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A synthesis of regional inputs and damage costs of reactive nitrogen in the United States
Citation:
Sobota, D., J. Compton, AND S. Singh. A synthesis of regional inputs and damage costs of reactive nitrogen in the United States. Presented at International Nitrogen Initiative Conference, Kampala, Uganda, November 18 - 22, 2013.
Impact/Purpose:
Sound management of reactive nitrogen (N) requires up-to-date spatial data describing N inputs by source and information relating health and environmental impacts to specific N sources. ORISE post-doc Dan Sobota, together with EPA ecologist Jana Compton and NRC post-doc Shweta Singh, present a new analysis in which we connect spatial data on current (1990s – 2000s) watershed N inputs in the conterminous United States (US) to benefits and damage costs associated with specific N sources. To do this, we estimated total N inputs to watersheds (8-digit US Geologic Survey Hydrologic Unit Codes) for the late 1990s – early 2000s from existing data and landscape models. Our analysis suggests that at the national scale, the impacts of N released to the environment on human health and coastal ecosystems currently outweigh the direct economic benefits of enhanced crop production by more than twofold.
Description:
We estimated the fate of N in crops and in the environment (air, land, freshwater, groundwater, and coastal zones) with published coefficients describing nutrient uptake efficiency, gaseous emissions, and leaching losses. Benefits and damage costs of anthropogenic N inputs were estimated by multiplying specific N inputs with estimates of health, environmental, and climate benefit/damage costs (2000 US dollars) per unit of N. Our analysis showed that current N inputs range from <5 kg N ha-1 yr-1 in the Western US to >100 kg N ha-1 yr-1 in the Upper Midwest. Synthetic fertilizer was the single largest anthropogenic N source to 41% of watersheds, followed by atmospheric deposition (33%). Crop profits due to N fertilizers ranged from $0.01 to $142 million among watersheds, with a median of $6 million. Damage costs due to N ranged from $12 to $344 million among watersheds, with a median of $22 million. Crop profits exceeded total damage costs in only 5% of watersheds. Damage associated with NOx was the single largest cost among watersheds (47%), followed by N loading to coastal zones (40%). PLEASE NOTE: complete abstract is attached - the entire abstract exceeded the space in STICS.