The document discusses three biogeochemical cycles - the water cycle, nitrogen cycle, and carbon cycle. The water cycle describes how water moves between the atmosphere and Earth's surface through processes like evaporation and precipitation. The nitrogen cycle involves nitrogen moving between the atmosphere, soil, organisms and back through processes like nitrogen fixation and decay. The carbon cycle describes carbon moving between the atmosphere, living things, and non-living matter through photosynthesis, respiration and the burning of fossil fuels.