Measurement of trace gas species at White Island volcano, New Zealand, using chemical traps

摘要

Measurements of trace element emissions from volcanoes increases the understanding of magmatic systems, effects of volcanism on atmospheric chemistry, as well as the role of magma degassing in ore genesis. Volcanic emission rates of Cl, F, Pb, As, Hg Sb and Se were determined at White Island, New Zealand, using chemical traps containing 4 N NaOH solutions. Traps were located in both the fumarole area and at the crater rim where they would be exposed to the main volcanic gas plume. The chemical ratios relative to sulfur of the fumarole samples were distinctly different from the ratios of samples exposed to the gas plume. The trace metal fluxes were determined using the species to S ratios in the solutions combined with independently determined SO_2 emission rates measured by correlation spectrometer. At White Island, chemical traps yielded flux values of Cl = 84, F = 0.8Mg·d~(-1)(tonnes per day) and Pb = 28, As =17, Hg = 0.84, Sb=1.8 and Se = 1.3kg·d~(-1).