Publication Date:
2021-08-30
Description:
With this study a nine-year hiatus (May 2010-April 2019) in the
quantification of the CO2 content of Lago Albano by our working group
has been resolved through the acquisition and analysis from two new
field campaigns. Based on a CO2 budget analysis the dynamics of CO2
degassing throughout the past thirty years (1989-2019) is detailed
and quantified. The decreasing CO2 content (expressed as dissolved
inorganic carbon, DIC) in the lake, since the co-seismic CO2 input
during the 1989-1990 seismic swarm beneath Colli Albani volcano, was
accelerated at lake bottom layers (-140 m to bottom, near -160 m) in the
4-5 years after the swarm, continued afterwards at lower depths (-125
to -95 m), and seems to have reached steady-state conditions during
recent years. The peculiar lake basin morphology has control on the
degassing dynamics. The low chemical gradients detected during the
April 2019 survey have induced near-zero degassing conditions, and
arguably stopped the gas-self lifting process: Lago Albano might not
become CO2-free in the future. This finding has implications for gas
hazard when the next seismic swarm will hit the area. The updated
degassing model also takes into account the lake level drop, and
hence the volume decrease of Lago Albano, caused by excessive well
pumping for anthropic purposes. This volume decrease appears to have
a destabilizing effect on the degassing dynamics, which renders Lago
Albano’s gas release less predictable in the future. Enhanced gas surveys
(high-frequency and fine-scale spatial measurements) are needed to
shed light on how Lago Albano degasses in this quiescent stage during
the Anthropocene. A submersible infra-red detector to directly measure
in-lake dissolved CO2 concentrations, applied satisfactorily during this
study, is an adapted instrument to do so.
Description:
This study was funded by CALAPA-FISR
2016 (2018-2019).
Description:
Published
Description:
29-41
Description:
6V. Pericolosità vulcanica e contributi alla stima del rischio
Description:
JCR Journal
Keywords:
Volcanic lake
;
degassing dynamics
;
dissolved CO2
;
lake stability
;
limnology
;
hazard assessment
;
lake
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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