Scientists shed light on forest soil and nitrous oxide connection
Greenhouse gas nitrous oxide (N2O) emissions have swelled due to reactive nitrogen compounds from transport, industry and agriculture, new research shows. Presented in the journal Nature, the European Nitrogen Assessment (ENA) study reveals that forest soil-generated N2O emission is at least twice as high as the figure projected by the Intergovernmental Panel on Climate Change (IPCC). The findings, presented at the 'Nitrogen and global change 2011' international conference in Edinburgh, UK from 11 to 15 April, are not promising. Participating in the ENA study were 200 experts from both the scientific and political spheres in 21 countries. The data show that on average, 4 % of the atmospheric reactive nitrogen is converted into N2O that is reabsorbed into the atmosphere. Compared to the IPCC estimate, just 1 kg of N2O is around 300 times as greenhouse-effective as the same amount of carbon dioxide (CO2). Experts say reactive nitrogen compounds are for the most part of anthropogenic origin. They are partially converted into N2O, which is the third biggest culprit of the greenhouse effect. The researchers found that for 188 million hectares of forested area, reactive nitrogen deposition ballooned by 1.5 million tonnes each year during the period from 1860 to 2000, representing an 8 kg jump in reactive nitrogen per hectare of forest each year. Fertilisation in agriculture contributes to the rise in the atmospheric input of reactive nitrogen. Also responsible for the increase is the associated volatilisation of ammonia and the N2O emissions triggered by biomass burning and fossil fuel combustion. Besides leading to greater N2O emissions from forest soils that adversely impact the climate, increased deposition of reactive nitrogen on forests also leads to a loss of diversity of animal and plant species. Water also is affected, as nitrate emissions swell. A maiden study that puts the spotlight on the multiple threats of nitrogen pollution, the ENA research pays particular attention to how nitrogen impacts climate change and biodiversity loss across Europe, and identifies which European regions are at risk. Commenting on how important it is to cut nitrogen emissions, Dr Sutton from the Centre for Ecology & Hydrology in the UK says: 'This is an extremely important finding. It means that nitrogen release into the atmosphere from industry and agriculture is having a much bigger impact on nitrous gas emissions from soils than previously recognised. It provides a further argument of why it is vital to reduce emissions of nitrogen oxides and ammonia with benefits all round for climate, air quality, and biodiversity.' For his part, Professor Klaus Butterbach-Bahl of the Karlsruhe Institute of Technology (KIT, Germany) said at the presentation of the ENA study: 'The present atmospheric reactive nitrogen deposition is much too high.' The KIT researcher is chief of the Atmospheric Environmental Research Division of the Institute of Meteorology and Climate Research (IMK-IFU) in Germany, and senior author of the ENA chapter on reactive nitrogen jeopardising the greenhouse balance in Europe. In related research, Professor Butterbach-Bahl and colleagues reveal that atmospheric concentrations of the greenhouse gas N2O swelled 'since pre-industrial times owing to anthropogenic perturbation of the global nitrogen cycle, with animal production being one of the main contributions'. The research was funded in part by the NITROEUROPE ('The nitrogen cycle and its influence on the European greenhouse gas balance') project, which has clinched almost EUR 17 million under the 'Sustainable development, global change and ecosystems' Thematic area of the EU's Sixth Framework Programme (FP6).For more information, please visit: European Nitrogen Assessment (ENA):http://www.nine-esf.org/Nature:http://www.nature.com/IPCC:http://www.ipcc.ch/Karlsruhe Institute of Technology (KIT):http://www.kit.edu/english/
Countries
Germany, United Kingdom