Systems and Cycles Assignment-PZ

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Across
  1. 1. is a gas that contributes to the greenhouse effect.
  2. 3. This process involves first changing the ammonia to nitrites, then converting nitrites to nitrates.
  3. 5. When living things die, the nitrogen in their decaying organic matter is converted back to ammonia by yet another type of bacteria.
  4. 8. Location in which atoms of an element are held for a long period of time.
Down
  1. 2. The seventh element on the periodical table.
  2. 4. is a type of sedimentary rock made mostly of carbon.
  3. 6. The eighth element on the periodic table.
  4. 7. The sixth element on the periodic table.