Publication Date:
2022-05-04
Description:
Coatepeque (on the E slope of Santa Ana Volcano), Ilopango (inside Ilopango Caldera) and Chanmico (associated
with San Salvador Volcano) are volcanic lakes in El Salvador, showing a thermocline at a relatively shallowdepth
(from 30 to 40 m, from 20 to 40 m and from 5 to 15 m depth, respectively) and anoxic conditions below 33, 24
and 4 m depth, respectively. The Na+–Cl− composition of the Coatepeque and Ilopango lakes, displaying TDS
values up to 1226 and 1216 mg/L, respectively, is likely due to hydrothermal fluids that feed these two lakes,
as also confirmed by Cl−/Br− molar ratios ≤ 650, high As, B, Li and Si contents and Cl−/SO4 2− ratio N 1. The Mg2
+–HCO3
− water composition of Lake Chanmico, whose TDS values were between 566 and 856 mg/L, suggests
water-rock interaction processes with mafic/ultramafic rocks variably affected by serpentinization processes,
which produced high Mg2+, Si and B concentrations. Waters at depth were characterized by the presence of
CO2 from an extra-lacustrine source, as suggested by δ13C-CO2 values significantly less negative than those typically
related to biogenic processes, albeit this gas was found in smaller quantities when compared to those recorded
in other meromictic lakes hosted in quiescent volcanic systems (e.g. Lake Kivu in DRC, Monticchio,
Albano and Averno lakes in Italy, Hule and Rio Cuarto lakes in Costa Rica, Lake Pavin in France). The occurrence
of CH4, whose concentrations in Lake Chanmicowere up to two orders of magnitude higher than those recorded
in Coatepeque and Ilopango lakes, suggests bacterial methanogenesis.
Description:
Published
Description:
1-15
Description:
6V. Pericolosità vulcanica e contributi alla stima del rischio
Description:
JCR Journal
Keywords:
Volcanic Lakes
;
El Salvador
;
Water geochemistry
;
03. Hydrosphere
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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