ABSTRACT
This chapter describes wetland nitrogen cycle, summarizes knowledge about environmental factors that control nitrogen transformations, and provides approaches that can be used to design wetland treatment systems to treat nitrogen. Nitrogen compounds are among the principal constituents of concern in aquatic systems because of their role in eutrophication, and their impacts on aquatic invertebrate and vertebrate species. Treatment marshes, by virtue of the defining ranges of nitrogen species concentrations, are agronomic systems. Organic nitrogen compounds are a significant fraction of the dry weight of wetland plants, detritus, microbes, and soils. The total nitrogen content of living biomass in marsh wetlands varies considerably among species, among plant parts, and among wetland sites. The several nitrogenous chemical species are inter-related by a reaction sequence. Nitrogen is speciated in several forms in wetlands, and partitioned into water, sediment and biomass phases. The wetland nitrogen cycle includes a number of relatively minor physical processes, including atmospheric nitrogen inputs, ammonia adsorption, ammonia volatilization and diffusion.
