Article

Nitrogen Fixation (Acetylene Reduction) Associated with Decaying Leaves of Pond Cypress (Taxodium distichum var. nutans) in a Natural and a Sewage-Enriched Cypress Dome.

Center for Wetlands and Department of Environmental Engineering Science, University of Florida, Gainesville, Fłorida 32611.
Applied and Environmental Microbiology (Impact Factor: 3.67). 06/1981; 41(6):1413-8.
Source: PubMed

ABSTRACT

Surface litter from a natural and a sewage-enriched cypress dome in north-central Florida showed a pronounced seasonal pattern of nitrogenase (acetylene reduction) activity associated with seasonal leaf fall from deciduous trees in the domes. Samples of peat from cores indicated negligible nitrogenase activity below the surface layer. Integrating the monthly rates of nitrogen fixation (based on the theoretical molar ratio of 3:2 for C(2)H(4)/NH(3)) yielded 0.39 and 0.12 g of N/m per year fixed in the litter of the natural and sewage-enriched domes, respectively. The nitrogen fixed in the first 3 months after leaf fall in the natural dome represented about 14% of the nitrogen increment in the decomposing cypress leaves, but fixation contributed a negligible amount of nitrogen (<1%) to decomposing litter in the sewage-enriched dome.

Download full-text

Full-text

Available from: Patrick L Brezonik

  • No preview · Article · Jan 1984 · Australian Journal of Botany
  • [Show abstract] [Hide abstract]
    ABSTRACT: Nitrogen fixation was measured in four subarctic streams substantially modified by beaver (Castor canadensis) in Quebec. Acetylene-ethylene (C2H2 → C2H4) reduction techniques were used during the 1982 ice-free period (May–October) to estimate nitrogen fixation by microorganisms colonizing wood and sediment. Mean seasonal fixation rates were low and patchy, ranging from zero to 2.3 × 10−3 µmol C2H4 · cm−2 · h−1 for wood, and from zero to 7.0 × 10−3 µmol C2H4 · g AFDM−1 · h−1 for sediment; 77% of all wood and 63% of all sediment measurements showed no C2H2 reduction. Nonparametric statistical tests were unable to show a significant difference (p > 0.05) in C2H2 reduction rates between or within sites for wood species or by sediment depth. Nitrogen contributed by microorganisms colonizing wood in riffles of beaver influenced watersheds was small (e.g., 0.207 g N · m−2 · y−1) but greater than that for wood in beaver ponds (e.g., 0.008 g N · m−2 · y−1) or for streams without beaver (e.g., 0.003 g N · m−2 · y−1). Although mass specific nitrogen fixation rates did not change significantly as beaver transform riffles into ponds, the nitrogen fixed by organisms colonizing sediment in pond areas (e.g., 5.1 g N · m−2 · y−1) was greater than that in riffles (e.g., 0.42 g N · m−2 · y−1). The annual nitrogen contribution is proportional to the amount of sediment available for microbial colonization. We estimate that total nitrogen accumulation in sediment, per unit area, is enhanced 9 to 44 fold by beaver damming a section of stream.
    No preview · Article · Jan 1985 · Hydrobiologia
  • [Show abstract] [Hide abstract]
    ABSTRACT: The objective of this research was to determine the effects of polynuclear aromatic hydrocarbons (PAH) on N/sub 2/ fixation by the alga, Anabaena flos-aquea. The reduction of acetylene (C/sub 2/H/sub 2/) to ethylene (C/sub 2/H/sub 4/) was measured as a measure of the capacity of an organism to fix atmospheric N/sub 2/ and reduce it to an assimilable form. The primary advantage of this assay is its speed since chemical exposure and quantitative chromatographic analysis can be completed in a few hours.
    No preview · Article · Sep 1985 · Bulletin of Environmental Contamination and Toxicology
Show more