Across
- 3. planting different crops to prevent erosion
- 7. two primary atmospheric gases
- 8. harmful substance in the air
- 10. can not renew
- 11. when hydrocarbons and nitrogen oxides react
Down
- 1. a renewable source from the sun
- 2. reduce erosion by 75%.
- 4. we breathe it
- 5. two primary atmospheric gases
- 6. rocks removed from the ground
- 9. solid waste leftovers