What is DDT? What affect did it have on the population of brown pelicans in the 1960s?
· DDT is a chlorinated hydrocarbon. It was used as a pesticide until it was discovered it was causing damage to the ecosystem.
· The damage caused by DDT was high due to biological amplification. This occurs when levels of synthetic chemicals increase and concentrate into the flesh of organisms in higher trophic levels. The DDT began in plankton, but became stronger in concentration as the food web reached the brown pelican.
· The brown pelicans began to decline in number because the DDT softened the shells of the eggs. The eggs would crack before a chick would hatch. Then the adults would abandon the nest. The population declined rapidly.
· Rachel Carson wrote the book Silent Spring which discussed this very case in a way that was easy for everyone to understand. She began environmental activism and conservation in a way. She definitely changed the perspective about the impacts of humans on ecosystems
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A. forcing a layer of moist air to descend a mountain range B. creating shadows on the land surface C. heating the upper portion of an unsaturated layer of air D. lifting a stable air layer whose surface is humid and whose top is dry
What is the average length of time an atom spends in the ocean?
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What common social issues are faced by both Canadians and Americans? How do they differ?
What will be an ideal response?
Crystallization of molten rock can produce metamorphic rocks
Indicate whether this statement is true or false.