Trace element emissions during the 2018 Kilauea Lower East Rift Zone eruption

Emily Mason,Patricia Amanda Nadeau,Evgenia Ilyinskaya,Tamar Elias,Tamsin Mather,David J Schneider,Marie Edmonds,Penny Wieser,Clive Oppenheimer,Christoph Kern,Emma Liu,Rachel C W Whitty

doi:10.5194/egusphere-egu2020-162

Abstract

&lt;p&gt;The 2018 eruption on the Lower East Rift Zone of Kilauea volcano, Hawai&amp;#8217;i released unprecedented fluxes of gases (&gt;200 kt/d SO&lt;sub&gt;2&lt;/sub&gt;) and aerosol into the troposphere [1,2]. The eruption affected air quality across the island and lava flows reached the ocean, forming a halogen-rich plume as lava rapidly boiled and evaporated seawater.&lt;/p&gt;&lt;p&gt;We present the at-source composition &amp;#8211; gas and size-segregated aerosol &amp;#8211; of both the magmatic plume (emitted from &amp;#8216;Fissure 8&amp;#8217;, F8) and the lava-seawater interaction plume (ocean entry, OE), including major gas species, and major and trace elements in non-silicate aerosol. Trace metal and metalloid (TMM) emissions during the 2018 eruption were the highest recorded for Kilauea, and the magmatic &amp;#8216;fingerprint&amp;#8217; of TMMs (X/SO&lt;sub&gt;2&lt;/sub&gt; ratios) in the 2018 plume is consistent with measurements made at the summit lava lake in 2008 [3], and with other rift and hotspot volcanoes [4,5].&lt;/p&gt;&lt;p&gt;We show that the OE plume composition predominantly reflects seawater composition with a small contribution from plagioclase +/- ash. However, elevated concentrations of some TMMs (Bi, Cd, Cu, Zn, Ag) with affinity for Cl-speciation in the gas phase cannot be accounted for by the silicate correction and therefore may derive from degassing of lava in the presence of elevated Cl&lt;sup&gt;-&lt;/sup&gt;. In the case of silver and copper, concentrations in the OE plume are elevated above both the F8 plume and seawater.&lt;/p&gt;&lt;p&gt;At-vent speciation of TMMs in the F8 plume during oxidation (following a correction for ash contributions) was assessed using a Gibbs Energy Minimization algorithm (HSC chemistry, Outotec Research). We also demonstrate the sensitivity of speciation in the plume to the concentration of common ligand-forming elements, chlorine and sulfur. These results could be used as initial conditions in atmospheric reaction models to investigate how plume composition evolves as low-temperature chemistry takes over.&lt;/p&gt;&lt;p&gt;

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