United States Environmental Protection Agency Office of Research and Development National Exposure Research Laboratory Research Abstract Government Performance Results Act (GPRA) Goal 4 Annual Performance Measure 266 Significant Research Findings: Evaluation of Significant Uncertainties in Modeling Nitrogen Cycling to Support Multimedia Management Strategies Nitrogen, one of the most critical elements necessary to life, is also a multimedia pollutant that contributes to significant deleterious effects on human health and ecosystems. Various forms of reactive nitrogen (Nr) contribute to tropospheric ozone formation, stratospheric ozone depletion, air toxics, acid rain, global climate change, cold sensitivity of trees, toxicity to fish and humans, and nuisance algal blooms. Because nitrogen can enter the environment via combustion, fertilizers, and human and animal wastes via air, water, and soil pathways, effective nitrogen management strategies depend on integrated models that deal with the important nitrogen forms, sources, and pathways. These models also operate efficiently and effectively within the regulatory frameworks available to air and water quality managers. The objective of this project was to identify and evaluate the uncertainties in nitrogen modeling that present the greatest barriers to effective multimedia management strategies, in order to help prioritize EPA research efforts, Research The original project plan was to convene a workshop bringing together Approach experts in nitrogen cycling and program office staff in order to prioritize a lengthy list of research recommendations that had emerged from an international nitrogen workshop convened by ORD in 2001. As plans for this workshop were being made, EPA's Science Advisory Board (SAB) announced their intention to form a panel to study the nitrogen as a multimedia pollutant. Rather than developing a priority list that would be overtaken by the recommendations of the SAB panel, it was decided that this project could more effectively contribute it's objectives by systematically interviewing air and water quality managers in EPA's Program and Regional Offices in order to determine the sources of uncertainty in multimedia nitrogen modeling that created the most significant barriers to management actions by EPA and the States and Tribes, and to provide the results to the SAB panel for their consideration. Scientific Problem and Policy Issues Project staff then identified the most significant regulatory opportunities ------- (development of Total Maximum Daily Loads (TMDLs) and best management practices (BMPs) for nitrogen in streams and estuaries, development of water quality standards and nutrient criteria, and benefits assessments to support various nitrogen emissions reductions programs proposed by EPA's Office of Air and Radiation. Project staff and their contractor attended the Office of Water Joint Coordinators meeting in November, 2003, and subsequently conducted structured interviews with the TMDL Coordinators from each of the EPA Regions and the staff at the Office of Air Quality Planning and Standards involved with benefits assessment. The draft results were tabulated and summarized and submitted to OW and OAR management for comment, and a final report prepared for delivery to the SAB Nitrogen panel, ORD, and the Programs and Regions. Results and An unexpected result of the project was discovery of the wide range of Impact differing opinions as to the needs and priorities among the Regions with respect to nitrogen as a water pollutant. The most common regulatory endpoint was eutrophication of streams and estuaries, but nitrate and ammonia toxicity were the most significant in other regions. The most significant uncertainties were modeling of atmospheric deposition and non- point source runoff, depending on whether the regions considered atmospheric deposition as a component of TMDLs. Priorities and approaches for developing nitrogen criteria and standards varied significantly among regions, and there was significant differences of opinion as to the timeliness of new research tools (ranging from now or never to whenever). Most coordinators noted that because nutrient criteria for nitrogen would not be implemented until 2006-08, with many TMDLs to follow, research projects of 3-5 years duration could have a positive impact. Opinions as to important emerging issues with respect to nitrogen also varied significantly among regions, but the most common theme was the contribution of non-point and atmospheric sources of nitrogen to coastal waters. Among the most useful research outcomes would be: - Effects-based approaches for nutrient criteria development (determining appropriate aquatic effects endpoints, threshold nutrient concentrations for adverse effects, and linkages of effects endpoints with appropriate nutrient species) - Better understanding of the impacts of nitrogen-to-phosphorous (N:P) ratios and non-baseflow conditions -D Criteria effective for threatened and endangered species -D Tools for interpolating nitrogen deposition data - Source identification for non-point source N loads - High-flow criteria - Developing better mathematical forms for criteria - Developing truly multimedia N models with appropriately interlinked ------- time and space scales -D Better targeting approaches and methods for determining the effectiveness of BMPs -D Better modeling of the effects of denitrification in removing N from streams -D The beneficial effects of alternative wastewater technologies for removing N -D Better modeling of N loads from concentrated animal feeding operations (CAFOs). In the area of multimedia benefits estimation, the most useful research outcomes appear to be: -D Updating benefits related to reducing N emissions to air (the Chesapeake Bay data are 20 years old!) -D Better understanding of air N emissions from CAFOs -D Being able to model costs and benefits of the "nitrogen cascade" (the idea that a molecule of NOx released to the air can have multiple, different environmental costs and benefits as it is transported and transformed to reactive N entering the world ocean. These research suggestions are based on the priorities identified during the interviews. This project was conducted by a team of NERL staff scientists and an outside contractor consultant with many years of experience in water management (FTN Associates). EPA's Office of Water and Office of Air Quality Planning and Standards and TMDL Coordinators in each of EPA's Regions cooperated and provided technical input. The results are summarized in an internal EPA report: Assessment Science Improvements to Enhance Regulatory Programs Related to Nitrogen as a Multimedia Pollutant. The report has been internally reviewed and cleared, but is available for distribution only within EPA. It will be provided to the SAB Panel on Nitrogen through the ORD liaison with that panel. Future Research The information resulting from this project should be useful to inform ORD research planners and useful to the SAB integrated nitrogen planning team deliberations. Questions and inquiries can be directed to: Robin Dennis, Ph.D. US EPA, Mail Drop E243-01 National Exposure Research Laboratory Research Triangle Park, NC 27711 Phone: 919/541-2870 E-mail: dennis.robin@epa.gov Research Collaboration and Research Products Contacts for Additional Information Federal funding for this research was administered under EPA DOC/COMMITS Contract # 50-CMAA-9-00065. ------- ------- |