Journal article
Quantity and quality of organic matter (detritus) drives N2 effluxes (net denitrification) across seasons, benthic habitats, and estuaries
Global Biogeochemical Cycles, Vol.27(4), pp.1083-1095
2013
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Abstract
<p>N<sub>2</sub> flux rates (net denitrification) were measured over a diel cycle, seasonally, in 12 benthic habitats across three warm temperate Australian coastal systems. Dark N<sub>2</sub>-N fluxes were strongly controlled by sediment oxygen demand (SOD) across the 3 estuaries, 4 seasons, and 12 benthic habitats (<em>r</em><sup>2</sup> = 0.743; <em>p</em> < 0.001; <em>n</em> = 142; slope = 0.0170). However, some of the slopes differed significantly between seasons and among estuaries and habitats, and all of the slopes were correlated with the δ<sup>13</sup>C values and C:N ratios of sediment organic matter. Ternary mixing diagrams with the contribution of algal, seagrass, and terrestrial/mangrove material to sediment organic matter showed that habitats, seasons, and estuaries dominated by a mixture of seagrass and algal material had the lowest slopes, and slopes increase as habitats, seasons, and estuaries have an increasing contribution from terrestrial/ mangrove material. Overall, the slopes of dark N<sub>2</sub> fluxes versus SOD were low compared to previous studies, most likely due to either, or a combination of, the C:N ratio of the organic matter, the mixture of C:N ratios making up the organic matter, the structure of the organic matter, and/or the SOD rates. This study demonstrated that it is not only the quantity but also the type (quality), and maybe the mixture, of organic matter that is an important control on denitrification. As such, rapid global changes to detrital sources to coastal systems due to losses of mangrove, seagrasses, and saltmarshes, and associated increases in algae and macrophytes, are also expected to impact system level losses of nitrogen via denitrification.</p>
Details
- Title
- Quantity and quality of organic matter (detritus) drives N2 effluxes (net denitrification) across seasons, benthic habitats, and estuaries
- Creators
- Bradley D Eyre - Southern Cross UniversityDamien T Maher - Southern Cross UniversityPeter Squire - Southern Cross University
- Publication Details
- Global Biogeochemical Cycles, Vol.27(4), pp.1083-1095
- Grants
- Resolving uncertainty over the importance of N-fixation versus denitrification in coastal systems , DP0342956, Australian Research Council
- Grant note
- Funder: Australian Research Council, Grant ID: ARC/DP0342956, ARC/LP0212073, Grant links:
- Identifiers
- 3316; 991012821975502368
- Academic Unit
- Centre for Coastal Biogeochemistry; National Marine Science Centre; School of Environment, Science and Engineering; Southern Cross GeoScience; Faculty of Science and Engineering; Science
- Resource Type
- Journal article