## 3 Results and Discussions
### Atmospheric Mid- and Long-Range Transport of PM\({}_{2.5}\) and PM\({}_{10}\)  
The daily-averaged concentration of PM\({}_{2.5}\) in the atmosphere of Sevastopol, according to measurements on 15 May 2021, was 0.016 mg m\({}^{-3}\) (that is 0.5 of MPC), while the PM\({}_{10}\) concentration was 0.019 mg m\({}^{-3}\). According to the website [[https://www.ventusky.com](https://www.ventusky.com)]([https://www.ventusky.com](https://www.ventusky.com)) (accessed on 14 June 2022), dust was transported from the southern area of the Black Sea coast during this period. Figure 6 shows the dust cloud over the study region on 15 May 2021. The lifetime of aerosols in the atmosphere has been determined by wet and dry deposition [31]. Precipitation contributes to the deposition of microparticles from the air on the underlying surface. In addition, wet deposition is eventually more important locally or regionally, close to aerosols emission sources, whereas dry deposition would be more important in areas far from emission sources. In the atmospheric precipitation, it is possible to determine silicon, as an indicator of the dust transport from distant regions; phosphorus, as an indicator of small particles that appear during the transport of dust storms, grain trans-shipment or during the production of mineral fertilizers; and oxidized nitrogen, as an indicator of the operation of boilers and engines from various types of transportation. The daily-averaged concentrations of PM\({}_{2.5}\) and PM\({}_{10}\) for October 23-24 were 0.019 and 0.037 mg m\({}^{-3}\), respectively. According to the website [[https://www.ventusky.com](https://www.ventusky.com)]([https://www.ventusky.com](https://www.ventusky.com)) (accessed on 14 June 2022), the transport of dust aerosol over the Black Sea is visible (Figure 7). In October-November 2021, increased concentrations of nutrients in atmospheric precipitation were also determined. On October 24, when the south-western transport of dust air masses was observed, the concentrations of all nutrients in the samples from the open sampler were increased. The concentration of silicates was 11.46 \(\upmu\)mol L\({}^{-1}\), phosphates--5.44 \(\upmu\)mol L\({}^{-1}\), and inorganic nitrogen--297 \(\upmu\)mol L\({}^{-1}\). The excess of concentrations over the VWM for this type of sampler was 6.5; 3.2, and 3.7 times for silicates, phosphates, and inorganic nitrogen. Figure 7: Air pollution by PM\({}_{2.5}\) (**a**) and PM\({}_{10}\) (**b**) in 24 October 2021 according to the website. [[https://www.ventusky.com](https://www.ventusky.com)]([https://www.ventusky.com](https://www.ventusky.com)) (accessed on 14 June 2022). Data from the website [[https://www.ventusky.com](https://www.ventusky.com)]([https://www.ventusky.com](https://www.ventusky.com)) (accessed on 14 June 2022). For 29 November 2021 (Figure 9) a south-western direction of aerosol transport is also shown. On 29 November 2021, during the transport of dust air masses over Sevastopol (Figures 8 and 9), light rain was observed. This rain supported precipitation of the dust particles from the atmosphere at the underlying surface. Considering that precipitations washed out dust particles, the concentrations of PM in the atmosphere were not measured. However, concentrations of nutrients in these precipitations were analyzed. The concentration of silicates in the atmospheric depositions collected with the open sampler was 12.43 umol L\({}^{-1}\). This value was more than 7 times higher than the VWM concentration of this element in 2021 for an open sampler and almost 38 times higher than the VWM concentration for a wet-only sampler, which is not affected by dry precipitation. The consequences of the dust air masses transport over the territory of Crimea in the form of settled particles of terrigenous origin on the cars are shown in the photograph (Figure 10). These  
Figure 8: Air masses back-trajectories on 29 (**a**) and 30 (**b**) November 2021 (“—location of station Sevastopol).