Shallow Sea Gas Manifestations in the Aegean Sea (Greece) as Natural Analogs to Study Ocean Acidification: First Catalog and Geochemical Characterization

Abstract

The concepts of CO2 emission, global warming, climate change, and their environmental impacts are of utmost importance for the understanding and protection of the ecosystems. Among the natural sources of gases into the atmosphere, the contribution of geogenic sources plays a crucial role. However, while subaerial emissions are widely studied, submarine outgassing is not yet well understood. In this study, we review and catalog 122 literature and unpublished data of submarine emissions distributed in ten coastal areas of the Aegean Sea. This catalog includes descriptions of the degassing vents through in situ observations, their chemical and isotopic compositions, and flux estimations. Temperatures and pH data of surface seawaters in four areas affected by submarine degassing are also presented. This overview provides useful information to researchers studying the impact of enhanced seawater CO2 concentrations related either to increasing CO2 levels in the atmosphere or leaking carbon capture and storage systems.

Characterization of undocumented CO2hydrothermal vent’s system in the Mediterranean Sea: implications for ocean acidification forecasting

“…In the Tyrrhenian, the areas characterized by hydrothermalism are in the Aeolian archipelago, at Vulcano, Stromboli, Filicudi and Panarea Islands and nearby islets, at Capo Palinuro (Campania), at the Pontine Archipelago (Latium), and at Ischia island and the Bay of Naples [28,29,30]. In the Balearic Sea, a vent systems has been described at the Columbretes islands [31], while in the Aegean, major hydrothermal vent systems are found along the Volcanic Arc at Euboea, Milos, Santorini, Kos, and Yali Nisiros [27,32]. The aim of this paper is to provide the first multidisciplinary description of a new discovered CO 2rich hydrothermal site located in the southern Tyrrhenian Sea, with the objective to characterize the area and discuss the implications of its use in ocean acidification experimental studies.…”

“…Nowadays, about 25 shallow hydrothermal vent’s systems are studied around the world as proxy to study the effects of climate change and OA [13, 15, 23, 24] receiving further impulse by recent developments of exploration and detection methods [25]. A few other systems have been described recently [15, 26, 27]. There is a relatively large body of research on the species and communities inhabiting shallow hydrothermal vents characterized by OA conditions, and also a few reviews on the main structural changes showing a general reduction of taxonomic and functional diversity in the areas of major venting and critical low pH conditions [13, 16, 24].…”

“…In contrast, deep-sea hydrothermal fluids are derived exclusively from seawater, except in special cases where magmatic fluids are involved [19, 20]. To date, about 25 shallow systems are known worldwide [21, 22, 23], but a significant number may not yet have been recognized [24].…”

“…In the Mediterranean Sea, hydrothermal areas are reported from Tyrrhenian, Balearic and Aegean Sea. Tyrrhenian hydrothermal fields are known in the Aeolian archipelago, i.e., at Vulcano, Stromboli, Filicudi and Panarea Islands and nearby islets, at Capo Palinuro, Ischia island and other sites within the Bay of Naples (Campania), at the Pontine Archipelago (Latium), [22, 23, 25, 26], and Scoglio d’Africa (Tuscan Archipelago) [27]. In the Balearic Sea, a vent system has been described at the Columbretes islands [28], while in the Aegean, major hydrothermal vent systems are found along the Volcanic Arc at Euboea, Milos, Santorini, Kos, and Yali Nisiros [22, 29].…”

“…Tyrrhenian hydrothermal fields are known in the Aeolian archipelago, i.e., at Vulcano, Stromboli, Filicudi and Panarea Islands and nearby islets, at Capo Palinuro, Ischia island and other sites within the Bay of Naples (Campania), at the Pontine Archipelago (Latium), [22, 23, 25, 26], and Scoglio d’Africa (Tuscan Archipelago) [27]. In the Balearic Sea, a vent system has been described at the Columbretes islands [28], while in the Aegean, major hydrothermal vent systems are found along the Volcanic Arc at Euboea, Milos, Santorini, Kos, and Yali Nisiros [22, 29].…”