Contribution of Animal Feeding Operations and Synthetic Fertilizers to Ammonia Deposition in Rocky Mountain National Park

IPNI-2008-USA-CO13

29 Jan 2010

2009 Annual Interpretive Summary


Ammonia (NH3) deposition has been identified as a concern from both human health and environmental protection standpoints and has recently been targeted by Colorado as a primary contributor to atmospheric and ecosystem changes in Rocky Mountain National Park (RMNP). Ecological ramifications, including increased forest and grassland productivity, eutrophication and acidification of fresh waters, hypoxia, and loss of biodiversity have been documented in terrestrial, freshwater, and coastal ecosystems. The Colorado Department of Public Health and Environment has estimated that 60% of the NH3 deposition in RMNP comes from agricultural activities with 40% from animal feeding operations and 20% from fertilizer. However, these estimates have not been verified by scientific measurement, and verification is especially important if future regulations require that agriculture be held accountable for NH3-related ecosystem damage. One promising way to track N to its original source is via N isotopic signatures (15N) since the ratio between the 14N and 15N isotopes is influenced by source. A major goal of this project is to assess the ability of isotopes as tracers, and in turn, to determine sources of NH3 contributing to N deposition in RMNP. To ensure that agricultural producers are being treated fairly, this study seeks to 1) determine the major sources of NH3 deposition in RMNP based on N isotopic signatures of different NH3 sources (i.e., agricultural, natural, and industrial), and 2). quantify the relative contribution of NH3 to RMNP from animal feeding operations, synthetic fertilizers, and other sources.

The first year of this study was spent determining the best approach to isotope analysis. After laboratory methods were established, construction of appropriate equipment was initiated. Progress over the past year includes completion of laboratory apparatuses and preliminary field sampling. To enhance simultaneous site sampling capabilities, three stationary samplers are being assembled for future NH3 studies with anticipated sampling to begin this winter. Once construction of the field samplers is completed, sampling in earnest is anticipated at sites involving fertilized soils, waste water remediation plants, vehicle emissions, etc. As with any novel and large-scale effort, considerable background work and evaluation is required. Support for this work is scheduled to terminate in 2010. CO-13F