The results of a new scientific study showed that the concentration of ammonia gas is constantly rising in the atmosphere of Africa, and researchers have linked this rise to the phenomena of burning biomass and the expansion and intensification of agricultural practices.
The study, which is the first of its kind conducted by NASA during the decade between 2008 and 2018, identified “hot spots” located in West Africa and in the Lake Victoria region, where the highest levels of this polluting gas to the environment and harmful to health were recorded.
Ammonia potential sources
Ammonia is emitted naturally from soils and vegetation fires, but agricultural activities such as raising livestock and using fertilizer are also major sources. As agriculture scales up to meet the needs of growing populations, it is likely that ammonia emissions will rise too. To create this current view of ammonia emissions, the researchers used satellite data from 2008 to 2018, identifying rises and falls in ammonia concentrations across the continent and the likely causes of those changes.
“We’ve shown here that we can use satellite data to observe trends and monitor emissions of ammonia in specific regions, linked to specific activities or environmental events,” said Enrico Dammers, a scientist at the Netherlands Organization for Applied Scientific Research and co-author of the paper.
Hotspots
The results of satellite data analysis showed – according to a statement published on the NASA website – that West Africa is among the global hotspots for ammonia emissions in the atmosphere.
The annual increase in the concentration of this gas across Nigeria, for example, is 6% during the months of February and March, coinciding with a rise in carbon monoxide in the atmosphere.
This period coincides with the end of the dry season and farmers preparing their lands by burning them before adding fertilizer, which negates what previous studies have suggested that the increase in ammonia emissions in the region is due to the use of chemical fertilizers in agriculture.
The study also identified areas of the Lake Victoria Basin and wetlands in southern Sudan, as regional hotspots for ammonia emissions.
In the Lake Victoria region, the results of the study indicate that the expansion of the agricultural area and the use of fertilizers led to an increase in ammonia concentration during the study period.
The researchers linked the growth of concentrations of this gas over this area with data indicating that farmers were using more fertilizers in agricultural lands that are witnessing a steady increase in their area, according to the statement.
In South Sudan, soil moisture caused a decrease in ammonia concentration during the study period. The wetlands in the “Al-Sad” area, which covers an area of 30,000 square kilometers and is fed by the Nile River, was the only area that showed a clear decrease in the ammonia level during the study period, which amounted to about 1.5 percent annually.
The researchers found that ammonia concentrations increase in dry years, when more wetlands dry out, and decrease in rainy years.
Sustainable agriculture to reduce ammonia emissions
According to the researchers, agriculture is the largest source of ammonia in the world, although it is also emitted naturally from the soil. The burning of biomass is the second largest source of this polluting gas in the world, and Africa is the origin of nearly 70% of these fires.
As African nations expand their agricultural activity to feed a growing population that will double by mid-century, ammonia concentrations are expected to continue to rise in the atmosphere over the continent in the future.
“These results are important to keep in mind as the world experiences a growing population and huge challenges with food security,” Hickman said. “Understanding how human-made and natural ammonia emission sources are changing is important for ensuring policies and technologies that promote sustainable agricultural development.”
Understanding how sources of ammonia emissions change, according to the researchers, is important for developing policies and technologies that promote sustainable agricultural development, and help mitigate its potential effects on the atmosphere.
Sources:
https://acp.copernicus.org/articles/21/16277/2021/
https://www.nasa.gov/feature/enst/2021/nasa-study-traces-decade-of-ammonia-air-pollution-in-africa/