University of Missouri
University of Missouri: The Nitrogen Cycle
This resource provides an explanation, accompanied by diagrams, of the nitrogen cycle, and also about how it can impact on water quality.
National Earth Science Teachers Association
Windows to the Universe: Biogeochemical Cycles
Biogeochemical cycles happen when individual elements are recycled over and over in different parts of the Earth. Two examples are the Nitrogen Cycle and Carbon Cycle. Read an explanation of biogeochemical cycles and view a diagram of...