engleski

Seasonal variabilities of nitrogen and phosphorus atmospheric deposition to the Central Adriatic area and biogeochemical implications

The atmosphere is not only a significant, but in some cases the dominant pathway by which natural and anthropogenic material is transported from the continents to the coastal areas and open seas [1, 2]. Once deposited through dry and wet processing, atmospheric particles provide the aqueous ecosystems with an external source of macronutrients (N and P) [3]. This, in turn, influences the quality and quantity of organic matter (OM) produced by the phytoplankton within the photic zone, changes CO2 uptake and indirectly affects the climate. The input of atmospheric deposition (AD) can be of particular importance in oligotrophic regions such as the Mediterranean Sea (Med) which continuously receives anthropogenic aerosols from European regions. The impacts of human activities, including open-field biomass burning (BB) from wildfires and agricultural practices, are thought to be stronger in the Med than in any other sea in the world. The effect of the AD inputs to oligotrophic surface waters of Adriatic Sea is generally unknown. Atmospheric particulate matter as well as bulk and wet atmospheric deposition samples were collected simultaneously during a field campaign conducted from February to July 2019 at the coastal zone of the Šibenik archipelago (Central Adriatic) in order to assess the AD impact of nutrients on sea surface responses of this oligotrophic coastal region. The first comprehensive insight into concentration levels of dissolved inorganic N (DIN) and P in atmospheric samples, their transport history, and dry and wet deposition fluxes to the investigated Central Adriatic area will be presented. The results suggest that dissolved inorganic N and P deposited from the atmosphere to the central Adriatic coastal area can theoretically support up to 8% of new primary production. However, considering the highest values of total DIN and P deposition fluxes related to the intense BB events which occurred during the investigated period, atmospheric nutrient fluxes can sustain up to 12% of primary production in this coastal area. Regional open-field BB episodic emissions commonly occurring at the coastal Adriatic area, accompanied with the rainfalls, could significantly enhance already imbalanced atmospheric N and P deposition and appears to have a significant role in altering nutrient availability and strengthening P limitation in sea surface layers of coastal areas.

atmospheric deposition ; wet deposition ; dry deposition ; macronutrients ; Central Adriatic

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