Denitrification and Denitrifying Efficiencies in Sediments of Port Phillip Bay: Direct Determinations of Biogenic N2 and N-metabolite Fluxes with Implications for Water Quality  

Authors / CoAuthors

Heggie, D.T. | Skyring, G.W. | Orchardo, J. | Longmore, A.R. | Nicholson, G.J | Berelson, W.M.

Abstract

High-precision measurements of N2 in benthic chamber waters indicated that denitrification occurs within the major sedimentary facies in Port Phillip Bay. The integrated fluxes of biogenic N2 , ammonia, nitrate and nitrite showed that the stoichiometric relationship between organic C and N in the muddy sediments, occupying about 70% of the seafloor, was 5.7, this being similar to the Redfield ratio of 6.6. High denitrifying efficiencies (75-85%; denitrification rates ~1.3 mmol N2 m-2 day-1) at organic carbon loadings of ~15-25 mmol m-2 day-1 indicate that most N processed through the sediments was returned to the overlying waters as biologically (generally) unavailable N2. At sites of high organic carbon loadings to the sediments (>100 mmol m-2 day-1) denitrification rates and denitrifying efficiencies were near zero and most N is returned to the Bay waters as biologically available ammonium. In chambers 'spiked' with 15NO3 , denitrifyers used nitrate produced in the sediments in situ, rather than the exogenous nitrate in overlying waters. The sedimentary microbial processes of ammonification, nitrification and denitrification are therefore tightly coupled.

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nonGeographicDataset

eCat Id

70213

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Digital Object Identifier

http://dx.doi.org/10.1071/MF98054

Keywords

• External PublicationScientific Journal Paper

( Theme )

• marine biodiversity

( Theme )

• marine

• AU-VIC

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_External

Publication Date

1999-01-01T00:00:00

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Australian Government Security ClassificationSystem    

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Creative Commons Attribution 4.0 International Licence    

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geoscientificInformation

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[-38.4, -37.8, 144.3, 145.1]

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