Surge in sulphur and halogen degassing from Ambrym volcano, Vanuatu

Volcanoes provide important contributions to
atmospheric budgets of SO2 and reactive halogens, which
play significant roles in atmospheric oxidative capacity and
radiation. However, the global source strengths of volcanic
emissions remain poorly constrained. These uncertainties
are highlighted here by the first measurements of gas
emission rates from Ambrym volcano, Vanuatu. Our initial
airborne ultraviolet spectroscopic measurements made in
January 2005 indicate fluxes of 18–270 kg s-1 of SO2, and
62–110 gs-1 of BrO, into the atmosphere, placing Ambrym
amongst the largest known contemporary point sources of
both these species on Earth. We also estimate high Cl and F
fluxes of ~8–14 and ~27–50 kg s-1, respectively, for this
period. Further observations using both airborne and
spaceborne remote sensing reveal a fluctuating SO2 output
between 2004 and 2008, with a surge in the first half of
2005, and underline the substantial contribution that a
single passively degassing volcano can make to the
atmospheric budget of sulfur and halogens.

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