Jani, Jariani and Toor, Gurpal S. (2018) Composition, sources, and bioavailability of nitrogen in a longitudinal gradient from freshwater to estuarine waters. Water Research, 137. pp. 344-354. ISSN 0043-1354, DOI https://doi.org/10.1016/j.watres.2018.02.042.
Full text not available from this repository.Abstract
Nitrogen (N) transport from land to water is a dominant contributor of N in estuarine waters leading to eutrophication, harmful algal blooms, and hypoxia. Our objectives were to (1) investigate the composition of inorganic and organic N forms, (2) distinguish the sources and biogeochemical mechanisms of nitrate–N (NO3–N) transport using stable isotopes of NO3 − and Bayesian mixing model, and (3) determine the dissolved organic N (DON) bioavailability using bioassays in a longitudinal gradient from freshwater to estuarine ecosystem located in the Tampa Bay, Florida, United States. We found that DON was the most dominant N form (mean: 64%, range: 46–83%) followed by particulate organic N (PON, mean: 22%, range: 14–37%), whereas inorganic N forms (NOx–N: 7%, NH4–N: 7%) were 14% of total N in freshwater and estuarine waters. Stable isotope data of NO3 − revealed that nitrification was the main contributor (36.4%), followed by soil and organic N sources (25.5%), NO3 − fertilizers (22.4%), and NH4 + fertilizers (15.7%). Bioassays showed that 14 to 65% of DON concentrations decreased after 5-days of incubation indicating utilization of DON by microbes in freshwater and estuarine waters. These results suggest that despite low proportion of inorganic N forms, the higher concentrations and bioavailability of DON can be a potential source of N for algae and bacteria leading to water quality degradation in the estuarine waters.
| Item Type: | Article |
|---|---|
| Funders: | UNSPECIFIED |
| Uncontrolled Keywords: | Nitrogen; Stable isotopes; Dissolved organic nitrogen; Bioavailability; Freshwater; Estuarine; Tampa bay estuary |
| Subjects: | Q Science > Q Science (General) Q Science > QD Chemistry |
| Divisions: | Faculty of Science > Department of Chemistry |
| Depositing User: | Ms. Juhaida Abd Rahim |
| Date Deposited: | 02 Aug 2019 03:37 |
| Last Modified: | 02 Aug 2019 03:37 |
| URI: | http://eprints.um.edu.my/id/eprint/21754 |
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