A high-resolution FT-IR study of the fundamental bands v(7), v(8), and v(18) of ethene secondary ozonide

Ozonization reaction of ethene in neat film at 77 K was performed. Separation of ethene secondary ozonide from the other products of the reaction was performed by continuous pumping of the reactor. Only the products, which evaporated from the walls of the reactor at 185 K, were transferred to the gas cell. The high-resolution infrared absorption spectrum of gaseous ethene secondary ozonide (C2H4O3) in a static gas long-path absorption cell has been recorded in the 900-1100 cm(-1) spectral region at 185 K. The spectral resolution was 0.003 cm(-1). Analyses of the nu(7)(A) band at 1037.0 cm(-1), the nu(8)(A) band at 956.1 cm(-1), and the nu(18)(B) band at 1082.1 cm(-1) have been performed using the Watson Hamiltonian model (A, reduction; IIIr, representation). A set of ground-state rotational and quartic centrifugal distortion constants have been obtained, and upper state spectroscopic constants have been determined for the bands investigated. A local resonance observed in vis is explained as c-Coriolis interaction with nu(10) + nu(11)

A bioturbator, a holobiont, and a vector: The multifaceted role of Chironomus plumosus in shaping N-cycling

Tube-dwelling chironomid larvae are among the few taxa that can withstand and thrive in the organic-rich sediments typical of eutrophic freshwater ecosystems. They can have multiple effects on microbial nitrogen (N) cycling in burrow environments, but such effects cease when chironomid larvae undergo metamorphosis into flying adults and leave the sediment. Here we investigated the ecological role of Chironomus plumosus by exploring the effect of its different life stages (as larva and adult midge) on microbial N transformations in a shallow freshwater lagoon by means of combined biogeochemical and molecular approaches. Results suggest that sediment bioturbation by chironomid larvae produce contrasting effects on nitrate ((Formula presented.))-reduction processes. Denitrification was the dominant pathway of (Formula presented.) reduction (>90%), primarily fuelled by (Formula presented.) from bottom water. In addition to pumping (Formula presented.) -rich bottom water within the burrows, chironomid larvae host microbiota capable of (Formula presented.) reduction. However, the contribution of larval microbiota is lower than that of microbes inhabiting the burrow walls. Interestingly, dinitrogen fixation co-occurred with (Formula presented.) reduction processes, indicating versatility of the larvae's microbial community. Assuming all larvae (averaging 1,800 ind./m2) leave the sediment following metamorphosis into flying adults, we estimated a displacement of 47,787 µmol of organic N/m2 from the sediment to the atmosphere during adult emergence. This amount of particulate organic N is similar to the entire N removal stimulated by larvae denitrification over a period of 20 days. Finally, the detection of N-cycling marker genes in flying adults suggests that these insects retain N-cycling microbes during metamorphosis and migration to the aerial and terrestrial ecosystems. This study provides evidence that chironomids have a multifaceted role in shaping the N cycle of aquatic ecosystems

Seasonal observation and source apportionment of carbonaceous aerosol from forested rural site (Lithuania)

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