Tuesday 24 Jun 2014Development of a closed budget global nitrogen cycle model

Dr Diego Gomez -

Harrison 170 14:00-15:00

Nitrogen compounds emissions due to human activities have been increasing steadily since the introduction of modern agriculture and in particular, the utilization of the Haber-Bosch process to synthesize ammonia based fertilizers from atmospheric molecular nitrogen. These compounds can have a significant impact on water quality, human health, global warming, biodiversity and food availability. Nitrous oxide (N2O) has a global warming potential over 200 times greater than CO2; Nitrogen oxides (NOx) are a significant source of ground-level ozone formation; N2O breaks down in the stratosphere where it acts as a catalyst that destroys the ozone layer; ammonia-based fertilizer can form anoxic dead zones due to algal blooms in rivers, lakes and oceans. We are developing a global nitrogen cycle box model that considers the interactions between the three main geochemical compartments: atmosphere, hydrosphere and pedosphere with land biota (vegetation and crops). The model tracks the main groups of nitrogen species: molecular nitrogen, N2O, NOx, NHx, and nitrogenous organic matter. Interactions between the model compartments are treated as linear coefficients, first order coefficients, constants or time series, depending on the nature of the process. We are implementing the system using Simulink in MATLAB. The model incorporates anthropogenic emissions from agricultural activities, biomass burning and fuel utilization, from FAO, UNDEP, IPCC and a variety of other sources. We believe this is a timely study that could help guide policy and future research on emerging environmental technologies aimed at reducing global warming emissions. Focus on a carbon based point of view for life cycle assessments, while ignoring nitrogen compounds, could result in replacing one problem with another, potentially worse, problem.

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