Geochemistry of the thermomineral waters in Greece

Many 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 ph…

The history of Ludovico Sicardi and the birth of geochemical

Ludovico 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 Vulca…

Major and trace elements characterization of atmospheric deposition in volcanic, urban, and industrial areas of Sicily (Italy): preliminary results

The source of chemical elements dissolved in rainwater can be both natural and anthropogenic. A group of trace elements has been recently brought to attention for their possible environmental impacts, the Technology-critical elements (TCEs). The current knowledge about the geochemical cycle of TCEs is still scarce, nevertheless recent studies [e.g. Brugnone et al., 2020] evidenced a contribution from the volcanic activity for some of them (Te, Tl, and REE). Our research aims to produce a geochemical database on major and trace element depositions in different areas of Sicily: a volcanic area (Etna), two urban areas (Palermo, Catania), two industrial areas (Milazzo, Priolo), and a rural moni…

Geochemical investigation of trace metal pollutants in the Oreto river, Palermo (Italy)

In the past, three main rivers, named Kemonia, Papireto and Oreto, were present in the plain of Palermo, in northwestern Sicily. Today, only the latter one has been preserved from the unregulated urban expansion. Fortunately, over the last ten years, attention and consciousness towardsthe Oreto river and its delicate ecosystem has grown considerably, also thanks to many associations and citizens’ committees involved in protecting, preserving and valorising the precious area. In this context, our study is focused on a hydrogeochemical investigation of its surface water quality. The Oreto river flows for about 20 km within a catchment area of about 130 km2. Over the past three years, numerous…

Estimation of CO2 release from thermal springs to the atmosphere

Introduction Geodynamically active regions have long been recognized as areas of anomalous Earth degassing [Irwin and Barnes, 1980]. Areas found at plate boundaries are characterized by seismic, volcanic and geothermal activity as well as ore deposition. These processes are enhanced by the circulation of hydrothermal fluids in the crust, which transport volatiles from the deep crust or mantle to the surface [King, 1986]. Kerrick and Caldera, [1998], were the first to indicate the significant contribution of the CO2 degassing by extensional tectonic and hydrothermal activity in metamorphic belts during the Phanerozoic. Moreover, further studies concerning gas emissions from diffuse degassing…

The impact of Mt. Etna's ash plume on the chemical composition of meteoric deposition

Mt. 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 even…

The recent Nyiragongo (Democratic Republic of Congo) eruption: the impact of volcanic ash fallout on drinking water and edible plants

Nyiragongo 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…

Mount Etna volcanic emissions signature on the chemical composition of bulk atmospheric deposition in Sicily, Italy.

Mt. Etna, on the eastern coast of Sicily (Italy), is one of the most active and most intensely monitored volcanoes on the Earth, widely recognized as a big source of volcanic gases, such as CO2, SO2, halogens, and many trace elements, including technological critical elements (TCEs), to the atmosphere on a regional and global scale. Mt. Etna emissions account for a significant percentage of the worldwide average volcanic budget and especially during eruptive periods, its products can be dispersed over great distances and they influence the chemical composition of the atmosphere of other continents too. The current knowledge about the geochemical cycle of TCEs is still scarce, nevertheless, …

Natural and anthropogenic impacts on Greek karst water quality

Impact of geogenic degassing on C-isotopic composition of dissolved carbon in karst systems of Greece

The 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 tect…

Environmental effects and potential impact on human health caused by the recent Nyiragongo eruption (Democratic Republic of Congo)

Volcanic 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 recen…

The precious "scientific heritage" of Mariano Valenza: the unknown history of Ludovico Sicardi and the birth of the modern volcanology

Mariano 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 subje…

Impact of Etna’s volcanic emission on major ions and trace elements composition of the atmospheric deposition

Mt. Etna, on the eastern coast of Sicily (Italy), is one of the most active volcanoes on the planet and it is widely recognized as a big source of volcanic gases (e.g., CO2 and SO2), halogens, and a lot of trace elements, to the atmosphere in the Mediterranean region. Especially during eruptive periods, Etna’s emissions can be dispersed over long distances and cover wide areas. A group of trace elements has been recently brought to attention for their possible environmental and human health impacts, the Technology-critical elements. The current knowledge about their geochemical cycles is still scarce, nevertheless, recent studies (Brugnone et al., 2020) evidenced a contribution from the vol…

CO2 release to the atmosphere from thermal springs of Sperchios Basin and northern Euboea (Greece): The contribution of “hidden” degassing

Abstract Greece is a region characterised by intense geodynamic activity that favours the circulation of hydrothermal fluids in the crust transporting volatiles from either the deep crust or the mantle to the surface. Elevated heat flow values are detectable at Sperchios Basin and North Euboea (central Greece), two areas defined by a system of deeply rooted extensional faults and Quaternary volcanic activity. This setting contributed to the formation of numerous hydrothermal systems, which are mostly expressed as CO2-rich thermal springs with intense bubbling. The CO2 output from six bubbling pools has been determined by flux measurements with the use of the floating chamber method. The hig…

Serum levels of soluble adhesion molecules in pre-dialysis, on chronic hemodialysis and kidney transplanted patients. Which correlation with inflammation and nutrition?

The impact of Mt. Etna volcanic emissions on the atmospheric deposition: developments and improvements during three decades of studies

Volcanic emissions are an important source of gases and particles to the atmosphere. Mount Etna discharges a permanent volcanic plume consisting of water vapor and gaseous species (CO2, SO2, HCl and HF, mainly), metals, acid droplets, and solid particles. This plume interacts with meteoric water during precipitations events, so the chemical signature of the plume is impressed on the rainwater. Over the past 32 years, the impact of Etna's emissions on atmospheric deposition has been investigated in many research projects by our team. Sampling methodologies and analytical procedures have been improved over the years. The first study of the concentration of water-soluble inorganic ions in week…

Trace elements in thermomineral waters in Greece

Trace 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 (te…

Microbial impact on the isotope composition of methane in both thermal and hyperalkaline waters of central Greece

Introduction The different origins of methane can be subdivided in biogenic (either directly produced by microbial activity or deriving by decay of organic matter at T > 150°C) and abiogenic (from pure inorganic reactions). Among the latter, one of the most debated origins comes from serpentinization processes of ultramafic rocks in ophiolitic sequences at low temperatures (T < 80 °C). Moreover, further secondary processes (diffusion, inorganic or microbial oxidation, etc.) may also contribute and thus mask the original chemical and/or isotope composition. Primary and secondary processes acting on CH4 can be recognised mainly through its isotope (d13C and d2H) composition and the rati…

Major ions and trace elements composition of rainwater around the two industrial areas of Milazzo and Priolo Gargallo (Sicily - Italy)

This database shows the concentration of major ions and trace elements in rainwater from two polluted industrial areas of Sicily, Milazzo and Priolo Gargallo, collected from June 2018 to July 2019, through a network of 11 bulk collectors to sample bulk atmospheric deposition, for a total of 131 samples collected. Different sources, both natural and anthropogenic, for both major ions and trace elements have been recognised. This study also highlighted some critical issues with common methods of sampling and analysing atmospheric deposition. The analysis and comparison of two different aliquots, filtered and unfiltered rainwater, has shown that the filtration method removes from the sample a …