Allison M Leach

University of New Hampshire | UNH · Department of Natural Resources & the Environment

The development of nitrogen footprint tools has allowed a range of entities to calculate and reduce their contribution to nitrogen pollution, but these tools represent just one aspect of environmental pollution. For example, institutions have been calculating their carbon footprints to track and manage their greenhouse gas emissions for over a deca...

The human use of reactive nitrogen (Nr) in the environment has profound beneficial and detrimental impacts on all people. Its beneficial impacts result from food production and industrial application. The detrimental impacts occur because most of the Nr used in food production and the entire amount of Nr formed during fossil fuel combustion are los...

Humanity's nitrogen pollution footprint has increased by a factor of six since the 1930s. A global analysis reveals that a quarter of this nitrogen pollution is associated with the production of internationally traded products.

Humanity’s enormous and increasing demand for the planet’s natural resources has resulted in a dramatic loss of biodiversity. Many of the pressures and underlying causes affecting ecosystems interact at a variety of scales from local to global. Trying to reverse or prevent further detrimental effects on nature within such a complex web of interdepe...

Evaluating sustainability stewardship at higher educational institutions is essential to working towards improving our environment. Many institutions have used environmental footprint indicators as a way to evaluate, track, and improve their impact on the environment. In this article, we present the web-based Integrated Environmental Footprint Tool...

Food and energy production have negative impacts due to the buildup of reactive nitrogen in the environment and subsequent nitrogen (N) impacts. To quantify the nitrogen footprint left in the environment by an individual, scientists from the University of Virginia USA developed a model to calculate nitrogen footprints, the N-Calculator, which trans...

Phosphorus (P) and nitrogen (N) are essential nutrients for food production but their excess use in agriculture can have major social costs, particularly related to water quality degradation. Nutrient footprint approaches estimate N and P release to the environment through food production and waste management and enable linking these emissions to p...

The nitrogen footprint tool (NFT) provides a novel way for communities to understand the environmental impacts of their collective activities and consumption. Reactive nitrogen (Nr; all N species except N 2 ) is created by the Haber–Bosch process for food production and as a by-product of fossil fuel combustion and two natural processes, biological...

We estimated the reactive nitrogen (Nr) lost per unit food Nr consumed for organic food production in the United States and compared it to conventional production. We used a nitrogen footprint model approach, which accounts for both differences in Nr losses as well as differences in productivity of the two systems. Additionally, we quantified the t...

Our aim in this paper is to describe an opportunity for physics students and faculty to learn about an environmental issue of much current interest: the quantification, or footprint analysis, of carbon dioxide (CO2) and reactive nitrogen emissions. These can originate from human activities such as energy use, food consumption, and transportation, a...

We define a family of environmental footprints. • We identify overlaps between different footprints. • We analyse how they relate to the nine planetary boundaries. • We discuss the relation with SDGs, WEFE nexus and ecosystem services. • We argue that the footprint family is a flexible framework. Editor: Damia Barcelo The number of publications on...

The number of publications on environmental footprint indicators has been growing rapidly, but with limited efforts to integrate different footprints into a coherent framework. Such integration is important for comprehensive understanding of environmental issues, policy formulation and assessment of trade-offs between different environmental concer...

Nitrogen (N) footprints quantify the anthropogenic release of reactive nitrogen (Nr) from resource consumption, but do not connect to the resulting environmental impacts. Australia has the largest measured N footprint, but is generally perceived as a “green and clean” country. To explore this discrepancy, we developed an indicator, Nr spatial inten...

Reactive nitrogen (Nr; all species of nitrogen other than N2 gas) is a major cause of air and water pollution, with worldwide costs of billions in human health and ecosystem damages. The nitrogen (N) footprint, which quantifies the anthropogenic release of Nr from the production and consumption of both food and energy, has been used as an indicator...

Reducing nitrogen pollution across the food chain requires the use of clear and comprehensive indicators to track and manage losses. The challenge is to derive an easy-to-use robust nitrogen use efficiency (NUE) indicator for entire food systems to help support policy development, monitor progress and inform consumers. Based on a comparison of four...

Food production has tripled over the past half century and has allowed the world's population to increase by 4.5 billion people. This boom in food supply as a result of the Green Revolution avoided widespread famine but carried with it substantial environmental costs including depletion of freshwater resources, eutrophication from injudicious ferti...

People have increased the amount of reactive nitrogen (Nr) in the environment as a result of food production methods and consumption choices. However, the connection between dietary choices and environmental impacts over time has not yet been studied in China. Here we combine a nitrogen footprint tool, the N-Calculator, with a food chain model, NUF...

Anthropogenic sources of reactive nitrogen have local and global impacts on air and water quality and detrimental effects on human and ecosystem health. This article uses the Nitrogen Footprint Tool (NFT) to determine the amount of nitrogen (N) released as a result of institutional consumption. The sectors accounted for include food (consumption an...

A nitrogen (N) footprint quantifies the amount of reactive nitrogen released to the environment and can be measured at different scales. The N footprint of a university includes activities and consumption within its geographic boundar-ies as well as activities that support the institution. Determining system bounds of an N footprint depends on the...

The water footprint for fossil fuels typically accounts for water utilized in mining and fuel processing, whereas the water footprint of biofuels assesses the agricultural water used by crops through their lifetime. Fossil fuels have an additional water footprint that is not easily accounted for: ancient water that was used by plants millions of ye...

This article estimates the damage costs associated with the institutional nitrogen (N) footprint and explores how this information could be used to create more sustainable institutions. Potential damages associated with the release of nitrogen oxides (NOx), ammonia (NH3), and nitrous oxide (N2O) to air and release of nitrogen to water were estimate...

When multiple institutions with strong sustainability initiatives use a new environmental impact assessment tool, there is an impulse to compare. The first seven institutions to calculate nitrogen footprints using the Nitrogen Footprint Tool have worked collaboratively to improve calculation methods, share resources, and suggest methods for reducin...

We present the first nitrogen footprint model for a developing country: Tanzania. Nitrogen (N) is a crucial element for agriculture and human nutrition, but in excess it can cause serious environmental damage. The Sub-Saharan African nation of Tanzania faces a two-sided nitrogen problem: while there is not enough soil nitrogen to produce adequate f...

Once upon a time there was enough naturally occurring nitrogen (N) to provide food for the world's peoples. Then there was not in the western regions. Now there is due to industrially produced NH3. But this transition from plenty, to scarcity, to plenty has come with a tremendous environmental cost. This paper provides an historical overview of the...

Anthropogenic release of reactive nitrogen (Nr; all species of N except N2) to the global nitrogen (N) cycle is substantial and it negatively affects human and ecosystem health. A novel metric, the N footprint, provides a consumer-based perspective for Nr use efficiency and connects lifestyle choices with Nr losses. Here we report the first full-sc...

Nitrogen (N) management presents a sustainability dilemma: N is strongly linked to energy and food production, but excess reactive N causes environmental pollution. The N footprint is an indicator that quantifies reactive N losses to the environment from consumption and production of food and the use of energy. The average per capita N footprint (c...

Meeting the food needs of the growing and increasingly affluent human population with the planet’s limited resources is a major challenge of our time. Seen as the preferred approach to global food security issues, ‘sustainable intensification’ is the enhancement of crop yields while minimizing environmental impacts and preserving the ability of fut...

The question of how to minimize monetary cost while meeting basic nutrient requirements (a subsistence diet) was posed by George Stigler in 1945. The problem, known as Stigler's diet problem, was famously solved using the simplex algorithm. Today, we are not only concerned with the monetary cost of food, but also the environmental cost. Efforts to...

The New Dietary Interventions to Enhance the Treatments for weight loss (New DIETs) study was a 6-month weight-loss intervention in which adults (n = 63) were randomized to follow one of 5 different diets: vegan, vegetarian, pesco-vegetarian, semi-vegetarian, and omnivorous. Participants completed 24-hr dietary recalls and reported food expenditure...

It is now clear that the nitrogen problem is one of the most pressing environmental issues that we face. But in spite of the enormity of our influence on the N cycle and consequent implications for the environment and for human well-being, there is surprisingly little attention paid to the issue. While biodiversity loss and climate change have spaw...

In this paper we use nitrogen (N) footprints as indicators of potential environmental impacts of food production in Austria. These footprints trace the losses of reactive nitrogen (Nr), i.e. N compounds that are generally accessible to biota, in connection to the chain of food production and consumption. While necessary for food production, Nr is k...

The human alteration of the nitrogen cycle has evolved from minimal in the mid-19th century to extensive in the present time. The consequences to human and environmental health are significant. While much attention has been given to the extent and impacts of the alteration, little attention has been given to those entities (i.e., consumers, institu...

We propose a novel indicator measuring one dimension of the sustainability of an entity in modern societies: Nitrogen-neutrality. N-neutrality strives to offset Nr releases an entity exerts on the environment from the release of reactive nitrogen (Nr) to the environment by reducing it and by offsetting the Nr releases elsewhere. N-neutrality also a...

Humans increase the amount of reactive nitrogen (all N species except N2) in the environment through a number of processes, primarily food and energy production. Once in the environment, excess reactive nitrogen may cause a host of various environmental problems. Understanding and controlling individual nitrogen footprints is important for preservi...

Agriculture contributes about 70–75% of Canadian and US anthropogenic emissions of nitrous oxide (N2O). Although progress has been made in recent decades to improve nitrogen use efficiency (NUE) in North America, including a decrease in N2O emissions per kilogram of harvested grain, significant technological, economic, and social impediments remain...

Background/Question/Methods Chicken is the most consumed meat in the US, and production continues to intensify rapidly around the world. The intensive production of chicken and the grains used to feed them is a major contributor to reactive nitrogen, including nitrous oxide (N2O, a potent greenhouse gas), ammonia (NH3, a contributor to acidificat...

Ecosystem services are defined as the ecological and socio-economic value of goods and services provided by natural and semi-natural ecosystems. Ecosystem services are being impacted by many human induced stresses, one of them being nitrogen (N) deposition and its interactions with other pollutants and climate change. It is concluded that N directl...

It is clear that nitrogen (N) deposition impacts on the biodiversity and ecosystem services provided by natural and semi-natural ecosystems have been experienced in Europe, North America and Asia over the last 50 years. Impacts are also estimated to increase in line with increasing rates of N deposition in coming decades across the globe, especiall...

The alteration of the global nitrogen (N) cycle is creating severe environmental impacts. This paper analyses the increasing importance of the international trade of food and feed in the alteration of the N cycle at the global scale in two ways. First, using the information on food and feed trade across world countries, and assuming that N constitu...

The global nitrogen (N) cycle has been transformed by human use of reactive N as a consequence of increased demand for food and energy. Given the considerable impact of humans on the N cycle, it is essential that we raise awareness amongst the public and policy makers as this is the first step in providing individuals and governments the opportunit...

Nitrogen footprints connect entities, such as individuals, with the reactive nitrogen lost to the environment as a result of their activities. Reactive nitrogen contributes to a cascade of environmental and human health problems such as smog, eutrophication, acid rain, and climate change. We present the first institution-level model to estimate the...

The demand for more food is increasing fertilizer and land use, and the demand for more energy is increasing fossil fuel combustion, leading to enhanced losses of reactive nitrogen (Nr) to the environment. Many thresholds for human and ecosystem health have been exceeded owing to Nr pollution, including those for drinking water (nitrates), air qual...

Nitrogen over the ages! It was discovered in the eighteenth century. The following century, its importance in agriculture was documented and the basic components of its cycle were elucidated. In the twentieth century, a process to provide an inexhaustible supply of reactive N (Nr; all N species except N2) for agricultural, industrial and military u...

Global nitrogen fixation contributes 413 Tg of reactive nitrogen (Nr) to terrestrial and marine ecosystems annually of which anthropogenic activities are responsible for half, 210 Tg N. The majority of the transformations of anthropogenic Nr are on land (240 Tg N yr(-1)) within soils and vegetation where reduced Nr contributes most of the input thr...

Human actions have both intentionally and unintentionally altered the global economy of nitrogen (N), with both positive and negative consequences for human health and welfare, the environment and climate change. Here we examine long-term trends in reactive N (Nr) creation and efficiencies of Nr use within the continental US. We estimate that human...

Nitrogen (N) interacts strongly with climate change in determining the severity and extent of many human health and environmental issues, such as eutrophication, poor air quality, and the maintenance of a secure food system. We were motivated by such N-climate interactions and their environmental impacts as part of a broader assessment of N in the...

Presenting the first continental-scale assessment of reactive nitrogen in the environment, this book sets the related environmental problems in context by providing a multidisciplinary introduction to the nitrogen cycle processes. Issues of upscaling from farm plot and city to national and continental scales are addressed in detail with emphasis on...