Damage costs associated with both GHG and N were calculated for different usage categories (electricity, food, commuting, etc.). For N only, damage costs were also calculated for social-environmental sectors (human health, agriculture, ecosystems, climate), various media (land, water, air), and different N types (NO3, NH3, N2O, dissolved N). Damage costs associated with specific N fluxes were measured in terms of dollar per kg N released to the environment. The specific damage costs were largely obtained from a regional study of the Chesapeake Bay watershed (Birch et al., 2011), in which UVA is located, supplemented with other values from the literature (Compton et al., 2017 ). The values represent incremental or marginal increases in cost associated with the impacts of N use on a per unit of N basis and assume a linear response function (see Supplementary Table S9 ).
For the social costs of GHG (CO2-C and N2O-N), there is significant variance in the estimates depending on scope (global vs. national impacts) and discount rates. In a literature review, Tol (2005 ) found modal estimates of only $2/t GHG and concludes that mean values are likely less than $50/t GHG. The Interagency Working Group on the Social Cost of Greenhouse Gases (2016 ) estimated a global-scale social cost of GHG of from $14 to $74 per metric ton of carbon dioxide equivalent (MTCDE) for a range of discount rates, while current estimates from the EPA for national costs are from $1 to $7 per MTCDE. Values of $30 per ton of CO2 equivalent were used as an intermediate value. All dollar values were adjusted for inflation and pegged to the US dollar in 2016 using the consumer price index (US Bureau of Labor Statistics, n.d. ), to coincide with the 2016 IEFT data.
Marginal damage costs associated with GHG and N released by UVA were calculated using the IEFT based on GHG and N release by chemical compound and mode of impact. The N release from NOx-N, NH3-N, and N2O-N were combined with the damage costs associated with those forms. Virtual N from food production was apportioned into dissolved N, NH3, NOx, and N2O (Houlton et al., 2013 ). The hydrologic N released to water was used to estimate the damages associated with release to surface water, groundwater, and coastal systems.
Currently, there are no damage cost evaluations completed for P and W. If these data become available in the future, they can be included damage cost estimations.
For the social costs of GHG (CO2-C and N2O-N), there is significant variance in the estimates depending on scope (global vs. national impacts) and discount rates. In a literature review, Tol (2005 ) found modal estimates of only $2/t GHG and concludes that mean values are likely less than $50/t GHG. The Interagency Working Group on the Social Cost of Greenhouse Gases (2016 ) estimated a global-scale social cost of GHG of from $14 to $74 per metric ton of carbon dioxide equivalent (MTCDE) for a range of discount rates, while current estimates from the EPA for national costs are from $1 to $7 per MTCDE. Values of $30 per ton of CO2 equivalent were used as an intermediate value. All dollar values were adjusted for inflation and pegged to the US dollar in 2016 using the consumer price index (US Bureau of Labor Statistics, n.d. ), to coincide with the 2016 IEFT data.
Marginal damage costs associated with GHG and N released by UVA were calculated using the IEFT based on GHG and N release by chemical compound and mode of impact. The N release from NOx-N, NH3-N, and N2O-N were combined with the damage costs associated with those forms. Virtual N from food production was apportioned into dissolved N, NH3, NOx, and N2O (Houlton et al., 2013 ). The hydrologic N released to water was used to estimate the damages associated with release to surface water, groundwater, and coastal systems.
Currently, there are no damage cost evaluations completed for P and W. If these data become available in the future, they can be included damage cost estimations.
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