## 3 Results  
In total, for the period 2010-2019, about 400 atmospheric precipitations samples were collected and processed (Table 1). The contribution of dry depositions to the nutrient's content in atmospheric precipitation over the study period was on average 33% for inorganic nitrogen, 281% for phosphates, and 405% for silica acid. The maximum concentrations of inorganic phosphorus and silicon in the open sampler over those in the wet-only one was 105 times. The results of the analysis of the chemical composition of atmospheric precipitation make it possible not only to assess the contribution of local sources of pollutant emissions, but also the transfer of these pollutants with air masses. Air masses circulating over the Black Sea and beyond bring into the atmosphere significant amounts of various \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Nitrogen**} & \multicolumn{2}{c}{**Phosphorus**} & \multicolumn{2}{c}{**Silicon**} \\ \hline  & **Wet-Only** & **Open** & **Wet-Only** & **Open** & **Wet-Only** & **Open** \\  & **Sampler** & **Sampler** & **Sampler** & **Sampler** & **Sampler** & **Sampler** \\ \hline Amount of & & & & & & \\ data & 391 & 361 & 385 & 354 & 387 & 357 \\ \hline Max, \(\mu\)M & 464.8 & 799.6 & 18.2 & 37.1 & 34.5 & 36.8 \\ \hline Min, \(\mu\)M & 19.5 & 17.0 & 0.0 & 0.0 & 0.0 & 0.0 \\ \hline VWM, \(\mu\)M & 75.6 & 90.5 & 0.4 & 1.3 & 0.9 & 2.0 \\ \hline St. deviation, & & & & & & \\ \(\mu\)M & 68.4 & 97.2 & 1.7 & 3.5 & 3.1 & 5.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Some statistical characteristics of nutrients’ concentrations. mineral dust, the suspension of which contains soil particles from other regions, industrial emissions, gases from mud volcanoes, etc. The maximum concentration of silica acid in the entire period was observed on 14 September 2010. Analysis of the back trajectories according to the AERONET and HYSPLIT data showed the presence of transport from the Sahara Desert on this day (Savastopol, 2010) (Figure 2). Operational monitoring has demonstrated that atmospheric precipitation is one of the main sources of inorganic nitrogen, phosphorus, and silicon on the surface of the Black Sea. It results in more intensive primary production in regions where precipitations were observed. An increase of chlorophyll-A concentration in the Black Sea surface layer after precipitation is noticeable in the region where dust air masses pass (Figure 3a,b). The rectangle shows the area of passage of dusty air masses with subsequent atmospheric precipitation, in which a change in the concentration of chlorophyll-A is observed. The numerical change in the concentration of chlorophyll-A in the sea surface layer during the study period is shown in Figure 4. As we can see, the concentration of chlorophyll-A increased after precipitations by \(\sim\)36%. Figure 2: Seven-day reverse trajectories of the air mass transfer on 14 September 2010 according to the AERONET model. Figure 4: Graph of changes in the chlorophyll-A concentration in the Black Sea surface layer from 29 August to 8 October 2010. Figure 3: Concentration of chlorophyll-A in the surface layer of the Black Sea before (**a**) and after (**b**) precipitation 14 September 2010; (**(a)**) time period 6 September 2010–13 September 2010; (**b**) time period 14 September 2010–21 September 2010. As seen in Figures 3 and 4, after precipitation on September 14, the concentration of chlorophyll-A increased by 1.3 times. At the same time, the sea surface temperature in the study area showed no decrease (Figure 5a,b), i.e., the involvement of the lower, colder, and nutrient-rich sea water could not affect the chlorophyll-A concentration. These sea surface temperature maps are based on observations by the MODIS sensors on NASA's Terra and Aqua satellites. The rectangle shows the area of passage of dust air masses with subsequent atmospheric precipitation, in which a change in the concentration of chlorophyll-A is observed.