## 1 Introduction  
Information about the sources of nutrients for aquatic ecosystems is of key importance for scaling the level of productivity in a particular water system. The presence and quantity of the main inorganic nutrients (inorganic nitrogen and phosphorus, as well as silicon) along with the intensity of light determines the growth and development of various types of phytoplankton in marine ecosystems, production of organic carbon, consumption of oxygen, when this organic matter sinks and is oxidized below the euphotic zone. This is specifically important for coastal areas because of higher production of organic matter in strong phytoplankton blooms and limited inventory of oxygen below the euphotic zone due to shallow waters. Any additional source of nutrients may support and result in oxygen deficit and suboxic conditions on a short time scale. Traditionally, the coastal runoff, including riverine input, and the inflow from deeper water layers by upwelling and mixing processes, are considered as the main sources of nutrients for the productive layer of the sea. However, the characteristics (distribution and capacity) of these sources often cannot explain the peculiarities of the balance of nutrients and production characteristics of a particular water area. The transfer of nutrients with air masses and their input with atmospheric precipitations is one of important but less studied processes even at the qualitative level, not to mention its quantitative and spatio-temporal characteristics. Various substances and elements are loaded with atmospheric depositions [1; 2; 3; 4; 5] onto the underlying surface. Depositions from the atmosphere with snow, fog, or rain are called wet depositions, while depositions as dry particles or gases are called dry deposition. The most influential elements loaded with atmospheric depositions to aquatic systems are nutrients, such as nitrogen in the form of nitrate and ammonium, phosphorus in the form of phosphate and silicon in the form of silicates. The presence of nutrients fuels production of organic matter, while their ratio influences the composition of produced organic matter. They either critically support the export production in offshore areas, where other sources of nutrients are limited, or provide additional input to coastal areas, where other natural and/or anthropogenic sources have already resulted in intensive eutrophication and lead, in particular, to deoxygenation of the marine environment, increased prevalence of hypoxia and anoxia, and fish kills [6]. Excessive deposition of nutrient may result in algal blooms. Atmospheric depositions may also alter the ratios of nutrient, which in turn may affect compositions of blooming algal species. The ultimate cost of continued high deposition rates may be long-term ecosystem degradation. This is especially true for coastal waters near industrially developed cities or cites of intensive agricultural activity, which are powerful local sources of nutrients into the atmosphere, and then to the surface of the sea with atmospheric precipitation. Therefore, the lack of data on the flows of nutrients with atmospheric precipitation may lead to an incomplete understanding of the anthropogenic impact on the nutrients cycle, incorrect assessment of the magnitude, variability, and biogeochemical consequences of the input of nitrogen, phosphorus, and silicon compounds of anthropogenic origin into the marine environment. Since the Black Sea is one of the largest inland seas, it plays a significant role in the regional economy of coastal states for fishing, marine tourism, oil production, etc. Its coastal areas are also exceptionally recreational. At the same time, the coastal areas of the Black Sea are vulnerable to anthropogenic impact, including an increased input of nutrients. This results in an increase in the production of phytoplankton, fish, and shellfish [7; 8]. The atmospheric input is expectedly a significant source of nutrients for the seashoare of urbanized and industrial regions.