Impact Of Volcanoes Research Articles

Development and application of a sampling method for the determination of reactive halogen species in volcanic gas emissions.

Volcanoes release large amounts of reactive trace gases including sulfur and halogen-containing species into the atmosphere. The knowledge of halogen chemistry in volcanic plumes can deliver information about subsurface processes and is relevant for the understanding of the impact of volcanoes on atmospheric chemistry. In this study, a gas diffusion denuder sampling method using 1,3,5-trimethoxybenzene (1,3,5-TMB)-coated glass tubes for the in situ derivatization of reactive halogen species (RHS) was characterized by a series of laboratory experiments. The coating proved to be applicable to collect selectively gaseous bromine species with oxidation states (OS) of +1 or 0 (such as Br2, BrCl, HOBr, BrO, and BrONO2) while being unreactive to HBr (OS -1). The reaction of 1,3,5-TMB with reactive bromine species forms 1-bromo-2,4,6-TMB-other halogens give corresponding derivatives. Solvent elution of the derivatives followed by analysis with GC-MS results in absolute detection limits of a few nanograms for Br2, Cl2, and I2. In 2015, the technique was applied on volcanic gas plumes at Mt. Etna (Italy) measuring reactive bromine mixing ratios between 0.8 and 7.0ppbv. Total bromine mixing ratios between 4.7 and 27.5ppbv were derived from alkaline trap samples, simultaneously taken by a Raschig tube and analyzed with IC and ICP-MS. This leads to the first results of the reactive bromine contribution to total bromine in volcanic emissions, spanning over a range between 12% (±1) and 36% (±2). Our finding is in an agreement with previous model studies, which imply values <44% for plume ages <1min, which is consistent with the assumed plume age at the sampling sites. Graphical abstract Illustration of the measurement procedure for the determination of reactive halogen species in volcanic plumes.

Model Estimation of Sulfate Aerosol Sources Collected at Cape Hedo during an Intensive Campaign in October-November, 2015

ABSTRACTAn intensive observation campaign at Cape Hedo, Okinawa, Japan was conducted from late October to early November 2015 to investigate the behavior of long-range transported atmospheric pollutants. During this period, sulfate (SO42–) was the dominant aerosol component. The sources of SO42– were estimated by using the air quality model with the tagged tracer method. The main source of high SO42– concentration varied day-to-day. When the westerly wind was dominant (October 27), the main source was anthropogenic SO2 emissions in China. When the northerly wind prevailed (November 1), the impact of volcanoes in western Japan was significant and the conversion ratio from SO2 to SO42– was lowest, at less than 70%, because of the faster transport. During the latter part of the campaign, the northerly to easterly winds were prominent, and the impacts of Korea, Japan, and ships on SO42– observed at Cape Hedo were also clear. When the contributions from Korea, Japan, and ships were the highest (November 4), the conversion ratio was also the highest, at greater than 95% because of long-range transport. The modeled sources of volcanoes and ship emissions corresponded well with the observed coarse-mode SO42– and V/Mn ratio, respectively. The mutual evaluation of sources from model and observations enable SO42– sources to be estimated with higher confidence.

Reclaiming biology

Reclaiming biology

The impact of volcanoes through human history

Volcanic Activity and Human Ecology. Edited by Payson D. Sheets and Donald K. Grayson. Pp. 644. (Academic: 1980.) $52, £33.80.