Overview
  Biogeochemical Cycles
  Spheres of B. Cycles
  Nitrogen Properties
  Simple Nitrogen Cycle
  Human Influences
  Spheres of the N Cycle
  Choose a Sphere

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Glossary

 
Illinois Council on Food and Agricultural Research (C-FAR)
Strategic Research Initiative on Water Quality
Project 00Si-040-5A-MBL


 

CONCEPTUAL MODEL OF NITROGEN CYCLING

Contents:
1. Overview
    Instructions to Reviewers
2. Biogeochemical Cycle
3. Spheres of Biogeochemical Cycles
4. Nitrogen Properties
5. Simplified Nitrogen Cycle
    Abridged Version
Full Text Version
6. Human Influences on the Nitrogen Cycle
7. Spheres of the Nitrogen Cycle
8. Choose a Nitrogen Cycle Sphere
    Atmosphere
Biosphere
Geosphere
Hydrosphere

Principal Investigator:
    Derek Winstanley

Co-Principal Investigators:
    Mike Demissie
    Steven E. Hollinger

Contributors:
    Kingsley M. Allan
    Deva K. Borah
    Yiping Guo
    Thomas R. Holm
    Laura L. Keefer
    Walt Kelly
    Edward C. Krug
    Kevin B. Merrifield
    Gary J. Stensland

Project Overview:
Nitrogen (N) is an essential element in all living matter. If N is deficient in the environment, it can limit biological growth and productivity. If N occurs in sufficient quantities, it can lead to eutrophication (organic over-enrichment) of surface waters and accumulation of toxic amounts of nitrate (NO3-) in terrestrial vegetation.

A national drinking water standard exists for nitrate (NO3-N) concentration (10 mg/L) and some surface-and ground waters in Illinois exceed this. The United States Environmental Protection Agency (USEPA) has recently set new criteria for N concentrations, which are to provide a basis for states to establish new standards. The establishment of N criteria and standards must also take into consideration downstream effects of excess N concentrations and loads, such as eutrophication of estuaries and coastal waters. As N is implicated in eutrophication and hypoxia (depletion of dissolved oxygen) in coastal waters of the Gulf of Mexico, it is likely that the transport of excess N from Illinois and other states in the Mississippi River Basin to the Gulf of Mexico via the Mississippi River will be considered in setting N criteria and standards in Illinois.

Scientists need to be able to account for all the sources, transformations, and pathways of N in the environment to be able to determine the confidence, efficiency and effectiveness of N control strategies and policies.

The purpose of this project is to provide an improved scientific basis for developing and testing improved mathematical process models for simulating the biogeochemical cycling of N in Illinois' environments, and for conducting N mass-balance studies. The application of such models and the conduct of improved mass-balance studies will provide decision makers with data and tools to determine, with known confidence, the need for further N control and the efficiency and effectiveness of N control strategies and policies.

The project is jointly funded by the Illinois Council on Food and Agricultural Research (C-FAR) and the Illinois State Water Survey (ISWS). The focus of the C-FAR funded project is the development of a suite of conceptual models of N cycling in a number of environments in Illinois which can also serve as an educational tool. Once developed these models will be presented on the Web and can be accessed by the general public and interested researchers. Comments and suggestions for modification and improvement will be solicited and incorporated into the Web site.

The objective for the ISWS component is to conduct a thorough literature review to better quantify the processes and rates of N cycling for selected Illinois watersheds. Where possible, the temporal and geographical scales will be identified at which different transport methods function. The specific objectives are: i) identify and quantify, with confidence levels, the processes and rates of N cycling in the 1990s; ii) express these in a graphical, Internet-based presentation, with references; and iii) prepare and distribute a report.

This is the Internet-based presentation of the C-FAR project data.

The presentation is in the form of increasingly more complex and detailed processes and rates of N cycling. We start by discussing the general concept of biogeochemical cycles. We then identify the 4 major conceptual spheres (reservoirs) and fluxes among spheres and provide more detailed information about N cycling within and among the four spheres. All the above information provides a basis for improved mathematical modeling of N cycling and N mass balance studies in Illinois watersheds.


Overview w B. Cycle w Spheres w N Props w N Cycle w Influences w N Spheres