Keywords: ammonification, anthropogenic CO2 emissions, assimilation, biogeochemical cycles, biological components of the earth system, biological nitrogen fixation, decomposers, denitrifying bacteria, eutrophication, evaporation, evapotranspiration, fluxes, greenhouse gases, groundwater discharge, infiltration, land use change, leaching, nitrification, photosynthesis, physical components of the earth system, pools, precipitation, primary producers, respiration, streamflow, surface runoff

Summary: In this module, the following topics will be covered: 1) biogeochemical cycle, 2) the natural cycles of carbon, water, and nitrogen, and 3) important ways human activity disrupts those cycles.