Researchers from INGV, CNR and Sapienza University of Rome together on the oceanographic vessel Minerva-uno, to study the underwater hydrothermal system off the island of Zannone in the Pontine Archipelago and place an observatory on the seabed for environmental monitoring
To study the emissions of hydrothermal fluids (water and gas dissolved in it) located off the Zannone Island in the Pontine Archipelago. Researchers from the Palermo and La Spezia-Roma2 Sections of the National Institute of Geophysics and Volcanology (INGV), the Institutes of Environmental Geology and Geoengineering (IGAG) and Geosciences and Georesources (IGG) of the National Council of Research (CNR) and the Earth Sciences Department of the Sapienza University of Rome, during the ZHF (Zannone Hydrothermal Field) oceanographic campaign.
“Multidisciplinary investigations (geophysical, geochemical, micro-paleontological, mineralogical-petrographic) were conducted on board the CNR oceanographic vessel Minerva-uno”, says Francesco Italiano, director of the Palermo-INGV Section. In particular, with the aid of a ROV (wire-guided underwater vehicle), fluid emissions at a depth of 120-150 meters were identified and sampled and the temperatures measured directly at the emission points stood between 60 and 70° . On this occasion, an INGV multidisciplinary observatory dedicated to environmental monitoring was also placed on the seabed, which will remain in operation for a few months, to study the behavior of emissions over time in both the liquid (thermal waters) and gaseous phases".
The gaseous emissions off Zannone were discovered in 2014 as part of the MAGIC Project (funded by the Civil Protection for the identification of elements of geological risk in the Italian seas and whose results were recently published in the Journal Geophysical Research - Solid Earth) when some large craters were identified, probably due to the expulsion of fluids from the seabed in geologically recent times.
"The area is of great interest both for understanding the deep geological processes and for the evidence of the existence of a vast underwater hydrothermal system, hitherto absolutely unknown perhaps also due to the depth at which it is located", continues Italiano. “The emissions mainly consist of carbon dioxide accompanied by methane and hydrogen sulphide, the origin of which is attributed to a deep magmatic source”.
From a biological point of view, the presence of hydrothermal emissions causes dissolution/acidification phenomena which influence microorganisms and allow the establishment of habitats dominated by chemosynthetic microbial communities.
"The habitat in the areas affected by the ascent of thermal fluids", adds the director, "is characterized by the formation of whitish hydrothermal deposits of a sulphurous nature with the presence of hardened crusts and raised structures, even several meters high compared to the surrounding areas".
The ZHF campaign aims to define the submarine hydrothermal system by analyzing both the emission methods of the fluids, their chemical-physical characteristics and temporal variations, as well as the extension of the thermalized areas, the modeling of the possible magmatic source and the relationships between the benthic communities , developed in "extreme" conditions inside the hydrothermal field, and the "normal" conditions located on the adjacent seabed.
“The presence on the seabed of a new technology underwater observatory system for long-term monitoring, created as part of a marine infrastructure upgrading project of the Ministry of Education, University and Research (MIUR), will then allow to investigate whether the behavior of thermal fluids in the deep marine environment over time is only a response to natural forces or also to possible impulsive events of a volcanic-tectonic nature", concludes Francesco Italiano.
Photo1. ROV (wire-guided underwater vehicle) with probe for measuring temperature and prototype for sampling gas created by researchers at INGV in Palermo mounted on ROV
Photo 2: Gas emissions (measured temperature T= 50°C)
Photo 3: Deployment of multidisciplinary submarine observatory
Photo 4: ROV image of the multidisciplinary observatory located at a depth of 146 m