Nitrogen in urban infrastructure

The nitrogen cycle is the sum of the processes by which nitrogen moves and transforms throughout the environment. While there are a number of natural factors that contribute to natural nitrogen biogeochemistry, the establishment of human infrastructure has created a number of unique nitrogen environments. Such infrastructure includes water and wastewater conveyance systems. Stormwater pipes allow for nitrogen compounds in runoff to be conveyed directly to receiving water bodies. Wastewater pipes transport organic nitrogen in sewage from homes to treatment plants. Water pipes where chloramine is used as a disinfection also move nitrogen around the environment.

Wastewater and stormwater collection pipes have long been assumed to have minimal biogeochemistry associated with nitrogen cycling.  However, throughout the United States pipe systems are beginning to reach and exceed their design lives. Thus, many of such systems have been substantially degraded, leading to significant exchanges of water and wastewater between the built and natural environment in ways that may alter nitrogen transformations.  The present work seeks to examine the altered fate of nitrogen in subsurface infrastructure.