Stable carbon and nitrogen isotope ratio in PM1 and size segregated aerosol particles over the Baltic Sea

We analysed delta C-13 of total carbon (TC) and PN of total nitrogen (TN) in submicron (PM1) and size segregated aerosol particles ( PM0.056-2.5) collected during a cruise in the Baltic Sea from 9 to 17 November 2012.

PM1 were characterized by the highest delta C-13 (-26.4 parts per thousand) and lowest delta N-15 (-0.2 and 0.8 parts per thousand) values when air masses arrived from the southwest direction (Poland). The obtained delta C-13 values indicated that combined emissions of coal and diesel/gasoline combustion were the most likely sources of TC. The depleted delta N-15 values indicated that TN originated mainly from liquid fuel combustion (road traffic, shipping) during this period. The lowest PC and highest delta N-15 values were determined in PM1 samples during the western airflow when the air masses had no recent contact with land. The highest delta N-15 values were probably associated with chemical aging of nitrogenous species during long-range transport, the lowest delta C-13 values could be related to emissions from diesel/gasoline combustion, potentially from ship traffic.

The delta C-13 analysis of size-segregated aerosol particles PM0.056-2.5 revealed that the lowest delta C-13 values were observed in the size range from 0.056 to 0.18 mu m and gradual C-13 enrichment occurred in the size range from 0.18 to 2.5 mu m due to different sources or formation mechanisms of the aerosols.