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Funder: EPSRC-CASE studentship, Funder: NERC studentship, Funder: Leverhulme Trust; doi: https://doi.org/10.13039/501100000275, Funder: NERC-CASE studentship, Funder: Rolex Institute, Volcanoes represent one of the largest natural sources of metals to the Earth’s surface. Emissions of these metals can have important impacts on the biosphere as pollutants or nutrients. Here we use ground- and drone-based direct measurements to compare the gas and particulate chemistry of the magmatic and lava–seawater interaction (laze) plumes from the 2018 eruption of Kīlauea, Hawai’i. We find that the magmatic plume contains abundant volatile metals and metalloids whereas the laze plume is further enriched in copper and seawater components, like chlorine, with volatile metals also elevated above seawater concentrations. Speciation modelling of magmatic gas mixtures highlights the importance of the S2− ligand in highly volatile metal/metalloid degassing at the magmatic vent. In contrast, volatile metal enrichments in the laze plume can be explained by affinity for chloride complexation during late-stage degassing of distal lavas, which is potentially facilitated by the HCl gas formed as seawater boils.

Many explosive terrestrial volcanic eruptions are accompanied by lightning and other atmospheric electrical phenomena. The plumes produced generate large perturbations in the surface atmospheric electric potential gradient and high charge densities have been measured on falling volcanic ash particles. The complex nature of volcanic plumes (which contain gases, solid particles, and liquid drops) provides several possible charging mechanisms. For plumes rich in solid silicate particles, fractoemission (the ejection of ions and atomic particles during fracture events) is probably the dominant source of charge generation. In other plumes, such as those created when lava enters the sea, different mechanisms, such as boiling, may be important. Further charging mechanisms may also subsequently operate, downwind of the vent. Other solar system bodies also show evidence for volcanism, with activity ongoing on Io. Consequently, volcanic electrification under different planetary scenarios (on Venus, Mars, Io, Moon, Enceladus, Tethys, Dione and Triton) is also discussed. © 2008 Springer Science+Business Media B.V.

We present the first application of a multi-stage impactor to study volcanic particle emissions to the troposphere from Masaya volcano, Nicaragua. Concentrations of soluble SO42−,Cl−, F−, NO3−, K+, Na+,NH4+, Ca2+ and Mg2+ were determined in 11 size bins from ∼0.07 μm to >25.5 μm. The near-source size distributions showed major modes at 0.5μm (SO42−, H+,NH4+); 0.2 μm and 5.0 μm (Cl−) and 2.0–5.0 μm(F−). K+ and Na+ mirrored the SO42− size-resolvedconcentrations closely, suggesting that these were transported primarily asK2SO4 and Na2SO4 in acidic solution, while Mg2+ andCa2+ presented modes in both 1 μm particles. Changes in relative humidity were studied by comparing daytime (transparent plume) and night-time (condensed plume) results. Enhanced particle growth rates were observed in the night-time plume as well as preferential scavenging of soluble gases, such as HCl, by condensed water. Neutralisation of the acidic aerosol by background ammonia was observed at the crater rim and to a greater extent approximately 15 km downwind of the active crater. We report measurements of re-suspended near-source volcanic dust, which may form a component of the plume downwind. Elevated levels ofSO42−, Cl−, F−,H+, Na+, K+ and Mg2+ were observed around the 10 μm particle diameter in this dust. The volcanic SO42− flux leaving the craterwas ∼0.07 kg s−1.

This paper presents a new tool, AshCalc, for the comparison of the three most commonly used models for the calculation of the bulk volume of volcanic tephra fall deposits: the exponential model, the power law model and the Weibull model. AshCalc provides a simple and intuitive tool to speed up the analysis of tephra deposits and compare and contrast the fits for each model. Two improvements in terms of computational performance are implemented in AshCalc for the estimation of the parameters for the Weibull model. The first is an analytic method for reducing the number of free parameters, whilst the second exaggerates the minima in parameter space, leading to a more robust solution. We show that AshCalc provides volume estimates in line with other previously published estimates and hence can be used with a high degree of confidence. We include the open source python code for Ashcalc with the intention that it can be used both as a stand-alone program and integrated into other python projects.