Spatiotemporal Analysis of NH3 Emission Sources and Their Relation to Land Use Types in the Eastern German Lowlands

Ammonia (NH3) emissions, which are key precursors of fine particulate matter, pose significant environmental challenges. This study investigated the spatiotemporal variations in NH3 emissions across the eastern German lowlands from 2013 to 2022 using IASI-B satellite data. Five major Land Cover Classes (LCC) –tree, grassland, cropland, built-up areas, and water bodies– were analyzed. The results showed distinct diurnal variations, with nighttime NH3 concentrations exceeding 2.0 × 1016 molecules cm−2 in the peak months. Seasonal patterns indicated significant emissions in March (1.2 × 1016 molecules cm−2), April (1.1 × 1016 molecules cm−2), and August (9.6 × 1015 molecules cm−2), while the lowest concentrations occurred in September (0.6 × 1015 molecules cm−2). Persistent hotspots were identified in the northwestern region, where emissions peaked in spring (1.8 × 1016 molecules cm−2) and summer (1.3 × 1016 molecules cm−2), primarily due to agricultural activities. Over the study period, the annual NH3 concentration peaked in 2015, 2018, and 2022. Using k-means clustering, three distinct emission zones were identified, with Cluster 3 showing the highest NH3 emission values, particularly in urban centers, and agricultural zones were identified, covering less than 20% of the study area, where cropland predominates (8%). Meteorological factors significantly influenced NH3 levels, with negative correlations obtained for precipitation, wind speed, and evaporation, while solar radiation, boundary layer height, and instantaneous moisture fluxes showed positive correlations. A case study from March 2022, employing the HYSPLIT trajectory model, confirmed that agricultural practices are the dominant NH3 source, with emissions reaching 3.2 × 1016 molecules cm−2 in hotspot regions.