Exceptional sulfur degassing from Nyamuragira volcano, 1979-2005

The sulfur dioxide (SO2) output from Nyamuragira volcano has been monitored by the Total Ozone Mapping Spectrometer (TOMS) since 1979, and is evaluated here to quantify the emissions from this highly productive volcano. The majority of Nyamuragira's emissions were emplaced in the lower to middle troposphere, with SO2 removal rates of 30-90% per day (k = 4.13 x 10(-6) to 2.66 x 10(-5)s(-1)). We have tested a new method of back-calculating persistent, effusive emission fluxes from once-daily observations, which accounts for this rapid daily removal of SO2 that cannot be measured using satellite 'snapshots'. Twelve of the 14 eruptions during this period each produced >= 0.8 teragrams (Tg) of SO2. Nyamuragira erupted nearly 25 Tg of SO2 during these eruptions, and probably emitted significantly more than we could measure by TOMS. Nyamuragira may be the largest volcanic source of sulfur to the atmosphere for the past few decades.