Stable Isotopes as Tracers of Anthropogenic Nitrogen Sources, Deposition, and Impacts

The global nitrogen cycle has been perturbed by human activities, including agriculture, land-use change, and fossil fuel burning. This perturbation ranges from the local to global scale, as anthropogenic reactive nitrogen can be transported over long distances in the atmosphere, in groundwater, and in stream networks and can even impact the open ocean. Stable isotope signatures characteristic of reactive nitrogen can be used to trace its deposition in the present day, as well as in the past. Here we focus on the use of stable isotopes to trace the sources, transport, and impacts of anthropogenic nitrogen in the modern nitrogen cycle.