acid rain: A destructive form of pollution that is caused when sulfur dioxide and nitrogen oxide interact with precipitation in the atmosphere.

aquifer: Geological basins beneath the earth where groundwater is found.

biohydrometallurgy: A form of technology that uses natural microorganisms instead of chemicals to remove metals from rock.

carbon dioxide (CO₂): A gas that occurs naturally in the atmosphere, and is also produced during the decaying of living things or when fossil fuels are burned.

fossil fuels: Crude oil, coal, and natural gas that formed from the decaying remains of ancient organisms.

gene: The chemical "blueprint" that determines an organism's specific traits.

genetic modification (GM): Altering the genetic material of cells or organisms to enable them to perform new functions (also called genetic engineering).

global warming: An increase in the average global climate over a period of time.

greenhouse effect: The natural process whereby atmospheric gases act...