Using a moving measurement platform for determining the chemical composition of atmospheric aerosols between Moscow and Vladivostok
The TROICA-9 expedition (Trans-Siberian Ob- servations Into the Chemistry of the Atmosphere) was car- ried out at the Trans-Siberian railway between Moscow and Vladivostok in October 2005. Measurements of aerosol physical and chemical properties were made from an obser- vatory carriage connected to a passenger train. Black carbon (BC) concentrations in fine particles (PM2.5, aerodynamic di- ameter <2.5µm) were measured with an aethalometer using a five-minute time resolution. Concentrations of inorganic ions and some organic compounds (Cl−, NO− NH+ were measured continuously by using an on-line system with a 15-min time resolution. In addition, particle volume size distributions were determined for particles in the diameter range 3–850nm using a 10-min time resolution. The contin- 4 , K+, Ca2+, Mg2+, oxalate and methane sulphonate) uous measurements were completed with 24-h PM2.5 filter samples stored in a refrigerator and analyzed later in a chem- ical laboratory. The analyses included the mass concentra- tions of PM2.5, ions, monosaccharide anhydrides (levoglu- cosan, galactosan and mannosan) and trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sb, V and Zn). The cle mass consisted mainly of BC (average 27.6%), SO2−4 (13.0%), NH+ constituentswas obviously organic carbon whichwas not de- termined. The contribution of BC was high compared with other studies made in Europe and Asia. High concentra- tions of ions, BC and particle volume were observed between Moscow and roughly 4000 km east of it, as well as close to Vladivostok, primarily due to local anthropogenic sources. In the natural background area between 4000 and 7200 km away from Moscow, observed concentrations were low, even though local particle sources, such as forest fires, occasion- ally increased concentrations. During the measured forest fire episodes, most of the aerosol mass appeared to consist of organic particulate matter. Concentrations of the biomass burning tracers levoglucosan, oxalate and potassium were el- evated close to the forest fire areas observed by the MODIS satellite. The polluted air masses from Asia seem to have significant influences on the concentration levels of fine par- ticles over south-eastern Russia.