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|Authors: ||Boatta, F.*|
|Title: ||Another kind of “volcanic risk”: the acidification of sea-water. Vulcano Island (Italy) a natural laboratory for ocean acidification studies|
|Editors: ||Corsaro, R.A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia|
|Issue Date: ||12-Dec-2012|
|Keywords: ||ocean acidification|
environmental impact of volcanic activity
|Abstract: ||Acidification of seawater is one of the aspect tightly linked to volcanic risk, due to the presence of submarine
vents releasing abundant volcanic fluids. In aquatic system CO2 gas dissolves, hydrates and dissociates to
form weak carbonic acid, which is the main driver of natural weathering reactions [Drever, 1997]. The result
of the CO2 increase is seawater acidification.
Vulcano Island, the southernmost of Aeolian Islands, is located in the Southern Tyrrhenian Sea (Italy),
approximately 18 miles off the NE coast of Sicily. The Baia di Levante can be considered a natural
laboratory where almost all of the biogeochemical processes related to the ocean acidification can be studied.
In this area many submarine vents release CO2. Four geochemical surveys of the Bay were carried out in
April - September 2011 and May - June
2012. The main physic-chemical
parameters (T, pH, Eh, electric
conductivity) were measured at more
than 70 sites and more than 40 samples
for chemical analyses were collected at
representative points. Major (Na, K,
Mg, Ca, Cl, SO4) and some minor
components (B, Sr, Fe) and trace
elements (Mn, Mo, Al, U, Ce, Pb, Tm,
Tb, Nd, Th) dissolved in water, the
chemical composition of dissolved
gases (He, H2, O2, N2, CH4 and CO2)
and the isotopic composition of total
dissolved inorganic carbon were
determined in the laboratory. The
bubbling CO2 produces a strong
decrease in pH from the normal
seawater value of 8.2 down to 5.5
(Figure 1). In the area close to the main
degassing vents, characterized by very
low pH, macroorganisms were absent.
Acidification of sea water is one of the
aspect tightly linked to volcanic risk,
due to the presence of submarine vents
releasing abundant volcanic fluids.
At Baia di Levante, about 300 m from
the main vents the seawater is only
slightly acidic (pH 6.5 - 7.0) resembling the ocean water conditions in equilibrium with the high atmospheric
CO2 concentrations expected in the near future. Therefore environments like this, naturally enriched in CO2,
are good laboratories to study the consequences of ocean acidification on aquatic biota [Doney et al., 2009].
Furthermore acidification is tightly linked with the mobility and bio-availability of heavy metals [Millero et
al., 2009] in sea water and volcanoes were always the favourite choice for human settlements; as a
consequence economic anthropological activity, such as fishing, could be dangerous for human health,
because of the presence toxic level of trace metals in the food chain due to the presence of the volcano’s.
The present study could provide important information about the best environmental management of
volcanic areas such as Vulcano Island|
|Appears in Collections:||03.04.01. Biogeochemical cycles|
03.04.03. Chemistry of waters
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