Stewart, C.; Rosenberg, M.D.; Kilgour, G.N. 2022 Ash leachate characteristics of the 27 April 2016 and 13 September 2016 eruptions of Whakaari / White Island volcano. Lower Hutt, N.Z.: GNS Science. GNS Science report 2020/39. 15 p.; doi: 10.21420/5HBH-MX20
Abstract
Volcanic ash samples from the 27 April 2016 and 13 September 2016 eruptions of Whakaari / White Island volcano were collected on-island within 24 hours of each eruption. Water-extractable concentrations of a range of elements were determined in these samples, following the International Volcanic Health Hazard Network (IVHHN) protocol. These results are reported here to add to the broader geochemical data series for Whakaari / White Island and because of interest in the 2016 ash as an analogue for ash from the 9 December 2019 eruption, which could not be sampled due to access restrictions. The 2016 ash samples were strongly acidic and carried water-soluble salts in concentrations sufficiently high to be of potential concern for impacts on human and agricultural activities if ash of similar composition were to reach the North Island mainland in future eruptions. Many of the water-extractable elements in one sample exceed previously reported global maximum values and set new global high points for ash leachate compositions. This is the case for the elements Ca, Na, Al, Fe, B, Sr, Li, Ni, Cr, Co, V, Sb, SO4-S, Cl and Br. Results of Whakaari / White island ash leaching support previous findings that a re-extraction methodology is necessary to provide complete appraisal of the elements S and F, which can have a significant impact on agriculture. (auth)
