A delicate balance

Galloway.
Photo by Jack Mellott.

Nitrogen is the seventh element in the periodic table and the most abundant of the five elements that are necessary for life. The percentage of reactive nitrogen, the form of nitrogen usable by most organisms, is quite small, however, and, until recently, fairly stable. Lightning and nitrogen-fixing bacteria add to our supply of reactive nitrogen, a process that is canceled by natural de-nitrification processes. Human intervention has upset this balance, with effects that have rippled through the environment.

“Each year, humans add 160 million metric tons to our supply of reactive nitrogen,” notes Professor James Galloway. “You get a real sense of how significant this is when you realize that it far exceeds the amount of reactive nitrogen created by all the terrestrial ecosystems of the world.” We do so by cultivating legumes, rice, and other crops that promote nitrogen fixing, by burning fossil fuels, and by transforming non-reactive atmospheric nitrogen to fertilizer to sustain food production.

This reactive nitrogen can cascade through a variety of environmental systems, damaging them significantly and exacting a toll on human health. Reactive nitrogen is implicated in the high concentration of ozone in the lower atmosphere; the eutrophication of coastal ecosystems; the acidifications of forests, soils, and freshwater streams and lakes; and the loss of biodiversity. In the form of nitrous oxide, a greenhouse gas, nitrogen contributes to global warming and stratospheric ozone depletion.

All these drawbacks have to be weighed against one inescapable fact: a large percentage of the world’s population depends on the food produced with this additional reactive nitrogen. And while problems related to nitrogen exist everywhere, some parts of the world, notably Africa, suffer from a deficiency of reactive nitrogen in the soil, contributing to low crop yields and malnutrition.

As Galloway sees it, the most effective solutions to the nitrogen imbalance can be found only by coordinating global and local approaches. As chair and one of the founders of the International Nitrogen Initiative (INI), he is doing just that. “It’s a fascinating problem,” he says. “How do you minimize the detrimental consequences of nitrogen while augmenting its beneficial effects? Finding answers to questions like these goes far beyond understanding the biogeochemistry of the system, though this is an essential first step.”

INI is moving forward on a number of fronts. It secured the sponsorship of two prestigious scientific organizations, the Scientific Committee on Problems of the Environment, part of UNESCO, and the International Geosphere Biosphere Program, which coordinate much of the biogeochemical research in the world. It has established regional centers in Africa, Asia, Europe, Latin America, and North America; held workshops in Kampala, Uganda, and Woods Hole, Massachusetts; and is helping to organize the Third International Nitrogen Conference, which will be held in Nanjing, China, to set the stage for future initiatives.

Galloway’s work on the INI keeps him traveling, but he believes the organization gains strength from its affiliation with the University. “INI has a natural home at U.Va.,” Galloway says. “It promotes sound science in an interdisciplinary environment and it has direct societal implications.”

This article originally appeared in the fall 2004 issue of Explorations.