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Article

Origin and Distribution of Thiophenes and Furans in Gas Discharges from Active Volcanoes and Geothermal Systems

by
Franco Tassi
1,2,*,
Giordano Montegrossi
2,
Francesco Capecchiacci
1 and
Orlando Vaselli
1,2
1
Department of Earth Sciences, University of Florence, Via G. La Pira, 4, 50121 Florence, Italy
2
CNR-IGG Institute of Geosciences and Earth Resources, Via G. La Pira, 4, 50121 Florence, Italy
*
Author to whom correspondence should be addressed.
Int. J. Mol. Sci. 2010, 11(4), 1434-1457; https://doi.org/10.3390/ijms11041434
Submission received: 7 January 2010 / Revised: 30 March 2010 / Accepted: 30 March 2010 / Published: 31 March 2010
(This article belongs to the Section Physical Chemistry, Theoretical and Computational Chemistry)
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Abstract

:
The composition of non-methane organic volatile compounds (VOCs) determined in 139 thermal gas discharges from 18 different geothermal and volcanic systems in Italy and Latin America, consists of C2–C20 species pertaining to the alkanes, alkenes, aromatics and O-, S- and N-bearing classes of compounds. Thiophenes and mono-aromatics, especially the methylated species, are strongly enriched in fluids emissions related to hydrothermal systems. Addition of hydrogen sulphide to dienes and electrophilic methylation involving halogenated radicals may be invoked for the formation of these species. On the contrary, the formation of furans, with the only exception of C4H8O, seems to be favoured at oxidizing conditions and relatively high temperatures, although mechanisms similar to those hypothesized for the production of thiophenes can be suggested. Such thermodynamic features are typical of fluid reservoirs feeding high-temperature thermal discharges of volcanoes characterised by strong degassing activity, which are likely affected by conspicuous contribution from a magmatic source. The composition of heteroaromatics in fluids naturally discharged from active volcanoes and geothermal areas can then be considered largely dependent on the interplay between hydrothermal vs. magmatic contributions. This implies that they can be used as useful geochemical tools to be successfully applied in both volcanic monitoring and geothermal prospection.

1. Introduction

Chemical constituents released from gas discharges in active and quiescent volcanic complexes and geothermal systems can be related to: 1) primary (magma degassing) and 2) secondary (gas-water-rock interactions occurring at relatively shallow depth) sources. The ratio between magmatic vs. hydrothermal contributions is generally indicative of the state of activity of a volcanic system and is a basic parameter in terms of volcanic surveillance [1–4]. Magma degassing produces highly acidic and corrosive gas compounds that may affect the geothermal potential of a hydrothermal reservoir. Hydrothermal fluid composition is constituted by water vapor and CO2 and show significant concentrations of reduced gas species, such as H2S, H2 CO and CH4 [5,6]. Magmatic-related fluid contributions, although mainly consisting of the same gases dominating hydrothermal fluids, i.e., water vapor and CO2, can unequivocally be recognized in thermal discharges by the presence of highly acidic compounds, especially SO2 [7–9]. Secondary interactions, such as gas scrubbing processes within shallow aquifers [10,11], are able to strongly affect this highly soluble and reactive gas compounds, frequently masking any clue of magmatic-related fluid contribution at surface. The behaviour of hydrocarbons in natural fluid discharges has recently been considered as a potential tool to investigate the thermodynamic conditions controlling fluid reservoirs feeding fumarolic exhalations in volcanic and geothermal systems [12–15]. These investigations have demonstrated that light hydrocarbons, especially the C2–C4 alkenes-alkanes pairs, play an important role in both geochemical surveillance of volcanic systems and geothermal prospection. On the contrary, little attention was devoted to heavier organic compounds for similar purposes.
In the present work, 139 gas emissions from active volcanoes and geothermal systems set in different geodynamical environments were analysed for the determination of non-methane VOC (Volatile Organic Compound) composition, especially that of heteroaromatic and aromatic compounds. On the basis of this dataset, the main goals were to: 1) assess the origin of thiophenes and furans in naturally discharged fluids and 2) evaluate the possible use of these compounds as geochemical tracers to discriminate different fluid source regions in volcanic-hydrothermal environment.

2. Results and Discussion

2.1. Chemical Composition of the Main Gas Species

A representative composition of the main gas components in fluid discharges from the volcanic and geothermal systems investigated in the present study is listed in Table 1. Gas concentrations are expressed in μmol/mol and referred to the dry gas phase. Gas samples from Teide (Spain), Turrialba (Costa Rica), Vulcano (Italy), Lascar and Tacora (Chile) volcanoes have outlet temperatures varying in a wide range (from 72 to 405 °C) and show a chemical composition dominated by CO2 and characterised by variable amounts of SO2 (from 1.2 to 569394 μmol/mol).
Such features, coupled with relatively low concentrations of CH4 (<690 μmol/mol) and high concentrations of HCl (from 351 to 74540 μmol/mol) and H2 (up to 32591 μmol/mol), indicate that the gas chemistry of these systems is strongly controlled by magma degassing [16]. This hypothesis is in agreement with previous studies [17–20] that investigated the source of fluids produced by the intense fumarolic activity recently observed at these volcanic systems. A different chemistry characterises gases from (1) El Tatio (Chile), Larderello (Italy) and Tendaho (Ethiopia) geothermal systems [21–23] (samples #48–64), and (2) volcanoes whose degassing activity is considered to be mainly related to boiling of extended hydrothermal reservoirs (Copahue, Argentina; Deception, Antarctica; El Chichon, Mexico; Ischia, Pantelleria, Phlegrean Fields and Vesuvio, Italy; Nisyros, Greece; Tatun, Taiwan; Yellowstone, USA) [24–31] (samples #65–139). This group shows SO2 below the instrumental detection limit (≈0.01μmol/mol: samples #48–138), relatively low outlet temperatures <118 °C, high CH4 concentrations (up to 64103 μmol/mol), and HCl not exceeding 500 μmol/mol.

2.2. VOC Composition

Up to 129 different non-methane VOCs, pertaining to the alkane (27 compounds), aromatic (21 compounds), cyclic (17 compounds), alkene (15 compounds), Cl-bearing (13 compounds), O-bearing (ketones, aldehydes, organic acids and alcohols; 36 compounds) and heteroaromatic (7 compounds) groups, were determined (Table 2; gas concentrations are expressed in ppb by volume and referred to the dry gas phase). The total VOC concentrations in gases with a dominating magmatic contribution (samples #1–47, hereafter M gases) are relatively low (from 61 to 1664 ppbv), whereas they range from 180 to 1235942 ppbv (Table 2) in those gases (#48–141) characterised by prevalent hydrothermal contribution (hereafter H gases). Hydrothermal reservoirs, even when associated with volcanic systems, are commonly recharged by fluids circulating within organic-bearing sedimentary rocks. This organic source is then transformed into VOCs through biogenic and thermogenic processes [32]. Therefore, relatively high VOC concentrations in the H gases are expected. On the contrary, the organic-rich component constitutes a minor fraction of the M gases, since it is generally destroyed by high-temperature, oxidizing fluids released from the magmatic melts [13]. The relative percentages (mean values) of the different groups of VOCs can provide preliminary indications to distinguish the M and H gases: in the M gases, alkane, Cl-bearing, aromatic, heteroaromatic and alkene compounds are present in almost comparable amounts (31, 28, 16, 16 and 9% of total VOCs, respectively), whereas cyclic and O-bearing species represent a small VOC fraction (<0.04%) (Figure 1a). The organic fraction of the H gases is largely dominated by alkanes and aromatics (54 and 24%, respectively) with minor cyclic, alkene, heteroaromatic and O-bearing compounds (from 0.7 to 1.4%), and traces (<0.04%) of Cl-bearing compounds (Figure 1b). These evidences are consistent with recent investigations that have highlighted a recurrent relation between VOC speciation and thermodynamic conditions at the fluid source in gas discharges from volcanic and geothermal systems [33–36]. Predominance of alkanes and aromatics in both the M and H gases was considered to reflect the proceeding of “reforming” processes, which in geothermal areas, as well as in hydrothermal systems commonly surroundings active volcanoes, are favoured by the large availability of catalytic agents, such as free acids, allumosilicates and sulphur gas species [37,38]. Pyrolysis of organic material was found to produce mostly alkanes and, secondarily, aromatics [39,40], whereas Fischer-Tropsch reactions were invoked for the production of light alkanes and, at a minor extent, alkenes [41]. The presence of halocarbons in volcanic gas emissions was attributed to either the product of pyrolysis of adjacent vegetation [42,43] or, alternatively, air contamination [44,45]. Conversely, organic geochemical evidence supported a pristine abiogenic origin by high-temperature gas-phase radical reactions [46,47].

2.3. Distribution and Origin of the Heteroaromatic Compounds

Concentrations (in ppbv, referred to the dry gas phase) of C4H4O, 3-C5H6O, C4H8O, 2-C5H10O, C4H4S, 3-C5H6S and 2,5-C6H8S, and those of the simplest aromatics (C6H6 and C7H8), are reported in Table 3. In the M gases, the concentrations of furans tend to be higher than those of thiophenes (their sum ranging from 1.9 to 35 and from 0.2 to 26 ppbv, respectively); C4H4S is largely the most abundant S-bearing compound (up to 1.9 ppbv), whereas C4H4O (up to 31 ppbv) dominates the furan composition. Conversely, the H gases have relatively high concentrations of C4H4S and 3-C5H6S (up to 191 and 121 ppbv, respectively), minor 2,4-C6H8S (up to 13 ppbv), and no furans, with the only exception of those from Deception, Nisyros, Vesuvio, Copahue and El Chichon volcanoes. As shown in Figure 2, in the H gases thiophenes are strongly related to H2S, (in hydrothermal environment SO2 concentrations are the below detection limit; Table 1). This correlation would imply that the formation of the S-bearing heteroaromatics intimately depends on sulphur fugacity (fS) at the fluid source, and likely occurs within deep fluid reservoirs where H2S is also produced. This hypothesis is consistent with the composition of fluids from carbonate reservoirs affected by thermochemical sulphate reduction: the higher the H2S fugacity, the higher content of organic sulphur compounds in the coexisting hydrocarbon phase [48,49]. Moreover, sulphidation of organic matter giving rise to thiophenes was found to be associated with gold mineralization deriving from hydrothermal fluids [50,51]. According to these considerations, it is reasonable to suppose that thiophenes can efficiently be produced in a hydrothermal reservoir, this environment being commonly characterised by reducing conditions, relatively high fS and temperature <350 °C [5,6]. Production of C4H4S by reaction of light alkenes, such as C2H4, with FeS2 and H2S was invoked to explain their presence in the volcanic gases emitted from Mt. Etna [52].
On an industrial scale thiophene is synthesized through the following catalytic processes: 1) reaction of C4+ alcohols or carbonyls with CS2 over alkali-promoted alumina; 2) reaction of unsaturated aldehydes with H2S over an alkali-promoted alumina; 3) reaction of C4+ alkyl hydrocarbons or olefins with CS2, S, and H2S over alkali-promoted alumina; 4) catalytic dehydrogenation of tetrahydrothiophene; 5) synthesis from furan and H2S over alumina [53–56]. The thiophene Paal-Knorr synthesis involves the reaction of 1,4-diketones with H2S as sulphurising agent [57]. Generally speaking, in gases from natural fluid discharges, the most reliable genetic mechanism for the formation of thiophene is through the addition of H2S to dienes in the presence of H+ and metal catalysts (Scheme 1).
In the M gases heteroaromatics and inorganic sulphur-bearing gases, the latter being constituted by SO2 and H2S at comparable concentrations (Table 1), are apparently showing an inverse correlation (Figure 2). This suggests that thiophenes, which are less reactive than other five-membered heteroaromatics, including furans, serving as dienes during Diels-Alder reactions [58], tend to be destroyed when fluid reservoirs are affected by conspicuous contribution from magmatic degassing.
The C4H4S concentrations and those of 3-C5H6S (Figure 3a) and C6H6 (Figure 3b) show a positive correlation in both H and M gases. This supports the following hypotheses: 1) at hydrothermal conditions mono-aromatics and thiophenes are efficiently produced by similar genetic processes; 2) all these compounds have a similar behaviour in response to thermodynamic conditions caused by presence of oxidizing and high temperature (>400 °C) magmatic fluids.
It is worth noting that the H gases have higher 3-C5H6S/C4H4S and C7H8/C6H6 ratios than the M ones (Figure 4). This may be caused by the large availability of CH4 (Table 1) and light hydrocarbons (Table 2) that at hydrothermal conditions can produce free and halogenated radicals that favour the production of 3-C5H6S from C4H4S, as well as that of C7H8 from C6H6. Attach of XCH3+ (X = F or Cl), whose formation likely occurs in both geothermal and volcanic fluid reservoirs where halogenated species are abundant [6–9], on thiophene may give rise to the corresponding methylated derivatives [59]. It is worthy of noting that 3-C4H4S is the only methyl-thiophene recognized in both geothermal and volcanic gases (Table 3), although electrophilic methylation of thiophene is able to produce different isomers. This may be explained by the occurrence of secondary isomerization of methylated thiophenes favouring 3-C4H4S that results the thermodynamically most stable isomer in natural environments. Alternatively, 3-C4H4S may be produced through H2S adding to dienes, such as 2-methylbutadiene originated by isomerization of 1.3-pentadiene (Scheme 2). Double methylation seems to be favoured when methyl substitutions are stabilized at positions 2 and 4 (Table 3).
In the M gases, C4H4O is inversely correlated to C4H4S (Figure 5). This suggests that the production of C4H4O is particularly efficient in a magmatic-related environment, where thermodynamic conditions promote the destruction of thiophenes and aromatics.
The main mechanism of formation of C4H4O may be related to the Paal-Knorr synthesis (Scheme 3), which is efficient under acidic conditions, such as those determined by the huge amounts of highly acidic gas species (HF, HCl and SO2) occurring in the M gases (Table 1).
As shown in Figure 6, the H and M gases can also be clearly distinguished on the basis of the relative concentrations of furans: C4H8O is dominant in the H gases, whereas C4H4O is the most abundant O-bearing heteroaromatic species in the M gases. This suggests that reducing conditions and relatively low temperature (<350 °C), typical of hydrothermal environments, tend to favour the consumption of C4H4O to produce C4H8O through catalytic hydrogenation (Scheme 4) [60,61].

3. Experimental Section

3.1. Gas Sampling Method

Gas samples for the determination of the main gas species were collected into pre-evacuated 60 mL glass flasks filled with 20 mL of a 4N NaOH and 0.15 M Cd(OH)2 suspension. Quartz-glass dewar tubes and a plastic funnel were used to convoy the gas into the sampling flasks from 1) fumarolic vents and 2) boiling pools, respectively. During sampling, CO2, SO2 and HCl dissolved into the alkaline solution, water vapour condensed, and H2S reacted with Cd2+ to form insoluble CdS, allowing the residual gases (N2, CH4, Ar, O2, H2, and light hydrocarbons) to be concentrated in the head-space [62–64]. Gas samples for the determination of VOC composition were collected with the same devices used for the conventional gas sampling, and stored into pre-evacuated 12 mL glass vials equipped with pierceable rubber septum (Labco Exetainer®).

3.2. Analytical Methods

Nitrogen, Ar, O2 and H2 were analysed with a Shimadzu 15A gas-chromatograph equipped with Thermal Conductivity Detector (TCD) and a 9 m, 5A molecular sieve column. Methane and C1–C4 alkanes and alkenes were analysed with a Shimadzu 14a gas-chromatograph equipped with Flame Ionization Detector (FID) and a 10 m long stainless steel column (φ = 2 mm) packed with Chromosorb PAW 80/100 mesh coated with 23% SP 1700. The alkaline solution, separated from the solid precipitate by centrifugation at 4,000 rpm for 30 min, was used for the determination of: 1) CO2 as CO32− by titration with 0.5 N HCl solution; 2) SO2 as SO42−, after oxidation with H2O2, by ion-chromatography (Metrohm Compact 761); 3) HCl, as Cl− by ion-chromatography. The solid precipitate was oxidized by H2O2 to determine H2S as SO42− by ion-chromatography [63,64]. The analytical error is <5%.
The VOCs were pre-concentrated and transferred from the sampling vials into the column headspace of a Thermo Trace GC Ultra gas chromatograph by using a manual SPME (solid-phase micro-extraction) device introduced through the silicon membrane of the glass vial to expose the gas mixtures to a divinylbenzene (DVB)-Carboxen-polydimethylsiloxane (PDMS), 50/30 μm, 2 cm long fibre assembly (Supelco; Bellefonte, PA, USA) for 15 min [65]. The usefulness of the SPME method [66] for the VOC analysis has widely been demonstrated [67–69]. The DVB-Carboxen-PDMS fibre was selected by its high retentive properties, a feature that is particularly appropriate for analysis aimed to the determination of the organic compounds of interest for the present paper. A Thermo Trace GC Ultra gas chromatograph coupled with a Thermo DSQ Quadrupole Mass Spectrometer was used for analytical separation and detection. The mass spectrometer operated in full scan mode, in the mass range 40–400 m/z. The transfer-line temperature was set at 230 °C. The mass detector was equipped with EI set at 70 eV. The source temperature was 250 °C. The gas chromatograph was equipped with a split/splitless injection port operating in the splitless mode with a dedicated SPME liner (0.75 mm i.d.). Analytes were desorbed from the SPME fiber through direct exposure for 2 min in the GC injection port, heated at 230 °C. The chromatographic column was a 30 m × 0.25 mm i.d. 0.25 μm film thickness TV1-MS fused silica capillary column (Thermo). The carrier gas was helium set to a flow-rate of 1.3 mL/min in constant pressure mode. The column oven temperature program was the following: 35 °C (hold 10 min), rate 5.5 °C/min to 180 °C (hold 3 min), rate 20 °C/min to 230 °C (hold 6 min) [65]. Compounds were identified by comparison of the mass spectra with those of the NIST05 library (NIST, 2005).
The VOCs identified by mass spectrometry were quantified using an external standard calibration procedure performed on the basis of calibration curves created by analyzing gaseous standard mixtures of the main VOC groups, i.e., alkanes, alkenes, aromatics, cyclics, chlorofluorocarbons, ketones, aldehydes and heteroaromatics. The values of the Relative Standard Deviation (RDS), calculated from seven replicate analyses of a gaseous mixture in which the compounds of interest were present at a concentration of 2 ppmv, are <7%. Eventually, the detection limits were determined by linear extrapolation from the lowest standard in the calibration curve using the area of a peak having a signal/noise ratio of 5 [68].

4. Conclusions

The distribution of thiophenes and furans in gases from hydrothermal and magmatic-hydrothermal systems have been revealed to be strongly dependent on the physical-chemical conditions acting on fluid reservoirs, where VOCs are produced via a complex series of catalytic processes, involving organic matter buried in sedimentary formations. Thiophene seems to be efficiently produced at hydrothermal conditions and tend to be destroyed in presence of hot, highly oxidizing fluids from a magma source. On the contrary, the formation of C4H4O seems to be favoured at highly acidic and oxidizing conditions that are determined by the presence of fluids from magmatic degassing. Methylated and hydrogenated heteroaromatics are also preferentially associated with hydrothermal conditions. According to these considerations, the composition of O- and S-bearing heteroaromatics can be utilized in both volcanic and geothermal systems to evaluate contributions of fluids produced in different “natural dominions”, i.e., hydrothermal and magmatic. These results may imply useful applications in volcanic monitoring and geothermal prospection, although the existing dataset should be expanded to better constrain the behaviour of these new geochemical tracers. Experimental runs, able to test the mechanisms of formation and stability of heteroaromatics at temperature, redox and catalytic conditions resembling those of a volcano-hydrothermal environment, would probably useful to better constrain their behaviour.

Acknowledgments

Many thanks are due two anonymous reviewers who improved an early version of the manuscript. This work partly benefited from the financial support of the Laboratories of CNR-IGG and Department of Earth Sciences of Florence (Italy).
  • Sample Availability: Available from the authors.

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Ijms 11 01434f1 1024
Figure 1. Relative concentrations, expressed as % of the total VOC abundances, of alkane, aromatic, cyclic, alkene, Cl-bearing, O-bearing and heteroaromatic compounds in (a) M and (b) H gases.
Figure 1. Relative concentrations, expressed as % of the total VOC abundances, of alkane, aromatic, cyclic, alkene, Cl-bearing, O-bearing and heteroaromatic compounds in (a) M and (b) H gases.
Ijms 11 01434f1
Ijms 11 01434f2 1024
Figure 2. (H2S + SO2) vs. (C4H4S + 3C5H6S + 2,4C6H8S) binary diagram. Green triangle: H gas; red circle: M gas.
Figure 2. (H2S + SO2) vs. (C4H4S + 3C5H6S + 2,4C6H8S) binary diagram. Green triangle: H gas; red circle: M gas.
Ijms 11 01434f2
Ijms 11 01434f3 1024
Figure 3. (a) 3-C5H6S vs. C4H4S and (b) C6H6 vs. C4H4S binary diagrams. Symbols as in Figure 2.
Figure 3. (a) 3-C5H6S vs. C4H4S and (b) C6H6 vs. C4H4S binary diagrams. Symbols as in Figure 2.
Ijms 11 01434f3
Ijms 11 01434f4 1024
Figure 4. 3-C5H6S/C4H4S vs. C7H8/C6H6 binary diagram. Symbols as in Figure 2.
Figure 4. 3-C5H6S/C4H4S vs. C7H8/C6H6 binary diagram. Symbols as in Figure 2.
Ijms 11 01434f4
Ijms 11 01434f5 1024
Figure 5. C4H4O vs. C4H4S binary diagram. Symbols as in Figure 2.
Figure 5. C4H4O vs. C4H4S binary diagram. Symbols as in Figure 2.
Ijms 11 01434f5
Ijms 11 01434f6 1024
Figure 6. C4H4O-C5H6O-C4H8O triangular diagram. Symbols as in Figure 2.
Figure 6. C4H4O-C5H6O-C4H8O triangular diagram. Symbols as in Figure 2.
Ijms 11 01434f6
Ijms 11 01434f7 1024
Scheme 1. Synthesis of C4H4S from butadiene.
Scheme 1. Synthesis of C4H4S from butadiene.
Ijms 11 01434f7
Ijms 11 01434f8 1024
Scheme 2. 3-Methylthiophene production from 2-methylbutadiene.
Scheme 2. 3-Methylthiophene production from 2-methylbutadiene.
Ijms 11 01434f8
Ijms 11 01434f9 1024
Scheme 3. Paal-Knorr synthesis of C4H4O.
Scheme 3. Paal-Knorr synthesis of C4H4O.
Ijms 11 01434f9
Ijms 11 01434f10 1024
Scheme 4. Furan hydrogenation to form C4H8O.
Scheme 4. Furan hydrogenation to form C4H8O.
Ijms 11 01434f10
Table
Table 1. Chemical composition of the main gas species. Concentrations are in μmol/mol.
Table 1. Chemical composition of the main gas species. Concentrations are in μmol/mol.
n°sampleLocationT °CCO2HClSO2H2SN2CH4ArO2H2
1Teide volcano 1Spain9896009235115021780715444152186884191
2Teide volcano 2Spain96968658469120316838770022824215044
3Lascar volcano 1Chile76753737573959954440207209488129346419269
4Lascar volcano 2Chile80784999506165264796179060734122546115917
5Lascar volcano 3Chile76755275857070785264200992689141655718226
6Lascar volcano 4Chile7274353414702204381029818629843198359720241
7Lascar volcano 5Chile737680922950624890859614400226733228520683
8Lascar volcano 6Chile827656751367021603818016744222525977020551
9Lascar volcano 7Chile1518349081652246074197781114538962216117
10Lascar volcano 8Chile17891109260452709215403663429605306655
11Lascar volcano 9Chile2508555791251348617151467155177865412146
12Lascar volcano 10Chile154841254126984232718179257745916776286
13Lascar volcano 11Chile1748404611418546693198684126511345128920
14Lascar volcano 12Chile1508539081279544835184074669441324858587
15Tacora volcano 1Chile84852515109362162679711184022212412873
16Tacora volcano 2Chile848743796833237251789496427379137857
17Tacora volcano 3Chile848058938914708288551564792891558101544
18Tacora volcano 4Chile8495076811416722276041345521143685
19Tacora volcano 5Chile8395893075640402232813640261655124
20Tacora volcano 6Chile8294177894562353618914544232312115
21Tacora volcano 7Chile84952234104248992915012384311526106
22Tacora volcano 8Chile84947883104360933106613550431525127
23Tacora volcano 9Chile9194290489157313595114193341525106
24Tacora volcano 10Chile90947666101045893321513219351419100
25Turrialba volcano 1Costa Rica9191452966941037296903694242.48.73.8302
26Turrialba volcano 2Costa Rica9090763643546982973642142333.6166450
27Turrialba volcano 3Costa Rica9196624414796569394172545402.50.42.21163
28Turrialba volcano 4Costa Rica9396356472144074652007455072.96.95.83628
29Vulcano Island crater 1Italy311930405318702132188307273451.5421679336
30Vulcano Island crater 2Italy317933226390261078708527162630.61810441895
31Vulcano Island crater 3Italy3168808157454037006515292268650.9361506945
32Vulcano Island crater 4Italy2369512726184878632511785340.715138866
33Vulcano Island crater 5Italy20896813115517554664584111120.5140.9642
34Vulcano Island crater 6Italy1029929712759846358030830.62.30.588
35Vulcano Island crater 7Italy27895290821738294335395168390.4627482310
36Vulcano Island crater 8Italy1029331026042147520917446022.2136226411
37Vulcano Island crater 9Italy251967834101412904510562109011.0103.4549
38Vulcano Island crater 10Italy209915616118814336520983400381.33714011304
39Vulcano Island crater 11Italy405949811211105408616790113060.41025950
40Vulcano Island crater 12Italy2459270503735812645813795173163.3122.84461
41Vulcano Island crater 13Italy295920470338858701331162129040.7176.31556
42Vulcano Island crater 14Italy21595060419154700224480170521.62413817304
43Vulcano Island crater 15Italy2899211212702310554523028202135.136958479
44Vulcano Island crater 16Italy390981526188612977640490600.49311083
45Vulcano Island crater 17Italy1019689382805120528632193430.317116150
46Vulcano Island crater 18Italy2139516972010471432064074121.0193318187
47Vulcano Island crater 19Italy3258483315438713255236150259404.631256432591
48El Tatio 1Chile86989864328565481164232114
49El Tatio 2Chile8498970736696278774725196
50El Tatio 3Chile86993055202044831974159144
51El Tatio 4Chile87992536118157972195557155
52El Tatio 5Chile849932047255472416504687
53Afar 1Ethiopia9997241959361818229121044339298.8
54Afar 2Ethiopia9997351077108248094115218634752416
55Afar 3Ethiopia9697383175122807526140718122952386
56Afar 4Ethiopia97959562491248420489115650557186.2
57Afar 5Ethiopia9897084778143657220202916324772680
58Afar 6Ethiopia92965397371254015743598383520027
59Afar 7Ethiopia9797518132117109043900222287710
60Larderello 1Italy939246632512915053144585327920364
61Larderello 2Italy95736044676219499542522734461479066
62Larderello 3Italy90936040130261388790185927927691
63Larderello 4Italy918343188977102383405614652764221158
64Larderello 5Italy859136031827015737244208815127881
65Deception Island 1Antarctica9998435051278196161801454678
66Deception Island 2Antarctica9898339159108373251772027120
67Deception Island 3Antarctica9998607960425712501234991495
68Copahue volcano 1Argentina9396069254210433145226443551947120
69Copahue volcano 2Argentina909584551999001455764844912010416
70Copahue volcano 3Argentina859795801853926944368722704288
71Copahue volcano 4Argentina929697206781139466845762281885546
72Copahue volcano 5Argentina759886595.324832701365910252457
73Copahue volcano 6Argentina9197279247677858707396626876162
74Copahue volcano 7Argentina93984796438141062951853.210168
75Copahue volcano 8Argentina929604725871774338026821823216465
76Copahue volcano 9Argentina80938355545101712591410270497348810761
77Copahue volcano 10Argentina92934503393200521276926963612325026
78Nysiros Island 1Greece99773472152013692581118968.89.410649
79Nysiros Island 2Greece1038674198.61310341743780.40.8985
80Nysiros Island 3Greece1048472577.21364491930756310146771
81Nysiros Island 4Greece1008206251217319977921693.89.13203
82Nysiros Island 5Greece988275608.316594358223001.42.03603
83Nysiros Island 6Greece1018251927.01511804058545224018957
84Nysiros Island 7Greece1027327438.31695481303631187449053344
85Nysiros Island 8Greece977817097.0162342279225678111527446
86Nysiros Island 9Greece988218095.81761327242002.46.51120
87Nysiros Island 10Greece1007786981221084458218452.00.78017
88Nysiros Island 11Greece1018211309.214384710159105113328814023
89Nysiros Island 12Greece1028950235.9607651131422953341989707
90Nysiros Island 13Greece9882276410160681103442752384.73407
91Nysiros Island 14Greece1008270675.81703242261240.71.32251
92Ischia Island 1Italy1019134792259667472026217067167
93Ischia Island 2Italy102960463243126029219710756202
94Ischia Island 3Italy999867462724915412134675546
95Ischia Island 4Italy969814715166555552252687463
96Ischia Island 5Italy1019189593957582941724518317211
97Phlegrean Fields 1Italy5999537527311159316.131667
98Phlegrean Fields 2Italy7899410630911721595.2141003
99Phlegrean Fields 3Italy10298855827082401817495.85.81055
100Phlegrean Fields 4Italy10198745137389101802408.0731343
101Phlegrean Fields 5Italy16197256544011090793114628177782
102Phlegrean Fields 6Italy163985513165109672002302.9161304
103Phlegrean Fields 7Italy16298676514098601843363.07.81344
104Phlegrean Fields 8Italy148984348201108672397524.8322098
105Phlegrean Fields 9Italy149977398238174182693544.37.42188
106Phlegrean Fields 10Italy10398956710580301406252.98.7855
107Phlegrean Fields 11Italy1019821521471380722102044.8171459
108Vesuvio volcano 1Italy8997324714224400242413347623
109Vesuvio volcano 2Italy879750461454519614145.3207532
110Pantelleria Island 1Italy619951723139143118535380.1
111Pantelleria Island 2Italy999783493051142685.037239540.3
112Pantelleria Island 3Italy10197746348061939736027558349
113El Chichon volcano 1Mexico789345001787112636508139134470
114El Chichon volcano 2Mexico10097355952150853394758.52.67883
115El Chichon volcano 3Mexico969525982235013983417349510457
116El Chichon volcano 4Mexico1019127949158729150992303517412947
117El Chichon volcano 5Mexico8382637214916101241100354258754430
118El Chichon volcano 6Mexico4692527134423205113410220619452
119Tatun 1Taiwan9871990112498381518641036857855955
120Tatun 2Taiwan987807171848292360610790331213
121Tatun 3Taiwan118915935604261657166812760300
122Tatun 4Taiwan1019758482606207445281201476.5
123Tatun 5Taiwan9593098562801508511806.91.02.9
124Tatun 6Taiwan919498408254844546711129814
125Tatun 7Taiwan988608491165739269115467.52.91753
126Yellowstone 1U.S.A.93987886739619672763081417
127Yellowstone 2U.S.A.8595977415997163321956414105450
128Yellowstone 3U.S.A.8799044064321925369292.7736
129Yellowstone 4U.S.A.91904177333392016299715.04819315
130Yellowstone 5U.S.A.92964894275855348443135191475
131Yellowstone 6U.S.A.929740362271524495604710157
132Yellowstone 7U.S.A.92771017211201760092865213426063111
133Yellowstone 8U.S.A.93953746382103321296284111512
134Yellowstone 9U.S.A.9495658219888159843549430773411
135Yellowstone 10U.S.A.949652092018144972050107297031
136Yellowstone 11U.S.A.115985033115442131411339.1793
137Yellowstone 12U.S.A.9397704418030262026559151952
138Yellowstone 13U.S.A.9196646323989555435301355.0250
139Yellowstone 14U.S.A.93935528235963012492817855479
Table
Table 2. Composition of main VOC groups. Concentrations are in ppbv.
Table 2. Composition of main VOC groups. Concentrations are in ppbv.
n°sampleAlkanesAromaticsCyclicsAlkenesCl-BearingO-bearingheteroaromaticssum
1Teide volcano 1400730.22191.80.1816710
2Teide volcano 2346910.22063.60.1715662
3Lascar volcano 3112250.225390.0727228
4Lascar volcano 498230.216340.0524195
5Lascar volcano 579270.136410.0627210
6Lascar volcano 681300.141360.0826214
7Lascar volcano 767220.152740.0725239
8Lascar volcano 873210.248370.0830209
9Lascar volcano 941160.116460.0326145
10Lascar volcano 1036180.115350.0423126
11Lascar volcano 1146150.121310.0223136
12Lascar volcano 1242160.115560.0321150
13Lascar volcano 1333170.118660.0521155
14Lascar volcano 1429170.114630.0419142
15Tacora volcano 15802621.11422.50.08191007
16Tacora volcano 27183050.9913.90.06221141
17Tacora volcano 312222670.81504.70.06201664
18Tacora volcano 4961160.3113.50.0529256
19Tacora volcano 5821470.2154.60.0718267
20Tacora volcano 6861570.3135.40.0820283
21Tacora volcano 7581820.4103.80.0618273
22Tacora volcano 8961760.5146.10.0414307
23Tacora volcano 91101970.5154.80.0914341
24Tacora volcano 101051960.4124.80.0515333
25Turrialba volcano 511110.07.3290.021371
26Turrialba volcano 612100.05.5280.011570
27Turrialba volcano 79.0100.06.3310.021369
28Turrialba volcano 813110.06.9360.031279
29Vulcano Island crater 1272.50.04.6640.0225123
30Vulcano Island crater 2379.40.04.5610.0319131
31Vulcano Island crater 3372.70.08.8150.023295
32Vulcano Island crater 4151.70.05.1690.0122113
33Vulcano Island crater 5101.40.02.3710.0125110
34Vulcano Island crater 64.31.20.01.7450.011668
35Vulcano Island crater 7201.70.03.9950.0130150
36Vulcano Island crater 876200.011360.028.3151
37Vulcano Island crater 98.41.90.01.8150.013461
38Vulcano Island crater 10412.50.010360.0123112
39Vulcano Island crater 11132.00.02.1350.024093
40Vulcano Island crater 12203.70.08.6420.032195
41Vulcano Island crater 13141.10.02.9740.0224116
42Vulcano Island crater 14273.60.06.0460.0126109
43Vulcano Island crater 15202.80.05.1260.012983
44Vulcano Island crater 16258.00.07.0310.0235106
45Vulcano Island crater 1724170.04.2260.015.376
46Vulcano Island crater 1897160.016380.0210177
47Vulcano Island crater 19561.40.013850.0122178
48El Tatio 121048617.2191.59.13.23005
49El Tatio 2271217155.91131.68.83.74560
50El Tatio 311655244.5191.24.53.71721
51El Tatio 412287152.6201.15.22.71975
52El Tatio 510636012.3171.83.32.31691
53Afar 1763229422421471.41201111096
54Afar 21106727893652452.31501614634
55Afar 31989635145222764.11681524395
56Afar 41622545121975171.61401321606
57Afar 5587974610205914268.07601667676
58Afar 636116456018368994.43301643761
59Afar 73599375145580.4110167580
60Larderello 1220132156631161.2512924429
61Larderello 24146227819394.141106536
62Larderello 341521110297310784.51062053831
63Larderello 42659112695917416.2981840240
64Larderello 54415314999821954.7793059543
65Deception Island 116306459177491.5357.317575
66Deception Island 214763516257691.9457.316127
67Deception Island 320023539218362.7657.321494
68Copahue volcano 114213196.31420.626171932
69Copahue volcano 220733169.5810.831132524
70Copahue volcano 318253585.8620.944132309
71Copahue volcano 473754499.91200.543158012
72Copahue volcano 533894829.81370.7569.34084
73Copahue volcano 67253519121030.643127942
74Copahue volcano 74275395.1130.836171038
75Copahue volcano 87894496.7230.938191325
76Copahue volcano 929144628.6511.155193511
77Copahue volcano 1029544157.61400.991223631
78Nysiros Island 2438456932320.7111135195
79Nysiros Island 387728897.5452.120863927
80Nysiros Island 469053396142440.54310210704
81Nysiros Island 530123836341152.6541267180
82Nysiros Island 63396268418971.740676305
83Nysiros Island 7566339748391.512674131
84Nysiros Island 82084337116511.818665608
85Nysiros Island 9497035010.61171.620778687
86Nysiros Island 10748321512401.320664103
87Nysiros Island 1179573056392711.55413611515
88Nysiros Island 123089358926371.921826846
89Nysiros Island 1386434515.3251.640504437
90Nysiros Island 1567529161.5151.520683697
91Nysiros Island 1643626151.6312.423663174
92Ischia Island 121144064.9892.6825.92704
93Ischia Island 210163612.2450.2464.51474
94Ischia Island 438334694.1960.5776.84487
95Ischia Island 514204983.8511.4285.92009
96Ischia Island 624264223.9690.5925.23018
97Phlegrean Fields 13735974.92.21.1335.41017
98Phlegrean Fields 25865563.63.14.0664.91224
99Phlegrean Fields 35916683.82.72.0485.41321
100Phlegrean Fields 49703493.94.91.5326.01367
101Phlegrean Fields 518048537.9142.3768.12765
102Phlegrean Fields 622487167.1182.1518.13050
103Phlegrean Fields 716313844.48.82.1546.82091
104Phlegrean Fields 811025162.46.61.7369.01673
105Phlegrean Fields 98274121.95.42.025101283
106Phlegrean Fields 106424595.13.52.2376.21155
107Phlegrean Fields 1121503343.6152.1335.02543
108Vesuvio volcano 178977835.6431.436128778
109Vesuvio volcano 275996516.1371.632138340
110Pantelleria Island 1811962.44.40.11.84.2290
111Pantelleria Island 2241481.32.30.11.23.1180
112Pantelleria Island 32391863.7100.15.24.3449
113El Chichon volcano 142750311341.65.0521034
114El Chichon volcano 292851364552842.7217211084
115El Chichon volcano 3142171813301.09.0702262
116El Chichon volcano 41305611131151.57.0742126
117El Chichon volcano 557040810340.34.0371064
118El Chichon volcano 630941711180.91.745802
119Tatun 136275937219955731508.42759282415733
120Tatun 2515633104524007986.0109332387227
121Tatun 3374313074924117273.15668571973
122Tatun 440785195238850.27259674
123Tatun 5168621304815193471.92208132078
124Tatun 67363593199640.81401.08361
125Tatun 72954825816973625.57834534022
126Yellowstone 133911936594020269426227422351814
127Yellowstone 212160282813237404021159924138804
128Yellowstone 3174226169871739466249138715199066
129Yellowstone 4190197185163805209165156169216304
130Yellowstone 515063283111634129528127543163218
131Yellowstone 6258551102883019275729176743276453
132Yellowstone 7489610941010816422675360540517782
133Yellowstone 879168216413272274356393585641
134Yellowstone 932024133991987355628125035330496
135Yellowstone 104092311878711296493564344725
136Yellowstone 111012181899696859178786698271046843
137Yellowstone 12477276715601313202102150522
138Yellowstone 1341372552149650422466181841434738
139Yellowstone 14115678527956345529520766999541235942
Table
Table 3. Composition of heteroaromatics, C6H6 and C7H8. Concentrations are in ppbv.
Table 3. Composition of heteroaromatics, C6H6 and C7H8. Concentrations are in ppbv.
n°sampleC4H4O2-C5H6OC4H8O3-C5H10OC4H4S3-C5H6S2,4-C6H8SC6H6C7H8
1Teide volcano 11.30.60.3<0.1121.8<0.1710.5
2Teide volcano 21.60.70.4<0.1111.7<0.1890.5
3Lascar volcano 3161.94.50.92.60.7<0.1210.8
4Lascar volcano 4121.56.30.93.10.5<0.1190.7
5Lascar volcano 5111.87.81.24.50.6<0.1230.8
6Lascar volcano 6131.46.30.83.90.3<0.1260.8
7Lascar volcano 7101.35.60.96.30.5<0.1180.7
8Lascar volcano 8121.97.80.67.20.4<0.1170.7
9Lascar volcano 9141.57.50.71.90.3<0.1130.6
10Lascar volcano 10121.36.30.91.80.2<0.1140.8
11Lascar volcano 11131.75.70.71.60.3<0.1120.6
12Lascar volcano 12121.65.40.51.80.1<0.1120.7
13Lascar volcano 13131.24.60.51.50.3<0.1130.7
14Lascar volcano 14101.35.10.61.60.2<0.1140.5
15Tacora volcano 11.20.40.5<0.1151.60.22385.8
16Tacora volcano 20.80.60.40.1181.90.12747.6
17Tacora volcano 31.30.80.4<0.1161.30.12435.8
18Tacora volcano 41.40.70.60.2242.10.1964.4
19Tacora volcano 51.60.90.60.3122.20.21167.6
20Tacora volcano 61.30.60.4<0.1161.90.11326.7
21Tacora volcano 71.40.60.80.2131.60.21557.1
22Tacora volcano 81.30.70.5<0.1101.30.31526.2
23Tacora volcano 91.40.80.40.1101.50.21687.1
24Tacora volcano 101.10.40.6<0.1111.80.21647.6
25Turrialba volcano 54.40.61.70.85.70.1<0.19.10.3
26Turrialba volcano 64.40.82.30.76.20.3<0.18.80.1
27Turrialba volcano 76.30.72.10.62.60.2<0.18.70.2
28Turrialba volcano 87.10.91.60.81.10.1<0.1100.2
29Vulcano Island crater 1162.24.81.50.40.1<0.11.50.2
30Vulcano Island crater 2101.55.51.30.70.1<0.16.00.3
31Vulcano Island crater 3232.34.41.50.5<0.1<0.12.50.1
32Vulcano Island crater 4141.25.21.80.2<0.1<0.11.5<0.1
33Vulcano Island crater 5161.55.61.90.2<0.1<0.11.2<0.1
34Vulcano Island crater 6131.40.80.20.50.3<0.11.2<0.1
35Vulcano Island crater 7192.36.31.70.2<0.1<0.11.6<0.1
36Vulcano Island crater 84.70.60.70.21.90.2<0.1180.5
37Vulcano Island crater 9253.33.81.50.6<0.1<0.11.4<0.1
38Vulcano Island crater 10151.25.21.50.4<0.1<0.12.30.1
39Vulcano Island crater 11313.14.11.80.2<0.1<0.11.7<0.1
40Vulcano Island crater 12141.13.71.60.3<0.1<0.13.00.1
41Vulcano Island crater 13161.35.21.80.2<0.1<0.11.00.1
42Vulcano Island crater 14171.25.81.70.3<0.1<0.13.1<0.1
43Vulcano Island crater 15212.04.61.40.2<0.1<0.11.50.1
44Vulcano Island crater 16262.74.51.60.50.1<0.17.00.3
45Vulcano Island crater 172.20.50.60.31.50.2<0.19.80.5
46Vulcano Island crater 184.50.93.21.20.4<0.1<0.1140.4
47Vulcano Island crater 19151.83.91.30.3<0.1<0.11.20.1
48El Tatio 1<0.1<0.1<0.1<0.11.51.10.6673180
49El Tatio 2<0.1<0.1<0.1<0.11.51.60.61009657
50El Tatio 3<0.1<0.1<0.1<0.11.41.70.742586
51El Tatio 4<0.1<0.1<0.1<0.11.11.10.5520181
52El Tatio 5<0.1<0.1<0.1<0.10.71.20.449495
53Afar 1<0.1<0.1<0.1<0.15.64.11.6288745.5
54Afar 2<0.1<0.1<0.1<0.16.18.70.9269875
55Afar 3<0.1<0.1<0.1<0.17.36.31.33324180
56Afar 4<0.1<0.1<0.1<0.15.96.10.94102360
57Afar 5<0.1<0.1<0.1<0.16.67.42.13845725
58Afar 6<0.1<0.1<0.1<0.16.18.61.64175365
59Afar 7<0.1<0.1<0.1<0.15.59.11.8370242.0
60Larderello 1<0.1<0.1<0.1<0.111125.51274873
61Larderello 2<0.1<0.1<0.1<0.13.24.42.11368899
62Larderello 3<0.1<0.1<0.1<0.1105.64.368884129
63Larderello 4<0.1<0.1<0.1<0.186.93.484094276
64Larderello 5<0.1<0.1<0.1<0.112134.7122982660
65Deception Island 10.30.60.4<0.12.82.11.135199
66Deception Island 20.20.70.5<0.12.92.20.841584
67Deception Island 30.30.60.4<0.12.92.30.8426101
68Copahue volcano 10.20.81.90.85.15.62.6189120
69Copahue volcano 20.10.41.10.84.34.12.425646
70Copahue volcano 30.30.61.70.63.83.52.528955
71Copahue volcano 40.20.72.10.73.63.93.637765
72Copahue volcano 50.30.61.50.92.12.51.444930
73Copahue volcano 60.30.81.20.53.93.41.648726
74Copahue volcano 70.20.51.70.84.95.63.252011
75Copahue volcano 80.40.61.10.46.15.24.842611
76Copahue volcano 90.30.41.00.55.64.96.144113
77Copahue volcano 100.30.70.90.46.26.66.938912
78Nysiros Island 20.20.10.6<0.161465.64260295
79Nysiros Island 30.20.10.5<0.136446.22750125
80Nysiros Island 40.30.20.8<0.144517.43159230
81Nysiros Island 50.1<0.10.4<0.153675.93715110
82Nysiros Island 60.1<0.10.3<0.137255.42518155
83Nysiros Island 7<0.1<0.10.4<0.139226.23196185
84Nysiros Island 80.20.10.5<0.141204.83239110
85Nysiros Island 9<0.1<0.10.4<0.142295.93291180
86Nysiros Island 10<0.1<0.10.6<0.144184.2310295
87Nysiros Island 110.20.10.7<0.158743.82881130
88Nysiros Island 120.30.10.7<0.143336.13470105
89Nysiros Island 130.30.20.9<0.130137.23248185
90Nysiros Island 15<0.1<0.10.4<0.136266.22735160
91Nysiros Island 16<0.1<0.10.3<0.137226.62469125
92Ischia Island 1<0.1<0.1<0.1<0.12.32.80.835739
93Ischia Island 2<0.1<0.1<0.1<0.12.11.50.932334
94Ischia Island 4<0.1<0.1<0.1<0.12.63.30.939265
95Ischia Island 5<0.1<0.1<0.1<0.13.12.30.545238
96Ischia Island 6<0.1<0.1<0.1<0.12.12.50.636448
97Phlegrean Fields 1<0.1<0.1<0.1<0.13.31.50.657312
98Phlegrean Fields 2<0.1<0.10.2<0.12.81.60.550742
99Phlegrean Fields 3<0.1<0.1<0.1<0.12.12.60.760947
100Phlegrean Fields 4<0.1<0.10.1<0.12.62.60.830439
101Phlegrean Fields 5<0.1<0.10.1<0.13.43.90.876284
102Phlegrean Fields 6<0.1<0.1<0.1<0.13.14.10.9579130
103Phlegrean Fields 7<0.1<0.10.2<0.12.63.60.6567110
104Phlegrean Fields 8<0.1<0.1<0.1<0.13.54.60.940890
105Phlegrean Fields 9<0.1<0.1<0.1<0.14.15.10.932275
106Phlegrean Fields 10<0.1<0.1<0.1<0.12.43.10.736485
107Phlegrean Fields 11<0.1<0.1<0.1<0.12.02.40.630323
108Vesuvio volcano 10.20.10.4<0.15.65.90.576313
109Vesuvio volcano 20.20.10.3<0.15.86.10.76329.8
110Pantelleria Island 1<0.1<0.1<0.1<0.11.91.50.813548
111Pantelleria Island 2<0.1<0.1<0.1<0.11.51.10.59544
112Pantelleria Island 3<0.1<0.1<0.1<0.12.31.40.612943
113El Chichon volcano 10.30.71.60.811361.541675
114El Chichon volcano 20.40.51.50.612561.3607750
115El Chichon volcano 30.20.42.20.711541.5317390
116El Chichon volcano 40.20.61.40.510592.2269325
117El Chichon volcano 50.30.81.80.57.8260.333260
118El Chichon volcano 60.30.91.60.710310.433770
119Tatun 1<0.1<0.1<0.1<0.1156113132652210650
120Tatun 2<0.1<0.1<0.1<0.119112111230487800
121Tatun 3<0.1<0.1<0.1<0.154282.9215799050
122Tatun 4<0.1<0.1<0.1<0.12.32.10.338711250
123Tatun 5<0.1<0.1<0.1<0.142362.596963350
124Tatun 6<0.1<0.1<0.1<0.10.60.30.1407180
125Tatun 7<0.1<0.1<0.1<0.124201.01929600
126Yellowstone 1<0.1<0.1<0.1<0.110120.62999625
127Yellowstone 2<0.1<0.1<0.1<0.111130.466021655
128Yellowstone 3<0.1<0.1<0.1<0.18.76.10.3136153295
129Yellowstone 4<0.1<0.1<0.1<0.131361.5149093555
130Yellowstone 5<0.1<0.1<0.1<0.119230.866001680
131Yellowstone 6<0.1<0.1<0.1<0.116261.19382870
132Yellowstone 7<0.1<0.1<0.1<0.115241.275901770
133Yellowstone 8<0.1<0.1<0.1<0.118160.61573560
134Yellowstone 9<0.1<0.1<0.1<0.114210.52435925
135Yellowstone 10<0.1<0.1<0.1<0.116261.1816325
136Yellowstone 11<0.1<0.1<0.1<0.110160.577951155
137Yellowstone 12<0.1<0.1<0.1<0.18.9120.3532125
138Yellowstone 13<0.1<0.1<0.1<0.119211.232601930
139Yellowstone 14<0.1<0.1<0.1<0.124291.1233114575

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Tassi, F.; Montegrossi, G.; Capecchiacci, F.; Vaselli, O. Origin and Distribution of Thiophenes and Furans in Gas Discharges from Active Volcanoes and Geothermal Systems. Int. J. Mol. Sci. 2010, 11, 1434-1457. https://doi.org/10.3390/ijms11041434

AMA Style

Tassi F, Montegrossi G, Capecchiacci F, Vaselli O. Origin and Distribution of Thiophenes and Furans in Gas Discharges from Active Volcanoes and Geothermal Systems. International Journal of Molecular Sciences. 2010; 11(4):1434-1457. https://doi.org/10.3390/ijms11041434

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Tassi, Franco, Giordano Montegrossi, Francesco Capecchiacci, and Orlando Vaselli. 2010. "Origin and Distribution of Thiophenes and Furans in Gas Discharges from Active Volcanoes and Geothermal Systems" International Journal of Molecular Sciences 11, no. 4: 1434-1457. https://doi.org/10.3390/ijms11041434

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