Preliminary Study of the Isotopic Characteristics of Atmospheric Ammonia at a Coal Coking Industrial Park in Taiyuan, China, Using OGAWA Sampling

Ammonia (NH3) is an important alkaline gas and a key precursor to secondary inorganic aerosol. In the Fen River valley, coking plants are concentrated due to transportation advantages, while NH3 emissions from coking processes have received limited attention despite their potential importance. In this study, atmospheric NH3 was sampled by OGAWA samplers in a typical coal coking industrial park in Taiyuan during autumn and winter of 2024–2025, and its nitrogen isotopic composition was used for source apportionment. The results showed that the NH3 concentration in the industrial park was 27.4 ± 3.8 μg m−3, significantly higher than that in the urban area (9.3 ± 4.2 μg m−3) and higher than winter levels reported for North China cities. The δ15N-NH3 was −29.7 ± 1.6‰ and increased to −14.7 ± 1.6‰ after correcting for passive sampling bias. Source apportionment further indicated that NH3 in the industrial park was dominated by non-agricultural sources (80.7%), with ammonia slip as the largest contributor (34.2 ± 20.1%), followed by coal combustion (25.8 ± 16.5%), traffic emissions (20.7 ± 11.6%) and agricultural sources (19.3 ± 11.6%). Therefore, some measures should be taken to reduce the NH3 emissions from ammonia slip and traffic during autumn and winter.