Biomagnification of Mercury & DDT Flashcards

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Questions and Answers

What is biomagnification?

Biomagnification is the increase in concentration of a substance, such as mercury, that occurs in a food chain.

Where does mercury exist?

Mercury occurs naturally in the earth's crust and is released into the environment from volcanic activity, weathering of rocks, and human activity.

What is the main cause of mercury in our environment?

Human activity, particularly from burning of coal and other fossil fuels.

How does mercury get into the food chain?

Mercury is released into the environment and then is absorbed by plants. Signup and view all the answers

After the plants absorb the mercury, how does it magnify through the food chain? If each piece of plant material has 1 microscopic drop of methyl mercury and one insect eats 25 pieces of plant material, that would mean that each insect would have _____ microscopic drops of methyl mercury in its body.

25 Signup and view all the answers

If one small fish needs 10 insects to live, then one fish would have _____ microscopic drops of methyl mercury.

2500 Signup and view all the answers

One big fish eats 5 small fish to live. Therefore, one big fish would collect a total of _____ microscopic drops of methyl mercury in its body.

12500 Signup and view all the answers

If we eat 1 big fish a day for 3 days, we would collect a total of _____ drops of methyl mercury in our body over the 3 days.

3750 Signup and view all the answers

How was the Bald Eagle affected by biomagnification and bioaccumulation?

The use of DDT interfered with the bird's calcium metabolism, making it either sterile or unable to lay healthy eggs. Signup and view all the answers

What was 'Operation Cat Drop'?

Cats were brought in from neighboring towns to help control the rat population after many cats were killed or sickened by DDT. Signup and view all the answers

Why was DDT used in the first place?

The government was trying to kill mosquitoes that carried malaria. Signup and view all the answers

Why did DDT have a more deadly effect on larger animals (like cats) than on gecko lizards?

Biomagnification caused larger accumulation of DDT in cats. Signup and view all the answers

Draw a food chain that demonstrates how DDT traveled from the mosquito to the cat.

Insects poisoned by DDT were eaten by gecko lizards, which were then eaten by domestic cats. Signup and view all the answers

How does this story demonstrate bioaccumulation?

Bioaccumulation occurs when an organism absorbs a substance at a rate faster than it can be excreted. Signup and view all the answers

What other consequences of human activity can you compare this story to?

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Study Notes

Biomagnification Overview

Biomagnification refers to the increasing concentration of substances, such as mercury, as they move up the food chain.
This process can lead to harmful levels of toxic substances in higher trophic level organisms.

Mercury Sources

Mercury is naturally present in the Earth's crust.
It is released through volcanic activity, rock weathering, and primarily human activities like coal burning.

Human Impact on Mercury Levels

Human activities, especially fossil fuel combustion, significantly contribute to mercury's release into the environment.

Mercury Entry into the Food Chain

Mercury enters the food chain when plants absorb it from rainwater, which may contain mercury.

Trophic Level Concentration

Each plant piece contains trace amounts of methyl mercury.
A single insect consuming multiple plant pieces accumulates a larger quantity of methyl mercury.

Fish Mercury Accumulation

A small fish consuming many insects further magnifies the mercury concentration.
As the food chain continues, larger fish that consume smaller fish accumulate even greater amounts of methyl mercury.

Human Consumption

Regular consumption of large fish leads to significant methyl mercury accumulation in humans, exemplifying biomagnification.

Bald Eagle Case Study

In the mid-20th century, DDT use led to reproductive issues in Bald Eagles, including egg brittleness and sterility.
DDT disrupted calcium metabolism in these birds.

Operation Cat Drop

Cats were introduced to control rat populations after many were affected by DDT exposure.
DDT used to eliminate malaria-carrying mosquitoes inadvertently harmed local cat populations.

Purpose of DDT Use

DDT was initially used by the government to combat malaria by killing mosquitoes infecting humans.

Differential Impact of DDT

Larger animals, like cats, experienced heightened effects from DDT due to biomagnification, leading to severe health issues.

Food Chain Dynamics with DDT

The food chain illustrated the movement of DDT from poisoned insects to gecko lizards and then to domestic cats.
DDT exposure also occurred through direct contact, further impacting cats' health and local rodent populations.

Bioaccumulation Explanation

Bioaccumulation describes the build-up of harmful substances in an organism over time.
Cats exposed to DDT could not excrete it efficiently, leading to detrimental health consequences.

Broader Implications of Human Actions

The case of mercury and DDT highlights theme of unintended consequences in human activities, reflecting on previous lessons about environmental impacts.

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Description

Explore the concept of biomagnification through flashcards focusing on mercury and DDT. Learn how these substances increase in concentration within food chains and understand their environmental impacts. Ideal for students studying ecology and environmental science.