10. What can contaminate a river as a result of dredging?
a. potash
C. placer deposits
b. seawater
d. muddy sediments

Why should the united state be concerned about air pollution in china?

What environmental cues and landmarks do the geese use to determine the timing and direction of their migration over the mountains? how do they find their way?

Explain why ecosystem diversity results in species diversity in a healthy biosphere