This animation of the biogeochemical nitrogen cycle illustrates the main steps of the cycle in air, water, and soils. The video explains and connects the many forms of nitrogen, such as ammonia, ammonium, hydroxylamine, nitrite, nitrate, nitrous oxide, and nitrogen dioxide, and explains the role of nitrate in nitric oxide signaling in the human body. The video shows how nitrogen fertilizers influence the nitrogen cycle and cause algal blooms. The animation is built from Figure 1 in Edwards et al., 2024, doi.org/10.1016/j.scitotenv.2....
USGS video: www.usgs.gov/media/videos/ani...
Credits:
Except for those listed below, all images were drawn by USGS or modified from uncopyrighted images from Pixabay; all music and sound effects were also obtained from Pixabay, licensed under Creative Commons Zero (CC0) (pixabay.com)  (Science Documentary: pixabay.com/music/build-up-sc...)
Nitrogenase molecule: Jjsjjsjjs. 2012. “Structure of Nitrogenase”. Licensed under CC BY-SA 3.0 Deed. Nitrogenase - Nitrogenase - Wikipedia 
Salivary glands: Biyolojiyabikurdi. 2019.“Mouth and salivary gland ku.png”. Licensed under Creative Commons BY-SA 4.0 DEED. File:Mouth and salivary gland ku.png - Wikimedia Commons