Black carbon aerosol at McMurdo station, Antarctica

Aerosol light absorption as black carbon (BC) was measured from November 19 , 1995, to February 6, 1996, at a location 0.65 km downwind of the center o f McMurdo Station on the Antarctic coast. The results show a bimodal freque ncy distribution of BC concentrations. Approximately 65% of the measurement s were found in a mode at a low range of concentrations centered at similar to 20 ng/m(3). These concentrations are higher than those found at other r emote Antarctic locations and probably represent contamination from the sta tion. The remaining measurements were in a high-concentration mode (BC simi lar to 300 ng/m(3)), indicating direct impact of local emissions from combu stion activities at the station. High values of BC were associated with win ds from the direction of the station, and the BC flux showed a clear direct ionality. Maximum BC concentrations occurred between 7:00 and 11:00 a.m. Th e "polluted" mode accounted for more than 80% of the BC frequency-weighted impact at this location.