Pollution/Energy

2. A solid compound of methane trapped in ice crystals, often found in marine sediments.
3. A measure of the rate at which a material breaks down and therefore the length of time it remains.
4. A measure of the ease with which a material breaks down.
6. An issue related to general body cells, but not the gonads (ovaries and testes).
8. Exposure to a substance or symptoms that appear rapidly.
10. Exposure to a substance or symptoms that appear over long periods of time.
12. Embankments that absorb and deflect noise, especially around mines, airports and major roads.
13. A wall that surrounds a tank which would contain the contents if the tank leaked or burst.
14. Relating to ovaries and testes.

1. A method of decontaminating a polluted site by growing plants that absorb the toxic materials.
5. Stress cracking of a material caused by repetitive vibrations induced by sound.
7. A method of relieving traffic congestion which allows driving on the hard shoulder and reduces the speed limit during periods of heavy traffic flows.
9. so the body acts as a barrier reducing the noise that reaches the ground.
11. in this design the engines can be located on top of the