Abstract
Abstract. We present long-term (5-year) measurements of particulate matter with an upper diameter limit of ∼ 10 µm (PM10), elemental carbon (EC), organic carbon (OC), and water-soluble organic carbon (WSOC) in aerosol filter samples collected at the Zotino Tall Tower Observatory in the middle-taiga subzone (Siberia). The data are complemented with carbon monoxide (CO) measurements. Air mass back trajectory analysis and satellite image analysis were used to characterise potential source regions and the transport pathway of haze plumes. Polluted and background periods were selected using a non-parametric statistical approach and analysed separately. In addition, near-pristine air masses were selected based on their EC concentrations being below the detection limit of our thermal–optical instrument. Over the entire sampling campaign, 75 and 48 % of air masses in winter and in summer, respectively, and 42 % in spring and fall are classified as polluted. The observed background concentrations of CO and EC showed a sine-like behaviour with a period of 365 ± 4 days, mostly due to different degrees of dilution and the removal of polluted air masses arriving at the Zotino Tall Tower Observatory (ZOTTO) from remote sources. Our analysis of the near-pristine conditions shows that the longest periods with clean air masses were observed in summer, with a frequency of 17 %, while in wintertime only 1 % can be classified as a clean. Against a background of low concentrations of CO, EC, and OC in the near-pristine summertime, it was possible to identify pollution plumes that most likely came from crude-oil production sites located in the oil-rich regions of Western Siberia. Overall, our analysis indicates that most of the time the Siberian region is impacted by atmospheric pollution arising from biomass burning and anthropogenic emissions. A relatively clean atmosphere can be observed mainly in summer, when polluted species are removed by precipitation and the aerosol burden returns to near-pristine conditions.
Highlights
The Siberian forests cover about 70 % of the total area of the Eurasian boreal forest and are an important factor controlling global and regional climate
We present long-term (5-year) measurements of particulate matter with an upper diameter limit of ∼ 10 μm (PM10), elemental carbon (EC), organic carbon (OC), and water-soluble organic carbon (WSOC) in aerosol filter samples collected at the Zotino Tall Tower Observatory in the middle-taiga subzone (Siberia)
Visual analysis indicates that the highest concentrations of PM10 and total carbonaceous matter (TCM), observed in the spring and summer periods (Fig. 1a), correspond to high temperatures and lower levels of precipitation (Fig. 1b)
Summary
The Siberian forests cover about 70 % of the total area of the Eurasian boreal forest and are an important factor controlling global and regional climate. Siberia is one of the few possible background regions in the Northern Hemisphere where near-pristine conditions prevail for certain periods of the year (Chi et al, 2013). Such atmospheric observations in remote areas are very important for providing a reference for evaluating anthropogenic impacts in this and other regions (Andreae, 2007; Carslaw et al, 2013; Spracklen and Rap, 2013).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
