engleski

Climatology of dust deposition in the Adriatic Sea and biological response of Rogoznica Lake (central Adriatic)

Airborne desert dust is one of the most abundant aerosols and an important factor in climate change. After deposition in the sea, mineral dust acts as the nutrient. In this study, the climatology of desert dust deposition in the Adriatic Sea was investigated with special reference to the possible source and mineralogical characteristics of transported dust from North Africa. The effect is particularly examined in unique, isolated marine system, Rogoznica Lake (RL ; 43° 32 ’N, 15° 58’ E) through its biological response. For that purpose, the MERRA-2 reanalysis data for dust deposition in the period 1989- 2019 were used. Annual dust deposition cycle in the Adriatic Sea has maximum in spring and fall with stronger deposition in central and south. Wet deposition accounts for 63-92% of total deposition and 75% of data contains less than 1.5% of the mass. Intensity classes are defined for the remaining 25% and each refers to about 30% of the mass. On average, over 73 days per year is of weak, 14.6 of moderate, and 3.65 of extreme intensity, which varies spatially. In order to detect the specific synoptic patterns for the dust transport in relation to the dust sources activity and deposition in the Adriatic Sea, the EOF analysis on 850 hPa was utilized. Positive or negative mode phases correspond to deposition anomalies in the Adriatic Sea and can be related to particular dust sources in North Africa. Given the seasonal strong physicochemical stratification, relatively small volume, and only source of freshwater and nutrients through precipitation during stratification, the Rogoznica Lake proved ideal for monitoring desert dust deposition events, by monitoring nutrient concentration in the surface layer (0–2 m). For the 2000-2012 period no correlation with MERRA-2 deposition time series were found, but biological activity as a direct consequence of nutrient increase was observed during deposition events. Since the Adriatic Sea was proved to be phosphate (P) and iron (Fe) limited, the mineralogical database was used to estimate the amount of deposited P and Fe during intense deposition events.

Desert dust ; Dust deposition climatology ; EOF ; Adriatic Sea ; Primary production ; Marine system

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