## 4 Discussion
Our results show that after precipitation, the concentration of inorganic phosphorus in the surface layer of the Sevastopol Bay may increase over fivefold compared to the background concentration. The increase in the silicon concentration can reach 30%. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Sevastopol** & **Katsiveli** \\ \hline Winter & 186:1:2.4 & 340:1:1.3 \\ Spring & 161:1:2.4 & 239:1:0.9 \\ Summer & 161:1:1.5 & 220:1:1.4 \\ Autumn & 185:1:3.0 & 454:1:1.6 \\
2015–2020 & 172:1:2.3 & 297:1:1.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: VWM seasonal and average for 2015–2020 values of the N:P:Si ratio in atmospheric depositions in Sevastopol and Katsiveli normalized for phosphorus values. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Date** & **Sevastopol** & **Katsiveli** \\ \hline
24 June 2017 & 11:1:0.3 & 17:1:0.2 \\
29 May 2015 & 6.6:1:0.4 & 11:1:0.2 \\
15 July 2015 & 6.2:1:0.6 & 6.3:1:0.2 \\
13 May 2016 & 23:1:0.8 & 13.5:1:0.2 \\
28 May 2017 & 3:1:0.5 & 10.6:1:0.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: N:P:Si ratio for the cases with extremely high concentrations P in the atmospheric depositions. The input of precipitations containing a significant amount of nutrients into the bay can significantly change the Redfield ratio in surface layer (Table 6). This shift can reach three times the background value, especially during the warm stratification period. A change in the ratio towards one or another nutrient, in turn, can cause the flowering of some phytoplankton species and limit the development of others. Applying the Redfield C:N ratio we can estimate the effect of precipitation. [PERSON] et al. (2018) have studied the amount and influence of atmospheric phosphorus deposition to the Baltic Sea. The median daily deposition of phosphate has been estimated by 56 \(\upmu\)g m\({}^{-2}\) day\({}^{-1}\) (1.8 \(\upmu\)mol m\({}^{-2}\) day\({}^{-1}\)), the median annual phosphate deposition has leveled 16.7 kg km\({}^{-2}\) a\({}^{-1}\). The median TP-depositional rates have ranged between 19 and 70 kg km\({}^{-2}\) a\({}^{-1}\). The highest TP-depositional rates have been measured on summer. [PERSON] et al. (2019) have estimated the total atmospheric inorganic nitrogen deposition to the South China Sea. The authors conclude that this flux is comparable to large riverine inputs and potentially contributes 1.8-11.1% of nitrogen to new production and 0.7-1.8% of nitrogen to primary production. The average annual input of inorganic nitrogen with atmospheric precipitations in Sevastopol region according to data obtained in this work is 31.1 mmol\(\cdot\)m\({}^{-2}\cdot\)year\({}^{-1}\). This may support consumption of 205.9 mmol\(\cdot\)m\({}^{-2}\cdot\)year\({}^{-1}\) of inorganic carbon. According to ([PERSON] et al., 2019), the average annual primary production in coastal areas is 100-130 gC\(\cdot\)m\({}^{-2}\cdot\)year\({}^{-1}\). Based on these values, the average annual nitrogen input with atmospheric precipitation can lead to an increase in primary production by 1.9-2.5%. The annual input of dissolved inorganic phosphorus with atmospheric precipitation (0.33 mmol\(\cdot\)m\({}^{-2}\cdot\)year\({}^{-1}\)) corresponds to an additional carbon production of 35 mmol\(\cdot\)m\({}^{-2}\cdot\)year\({}^{-1}\). This contributes to an increase in primary production in the coastal areas of the Black Sea by \(\sim\)0.4% of its long-term average value. The additional supply of silicon with atmospheric precipitation (0.78 mmol\(\cdot\)m\({}^{-2}\cdot\)year\({}^{-1}\)) contributes to additional organic carbon production of 5.51 mmol\(\cdot\)m\({}^{-2}\cdot\)year\({}^{-1}\), which is a very small amount. The maximum effect on the value of primary production is due to the input of inorganic nitrogen with precipitation. For this possible increase in primary production (205.9 mmol\(\cdot\)m\({}^{-2}\cdot\)year\({}^{-1}\)), we have estimated the amount of oxygen that will be required for its oxidation.