16.4: Nutrient Cycles Last updated Jan 3, 2021 Save as PDF 16.3I: Freshwater Environments 16.4A: Sources and Sinks of Essential Elements Page ID8731 BoundlessBoundless ( \newcommand{\kernel}{\mathrm{null}\,}\) Topic hierarchy16.4A: Sources and Sinks of Essential Elements16.4B: The Carbon Cycle16.4C: Syntrophy and Methanogenesis16.4D: The Phosphorus Cycle16.4E: The Nitrogen Cycle16.4F: The Sulfur Cycle16.4G: The Iron Cycle