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12 years ago
I am preparing my examination on next week.
I face a challenge question on the textbook but it does not provide any answers.
Can someone help me? Two questions distribute 10 marks for each. How can I answer point by point to get all the marks in this questions. Many thanks!

Consider this problem. A train carrying a tank of Chemical X has overturned on a railway bridge. The bridge runs over a river located in a national park (see Figure 1).




Figure 1 Chemical X spilled into the river and onto the riverbank on the right (grey arrow). The river is surrounded by four small fish ponds (A-D), as well as waterbird habitat (shaded areas). Fish pond B is connected to the river by underground water flow, and the waterbird habitat on the right riverbank includes fish pond D. There are two fish species in the area, one that lives in the river, and one that lives in the fish ponds.

You know that Chemical X is a chlorinated, lipophilic pesticide. You also know that the waterbirds in the area consume primarily fish.

(a)   What do you think will be the most likely distribution of Chemical X in this environment? Justify your answer with reasons.    10 Marks

(b)   With reference to the diagram above, which habitats and which living organisms do you think would be most at risk? Justify your answer.    10 Marks
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12 years ago Edited: 12 years ago, bio_man
(b)   With reference to the diagram above, which habitats and which living organisms do you think would be most at risk? Justify your answer.    10 Marks

The birds more so than anything because they are the top predators in this community. The increase in the concentration of a substance in living organisms, called biomagnification, can occur at each step of the food chain. This is an issue that faces organisms where a certain chemical elements to accumulate or build up within food chains. Because biomagnification occurs at each step of the food chain, organisms at higher trophic levels can amass especially large concentrations of chemical X in their lipids. A typical pattern of biomagnification is illustrated below, which shows the relative amounts of DDT found in a Lake Ontario food chain. The largest concentration of the insecticide was found in gulls, tertiary consumers that feed on fish that, in turn, eat small insects. An unanticipated effect of DDT on bird species was its interference with the metabolic process of eggshell formation. The result was thin-shelled eggs that often broke under the weight of incubating birds. DDT was responsible for a dramatic decrease in the populations of many birds due to failed reproduction. Relatively high levels of the chemical were also found to be present in some game fish, which became unfit for human consumption.

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12 years ago
can someelse help me on queston A
Please Crying Face
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Staff Member
12 years ago
(a)   What do you think will be the most likely distribution of Chemical X in this environment? Justify your answer with reasons.    10 Marks

C and D will most likely be affected since there is a barrier separating those two regions from the other.
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