Estimates of mercury flux and temporal variability of Hg/SO2 ratio in the plume of Popocatépetl volcano (Mexico)

Abstract

Gaseous Elemental Mercury (GEM) and sulfur dioxide (SO2) concentration data measured simultaneously in real time are reported for the first time in the plume of the Popocatépetl volcano. Measurements were carried out in the Altzomoni Atmospheric Observatory (AAO) station, located to the NW and at ~10 km from the crater. We evaluated data from 24 h time in explosive volcano phases on the 28 and 29 March 2019, using Lumex and Teledyne techniques. We calculated a mean Hg/SO2 ratio of 1.36 × 10−3 for the entire time series (24 h measurement) and 1.76 × 10−4, 1.61 × 10−4 and 1.92 × 10−4, respectively, for three short series corresponding to different isolated periods when the plume passed through the station (downwind) and was detected by the instrument. Although the analytical methodologies were not applied directly in the plume or close to the crater, the Hg/SO2 ratio is in agreement with data reported for other active volcanoes around the world. The data measured during the three short time series were used to estimate the Popocatépetl Hg flux (average value of 40 ± 16 t yr−1, 32 ± 14 t yr−1 and 46 ± 22 t yr−1, respectively). These results are especially interesting since they represent an estimate of Hg emissions in a particularly explosive phase of the Popocatépetl volcano.