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Air pollution alters nutrient balance in ecosystems

It is widely accepted that human activity has altered the balance of nutrients in ecosystems and has led to a nutrient overload. This has led to soil degradation, biodiversity loss and pollution of freshwaters. Major nutrients important for plant growth are carbon and nitrogen, among others.

Specifically, nitrogen emissions such as nitrogen oxide (NOx) and ammonia emissions (NH3) from industrial production, transport, household consumption and agricultural practices have resulted in major pressures on the environment. As a result of scientific collaboration under UNECE’s Convention on Long-Range Transboundary Air Pollution , a new study on the impact of nitrogen deposition on the nutrient balance in soils was published in the scientific journal Biogeosciences.

Using a vast pool of data and the scientific models developed under the Convention's  Cooperative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe (EMEP) to document nutrient loads in Europe, the study finds that the last two decades have seen a decrease in the deposition of atmospheric nitrogen, with the most pronounced reductions in Eastern Europe. While the 1980s were a tipping point for nitrogen deposition, mitigation efforts of Parties to the Air Convention and its protocols, most notably the 1988 Protocol concerning the Control of Emissions of Nitrogen Oxides or their Transboundary Fluxes (Nitrogen Protocol) and the 1999 Protocol to Abate Acidification, Eutrophication and Ground-level Ozone (Gothenburg Protocol), resulting in a 40 per cent reduction of nitrogen emissions,  have helped to alleviate nitrogen pollution of soils in Europe.

However, nitrogen oxide and ammonia emissions still impact the soil environment with adverse effects on vegetation, including forests, and biodiversity. Further emission reduction efforts are thus needed in order for soils to fully recover. To this effect, Parties amended the Gothenburg Protocol in 2012 to set new ceilings for 2020 and beyond. Recently, UNECE also joined efforts with other international stakeholders on nitrogen flows in the environment and their impacts. The project will provide guidelines to improve the nitrogen management at the global and regional levels contributing to the establishment of an International Nitrogen Management System