CO2 fluxes of two lakes in volcanic caves in the Azores, Portugal

Andrade, César; Viveiros, Fátima; Cruz, J. Virgílio; Coutinho, Rui; Branco, Rafael

doi:10.1016/j.apgeochem.2019.02.006

Cited by 12 publications

(11 citation statements)

References 39 publications

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“…The GPS positioning of each measurement location was recorded, and a measurement grid with a uniform pattern was followed whenever possible ( Figures 1B and 2B-H). To carry out the CO 2 flux measurements, a modified accumulation chamber method (area = 594 cm 2 ; volume = 7603 cm 3 ) was applied [51], an approach that has been used in other studies in the Azores [24,35,36,52] and in similar studies worldwide [28,29,33]. A full description of the methodology, as well as the advantages and constraints, is provided in the literature [34], but basically consists of the increase of CO 2 concentration within a chamber of known volume during a certain period of time, which is usually about 60 s. With a maximum scale of 20,000 ppm, the infrared LICOR LI-820 detector installed in the device allows for the measurement of CO 2 flux in the range between 0 and 30,000 g m −2 d −1 [53].…”

Section: Co 2 Flux Measurementsmentioning

confidence: 99%

“…A full description of the methodology, as well as the advantages and constraints, is provided in the literature [34], but basically consists of the increase of CO 2 concentration within a chamber of known volume during a certain period of time, which is usually about 60 s. With a maximum scale of 20,000 ppm, the infrared LICOR LI-820 detector installed in the device allows for the measurement of CO 2 flux in the range between 0 and 30,000 g m −2 d −1 [53]. The calibration of the CO 2 equipment-a procedure that was previously described by [35,36] was made in the gas geochemistry laboratory of the IVAR (University of the Azores).…”

Section: Co 2 Flux Measurementsmentioning

confidence: 99%

“…Two statistical analysis procedures were applied to the CO 2 flux data, namely the graphical statistical approach (GSA) (e.g., [51]) and sequential Gaussian simulation (sGs) [56]. The GSA procedure is based on cumulative probability plots, leading to the identification of different populations in the geochemical data [57], which afterwards may be associated with diverse CO 2 sources, such as biogenic processes or volcanic-hydrothermal input (e.g., [24,35,36,51,56,58,59]).…”

Section: Co 2 Flux Data Processingmentioning

confidence: 99%

“…Over the last decade, studies of diffuse degassing CO 2 have been conducted in volcanic lakes all over the world and in other types of water bodies, and such studies have provided important information about their spatial and temporal flux variations and have been shown to be a relevant tool for mapping hidden active faults and/or for active volcano monitoring [10,[18][19][20][21][22][23][24][25]. In addition, these studies have contributed to improving the Earth's carbon budget (e.g., [9,24,[26][27][28][29][30][31][32][33][34][35][36]). Several studies on the CO 2 flux in lakes in the Azores have been conducted recently.…”

mentioning

confidence: 99%

“…The first was performed at Furnas Lake (52-600 t d −1 [24]), where, in addition to a biogenic source, volcanic/hydrothermal carbon is also being released at the bottom of the lake. The Furna do Enxofre Lake, located inside a volcanic cave on Graciosa Island, is also influenced by a volcanic source, and moreover, in the small area of the lake, the flux was estimated to be about 6.10 t d −1 (508.3 t km −2 d −1 ) [36]. In contrast, in lakes where the CO 2 flux is dominated by a single biogenic source, the CO 2 values are much lower, for example, 0.2 t d −1 in Lake Congro (0.88 t km −2 d −1 ) [35], about 0.61 t d −1 in Sete Cidades Lake, and 0.16 t d −1 in Fogo Lake, which are all located on São Miguel Island [37].…”

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confidence: 99%

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CO2 Flux from Volcanic Lakes in the Western Group of the Azores Archipelago (Portugal)

Andrade

Cruz

Viveiros

et al. 2019

Water

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Here, we present the first detailed study on diffuse CO 2 degassing in the lakes in the Western Group (Corvo and Flores islands) of the Azores archipelago. This research is of interest in order to determine (1) the overall CO 2 emission from such lakes, as volcanic lakes are often underrepresented in the databases of these water bodies, and (2) the diffuse CO 2 degassing estimates in active volcanic areas such as the Azores. The lake waters on Corvo and Flores islands are mainly of the Na-Cl type, which is likely caused by the lakes' sea salt signatures, arising from nearby seawater spraying; however, a few samples show evidence of slight alkali earth metal and bicarbonate enrichments in the lake waters, suggesting a contribution of water-rock interaction. In this study, diffuse CO 2 flux measurements were taken using the accumulation chamber method, and statistical analyses utilizing the graphical statistical approach (GSA) and sequential Gaussian simulation (sGs) were conducted on the CO 2 flux data, showing that the CO 2 flux values measured in these lakes were relatively low (0.0-18.6 g m −2 d −1 ). The results seem to indicate that there is a single source of CO 2 (a biogenic source), which is also supported by the waters' δ 13 C isotopic signatures. Significant differences in the final CO 2 output values were verified between surveys (e.g., 0.16 t d −1 in R1; 0.32 t d −1 in R2), and these differences are probably associated with the monomictic character of the lakes. CO 2 emissions ranged between 0.18 t d −1 (CE1) and 0.50 t d −1 (CW1) for the Corvo lakes and between 0.03 t d −1 (P1) and 0.32 t d −1 (R2) for the seven lakes studied on Flores Island. The presence of a dense macrophyte mass in a few of the lakes appears to enhance the CO 2 flux in these lakes. measurements should be obtained from the remainder and the fluxes added to the global databases in order to better understand the total volcanic CO 2 output.The study of volcanic lakes permits enhanced knowledge of volcanic systems, as such lakes present a wide range of chemical characteristics, from high total dissolved solid (TDS) brines to meteoric waters; indeed, they have been called "blue windows" into the depths of a volcano [11,12]. Volcanic gases, composed mainly of water vapor and varied amounts of carbon compounds, sulfur, halogens, and several minor constituents, are the main drivers of volcanic water composition [13][14][15][16].Natural CO 2 can have several origins in that it can originate from the mantle, from carbonate rocks existing in the crust, or as the result of biogenic activity [17]. Over the last decade, studies of diffuse degassing CO 2 have been conducted in volcanic lakes all over the world and in other types of water bodies, and such studies have provided important information about their spatial and temporal flux variations and have been shown to be a relevant tool for mapping hidden active faults and/or for active volcano monitoring [10,[18][19][20][21][22][23][24][25]. In addition, these studies have contributed to improvi...

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Section: Co 2 Flux Measurementsmentioning

confidence: 99%

Section: Co 2 Flux Measurementsmentioning

confidence: 99%

Section: Co 2 Flux Data Processingmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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CO2 Flux from Volcanic Lakes in the Western Group of the Azores Archipelago (Portugal)

Andrade

Cruz

Viveiros

et al. 2019

Water

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Quantification of diffuse CO2 flux emission from the crater lagoon of Vila Franca do Campo Islet (São Miguel, Azores)

et al. 2023

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To investigate unexplored areas and apply methodologies suitable for monitoring volcanic activity, a pioneer study was undertaken in the crater lagoon of Vila Franca do Campo Islet to identify possible CO2 degassing zones in the marine environment. This study was carried out using a floating accumulation chamber, which to the best of our knowledge, has only been applied to lacustrine environments.A survey was carried out in the crater lagoon in August 2017, resulting in a total of 143 CO2 flux measurements. Other parameters, such as water temperature, pH, electrical conductivity, and depth, were also determined at each measuring point, covering a study area of 0.02 km2. At one of the deepest sites with higher CO2 flux values, water samples were collected at depth for determination of stable isotopic composition.Water temperatures ranged between 21.0 and 27.0 °C, pH from 8.24 to 8.89, and electrical conductivity from 52.5 to 53.9 mS/cm. As expected, due to the marine water composition, sampled waters are of the Na-Cl type. CO2 flux varied between 0.581 and 1.0 g m-2 d-1 (average = 2.967 g m-2 d-1). A single CO2 population, characterized by low CO2 fluxes, points to a biogenic CO2 origin (δ13C = −9.62‰). The estimated value for the total CO2 emitted from the water surface is 0.05 t d-1. CO2 flux measurements were also compared with the structural features that cross the tuff cone, but no clear relation was observed with fractures/faults.This methodology should be applied to other coastal marine areas, especially where anomalous gas emissions have been reported.

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Hydrogeochemical evolution and characterization study in volcanic lakes of the Azores archipelago (Portugal)

Andrade,

Cruz,

Viveiros

et al. 2024

Applied Geochemistry

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CO2 fluxes of two lakes in volcanic caves in the Azores, Portugal

Cited by 12 publications

References 39 publications

CO2 Flux from Volcanic Lakes in the Western Group of the Azores Archipelago (Portugal)

CO2 Flux from Volcanic Lakes in the Western Group of the Azores Archipelago (Portugal)

Quantification of diffuse CO2 flux emission from the crater lagoon of Vila Franca do Campo Islet (São Miguel, Azores)

Hydrogeochemical evolution and characterization study in volcanic lakes of the Azores archipelago (Portugal)

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