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The precious "scientific heritage" of Mariano Valenza: the unknown history of Ludovico Sicardi and the birth of the modern volcanology
No full textMariano Valenza was an important scientific figure of the geochemical community and a person characterized by his great intellect, diplomacy and human qualities. Sadly, he passed away in July of 2018, leaving a great void. He left us a precious treasure for all the geochemists involved in volcanology: the story and the memory of Ludovico Sicardi. Indeed, Valenza carefully preserved in his office, for a long time, four boxes containing the scientific material belonged to Ludovico Sicardi. As often happens, a little by chance, the precious material returned to light thirty-five years later, on the 20th of April 2018, and was donated to the Museum of Mineralogy of Palermo. It is nowadays subject of study and cataloging by the volunteers of the Associazione Naturalistica Geode. The “scientific treasure” consists of the personal field-equipment of Sicardi, glassware, copies of the scientific articles, many old maps of volcanic areas, several historical photos of Vulcano and Solfatara. Among all these findings, several manuscript notes and three important unpublished researches about Vulcano, Vesuvio and Campi Flegrei. Who was Ludovico Sicardi? Sicardi was a chemist and a pharmacist, who was passionate about volcanoes and, in particular, enraptured by the island of Vulcano (Eolie - Sicily). During his several field trips in Vulcano, he observed and described the fumarolic field on systematic basis, measuring the temperatures and recording their variations over time (Sicardi, 1973). He was the first to perform chemical analysis of fluids emitted by fumaroles in Vulcano Island and Solfatara. Furthermore, he was the former to suppose the coexistence of SO2 and H2S in fumarolic discharges, which by that time was considered to be impossible. Also, he succeeded in measuring their ratio by developing an in situ method that chemically separate the S-gaseous species. This method was based on the sampling of fumarolic fluids using a glass flask that contained a NH4OHAgNO 3solution, with the aim to absorb the soluble acid gases (CO2, SO2 and HCl) and precipitate H2S as an insoluble Ag2S (Sicardi, 1955). Based on his remarkable scientific production, Sicardi can be considered as a precursor of the modern Volcanology and a pioneer of the volcanic monitoring techniques.We are extremely grateful to Mariano Valenza for giving us this fascinating story
Geochemistry of the thermomineral waters in Greece
No full textMany geothermal areas of Greece are located in regions affected by Miocene or Quaternary
volcanism and in continental basins characterized by elevated heat flow. Moreover, the majority of
them is found along the coast as well as in islands of the Aegean Sea and thus thermal water is
often brackish to saline due to marine intrusion into coastal aquifer.
In the present study, almost 300 thermal and cold mineral water samples were collected along the
Hellenic territory with their physicochemical parameters (temperature, pH, electrical conductivity and
Eh) and the amount of bicarbonates (titration with 0.1N HCl) being determined in situ. Additionally,
gases, found either in free or dissolved phase, were sampled. Both water and gas samples were
analyzed at the INGV-Pa laboratories for major ions (IC), silica (ICP-OES), chemical composition of
free and dissolved gases (GC) water isotopes (O and H) and carbon and helium isotopes of free and
dissolved gases (MS).
The temperature of the investigated waters ranges from 6.5 to 98°C, pH from 1.96 to 11.98, whilst
Total Dissolved Solids (TDS) from 0.06 to 43 g/L. Based on the temperature parameter, waters can
be divided into four groups: i) cold (< 23 °C), ii) warm (23 – 40 °C),
iii) thermal (40 – 75 °C) and iv) hyperthermal (> 75 °C). In terms of pH, most results vary from 5.5 to
8; few springs show either very low pH (< 4) suggesting interaction with H2S- rich gases or very high
pH values (> 10) proposing serpentinization processes.
Regarding TDS concentrations, collected waters can be subdivided into low salinity (up to
1.5 g/L), brackish (up to 20 g/L) and saline (up to 43 g/L). The medium – high salinities can be
justified by mixing with sea water and/or strong water-rock interaction processes. Isotope
composition of O and H ranges from -12.7 to +2.7 ‰ SMOW and from -91 to +12
‰ SMOW respectively and is generally comprised between the Global Meteoric Water Line and the
East Mediterranean Meteoric Water Line. Only few water samples show a positive shift for δ18O
possibly related to high temperature water-rock interaction processes.
Carbon dioxide (18 - 997,000 μmol/mol) or N2 (1100 - 989,000 μmol/mol) or CH4 (<0.5 - 913,000
μmol/mol) are the prevailing gas species found in the studied sites. The δ13CCO2 values ranged from
−20.1 to +8.5 ‰, whilst the isotope ratio of He from 0.21 to 6.71 R/R
Preliminary study on geogenic degassing through the big karstic aquifers of Greece
Full text linkNon-volcanic degassing contributes to the C-cycle by providing on a global scale a significant amount of CO2 emitted through diffuse earth degassing processes (Kerrick et al 1995). Due to the elevated solubility of the CO2 in water, in the areas where high CO2 fluxes directly affect regional aquifers, most of it can be dissolved, transported and released by groundwaters. Therefore, quantification of this contribution to the atmosphere has a substantial implication for modeling the global carbon cycle. According to Chiodini et al. (2000), total dissolved inorganic carbon (TDIC) concentrations and δ13CTDIC values of groundwaters are useful tools to both quantify the geogenic degassing and distinguish the different carbon sources. This approach was proved to be valid for central Italy and can possibly work for continental Greece; due to similar geodynamic history. Greece is considered one of the most geodynamically active regions and is characterized by intense geogenic degassing. The main source of degassing in the Hellenic area is concentrated on hydrothermal and volcanic environments (Daskalopoulou et al., 2019), however, the impact of geogenic CO2 released by tectonically active areas shouldn’t be disregarded. Aim of this work is to quantify the CO2 degassing through aquifers hosted in the carbonate successions in the Hellenic region. 95 karst, thermal and cold waters were collected in the northern and central part of Greece with some of which being characterized by bubbling of CO2-rich gases. Results show that karst waters have a typical Ca-HCO3 composition. Thermal and cold waters show two different compositions: some samples are characterized by Ca-HCO3 composition suggesting the presence of a carbonate basement, whilst others have a prevailing Na-HCO3 composition. On the basis of TDIC concentrations and δ13CTDIC values, the springs are divided into two groups. The first group includes karst waters and some of thermal waters and is characterized by low TDIC concentrations and negative δ13CTDIC values. This group shows no evidence of deep CO2 contributions, whereas the carbon of these waters derives from dissolution of carbonate minerals by organic derived CO2. Remaining samples belong to the second group and present intermediate to high TDIC concentrations and δ13CTDIC values, indicating a possible input of inorganic CO2. Some of these springs are characterized by gas bubbling at discharge, suggesting an extensive degassing
The history of Ludovico Sicardi and the birth of geochemical
No full textLudovico Sicardi was a chemist and a pharmacist, and a passionate researcher, enthusiastic about phenomena related to volcanic activity. Due to a field survey within a project of mining research committed by a private company, he has the opportunity to visit the island of Vulcano (Eolie - Sicily), from December 1921 to June 1922. He was completely fascinated by the wild island of Vulcano and its gas manifestations. During several successive field trips in Vulcano, he observed and described the fumarolic field on a systematic basis, measuring the temperatures and recording their variations over time. He was one of the first to perform chemical analysis of fluids emitted by fumaroles in Vulcano Island and Solfatara di Pozzuoli (Italy). Furthermore, he was the first to suppose the coexistence of SO2 and H2S in fumarolic fluids, which by that time was considered to be impossible. Also, he succeeded in measuring their ratio by developing an in situ method that chemically separate the gaseous S-species. As the pioneer of applied geochemistry in volcanic fluids, he developed a method based on the sampling of fumarolic fluids using a glass flask that contained a NH4OH-AgNO3 solution to absorb the soluble acid gases (CO2, SO2 and HCl) and precipitate H2S as an insoluble Ag2S.
A series of fortuitous coincidences allowed us to tell this story. Thanks to Prof. Marcello Carapezza and Prof. Mariano Valenza of the University of Palermo, the “scientific treasure” of Sicardi was preserved and it is nowadays studied and cataloged. It consists of Sicardi’s sampling-equipment, copies of the scientific articles, several historical maps and photos of Vulcano and Solfatara, manuscript notes and three important unpublished researches about Vulcano, Vesuvio and Campi Flegrei.
Based on the remarkable scientific production, Sicardi has to be considered a precursor of modern volcanic monitoring based on fluid geochemistry
The impact of Mt. Etna's ash plume on the chemical composition of meteoric deposition
No full textMt. Etna, in eastern coast of Sicily (Italy), is one of the most active and most intensely monitored volcanoes of the planet. It is the biggest volcanic point source of volcanic gases and particles to the troposphere in the Mediterranean basin. On the morning of December 24th 2018, a new lateral eruption of the Mount Etna started. This eruption was related to an intrusion of a magmatic dike on the high eastern flank of the volcano, which a two kilometers long fracture in the NNW - SSE direction. At the same time, the summit craters also produced a continuous strombolian activity generating a very dense dark ash plume, dispersed by the wind into the southeastern direction. This volcanic event well record from the atmospheric precipitations. During the period from June 2018 to May 2019, atmospheric precipitations were collected in the area of Priolo, eighty kilometer far SSE from Mt. Etna. The sampling and analytical protocols were chosen following the guidelines published by the main international agency involved in the monitoring of atmospheric precipitation. The rain gauges were open during the entire exposure time, collecting both wet and dry deposition (bulk collectors). All the collected water samples were analysed for major ion contents and for a large number of trace elements. The atmospheric precipitation of the period straddling the eruptive event is characterized by high concentration of major ions, such as Fluoride (up to 0.88 mg/l), Chloride (up to 124 mg/l) and Sulphate (23.1 mg/l). These derive mainly from the emitted volcanic gases (HF, HCl and SO2). On the another hand, an enrichment of some trace elements is also presented, such as Aluminum (up to 152 μg/l), Thallium (0.16 μg/l), Tellurium (0.025 μg/l). While Tl and Te are highly volatile elements typically enriched in volcanic emissions, Al is a refractory element that is probably correlated to the dissolution of the emitted volcanic ashes
Geogenic carbon transport through karst hydrosystems of Greece
No full textThe Earth C-cycle is complex, where endogenic and exogenic sources are interconnected, operating in a multiple spatial and temporal scale (Lee et al., 2019). Non-volcanic CO2 degassing from active tectonic structures is one of the less defined components of this cycle (Frondini et al, 2019). Carbon mass-balance (Chiodini et al., 2000) is a useful tool to quantify the geogenic carbon output from regional karst hydrosystems. This approach has been demonstrated for central Italy and may be valid also for Greece, due to the similar geodynamic settings. Deep degassing in Greece has been ascertained mainly at hydrothermal and volcanic areas, but the impact of geogenic CO2 released by active tectonic areas has not yet been quantified. The main aim of this research is to investigate the possible deep degassing through the big karst aquifers of Greece. Since 2016, 156 karst springs were sampled along most of the Greek territory. To discriminate the sources of carbon, the analysis of the isotopic composition of carbon was carried out. δ13CTDIC values vary from -16.61 to -0.91 ‰ and can be subdivided into two groups characterized by (a) low δ13CTDIC, and (b) intermediate to high δ13CTDIC with a threshold value of -6.55 ‰. The composition of the first group can be related to the mixing of organic-derived CO2 and the dissolution of marine carbonates. Springs of the second group, mostly located close to Quaternary volcanic areas, are linked to possible carbon input from deep sources
The recent Nyiragongo (Democratic Republic of Congo) eruption: the impact of volcanic ash fallout on drinking water and edible plants
No full textNyiragongo is an active intraplate volcano well known for its fascinating persistent lava lake inside the crater and is recognized as one of the most dangerous volcanoes in the world as more than two million people live on its slopes, 18-25 km far from the main crater. It is located in the Virunga Volcanic Province (VVP), in the western branch of the East African Rift System (EARS), at the intersection between the Democratic Republic of Congo, Rwanda, and Uganda. Unexpectedly, on 22 May 2021, Nyiragongo produced three different lateral lava flows in the low flanks and significant amounts of volcanic gas and ash were emitted from the summit crater. For several weeks, the ash fallout strongly impacted the main city of Goma and the numerous villages located in the vicinity of the volcano. During and after the eruption, 22 samples of volcanic ash, 135 drinking waters, and 32 leaf samples of different edible plants were collected in rural villages at different distances from the volcano. The samples were analyzed for the major, minor and trace constituents, including all those elements recognized as potentially toxic (PTEs) to human health and the ecosystem in general. The preliminary results are particularly alarming as most of the drinking water sampled was found to be heavily contaminated with fluoride, chloride, sulphur, and many trace metals (As, Cd, Cr, Cu, Mo, Pb, Sb, Se, Te, Tl, and V), potentially toxic to human health. The plants analyzed were also found to be strongly contaminated by the extensive deposition of volcanic ash, and by the consequent release of water-soluble ash-borne species (mainly sulphates and chlorides). The two processes that caused the heavy environmental contamination are mainly due to the interaction of rainwater with the volcanic plume and the leaching of the emitted ash. Further studies are still in progress to define the risk factors for the population exposed to the important event in the VVP
Environmental effects and potential impact on human health caused by the recent Nyiragongo eruption (Democratic Republic of Congo)
No full textVolcanic activity emits large amounts of gases and particles to the atmosphere subsequently spreading contaminants to rain, surface waters and soils, negatively impacting on the environment and the human health. The recent eruption of Nyiragongo occurred on 22nd of May, injected large quantities of ash affecting the environment of the Virunga area, and more than 2 million people living between 18-25 km far from the main crater of Nyiragongo.
Several studies demonstrated that drinking waters and plants may contain high contents of natural pollutants, and when ingested they become harmful to human health causing acute or chronic diseases.
In this study, we investigated the impact of the recent eruption on Virunga area through a multidisciplinary approach, analysing the chemical composition of drinking waters, soils, volcanic ash and edible plants. Samples were collected in several sites few days after the last eruption of Nyiragongo. All samples were analysed by ionic chromatography and inductively coupled mass and atomic emission spectrometry for a large suite of major and trace elements.
In general, the collected samples show significant enrichments of fluoride, sulfate and chloride, along with many trace elements such as Al, As, Cd, Cr, Cu, Fe, Mo, Pb, Sb, Se, Pb, Te, Tl and V. These elements are mostly linked to the volcanic activity, carried by the atmospheric depositions which were directly affected by volcanic emissions (gases, particulates and ashes). Especially, fluorine and some toxic metals may be harmful to the end users/local people. Some elements exceed concentration limits in drinking water (World Health Organisation), including fluoride, aluminium, copper and thallium, making the already scarce water resources (water traditional drainage or tanks collecting runoff from roofs) unsuitable for human consumption
Trace elements in thermomineral waters in Greece
No full textTrace elements have a fundamental role in natural and anthropogenic systems. In waters, they
present a great variability of concentrations that mostly depends on the degree of gas-water-rock
interactions and geochemical conditions such as pH, temperature, redox and/or exchange reactions,
etc. Even though, they are present in very low contents in host-rocks, elevated concentrations in
ground or surface waters may have a hazardous impact on human health and thus, it is important to
both quantify and understand their behavior in natural systems. Here we present the results of about
300 cold and thermal mineral waters collected along the entire Hellenic territory. Physicochemical
parameters (temperature, pH, electrical conductivity and Eh) were measured in situ, whilst samples
were analyzed by ICP-MS for their trace elements’ content. The great variability in hydrogeological
settings justifies the wide range of temperatures (6.5 - 98°C), pH (1.96 - 11.98) and Total Dissolved
Solids (TDS) (0.06 - 43 g/L). Based on the combination of pH, T and TDS, samples were divided
into 5 classes: i) thermal waters; ii) thermal waters affected by seawater contamination; iii) cold CO2-
rich waters; iv) hyperalkaline waters; and v) acidic waters.
The great variability in chemical composition of the sampled waters is reflected in the large range of
trace element contents (four to five orders of magnitude). Thermal waters affected by seawater
contamination show the strongest enrichments in Li (up to 17600 μg/L), B (up to 38200 μg/L), Sr (up
to 80000 μg/L) and Rb (up to 9230 μg/L), mostly deriving from water-rock interaction. Cold CO2-rich
waters display elevated concentrations of Mn (up to 3970 μg/L), Ni (up to 111 μg/L) and Fe (up to
218000 μg/L), whilst at the water outflow an extensive precipitation of iron oxi-hydroxides is
observed. Hyperalkaline waters are generally strongly depleted in trace elements due to the
precipitation of secondary minerals, however they are enriched in Al (up to 421 μg/L). Aluminum
becomes soluble at extreme pH conditions and therefore also acidic waters present enhanced
concentrations (up to 100000 μg/L). Acidic waters show also enrichments in Fe (up to 58400 μg/L),
Mn (up to 15600 μg/L) and Ni (up to 101 μg/L).
In some cases, the maximum contaminant levels (MCLs) fixed by the Directive 98/83/EC for drinking
water, are strongly exceeded in the under investigation waters. Such elevated concentrations of
harmful elements may create hazards to human health either via direct consumption of cold mineral
waters or through mixing of highly mineralized waters – even in small proportions - with shallow
groundwater. For instance, As (MCL 10 μg/L) in the sampled waters reaches concentrations up to
1820 μg/L that derive from high temperature water-rock interaction within the hydrothermal circuit
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