| Autor: |
Heggie, David T., Skyring, Graham W., Orchardo, Joseph, Longmore, Andrew R., Nicholson, Geoffrey J., Berelson, William M. |
| Zdroj: |
Marine and Freshwater Research; 1999, Vol. 50 Issue: 6 |
| Abstrakt: |
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 (7585%; denitrification rates ~1.3 mmol N2 m2 day1) at organic carbon loadings of ~1525 mmol m2 day1 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 m2 day1) 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. Extra keywords: nitrogen, benthic flux, Australia. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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