The first ever global map of nitrogen emissions has revealed that developed countries' nitrogen footprint is ten times worse than developing ones.
Created by researchers from the University of Sydney, Australia, the map shows that four countries – USA, China, India and Brazil – are responsible for 46 per cent of global nitrogen emissions. The worst per capita emitters, like Hong Kong and Luxembourg, produce over 100kg of nitrogen per person, while the least polluting states, including Papua New Guinea, Côte d'Ivoire and Liberia produce less than 7kg per head.
The worst nitrogen emitting sectors are agriculture, transport and energy generation.
"High-income nations are responsible for more than ten times the emissions of the poorest nations," said Arunima Malik, a PhD candidate at the University of Sydney and one of the report’s authors.
"This reflects greater consumption of animal products, highly processed foods and energy-intensive goods and services."
The map, which details nitrogen emissions of 188 countries from around the world, shows which states are the so-called 'nitrogen importers' and which export more nitrogen than they emit. The most common way of importing or exporting nitrogen is in the form of agricultural products, textiles and clothing.
The study found that developed nations are often directly responsible for nitrogen emissions abroad as nitrogen intensive production is moving more into the developing countries.
"Polices are needed to integrate nitrogen supply-chains globally in order to reduce pollution,” said Professor Manfred Lenzen, who oversaw the research.
"We know nitrogen emissions are increasing - just as carbon emissions are increasing as populations expand. We are now analysing the trends, such as increased affluence and consumption and looking at the various industries responsible for nitrogen pollution."
The major problem, the researchers said, is the fact that in addition to releasing naturally occurring nitrogen, the industry is producing increasing quantities of a synthetic form of the element.
The study was based on data from 2010. During that year, the global economy produced 189 teragrams of nitrogen –161 of these teragrams were emitted from industries and agriculture and only 28 teragrams directly by consumers, mostly from sewage.
A paper on the research has been published in the latest issue of the Nature Geoscience journal.