Nitrogen Pollution: An Emerging Focus of Campus Sustainability Efforts

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Many colleges and universities are working to transition toward sustainability in their academic programs, operations and engagement with communities. A major emphasis of their efforts has been reducing the environmental harms associated with campus operations. Typical initiatives include reducing emissions of climate changing greenhouse gases; reducing consumption of energy, water and other resources; building ‘green’ buildings; purchasing ecologically and socially preferable food and other products; and reducing waste generation and disposal in landfills.

While many of these initiatives can and do reduce nitrogen pollution, this has not been a significant or deliberate focus of college and university sustainability programs. That may be changing.

The University of Virginia (UVA) set a goal in 2013 to reduce its emissions of reactive nitrogen 25 percent by the year 2025 relative to base year 2009, the first to do so. Another eighteen schools, including Dickinson College where I work, and a research lab have joined UVA in a research network to study their nitrogen pollution and consider similar policies.

Why are these colleges and universities focusing on nitrogen pollution? Nitrogen is an essential nutrient for all living things. But you can have too much of a good thing. Humans have altered the nitrogen cycle at an astounding scale, creating 4 to 5 times as much reactive nitrogen as natural terrestrial processes. The result is excessive accumulation of reactive forms of nitrogen such as nitrate, nitrite, ammonia, ammonium and nitrous oxide, causing detrimental local and global impacts on public health, ecosystem health, air quality, water quality and the climate. For example, dead zones in the Chesapeake Bay, Gulf of Mexico and more than 400 other locations in the world’s oceans are caused by excessive nutrients, principally nitrogen, that produce algal blooms, depleting oxygen in the water and diminishing marine life.

Colleges and universities contribute to this nitrogen pollution. They cause reactive nitrogen to be released into the environment, directly and indirectly, by feeding their students and employees, burning fossil fuels to heat and power their facilities, commuting to work, traveling for study abroad, fertilizing campus grounds and conducting research. With roughly 20 million students attending college in the U.S., their collective contribution to nitrogen pollution is significant. As institutions of learning and research, they are also well positioned to explore solutions and model best practices.

So, it makes sense that colleges and universities would take actions to reduce their nitrogen pollution. But an initial hurdle is that you can’t readily manage what you don’t measure. Measuring a college or university’s contribution to nitrogen pollution is complicated by the fact that much of the pollution happens far upstream and downstream of the institution, beyond the direct control of the school. For example, nitrogen is released to the environment at distant farms where animals are raised that become the meat served in a campus dining hall. A downstream example is nitrogen that is released at the sewage treatment plant that serves a campus.

To get over this hurdle, Allison Leach developed the Nitrogen Footprint Tool (NFT) for measuring an institution’s contribution to nitrogen pollution as her undergraduate thesis project at UVA. Leach, Professor James Galloway, and others at UVA applied the NFT in 2009-2012 to measure UVA’s footprint and to simulate scenarios for reducing nitrogen. This work was instrumental in persuading administrators at the university to set targets for reducing UVA’s nitrogen footprint.

Others are getting in on the act. Elizabeth de la Reguera calculated Dickinson College’s nitrogen footprint using the NFT for her senior thesis in 2014. Later that year, UVA invited Dickinson and a handful of other institutions to join the newly forming Nitrogen Footprint Tool Network (NFTN). The NFTN, managed by Elizabeth Castner at UVA, seeks to engage higher education institutions in research to understand and measure their nitrogen footprints, analyze nitrogen mitigation options, and act to reduce nitrogen pollution as an integral part of their sustainability programs.

Seven member institutions of the NFTN recently participated in a comparison study, measuring their nitrogen footprints and analyzing nitrogen pollution reduction measures using the NFT. The research has engaged undergraduate and graduate students, faculty members and staff at the participating institutions, which include Brown University, Colorado State University, Dickinson College, Eastern Mennonite University, the Marine Biological Laboratory (MBL), the University of New Hampshire and the University of Virginia. Reguera, now a Research Assistant at MBL and a member of the NFTN, continues her nitrogen research, calculating MBL’s footprint and assisting me and two current Dickinson students, Steve Fitzpatrick and Olivia Boggiano-Peterson, in refining calculations of our footprint and simulating the effects of nitrogen mitigation measures.

The results of the network’s comparison study were just published in a special issue of Sustainability: The Journal of Record, with Leach and Castner serving as guest editors (a link to the journal appears at the end of this article). The calculated footprints range from 7.5 metric tons of nitrogen (MT N) at the Marine Biological Laboratory to 444 MT N at the University of Virginia. The nitrogen footprints correlate strongly with institutional population. But there is wide variation in per capita footprints, ranging from 7 kg N per full-time equivalent person at Eastern Mennonite University to 27 kg N at Dickinson College. Dickinson’s high per person footprint, a personal embarrassment, is due in part to over 90 percent of our students living on campus with full meal plans, and summer programs that bring significant numbers of visitors to campus who eat in our dining hall but are not counted in our population of students and employees.

Upstream food production is the largest source of nitrogen pollution for five of the institutions, contributing 50 percent of the footprint on average, followed by utilities, which contribute 33 percent on average. The exceptions are the University of Virginia, where utilities account for 52 percent of its nitrogen footprint due to heavy reliance on coal-fired power, and Colorado State University, which has extensive agricultural research activities that account for 49% percent of its nitrogen footprint when included in the total.

What can institutions do to reduce their nitrogen pollution? Participants in the NFTN comparison study simulated the effects of different nitrogen mitigation measures. At Dickinson, these included reducing total food purchases by improving efficiencies in inventory management, menu planning and purchasing; shifting from foods with high nitrogen footprints to foods with lower footprints (e.g. substituting poultry for beef, or substituting non-meat sources of protein for meat); shifting to renewable, non-fossil sources of electricity; reducing on-campus fossil fuel consumption; reducing employee commuting; and reducing use of fertilizers for grounds keeping.

Because food accounts for nearly 80 percent of Dickinson’s nitrogen footprint, its most effective measures focus on food. The next most effective measure for Dickinson is to carry through with a planned power purchasing agreement for a 3 MW solar installation that will supply 25 percent of the college’s electricity beginning next year. Combining several moderately aggressive nitrogen mitigation measures is estimated to reduce Dickinson’s footprint by nearly 15 percent. A more aggressive set of measures would reduce its footprint by roughly 25 percent. Both options would deliver financial cost savings for food purchases and electric utilities, but would require voluntary dietary changes that are likely to prove challenging.

Simulations of nitrogen mitigation measures yielded somewhat different results across the seven participating NFTN institutions, reflecting differences in the specific contexts in which they operate. But each found promising opportunities to constrain their nitrogen footprints. Some have already adopted nitrogen pollution reduction goals, and the others are considering their adoption. Thirteen more colleges and universities have joined the NFTN, bringing the total number of members to 20. The new members are in the process of measuring their footprints, analyzing mitigation options and adding to the shared knowledge about institutional nitrogen pollution. Members of the network are also working on a new tool that will allow them to integrate tracking and management of their nitrogen and carbon footprints.

At a time when enforcement of environmental regulations may be weakened due to budgetary cuts and policy changes at federal and state levels, colleges and universities can make an important statement by modeling responsible institutional behaviors through their sustainability programs. This can and should include more visible and forceful efforts to measure and reduce nitrogen pollution.

You can read the NFTN research articles in the special issue of Sustainability: The Journal of Record here:

Want to measure your personal nitrogen footprint? You can do that here:

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