The distribution of atmospheric black carbon (BC) in the marine boundary layer of the North Atlantic and Baltic, North, Norwegian, Barents, White, Kara and Laptev Seas was studied in research cruises with the RV “Akademik Mstislav Keldysh^ during July 23 to October 24, 2015. Air was filtered through Hahnemuhle Fineart Quarz-Microfibre filters. The mass of BC on the filter was determined by the measurement of the attenuation of a beam of light transmitted through the filter. Source areas were estimated by backwards trajectories of air masses calculated using NOAA’s HYSPLIT model (http://www.arl.noaa.gov/ ready.html) and FLEXPART model (http://www.flexpart.eu). During some parts of the cruises, air masses arrived from background areas of high latitudes, and the measured BC concentrations were low. Over other parts of the cruises, air masses arrived from industrially developed areas with strong BC sources, and this led to substantially enhanced measured BC concentrations. Model-supported analyses are currently performed to use the measurement data for constraining the emission strength in these areas