365 - Air Mercury Monitoring at the Baikal Area: Sources, Long-Term and Short-Term Variations

"The ongoing automatic mercury monitoring at the Listvyanka monitoring station shows average gaseous elemental mercury (GEM) concentration as 1.59 ng/m3 throughout the 2011-2022 years of observation. The particulate bound mercury (PBM) makes up about 0.8 % of GEM.

The long-term monitoring reveals the obvious seasonal variation of the background mercury concentration in air (both GEM and PBM), which increases in the cold and decreases in the warm season. The short-term anomalies are mainly associated with the wind carrying the air from the industrial areas of Irkutsk and Angarsk cities where several big coal-fired power plants are located. A positive correlation between the mercury, SO2 and NO2 concentrations is observed both in the short-term variations and in the monthly average concentrations. This confirms that the coal combustion plants located in the area of 70-100 km from the monitoring point are the main reason of the seasonal and short-term variations. Concentration-weighted trajectory (CWT) analysis revealed potential areas of the mercury emissions.

The monitoring data also show that forest fires could be a significant source of mercury in a period from April to August and can contribute to the increasing monthly average concentration in some years, for example, in June 2019 (1.73 ng/m3) and in July 2020 (1.94 ng/m3).

The average mercury concentration measured during a cruise along Lake Baikal is 1.10 ng/m3 that is notably less as compared with the average value of 1.60 ng/m3 obtained at the onshore Listvyanka GMOS station during the same days of the cruise. Thus, Baikal can be a sink of the atmospheric mercury and other pollutants due to the air temperature inversion in a warm season.

The long-term monitoring reveals the obvious seasonal variation of the background mercury concentration in air (both GEM and PBM), which increases in the cold and decreases in the warm season. The short-term anomalies are mainly associated with the wind carrying the air from the industrial areas of Irkutsk and Angarsk cities where several big coal-fired power plants are located. A positive correlation between the mercury, SO2 and NO2 concentrations is observed both in the short-term variations and in the monthly average concentrations. This confirms that the coal combustion plants located in the area of 70-100 km from the monitoring point are the main reason of the seasonal and short-term variations.

The monitoring data also show that forest fires could be a significant source of mercury in a period from April to August and can contribute to the increasing monthly average concentration in some years, for example, in June 2019 (1.73 ng/m3) and in July 2020 (1.94 ng/m3).

The average mercury concentration measured during a cruise along Lake Baikal is 1.10 ng/m3 that is notably less as compared with the average value of 1.60 ng/m3 obtained at the onshore Listvyanka GMOS station during the same days of the cruise. Thus, Baikal can be a sink of the atmospheric mercury and other pollutants due to the air temperature inversion in a warm season."

Authors: Vladimir Ryzhov, Nikolay Mashyanov, Vladimir Obolkin, Vladimir Potemkin, Elena Molozhnikova, Tamara Khodzher, Sergei Pogarev,Sergei Sholupov, Viktor Kalinchuk