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The Central Arctic Ocean is one of the most oligotrophic oceans on Earth because of its sea-ice cover and short productive season. Nonetheless, across the peaks of extinct volcanic seamounts of the Langseth Ridge (87°N, 61°E), we observe a surprisingly dense benthic biomass. Bacteriosponges are the most abundant fauna within this community, with a mass of 460 g C m−2 and an estimated carbon demand of around 110 g C m−2 yr−1, despite export fluxes from regional primary productivity only sufficient to provide <1% of this required carbon. Observed sponge distribution, bulk and compound-specific isotope data of fatty acids suggest that the sponge microbiome taps into refractory dissolved and particulate organic matter, including remnants of an extinct seep community. The metabolic profile of bacteriosponge fatty acids and expressed genes indicate that autotrophic symbionts contribute significantly to carbon assimilation. We suggest that this hotspot ecosystem is unique to the Central Arctic and associated with extinct seep biota, once fueled by degassing of the volcanic mounts. This study reports the discovery of dense sponge gardens across the peaks of permanently ice-covered, extinct volcanic seamounts of the Langseth Ridge and on the remnants of a now extinct seep ecosystem. Using approaches to sample and infer food and energy sources to this ice-covered community, the authors suggest that the sponges use refractory organic matter trapped in the extinct seep community on which they sit. [ABSTRACT FROM AUTHOR]

Premixed laminar flat ethylene flames were investigated for nascent nanoparticles through photoionization mass spectrometry (PIMS). Using an atmospheric McKenna burner and ethylene air flames coupled to an atmospheric sampling system, within a relatively narrow C/O range two modes of these particles were found, which can be clearly distinguished with regard to their temperature dependence, their reactivity, and their ionization behaviour. Behind a diesel engine the same particles were observed. These results were corroborated using a low pressure ethylene-O flame coupled to a high resolution mass spectrometer. In this case, due to a special inlet system, it was possible to operate the flame in a fairly wide C/O range without clogging of the inlet nozzles. This allowed pursuing the development of particle size distribution functions (PSDF) well into the regime of mature soot. In addition, on the low mass side of the particle spectra measurements with unity resolution were possible and this allowed gaining information concerning their growth mechanism and structure. Finally, in an attempt to mimic Laser Induced Incandescence (LII) experiments the soot-laden molecular beam was exposed to IR irradiation. This resulted in a near complete destruction of nascent particles under LII typical fluences. Small C clusters between 3 and 17 C atoms were found. In addition and with much higher intensities, clusters comprising several hundreds of C atoms were also detected, the latter even at very low fluences when small clusters were totally absent. [ABSTRACT FROM AUTHOR]

Abstract. The complementary REMPI (resonance-enhanced multi-photon ionisation) techniques using either a tuneable laser or a fixed-frequency laser are compared. Our Jet-REMPI apparatus, consisting of a tuneable laser unit (Nd:YAG pump laser and OPO) and a reflectron mass spectrometer, is briefly introduced. This machine has been upgraded to cope with the difficult conditions (such as vibrations, temperature fluctuations and dust) prevailing in an incinerator. On-line measurements of the raw gas have been carried out at the municipal waste incinerator (MWI) in Stuttgart. Although this test series could not be completed the results are encouraging. They show that wavelength resolution can provide valuable information beyond that which can be obtained by fixed-frequency REMPI. Examples discussed include identification of phenanthrene as major constituent of the isomeric pair phenanthrene/anthracene and the structural identification of xylene isomers in the incinerator raw gas. Both examples are also of more general interest, the former with regard to investigation of soot precursors and the latter for quality assessment of refinery products. Spectra of some deuterated aromatics are reported for use of these compounds as standards. In addition, a mass spectrum containing DDT is shown and a chlorobenzene profile measured earlier in a pilot scale incinerator as demonstration of the sensitivity of the instrument. As is to be discussed, significant further sensitivity gains through increase of the beam density are limited because of ion collisions within the sample beam. [ABSTRACT FROM AUTHOR]