Measurements of hydrogen cyanide (HCN) and acetylene (C2H2) from the Infrared Atmospheric Sounding Interferometer (IASI)

Hydrogen cyanide (HCN) and acetylene (C2H2) are ubiquitous atmospheric trace gases with medium lifetime, which are frequently used as indicators of combustion sources and as tracers for atmospheric transport and chemistry. Because of their weak infrared absorption, overlapped by the CO2 Q branch near 720 cm−1, nadir sounders have up to now failed to measure these gases routinely. Taking into account CO2 line mixing, we provide for the first time extensive measurements of HCN and C2H2 total columns at Reunion Island (21° S, 55° E) and Jungfraujoch (46° N, 8° E) in 2009–2010 using observations from the Infrared Atmospheric Sounding Interferometer (IASI). A first order comparison with local ground-based Fourier transform InfraRed (FTIR) measurements has been carried out allowing tests of seasonal consistency which is reasonably captured, except for HCN at Jungfraujoch. The IASI data shows a greater tendency to high C2H2 values. We also examine a nonspecific biomass burning plume over austral Africa and show that the emission ratios with respect to CO agree with previously reported values

Cryptospores from the Katian (Upper Ordovician) of the Tungus basin: The first evidence for early land plants from the Siberian paleocontinent

© 2015 Elsevier B.V.A diverse assemblage of cryptospores is reported for the first time from the Upper Ordovician of Siberia. It was discovered during a palynological study of a sedimentary succession of about 100 m, exposed along the Bolshaya Nirunda River, a right tributary of the Podkamennaya Tunguska River. The succession is located on the southern margin of the extensive epicontinental Tungus basin on the Siberian Platform between the Katanga and Yenisei land masses. The cryptospore assemblage was recovered from the siliciclastic-carbonate Dolbor Formation and scarcely from the overlying more carbonate Bur Formation. Both formations belong to the Katian Global Stage (Upper Ordovician). The cryptospores occur together with marine remnants (acritarchs, prasinophytes, chitinozoans, scolecodonts). It is similar to all known Upper Ordovician cryptospore assemblages in comprising naked and envelope-enclosed monads, dyads, tetrads and polyads. Although preservation is moderate to poor, the cryptospore taxa Velatitetras laevigata, Tetrahedraletes medinensis, Abditusdyadus laevigatus, Dyadospora murusdensa, Pseudodyadospora laevigata, Segestrespora laevigata and Sphaerasaccus glabellus can be identified. This report represents the first record of spores of the earliest land plants from the paleocontinent Siberia and therefore extends the global paleogeographical coverage of Late Ordovician cryptospores

Spectrometric Monitoring of Atmospheric Carbon Tetrafluoride (CF4) Above the Jungfraujoch Station Since 1989: Evidence of Continued Increase But at a Slowing Rate

The long-term evolution of the vertical column abundance of carbon tetrafluoride (CF4) above the high-altitude Jungfraujoch station (Swiss Alps, 46.5 ° N, 8.0 ° E, 3580 ma.s.l.) has been derived from the spectrometric analysis of Fourier transform infrared solar spectra recorded at that site between 1989 and 2012. The investigation is based on a multi-microwindow approach, two encompassing pairs of absorption lines belonging to the R-branch of the strong ν3 band of CF4 centered at 1283 cm-1, and two additional ones to optimally account for weak but overlapping HNO3 interferences. The analysis reveals a steady accumulation of the very long-lived CF4 above the Jungfraujoch at mean rates of (1.38 ± 0.11) x 1013 molec cm-2 yr-1 from 1989 to 1997, and (0.98 +/- 0.02) x 1013 molec cm-2 yr-1 from 1998 to 2012, which correspond to linear growth rates of 1.71 ± 0.14 and 1.04 ± 0.02% yr-1 respectively referenced to 1989 and 1998. Related global CF4 anthropogenic emissions required to sustain these mean increases correspond to 15.8 ±1.3 and 11.1 ± 0.2 Gg yr-1 over the above specified time intervals. Findings reported here are compared and discussed with respect to relevant northern mid-latitude results obtained remotely from space and balloons as well as in situ at the ground, including new gas chromatography mass spectrometry measurements performed at the Jungfraujoch since 2010