Nitrogen is an important molecule that makes up nearly 78 percent of the atmosphere. Burning fossil fuels and using fertilizers for agriculture are two ways that this number can increase. But the atmosphere isn’t the only place that nitrogen is found – it is also found in bodies of water. Of the nitrogen that is spread in fertilizers, only 25-30 percent is absorbed by plants, so that leaves a lot of nitrogen left to either be absorbed by the atmosphere or into water. Figure 1 shows the intricacies of the nitrogen cycle, from Physical Geography.net’s Fundamentals ...