy and nutrient transfer from one or more organisms to others in an
ecosystem.
Trophic Level
? Functional classification of organisms in a community according to feeding relationships; the
first trophic level includes green plants, the second level includes herbivores, and so on.
Grade 9 Geography - Unit 2
Bioaccumulation - DDT Case Stud y
The study of Dichloro-diphenyl-trichloroethane (DDT) provides a good example of
bioaccumulation and biomagnification of chemicals in the ecosystem. Bioaccumulation is the
accumulation of higher and higher concentrations of potentially toxic chemicals in individual
organisms. It occurs in the case of chemicals that are ingested but cannot be broken down or
excreted. Biomagnification is the bioaccumulation occurring through several levels of a food
chain.
Background Information
In the 1930's, Swiss chemist Paul Muller discovered DDT. This inexpensive, broad-spectrum,
persistent chemical was extremely toxic to insects. DDT was not toxic to humans and other
mammals, and it appeared to be the answer to many pest problems.
During WWII, DDT was used to control lice resulting in less typhus fever. Following the war,
DDT was used to control mosquitoes to reduce malaria, to control spruce budworm and beetles
spreading Dutch elm disease in forests, and to control pest on farm crops.
In the 1950's, Rachel Carson started to look into the effects of DDT on wildlife. Fish-eating birds,
robins and other insect-eating beings were dying from eating prey laden with DDT. The use of
DDT was banned in the early 1970's in Canada and the United States. Note: it is believed that
DDT still enters the Great Lakes ecosystem through rainfall and dust from input sources half
way around the world.
Today, pesticide technology has changed. New pesticides are “biologically-based” and break
down readily upon contact with the soil or in reaction to sunlight. They are much more targetspecific, and thus, they are less likely to harm non-target organisms. The persistence of the
chemical is rigorously tested…although the long-term effects and overall impacts of new and
existing chemicals on ecosystems can only be partially evaluated by current testing procedures.
Grade 9 Geography - Unit 2
Bioaccumulation
Case Study
You are an ecologist studying the presence of a persistent toxic chemical in a lake. You make
the following discoveries.
? The water has one molecule of the chemical for every billion molecules of water (1 ppb).
? The algae has one part per million (1 ppm) of the toxic chemical.
? Small aquatic animals such as zooplankton have 10 ppm.
? Small fish have 100 ppm.
? Large fish have 1000 ppm.
? An eagle has 10,000 ppm.
How do you explain the increase in this persistent toxic chemical to 10,000 ppm for the eagle?
Use a drawing to help support your answer.
The ecologist found the chemical was a pesticide sprayed on cropland 160 kilometres away
from the lake. How did so much of it get into the lake?
Identity three consequences of the pesticide entering the food chains.
Grade 9 Geography - Unit 2
Bioaccumulation, Biomagnification and Bioconcentration
Food Chain Biomagnification
? Bioaccumulation is the increase of a toxic substance in one species.
? Biomagnification is the increase of a toxic substance in larger and larger amounts
up the food chain.
Organochlorines are more soluble in fat than water. What does this mean?
In an aquatic environment, phytoplankton absorb organochlorines from the water…just
like phytoplankton absorb nutrients for growth. The phytoplankton are eaten by
zooplankton (e.g., Mysis) or invertebrate (e.g., Pontoporeia), and the organochlorines
are deposited into their fatty tissues. Fatty tissue is not excerted, and the toxic
substance accumulates. Biomagnification has occurred.
Table 1. Concentration of PCB and Mercury in Different Great Lakes
Species in 1982
Species
PCB (ppm)
Mercury (ppm)
Sculpin
1.7
0.07
Mysis
0.09
0.013
Herring Gulls (eggs)
60.0
0.54
1.7
0.09
0.01
0.004
Lake Trout
5.6
0.17
Pontoporeia
0.32
0.014
Smelt
Phytoplankton
What is the order of the food chain from Table 1?
Plot a bar graph for each data set (species versus ppm toxic substance).
Bioconcentration
The concentration of PCB in the open water of Lake Ontario in 1986 was 5 ppt (parts
per trillion).
What is the bioconcentration factor from the water to herring gulls? That is, how much
more concentrated are PCBs in herring gull eggs than in Lake Ontario water?
?
?
5 ppt = 0.000,005 ppm
The concentration of PCB in gull eggs was 60 ppm.
?
60 ppm in gull eggs is 12 million times greater than 0.000,005 ppm in water.
Species
Lake Water
PCB (ppm)
Bioconcentration Factor
0.000,005
Phytoplankton
0.01
plankton to water =
Mysis
0.09
zooplankton to water =
Pontoporeia
0.32
invertebrate to zooplankton =
Smelt
1.7
forage fish to invertebrate =
Lake Trout
5.6
predator to forage fish =
Herring Gull
60.0
gull egg to water = 12,000,000
gull egg to predator fish =
gull egg to phytoplankton =
Grade 9 Geography - Unit 2
Bioaccumulation, Biomagnification and Bioconcentration
Answers
Food Chain Biomagnification
? Bioaccumulation is the increase of a toxic substance in one species.
? Biomagnification is the increase of a toxic substance in larger and larger amounts
up the food chain.
Organochlorines are more soluble in fat than water. What does this mean?
In an aquatic environment, phytoplankton absorb organochlorines from the water…just
like phytoplankton absorb nutrients for growth. The phytoplankton are eaten by
zooplankton (e.g., Mysis) or invertebrate (e.g., Pontoporeia), and the organochlorines
are deposited into their fatty tissues. Fatty tissue is not excerted, and the toxic
substance accumulates. Biomagnification has occurred.
Table 1. Concentration of PCB and Mercury in Different Great Lakes
Species in 1982
Species
PCB (ppm)
Mercury (ppm)
Sculpin
1.7
0.07
Mysis
0.09
0.013
Herring Gulls (eggs)
60.0
0.54
1.7
0.09
0.01
0.004
5.6
0.17
0.32
0.014
Smelt
Phytoplankton
Lake Trout
Pontoporeia
What is the order of the food chain from Table 1?
? plankton, zooplankton, forage fish (Sculpin or Smelt), Lake Trout and Herring
Gull
Plot a bar graph for each data set (species versus ppm toxic substance).
Bioconcentration
The concentration of PCB in the open water of Lake Ontario in 1986 was 5 ppt (parts
per trillion).
What is the bioconcentration factor from the water to herring gulls? That is, how much
more concentrated are PCBs in herring gull eggs than in Lake Ontario water?
? 5 ppt = 0.000,005 ppm
? The concentration of PCB in gull eggs was 60 ppm.
? 60 ppm in gull eggs is 12 million times greater than 0.000,005 ppm in water.
Species
Lake Water
Phytoplankton
PCB (ppm)
0.000,005
0.01
Bioconcentration Factor
plankton to water = 2,000
Mysis
Pontoporeia
Smelt
0.09
0.32
1.7
zooplankton to water = 9
invertebrate to zooplankton = 3.6
forage fish to invertebrate = 5.3
Lake Trout
Herring Gull
5.6
60.0
predator to forage fish = 3.3
gull egg to water = 12,000,000
gull egg to predator fish = 10.7
gull egg to phytoplankton = 6,000