Abstract. Atmospheric fluxes of dissolved organic matter (DOM) were studied
for the first time on the island of Lampedusa, a remote site in the central
Mediterranean Sea (Med Sea), between 19 March 2015 and 1 April 2017. The main goals of this study were to quantify total atmospheric
deposition of DOM in this area and to evaluate the impact of Saharan dust
deposition on DOM dynamics in the surface waters of the Mediterranean Sea.
Our data show high variability in DOM deposition rates without a clear
seasonality and a dissolved organic carbon (DOC) input from the atmosphere
of 120.7 mmol DOC m−2 yr−1. Over the entire time series, the
average dissolved organic phosphorus (DOP) and dissolved organic nitrogen
(DON) contributions to the total dissolved pools were 40 % and 26 %,
respectively. The data on atmospheric elemental ratios also show that each
deposition event is characterized by a specific elemental ratio, suggesting
a high variability in DOM composition and the presence of multiple sources.
This study indicates that the organic substances transported by Saharan
dust on Lampedusa mainly come from a natural sea spray and that Saharan
dust can be an important carrier of organic substances even though the load
of DOC associated with dust is highly variable. Our estimates suggest that
atmospheric input has a larger impact on the Med Sea than on the global
ocean. Further, DOC fluxes from the atmosphere to the Med Sea can be up to
6 times larger than total river input. Longer time series combined with
modeling would greatly improve our understanding of the response of DOM
dynamics in the Med Sea to the change in aerosol deposition pattern due to
the effect of climate change