Haze related to particulate matter has become a big problem in eastern China, and ammonia (NH₃) plays an important role in secondary particulate matter formation. In this work, variations in the NH₃ mixing ratio showed that the contributions of NH₃ sources and sinks in urban and suburban areas were quite different, although the areas were under the influence of similar weather systems. This study furthers the understanding of the behavior of NH₃ in a megacity environment.