# Black Carbon in the Air of the Baikal Region, (Russia): Sources and Spatiotemporal Variations
## 2 Methods
### Listyanka Monitoring Station  
A rural station for atmospheric monitoring <<Listvyanka>> (51.8467 N, 104.8930 E, and 670 m a.s.l.) was established at Lake Baikal to monitor the high-altitude transport of air pollutants from industrial centers of the Baikal region. The Listvyanka station is situated on the top of the coastal hill (-210 m above lake level) near the source of the Angara River on the southwestern border of the Central Ecological Zone, on the territory of the Baikal Astrophysical Observatory (BAO) (Figure 2). The station is more than 1 km away from the local anthropogenic sources (roads, boiler hoses, and stove heating) of the large tourist settlement of Listvyanka. Its location on the top of the hill facilitates research into the long-range transport of pollutants, including eBC, from large regional sources along the route of the most likely entry of air masses to Lake Baikal proximal to large cities of the Baikal region. The nearest large industrial centers are Irkutsk and Angarsk (70 and 100 km to the NNW from the station, respectively) [37]. Continuous 24-h measurements of gas and aerosol air pollutants, precipitation, and meteorological conditions are organized at this station, recording anthropogenic pollutions in the southern basin in real time under certain synoptic and meteorological conditions (Figure 2). Figure 2 demonstrates the major emissions of pollutants from stationary heat source facilities in the cities of the region and on the lake's coast. The station has been operating since 2000 as part of the Asian Network for Acid Deposition, EANET (www.eanet.asia). Since 2011, the station participates in the Global Mercury Observation System (Former www.gmos.eu/, recently: www.gos4m.org).  
A 10-wave light absorption analyzer (BAC-10, Shenyang Chemetech Co., Ltd., Shenyang, China) was installed in 2023 at the Listvyanka station. It was used to determine eBC. The BAC-10 multispectral monitor analyzer is based on an optical attenuation method that uses the absorption characteristics of soot adsorbed on banded quartz filter paper in various optical ranges to monitor the total amount of soot aerosols. This device measures light absorption at ten wavelengths, from 370 to 950 nm, and calculates concentration in \(\upmu\)g m\({}^{-3}\) for each of 10 channels (waves), all in the automatic mode. The 880 nm absorption band is considered the most applicable for BC analysis. The measuring device was installed inside the station. The analyzed air was taken from the outside, through the roof, using a standard PM\({}_{10}\) sampler and a PM\({}_{2.5}\) cyclone, because the aerodynamic diameter of soot particles is predominantly <2.5 \(\upmu\)m. Measurement data is stored in the monitor's memory and then can be copied to a flash drive, transmitted over the Internet, via a COM port, or in other ways. The options include the ability to diagnose device components and calibrate readings. The calibration interval of the device is one year. SO\({}_{2}\) and NO\({}_{2}\) gas impurities and aerosol mass concentration (PM\({}_{10}\), PM\({}_{2.5}\), and PM\({}_{1.0}\)) were measured simultaneously, and meteorological parameters were recorded (Figure 2).