A multiple metrics approach to prioritizing strategies for measuring and managing reactive nitrogen in the San Joaquin Valley of California

Abstract

Human alteration of the nitrogen cycle exceeds the safe planetary boundary for the use of reactive nitrogen (Nr). We complement global analysis by analyzing regional mass flows and the relative consequences of multiple chemical forms of Nr as they 'cascade' through multiple environmental media. The goals of this paper are (1) to identify the amounts of Nr that flow through a specific nitrogen rich region, (2) develop multiple metrics to characterize and compare multiple forms of Nr and the different damages that they cause, and (3) to use these metrics to assess the most societally acceptable and cost effective means for addressing the many dimensions of Nr damage. This paper uses a multiple metrics approach that in addition to mass flows considers economic damage, health and mitigation costs and qualitative damages to evaluate options for mitigating Nr flows in California's San Joaquin Valley (SJV). Most analysis focuses attention on agricultural Nr because it is the largest flow in terms of mass. In contrast, the multiple metrics approach identifies mobile source Nr emissions as creating the most economic and health damage in the SJV. Emissions of Nr from mobile sources are smaller than those from crop agriculture and dairy in the SJV, but the benefits of abatement are greater because of reduced health impacts from air pollution, and abatement costs are lower. Our findings illustrate the benefit of a comprehensive multiple metrics approach to Nr management.

Managing a forgotten greenhouse gas under existing U.S. law: An interdisciplinary analysis

“…And because of the tightly coupled nature of the N cycle, efforts to reduce one particular component of the N cascade could impact N O emissions as well. Conversely, efforts to reduce N 2 O emissions could deliver a suite of benefits throughout the entire N cascade (Horowitz et al, 2016) (Velthof et al, 2014). Similar co-benefits could be achieved by implementing policies focused on reducing N 2 O emissions, a potential outcome this paper investigates.…”

“…For the damage costs associated with N pollution, we adapt the approach followed in Kanter et al (2015). We use a range of damage cost estimates, either based on attempts to monetize the economic impacts caused by the release of a kg of a particular N compound to the environment (Birch et al, 2010, Compton et al, 2011, Horowitz et al, 2016 or on the amount of money society is willing to pay to avoid these impacts (Gu et al, 2012, Van Grinsven et al, 2013. We then average these estimates to have one damage cost per N compound.…”

Integrated Modeling of U.S. Agricultural Soil Emissions of Reactive Nitrogen and Associated Impacts on Air Pollution, Health, and Climate

“…Agricultural soil Nr emissions can be estimated by emission factor methods, − which multiply N inputs by fixed factors; parametric models, ,,,− which compute emissions as functions of N inputs, meteorology, and other conditions; or mechanistic models, ,,,,− which represent nitrogen cycling as a series of processes such as nitrification and denitrification that are influenced by soil properties, meteorology, and farming practices. Because emission rates, sensitivities of air pollution to emissions, and human populations exposed to air pollution are all spatially heterogeneous, ,,− , it is important to assess agricultural Nr impacts employing a quantifiable index in a consistent and spatially explicit manner. , However, most previous studies simulated soil Nr emissions separately ,,,, (Table ) or insufficiently considered spatial heterogeneity or lacked an aggregate metric (Table S1). ,,,,,, Although a handful of studies have linked biogeochemical modeling with air quality modeling to capture the variable impacts of agricultural NO and NH 3 emissions on air quality and health, ,,,, the high computational burden of three-dimensional air quality models limits the number of cases that can be considered.…”

“…Because emission rates, sensitivities of air pollution to emissions, and human populations exposed to air pollution are all spatially heterogeneous, ,,− , it is important to assess agricultural Nr impacts employing a quantifiable index in a consistent and spatially explicit manner. , However, most previous studies simulated soil Nr emissions separately ,,,, (Table ) or insufficiently considered spatial heterogeneity or lacked an aggregate metric (Table S1). ,,,,,, Although a handful of studies have linked biogeochemical modeling with air quality modeling to capture the variable impacts of agricultural NO and NH 3 emissions on air quality and health, ,,,, the high computational burden of three-dimensional air quality models limits the number of cases that can be considered. Reduced-form models ease that burden by providing pre-calculated per-ton air pollution and monetized health impacts of each species emitted from each location and season. ,− Keeler et al applied a reduced-form air quality and health effect model to compute county-level impacts of fertilizer application in Minnesota, comparing the spatially variable health impacts of PM from NO x and NH 3 with the climate impacts of N 2 O.…”

Assessing the Social and Environmental Costs of Institution Nitrogen Footprints

“…Some of the research at regional scales has shown that the specific metrics chosen to illustrate these impacts are important. 7 , 11 For example, in the Chesapeake Bay watershed, the largest nitrogen sources did not cause the greatest damages because of the importance placed on the effects of air pollutio on human health. 7 These studies point to the benefit of examining the impact of environmental pollution using multiple metrics including flux, damage costs, abatement costs, and mortality.…”