Characterizing isotopic compositions of TC-C, NO3-N, and NH-N in PM in South Korea: Impact of China's winter heating.

The origin of PM has long been the subject of debate and stable isotopic tools have been applied to decipher. In this study, weekly PM samples were simultaneously collected at an urban (Seoul) and rural (Baengnyeong Island) site in Korea from January 2014 through February 2016. The seasonal variation of isotopic species showed significant seasonal differences with sinusoidal variation. The isotopic results implied that isotope species from Baengnyeong were mostly originated from coal combustion during China's winter heating seasons, whereas in summer, the isotopic patterns observed that were more likely to be from marine. In Seoul, coal combustion related isotopic patterns increased during China's winter heating period while vehicle related isotopic patterns were dominated whole seasons by default. Therefore, aerosol formation was originated from long-range transported coal combustion-related NO by vehicle-related NH in Seoul. δN-NH in Seoul showed highly enriched N compositions in all seasons, indicating that NH from vehicle emission is the important source of NH in PM in Seoul. In addition, Baengnyeong should be consistently considered as a key region for observing the changes of isotopic features depend on the contribution of individual emissions to the atmospheric as a result of the reduction of coal consumption in China.