Impact of summertime anthropogenic emissions on atmospheric black carbon at Ny-Alesund in the Arctic

Measurements of equivalent black carbon (EBC), calculated from aethalometer measurements of light attenuation, were carried out in July 2011 at Ny-Alesund in the Arctic. Highly elevated EBC concentrations were observed within the settlement of Ny-Alesund, with a median value of 17 ng m(-3), which was about two times the background level. Results from the ensemble empirical mode decomposition method suggested that about 60-80% of atmospheric EBC concentrations at Ny-Alesund were from local emissions, while only 20-40% arrived via atmospheric transport. The estimated average local emission rate was 8.1 g h(-1), with an uncertainty of approximately a factor of two. The pollution plume was confined to 10 km downwind of the settlement, with the total EBC deposition estimated to be 6.4-44 ng m(-2) h(-1). This may affect snow black carbon (BC) concentrations in nearby glaciated areas. The efficiencies of the long-range transport were estimated based on cluster analysis and potential precipitation contribution function, and the results implied that transport from western Europe is more efficient than from central Russia, on account of relatively rapid transport from western Europe and infrequent precipitation along this route. However, there was no correlation between air mass back-trajectories and EBC concentrations, suggesting that the contribution of long-range transport to EBC measured in Ny-Alesund might be not significant in this season.