Long-term monitoring of SO2 quiescent degassing from Nyiragongo’s lava lake

The activity of open-vent volcanoes with an active lava-lake, such as Nyiragongo, is characterized by persistent degassing, thus continuous monitoring of the rate, volume and fate of their gas emissions is of great importance to understand their geophysical state and their potential impact. We report results of SO2 emission measurements from Nyiragongo conducted between 2004 and 2012 with a network of ground-based scanning-DOAS (Differential Optical Absorption Spectroscopy) remote sensors. The mean SO2 emission rate is found to be 13 ± 9 kg s−1, similar to that observed in 1959. Daily emission rate has a distribution close to log-normal and presents large inter-day variability, reflecting the dynamics of percolation of magma batches of heterogeneous size distribution and changes in the effective permeability of the lava lake. The degassed S content is found to be between 1000 and 2000 ppm from these measurements and the reported magma flow rates sustaining the lava lake. The inter-annual trend and plume height statistics indicate stability of a quiescently degassing lava lake during the period of study

Validation of optical remote sensing measurement strategies applied to industrial gas emissions

In May 2004 a field-campaign was conducted at a power plant in Spain, aiming at validating the use of a miniaturized, fibre-optic, ultraviolet, differential optical absorption spectrometer (mini-DOAS) instrument for sulphur dioxide flux (SO2) quantification. Emissions were determined by integrating the total number of molecules in a vertical cross-section of the gas plume, and multiplying them by the wind component at plume height. Calculated wind data was compared with balloon soundings. Plume height, computed from a tomographic reconstruction of the plume was compared with stereo-photogrammetric methods and a plume rise model. Finally, SO2 fluxes were compared to emissions reported by the power station. Although the meteorological conditions during the field-campaign were adverse, with large fluctuations in wind-speed and wind-direction, the optical measurements performed proved to be practically feasible and compared well with the techniques used for the validation. SO2 fluxes derived by mini-DOAS were within 7% of the ones reported by the power station

Genome-wide meta-analysis identifies six novel loci associated with habitual coffee consumption

Coffee, a major dietary source of caffeine, is among the most widely consumed beverages in the world and has received considerable attention regarding health risks and benefits. We conducted a genome-wide (GW) meta-analysis of predominately regular-