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Feature Story

Bittersweet nature of nitrogen calls for better management practices

May 10, 2019

More efficient management of global nutrient cycles could contribute substantially to reducing pollution and to achieving the Sustainable Development Goals. Photo: iMoved Studio/Shutterstock.
More efficient management of global nutrient cycles could contribute substantially to reducing pollution and to achieving the Sustainable Development Goals. Photo: iMoved Studio/Shutterstock.

Nearly 80 per cent of the air we breathe is nitrogen, a harmless inert gas. However, nitrogen also combines with other atoms to form chemical compounds—known as “reactive nitrogen” or “fixed nitrogen” (Nr)—that are essential for life on Earth but, at high concentrations, also hugely damaging to the environment.

“Altogether, humans are producing a cocktail of reactive nitrogen that threatens health, climate and ecosystems, making nitrogen one of the most important pollution issues facing humanity,” says UN Environment’s 2019 Frontiers Report. “Yet the scale of the problem remains largely unknown and unacknowledged outside scientific circles.”

There are four main types of reactive nitrogen, with differing benefits and environmental impacts:

Ammonia (NH3) is found in manure, urine, fertilizers, and burning biomass. It’s the foundation for amino acids, protein and enzymes. In high concentrations however, it can cause algal blooms in lakes and forms particulate matter in the air which affects health and impacts terrestrial ecosystems such as peatlands and forests.

Nitrates (NO3) are widely used as fertilizers and in explosives. We would produce only about half of our food without the use of fertilizers such as nitrogen and phosphorus. However, their accumulation in the environment can be toxic for life on Earth. Since they are the most water soluble of all salts, they are essential to the nitrogen cycle and a key source of nitrate pollution. Nitrates have been found in wastewater, agricultural runoff and in the atmospheric oxidation of NOx.

NOx is a major air pollutant, also present in vehicle exhaust fumes, and known to cause heart disease and respiratory illness. Ground-level ozone, formed by reactions between methane, nitrous oxide (N2O), and volatile organic compounds in the presence of sunlight, is a damaging air pollutant.

Nitrous oxide is generated by agriculture, industry and combustion. It’s used in medical procedures and rocket propellants. It’s also a global warming gas 300 times more potent than carbon dioxide and depletes stratospheric ozone, which protects us from harmful radiation. 

Unfortunately, growing demand on the livestock, agriculture, transport, industry and energy sectors has led to a sharp increase in the presence of reactive nitrogen in our ecosystems.

Addressing nitrogen management is vital to meeting air quality, water quality, climate, stratospheric ozone, and biodiversity goals, while offering a huge economic opportunity to reduce the US$200 billion of reactive nitrogen that is wasted every year. More efficient management of global nutrient cycles could contribute substantially to reducing pollution and to achieving the Sustainable Development Goals.

The International Nitrogen Management System (INMS), a platform for better cooperation across science and policy, is working to build consensus on a way forward. Led by UN Environment, the International Nitrogen Management System is a collaborative effort of the Centre for Ecology & Hydrology and the International Nitrogen Initiative, with funding support from the Global Environment Facility (GEF) and the Global Challenges Research Fund of the United Kingdom, along with project contributions from project partners across the globe.

“We need joined-up thinking on mitigation and adaptation options and strategies linked to the circular economy. To help with this, we need a global assessment of the threats and benefits of the human alteration of the nitrogen cycle and the opportunities for improvement,” says nitrogen expert Mark Sutton, UN Environment’s director for the joint Global Environment Facility and International Nitrogen Management System project, and an Environmental Physicist at the Centre for Ecology & Hydrology.

First global resolution on nitrogen a huge step forward

At the Fourth UN Environment Assembly in March 2019, Member States approved the first ever global resolution on nitrogen, calling on UN Environment’s Executive Director to “consider the options to facilitate better coordination of policies across the global nitrogen cycle at the national, regional and global levels, including consideration of the case to establish an intergovernmental coordination mechanism on nitrogen policies (…)”.

“We have had great success here the last couple of days in engaging with the Committee of Permanent Representatives and intergovernmental processes through the high-level segment of the International Nitrogen Management System. It has allowed fast follow-up to the Resolution on Sustainable Nitrogen Management,” said Sutton after the fourth system’s plenary meeting in April 2019.

“Altogether, this now provides an excellent basis to move the global agenda forward to tackle this menace to the health of our air, land, water and oceans,” says UN Environment nutrient pollution expert Christopher Cox.

“We have been working on drafting a report to support the next steps on implementing the Nitrogen Resolution and will also be developing further recommendations for the Committee of Permanent Representatives annual meeting in October.”

This story was originally published by UN Environment.