Answer to Question 1
Natural systems have developed in the presence of physical rhythms. Adding
dams or other diversions changes the resonant frequencies of the local bodies of water.
Because the life will have adapted to nature as it existed, changing the rhythm will change
the conditions in which the organisms live.
Answer to Question 2
No, this is not true for all materials. It is truer for some materials than for others.
As Fig. 10 .3 shows, aluminum, copper, lead (in particular), and zinc utilize recycled scrap in
significant amounts.