Tunable diode laser measurements of hydrothermal/volcanic CO2 and implications for the global CO2 budget

Quantifying the CO2 flux sustained by low-temperature fumarolic fields in hydrothermal/volcanic environments has remained a challenge, to date. Here, we explored the potential of a commercial infrared tunable laser unit for quantifying such fumarolic volcanic/hydrothermal CO2 fluxes. Our field tests were conducted between April 2013 and March 2014 at Nea Kameni (Santorini, Greece), Hekla and Krýsuvík (Iceland) and Vulcano (Aeolian Islands, Italy). At these sites, the tunable laser was used to measure the path-integrated CO2 mixing ratios along cross sections of the fumaroles' atmospheric plumes. By using a tomographic post-processing routine, we then obtained, for each manifestation, the contour maps of CO2 mixing ratios in the plumes and, from their integration, the CO2 fluxes. The calculated CO2 fluxes range from low (5.7 ± 0.9 t d−1; Krýsuvík) to moderate (524 ± 108 t d−1; La Fossa crater, Vulcano). Overall, we suggest that the cumulative CO2 contribution from weakly degassing volcanoes in the hydrothermal stage of activity may be significant at the global scale

Tunable diode laser measurements of hydrothermal/volcanic CO2 and implications for the global CO2 budget

Quantifying the CO2 flux sustained by lowtemperature fumarolic fields in hydrothermal/volcanic environments has remained a challenge, to date. Here, we explored the potential of a commercial infrared tunable laser unit for quantifying such fumarolic volcanic/hydrothermal CO2 fluxes. Our field tests were conducted between April 2013 and March 2014 at Nea Kameni (Santorini, Greece), Hekla and Krýsuvík (Iceland) and Vulcano (Aeolian Islands, Italy). At these sites, the tunable laser was used to measure the path-integrated CO2 mixing ratios along cross sections of the fumaroles’ atmospheric plumes. By using a tomographic post-processing routine, we then obtained, for each manifestation, the contour maps of CO2 mixing ratios in the plumes and, from their integration, the CO2 fluxes. The calculated CO2 fluxes range from low (5.7 +/- 0.9 t d-1; Krýsuvík) to moderate (524 +/-108 t d-1; La Fossa crater, Vulcano). Overall, we suggest that the cumulative CO2 contribution from weakly degassing volcanoes in the hydrothermal stage of activity may be significant at the global scale

Brief communication: Small-scale geohazards cause significant and highly variable impacts on emotions

The impact of geohazards on the mental health of local populations is well recognised but understudied. We used natural language processing (NLP) of Twitter (now known as X) posts (n=10 341) to analyse the sentiments expressed in relation to a pre-eruptive seismic unrest and a subsequent volcanic eruption in Iceland in 2019–2021. We show that although these geohazards were of a small size and caused negligible material damage, they were associated with a measurable change in expressed emotions in the local population. The seismic unrest was associated with predominantly negative sentiments (positive-to-negative sentiment ratio of 1:1.3), but the eruption was associated with predominantly positive sentiments (positive-to-negative sentiment ratio of 1.4:1). We demonstrate a cost-effective tool for gauging public discourse that could be used in risk management

Degassing pathways through the shallow magmatic-hydrothermal system of Poás

We report results from a multidisciplinary campaign carried out at Poás crater-lake (Costa Rica) on 17-18 March 2009. Thermal imagery of fumaroles on the north side of the dome and the lake surface revealed mean apparent temperatures of 25-40°C (maximum of 80°C), and 30-35°C (maximum of 48°C), respectively. Mean radiative heat output of the lake, uncorrected for downwelling flux, was estimated as ~230 MW. The mean SO2 flux emitted by the crater measured by walking-traverses was 76 tonnes day-1, with approximately equal contributions from both the dome and the lake and fumarole plumes. Gas measurements by active open-path FTIR spectroscopy indicated molar ratios of H2O/SO2 = 151 and CO2/SO2 = 1.56. HCl and HF were not detected in measured spectra but based on the detection limits of these species, we calculate SO2/HCl > 40, and SO2/HF > 200. Particles were sampled from the plume by air filtration. The filters were analysed using ion chromatography, which revealed an abundance of K+ and SO42-, with smaller amounts of Ca2+, Mg2+ and Cl-. We discuss here the implications of the results for degassing pathways through the shallow magmatic-hydrothermal system

Impacts of the 2014-2015 Holuhraun eruption on the UK atmosphere

Volcanic emissions, specifically from Iceland, pose a pan-European risk and are on the UK National Risk Register due to potential impacts on aviation, public health, agriculture, the environment and the economy, both from effusive and explosive activity. During the 2014-2015 fissure eruption at Holuhraun in Iceland, the UK atmosphere was significantly perturbed. This study focuses one major incursion in September 2014, affecting the surface concentrations of both aerosols and gases across the UK, with sites in Scotland experiencing the highest sulfur dioxide (SO2) concentrations. The perturbation event observed was confirmed to originate from the fissure eruption using satellite data from GOME2B and the chemical transport model, EMEP4UK, which was used to establish the spatial distribution of the plume over the UK during the event of interest. At the two UK European Monitoring and Evaluation Program (EMEP) supersite observatories (Auchencorth Moss, SE Scotland and Harwell, SE England) significant alterations in sulfate (SO42-) content of PM10 and PM2.5 during this event, concurrently with evidence of an increase in ultrafine aerosol, most likely due to nucleation and growth of aerosol within the plume, were observed. At Auchencorth Moss, higher hydrochloric acid (HCl) concentrations during the September event (max = 1.21 µg m-3, c.f annual average 0.12 µg m-3 35 in 2013), were assessed to be due to acid displacement of chloride (Cl-) from sea salt (NaCl) to form HCl gas rather than due to primary emissions of HCl from Holuhraun. The gas and aerosol partioning at Auchencorth moss of inorganic species by thermodynamic modelling, confirmed the observed partioning of HCl. Using the data from the chemical thermodynamic model, ISORROPIA-II, there is evidence that the background aerosol, which is typically basic at this site, became acidic with an estimated pH of 3.8 during the peak of the event. Volcano plume episodes were periodically observed by the majority of the UK air quality monitoring networks during the first 4 months of the eruption (August – December 2014), at both hourly and monthly resolution. In the low resolution networks, which provide monthly SO2 averages, concentrations were found to be significantly elevated at remote “clean” sites in NE Scotland and SW England, with record high SO2 concentrations for some sites in September 2014. For sites which are regularly influenced by anthropogenic emissions, taking into account the underlying trends, the eruption led to statistically unremarkable SO2 concentrations (return probabilities >0.1, ~10 months). However for a few sites, SO2 concentrations were clearly much higher than has been previously observed (return probability 3000 months). The Holuhraun Icelandic eruption has resulted in a unique study providing direct evidence of atmospheric chemistry perturbation of both gases and aerosols in the UK background atmosphere. The measurements can be used to both challenge and verify existing atmospheric chemistry of volcano plumes, especially those originating from effusive eruptions, which have been under-explored, due to limited observations available in the literature. If all European data sets were collated this would allow improved model verification and risk assessments for future volcanic eruptions of this type

Volcanic air pollution and human health: recent advances and future directions

Volcanic air pollution from both explosive and effusive activity can affect large populations as far as thousands of kilometers away from the source, for days to decades or even centuries. Here, we summarize key advances and prospects in the assessment of health hazards, effects, risk, and management. Recent advances include standardized ash assessment methods to characterize the multiple physicochemical characteristics that might influence toxicity; the rise of community-based air quality monitoring networks using low-cost gas and particulate sensors; the development of forecasting methods for ground-level concentrations and associated public advisories; the development of risk and impact assessment methods to explore health consequences of future eruptions; and the development of evidence-based, locally specific measures for health protection. However, it remains problematic that the health effects of many major and sometimes long-duration eruptions near large populations have gone completely unmonitored. Similarly, effects of prolonged degassing on exposed populations have received very little attention relative to explosive eruptions. Furthermore, very few studies have longitudinally followed populations chronically exposed to volcanic emissions; thus, knowledge gaps remain about whether chronic exposures can trigger development of potentially fatal diseases. Instigating such studies will be facilitated by continued co-development of standardized protocols, supporting local study teams and procuring equipment, funding, and ethical permissions. Relationship building between visiting researchers and host country academic, observatory, and agency partners is vital and can, in turn, support the effective communication of health impacts of volcanic air pollution to populations, health practitioners, and emergency managers

Purification of a subtilisin-like serine proteinase from recombinant Bacillus subtilis during different phases of growth

Subtilisin-like proteinase Bacillus intermedius which is secreted at different stages of bacterial growth (at 28 h and 48 h) were purified from the culture media of recombinant strain Bacillus subtilis JB 20-36(pCS9) by chromatography on CM-cellulose and MonoS columns. MALDI-TOF mass spectroscopy of purified enzymes demonstrated that they were identical in regard to amino acid sequence. The molecular weights of both proteins were 27 kDa. Biochemical analysis revealed differences in Km values for proteinase isolated at different growth stages (1.85 and 0.86 mM for first and second fractions respectively), and in substrate specificity and sensitiveness to Ca2+ ions. Gel-filtration experiments demonstrated that subtilisin-like proteinase B. intermedius was produced as an active monomer (27 kDa) during early stationary phase (28 h of growth) and as a dimer (54 kDa) during the late stationary phase (48 h)

Spatial and Temporal Variations in SO₂ and PM₂.₅ Levels Around Kīlauea Volcano, Hawai'i During 2007–2018

Among the hazards posed by volcanoes are the emissions of gases and particles that can affect air quality and damage agriculture and infrastructure. A recent intense episode of volcanic degassing associated with severe impacts on air quality accompanied the 2018 lower East Rift Zone (LERZ) eruption of Kīlauea volcano, Hawai'i. This resulted in a major increase in gas emission rates with respect to usual emission values for this volcano, along with a shift in the source of the dominant plume to a populated area on the lower flank of the volcano. This led to reduced air quality in downwind communities. We analyse open-access data from the permanent air quality monitoring networks operated by the Hawai'i Department of Health (HDOH) and National Park Service (NPS), and report on measurements of atmospheric sulfur dioxide (SO2) between 2007 and 2018 and PM2.5 (aerosol particulate matter with diameter <2.5 μm) between 2010 and 2018. Additional air quality data were collected through a community-operated network of low-cost PM2.5 sensors during the 2018 LERZ eruption. From 2007 to 2018 the two most significant escalations in Kīlauea's volcanic emissions were: the summit eruption that began in 2008 (Kīlauea emissions averaged 5–6 kt/day SO2 from 2008 until summit activity decreased in May 2018) and the LERZ eruption in 2018 when SO2 emission rates reached a monthly average of 200 kt/day during June. In this paper we focus on characterizing the airborne pollutants arising from the 2018 LERZ eruption and the spatial distribution and severity of volcanic air pollution events across the Island of Hawai'i. The LERZ eruption caused the most frequent and severe exceedances of the Environmental Protection Agency (EPA) PM2.5 air quality threshold (35 μg/m3 as a daily average) in Hawai'i in the period 2010–2018. In Kona, for example, the maximum 24-h-mean mass concentration of PM2.5 was recorded as 59 μg/m3 on the twenty-ninth of May 2018, which was one of eight recorded exceedances of the EPA air quality threshold during the 2018 LERZ eruption, where there had been no exceedances in the previous 8 years as measured by the HDOH and NPS networks. SO2 air pollution during the LERZ eruption was most severe in communities in the south and west of the island, as measured by selected HDOH and NPS stations in this study, with a maximum 24-h-mean mass concentration of 728 μg/m3 recorded in Ocean View (100 km west of the LERZ emission source) in May 2018. Data from the low-cost sensor network correlated well with data from the HDOH PM2.5 instruments, confirming that these low-cost sensors provide a robust means to augment reference-grade instrument networks

Sulfide saturation and resorption modulates sulfur and metal availability during the 2014–15 Holuhraun eruption, Iceland

Mafic magmas may experience multiple stages of sulfide saturation and resorption during ascent and differentiation. Quenched tephra erupted during the 2014–15 Holuhraun eruption preserve abundant evidence for sulfide resorption, offering a rare opportunity to explore the sulfide life cycle from nucleation to resorption. Specifically, we combine detailed textural and chemical analyses of sulfides and silicate melts with geochemical models of sulfide saturation and degassing. This integrative approach demonstrates that sulfides began nucleating in melts with ~8 wt% MgO, persisted during fractionation to 6.5 wt% MgO, before resorbing heterogeneously in response to sulfur degassing. Sulfides are preserved preferentially in confined geometries within and between crystals, suggesting that kinetic effects impeded sulfur loss from the melt and maintained local sulfide saturation on eruption. The proportion of sulfides exhibiting breakdown textures increases throughout the eruption, coincident with decreasing magma discharge, indicating that sulfide resorption and degassing are kinetically limited. Sulfides likely modulate the emission of sulfur and chalcophile elements to the atmosphere and surface environment, with implications for assessing the environmental impacts and societal hazards of basaltic fissure eruptions