New insights into the degassing dynamics of Lago Albano (Colli Albani volcano, Rome, Italy) during the last three decades (1989-2019)

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.

This study was funded by CALAPA-FISR
2016 (2018-2019).

Amato A., Chiarabba C., Cocco M., Di Bona M. & Selvaggi G. (1994)
- The 1989-1990 seismic swarm in the Alban Hills volcanic area,
central Italy. J. Volcanol. Geotherm. Res., 61, 26-37.
Anzidei M, Carapezza M.L., Esposito A., Giordano G., Lelli M. &
Tarchini L. (2008) – The Albano Maar Lake high resolution
bathymetry and dissolved CO2 budget (Colli Albani
volcano, Italy): Constrains to hazard evaluation. J. Volcanol.
Geotherm. Res., 171, 258-268.
Cabassi J., Capecchiacci F., Magi F., Vaselli O., Tassi F., Montalvo F.,
Esquivel I., Grassa F. & Caprai A. (2019) – Water and dissolved
gas geochemistry at Coatepeque, Ilopango and Chanmico volcanic
lakes (El Salvador, Central America). J. Volcanol. Geotherm. Res.,
378, 1-15.
Cabassi J., Tassi F., Vaselli O., Fiebig J., Nocentini M., Capecchiacci
F., Rouwet D. & Bicocchi G. (2013) – Biogeochemical processes
involving dissolved CO2 and CH4 at Albano, Averno, Monticchio
meromictic volcanic lakes (Central-Southern Italy). Bull. Volcanol.,
75, 683.
Caliro S., Chiodini G., Izzo G., Minopoli C., Signorini A, Avino R. &
Granieri D. (2008) – Geochemical and biochemical evidence of lake
overturn and fish kill at Lake Averno, Italy. J. Volcanol. Geotherm.
Res., 178, 305-316.
Capasso G., Favara R., Grassa F., Inguaggiato S. & Longo M. (2005)
– On-line technique for preparing and measuring stable carbon
isotope of total dissolved inorganic carbon in water samples (δ13CTDIC).
Ann. Geophys., 48, 159-166.
Carapezza M.L. & Tarchini L. (2007) – Magmatic degassing of the Alban
Hills volcano (Rome, Italy): geochemical evidence from accidental
gas emission from shallow pressurized aquifers. J. Volcanol.
Geotherm. Res., 165, 5-16.
Carapezza M.L., Badalamenti B., Cavarra L. & Scalzo A. (2003) – Gas
hazard assessment in a densely inhabited area of Colli Albani
Volcano (Cava dei Selci, Roma). J. Volcanol. Geotherm. Res., 123,
81-94.
Carapezza M.L., Lelli M. &, Tarchini L. (2008) – Geochemistry of the
Albano and Nemi crater lakes in the volcanic district of Alban Hills
(Rome, Italy). J. Volcanol. Geotherm. Res., 178, 297-304.
Chiodini G. (1996) – Gases dissolved in groundwaters: analytical methods
and examples of applications in central Italy. L. Marini, G. Ottonello
(Eds.), Rome Seminar on Environmental Geochemistry. Pacini
Editore, Castelnuovo d Porto, Rome (Italy) (1996), pp. 135-148.
Chiodini G., Cioni R., Guidi M., Raco B. & Marini L. (1998) – Soil
CO2 flux measurements in volcanic and geothermal areas. Appl.
Geochem. 13, 543-552.
Chiodini G. & Frondini F. (2001) – Carbon dioxide degassing from the
Alban Hills volcanic region, Central Italy. Chem. Geol. 177, 67-83
Chiodini G., Tassi F., Caliro S., Chiarabba C., Vaselli O., Rouwet D.
(2012) – Time-dependent CO2 variations in Lake Albano associated
with seismic activity. Bull. Volcanol. https://doi.org/10.1007/
s00445-011-0573-x
Cioni R., Guidi M. Raco B, Marini L & Gambardella B. (2003) – Water
chemistry of Lake Albano (Italy). J. Volcanol. Geotherm. Res. 120,
179-195.
Evans W.C., Kling G.W., Tuttle M.L. & Tanyileke G. (1993) – Gas
buildup in Lake Nyos, Cameroon: the recharge process and its
consequences. Appl. Geochem., 8, 207-221.
Freda C., Gaeta M., Karner D., Marra F., Renne P.R., Taddeucci J.,
Scarlato P., Christensen J.N. & Dallai L. (2006) – Eruptive history
and petrologic evolution of the Albano multiple maar (Alban Hills,
Central Italy). Bull. Volcanol., 68, 567-591.
Funiciello R., Giordano G. & De Rita D. (2003) – The Albano maar lake
(Colli Albani Volcano Italy): recent volcanic activity and evidence of
pre-Roman Age catastrophic lahar events. J. Volcanol. Geotherm.
Res., 123, 43-46.
Funiciello R., Giordano G., De Rita D., Carapezza M.L., Barberi F. (2002)
– L’attività recente del cratere del Lago Albano di Castelgandolfo.
Rend. Acc. Lincei, 9-13, 113-143.
Giordano G., De Benedetti A., Diana A., Diano G., Gaudioso F., Marasco
F., Miceli M., Mollo S., Cas R.A.F. & Funiciello R. (2006) – The
Colli Albani mafic caldera (Roma, Italy): stratigraphy, structure and
petrology. J. Volcanol. Geotherm. Res., 155, 49-80.
Halbwachs M., Sabroux J-C & Kayser G. (2020) – Final step of the 32-
year Lake Nyos degassing adventure: Natural CO2 recharge is to be
balanced by discharge through the degassing pipes. J. Afric. Earth
Sci. https://doi.org/10.1016/j.jafrearsci.2019.103575.
Inguaggiato S & Rizzo A.L. (2004) – Dissolved helium isotope ratios in
ground-waters: A new technique based on gas-water re-equilibration
and its application to Stromboli volcanic system. Appl. Geochem.,
19, 665-673.
Kling G.W., M.A. Clark, Wagner G.N. & Koenigsberg E.J. (1987) – The
1986 Lake Nyos Gas Disaster in Cameroon, West Africa. Science,
236, 169-75.
Kusakabe M. (2015) – Evolution of CO2 content in Lakes Nyos and
Monoun, and sub-lacustrine CO2-recharge sys-tem at Lake Nyos
as envisaged from CO2/3He ratios and noble gas signatures.
Volcanic Lakes (Rouwet, D., Christenson, B., Tassi, F. and
Vandemeulebrouck, J., eds.), 427–450, Springer-Verlag, Berlin,
Heidelberg. https://doi.org/10.1007/978-3-642-36833-2_19
Kusakabe M. (2017) – Lakes Nyos and Monoun Gas Disasters
(Cameroon)—Limnic Eruptions Caused by Excessive Accumulation
of Magmatic CO2 in Crater Lakes. Geochem. Monogr. Series, 1,
1–50.
Marra F., Castellano C., Cucci L., Florindo F., Gaeta M., Jicha B.R.,
Palladino D.M., Sottili G., Tertulliani A., Tolomeo C. (2020) –
Monti Sabatini and Colli Albani: the dormant twin volcanoes at
the gates of Rome. Nature Scientific Reports, 10, 8666. https://doi.
org/10.1038/s41598-020-65394-2.
Martelli M., Nuccio P.M., Stuart F.M., Burgess R., Ellam R.M. &
Italiano F. (2004) – Helium–strontium isotope constraints on
mantle evolution beneath the Roman Comagmatic Province, Italy.
Earth Planet. Sci. Lett., 224, 295-308.
Martini M., Giannini L., Prati F., Tassi F., Capaccioni B. & Iozzelli, P.
(1994) – Chemical characters of crater lakes in the Azores and Italy:
the anomaly of Lake Albano. Geochem. J., 28, 173-184.
Mazot A., Rouwet D., Taran Y., Inguaggiato S. & Varley N. (2011) –
CO2 and He degassing at El Chichón volcano, Chiapas, Mexico: gas
flux, origin and relationship with local and regional tectonics. Bull.
Volcanol., 73, 423-441. https://doi.org/10.1007/s00445-010-0443-y
Mazza R., La Vigna F., Capelli G., Dimasi M., Mancini M. & Mastrorillo
L. (2016) – Idrogeologia del territorio di Roma. It. J. Groundwater.
https://doi.org/10.7343/AS-129-15-0156
Pérez N.M., Hernández P.A., Padilla G., Nolascoo D., Barrancos J.,
Melián G., Padrón E., Dionis S., Calvo D., Rodríguez F., Notsu K.,
Mori T., Kusakabe M., Arpa C.M., Reniva P. & Ibarra M. (2011) –
Global CO2 emission from volcanic lakes. Geology, 39(3). https://
doi.org/10.1130/G31586.1
Pedreschi L. (1995) – I centri lacuali della penisola italiana. III: I centri
dei laghi vulcanici di Castel Gandolfo e di Nemi e quelli dei bacini
artificiali. Accademia Lucchese di Scienze, Lettere ed Arti, Studi e
testi, Lucca, 39, 136 pp.
Rouwet D., Chiodini G., Ciuccarelli C., Comastri A. & Costa A. (2019)
– Lago Albano, the “anti-Nyos-type” lake: The past as a key for the
future. J. Afric. Earth Sci., 150, 425-440.
Sano Y. & H. Wakita (1985) – Geographical distribution of 3He/4He ratios
in Japan: Implications for arc tectonics and incipient magmatism.
J. Geophys. Res., 90, 8729-8741.
Tanyileke G., Ntchantcho R., Fantong W.Y., Aka F.T. & Hell J.V.
(2019) – 30 Years of the Lakes Nyos and Monoun Gas Disasters: A
scientific, technological, institutional and social adventure.
J. Afric. Earth Sci., 150, 415-424.
Tassi F. & Rouwet D. (2014) – Geochemical studies of Nyos-type lakes:
different approaches for data production and interpretation. An
overview. J. Limnol., 73, 39-54.
Tassi F., Vaselli O., Tedesco D., Montegrossi G., Darrah T., Cuoco
E., Mapendano M.Y., Poreda R., & Delgado Huertas A. (2009)
– Water and gas chemistry at Lake Kivu (DRC): geochemical
evidence of vertical and horizontal heterogeneities in a multibasin
structure. Geochem. Geophys. Geosyst., 10(2). https://doi.
org/10.1029/2008GC002191
Trigila R. (Ed.) (1995) – The volcano of the Alban Hills. Tipografia
SGS, Rome (1995), 283 pp.
Venturi S., Tassi F., Cabassi J., Vaselli O., Minardi I., Neri S., Caponi
C., Capasso G., Di Martino R.M.R., Ricci A., Capecchiacci F., Lelli
M., Sciarra A., Cinti D. & Virgili G. (2019) – A multi-instrumental
geochemical approach to assess the environmental impact of CO2-
rich gas emissions in a densely populated area: The case of Cava dei
Selci (Latium, Italy). Appl. Geochem., 101, 109-126. https://doi.
org/10.1016/j.apgeochem.2019.01.003