Other
Elmhurst College: Virtual Chembook: Carbon Cycle
A step-by-step discussion of the stages in the carbon cycle. Each step includes a diagram further explaining the processes involved, as well as pictures depicting combustion, respiration, photosynthesis, and decomposition.
University of Illinois
University of Illinois: Illinois State Water Survey: Nitrogen Cycle: Human Impact on the Nitrogen Cycle
An overview of the impact of human activities on the environment and how those actions effect the nitrogen cycle.