Agricultural sources impact on NH3 and PM levels in the South-Central Anatolia

Atmospheric ammonia (NH₃) is a significant pollutant that rapidly reacts with atmospheric acids like sulfuric acid (H₂SO₄) and nitric acid (HNO₃) to form fine particulate matter (PM_2.5), which has negative effects on both the environment and public health. NH₃ has several kinds of sources but main emitter is agriculture, which originates from crop production and livestock managements. Besides conventional emissions from agriculture, agricultural waste burning is also significant in some regions although prohibited.

Türkiye is an agricultural producing country, and the largest agricultural areas and livestock farms are located in South-Central Anatolia. This study aims to investigate the possible causes of high NH₃ and PM levels in this region, focusing on agricultural activities such as crop production, livestock farming, and agricultural residue burning. Using IASI Level-2 NH₃ retrievals, the spatio-temporal changes in NH₃ levels was investigated over the region. Annual and seasonal changes in NH₃ levels were evaluated together with meteorological parameters and ground-based PM₁₀ and PM_2.5 measurements. In order to understand the effect of agricultural burning on high NH₃ and PM levels in fall season, biomass burning regions were determined with VIIRS S-NPP Fire Radiative Power (FRP) product and aerosol types were examined with CALIOP Level-1 and Level-2 VFM product. High NH₃ levels were detected in the study area which has the highest agricultural activity in Türkiye. Seasonal distributions of the region showed that significant levels in fall season, unlike all other regions in Türkiye indicating highest summer NH₃ levels. These findings indicated a different source causing high NH₃ levels in the fall season other than the agricultural activities usually having highest impact in spring and summer seasons. In the fall seasons (2019-2023), the highest FRP values were observed with values three times or higher than of other seasons. Especially, the highest number of fires occurred in fall of 2020 and 2023, when higher NH₃ levels were also observed. Additional to regional high values, hotspots of NH₃ were identified in Konya–Eregli, Nigde–Bor, and Aksaray–Merkez. NH₃ levels were also observed higher during winter seasons in these hotspots where livestock farms are frequently located. Therefore, effects of livestock farming and residual burning as a NH₃ source stood out in this region rather than conventional fertilizer applications. It is important that these lesser known and investigated emission sources of NH₃ need to be evaluated to understand their role in secondary particulate matter formation and their impact on public health in the region.

Keywords: Ammonia, Agricultural residue burning, Livestock management

Acknowledgements: IASI is a joint mission of EUMETSAT and the Centre National d'Etudes Spatiales (CNES, France). The authors acknowledge the AERIS data infrastructure for providing access to the IASI data in this study and ULB-LATMOS for the development of the retrieval algorithms. This study was supported by the Scientific and Technological Research Council of Türkiye under the grant number 123Y364.