Cameo

PCBs in the Last Frontier by Michael Tessmer

Part III—Significant Difference?

Recent observations of PCB levels in arctic lakes have shown that the levels of PCBs are not the same in all lakes that are near each other and at the same altitude. In fact, lakes at the terminus (i.e., the start) of river systems had higher PCB levels than completely isolated lakes that were close by.

Questions

  1. What possible “explanatory story” might explain the observation described above? (Hint: Think of species that leave a lake but return later in life.)
  2. How would you test your hypothesis made above?

Go to Part IV—Riddle Solved


Originally published at http://www.sciencecases.org/last_frontier/last_frontier3.asp

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