Pig farms, Milford USA.
Satellite observations reveal ammonia hotspots
Researchers have used daily satellite observations to identify point sources of ammonia emissions over the globe. They found 248 hotspots (defined by the authors as areas with diameters of less than 50 kilometres) and a further 178 regional sources (which have no clearly defined hotspot). By using visible imagery, public inventories and online sources they were able to categorise most of the emitters. Of these hotspots, 83 sites were associated with intensive animal farming, either in open feedlots or within enclosed housing. Another 130 sites were identified as plants producing ammonia fertilisers. Other sources identified were nickel-cobalt mines, soda-ash plants and a complex of geothermal power plants. Only one of the hotspots detected was assumed to have a natural origin. They were also able to calculate nine-year averaged emission fluxes for both regions and hotspots.
The researchers then compared their findings with the EDGAR register, which is built on bottom-up reporting. One agricultural site and 69 industrial sites were completely missing from the EDGAR inventory. Emissions from almost all the hotspots were also underestimated in EDGAR, no matter their origin. One explanation for the latter could be the use of standard emission factors instead of estimating emissions from local data. This shows that satellite technology has the potential as an auditing tool for the national reporting of ammonia emissions.
Industrial and agricultural ammonia point sources exposed, Martin Van Damme, Lieven Clarisse, Simon Whitburn, Juliette Hadji-Lazaro, Daniel Hurtmans, Cathy Clerbaux & Pierre-François Coheur, Nature volume 564, pages 99–103 (2018)
Link to EDGAR register: http://edgar.jrc.ec.europa.eu/