Call for Papers (pdf)

WHRC

May 2-5, 2004

The Woods Hole Research Center

Workshop Summary

During the last few decades, the introduction of reactive nitrogen (N) into the biosphere by food and energy production has been greater than rates of N fixation in native terrestrial ecosystems. By far the largest uncertainty about the human domination of the N cycle on all scales is the amount of reactive N that is converted back to N2 during the last step of denitrification. Without this knowledge, it is impossible to determine the rate of accumulation of reactive N in most environmental reservoirs, and thus impossible to assess its long-term consequences. Nitrogen interacts with carbon and other nutrient cycles and has numerous cascading effects on water and air quality and climate. An improved understanding of where, when, and how much reactive N is denitrified could contribute to finding solutions to the problems created by excessive reactive N in the environment.

Unfortunately, we have little knowledge about rates of denitrification across landscapes and waterscapes. We know the environmental conditions under which denitrification occurs, but reliable quantification of N2 production in the field is still relatively rare. There are three primary reasons for lack of knowledge about N2 production: (1) it is difficult to measure due to the high atmospheric background concentrations; (2) N2 production rates are very heterogeneous in space and time; and (3) there is a lack of synergy between the scientific communities that determine N2 production rates.

We held a 3-day workshop in May 2004 of about 50 participants to focus on quantification of N2 production via biological denitrification. The objectives of this workshop were: (1) to evaluate the state of our knowledge of denitrification rates in a wide range of terrestrial and aquatic ecosystems; (2) to compare methodologies that have been adopted by different scientific disciplines, with the expectation that collaborations across disciplines could yield methodological advances; and (3) to chart out the current weaknesses and the actions needed to address those weaknesses for an improved global assessment of where, when, and how much reactive N is converted to N2 in the biosphere. Two important considerations were superimposed over a matrix of ecosystem types and methodological approaches: (1) What are the appropriate scales over which N2 production can and should be measured?; and (2) How can models be integrated with the measurements to improve mechanistic understanding of the processes and permit estimation of fluxes at larger spatial scales, longer temporal scales, and across a range of forecasted scenarios? The results of the workshop will be published as one or more synthesis papers in a peer reviewed journal. A final report is also available at this web site.

The broader impacts of this activity include an effort to direct our scientific understanding of the N cycle toward finding solutions to society’s concerns about eutrophication of the biosphere. The proposed workshop was organized as an integral part of the International Nitrogen Initiative (INI), a joint project of SCOPE and IGBP. The overall goal of the INI is to optimize nitrogen's role in sustainable food and energy production, while minimizing negative effects on human health and the environment. Hence, this workshop is part of an effort that has board implications for society by contributing knowledge to future management the global N cycle to meet objectives of both food security and environmental quality.