Within the past few decades, humans have dramatically altered the earth?s nitrogen (N) cycle. Introduction of reactive nitrogen (N) into the biosphere by humans now exceeds the rate of biological N2-fixation in native terrestrial ecosystems (Galloway et al. 2004). This increased reactive N is due primarily to N fertilizer production and fossil fuel combustion used to support the food and energy demands of a rapidly expanding human population. The negative human and environment health effects of this increased N are many (Galloway et al. 2008; Howarth et al. 2005; UNEP and WHRC 2007). Denitrification is the main process that permanently removes fixed N from the environment. Denitrification, the microbial production of N2 from nitrate [...]
