Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 11, 5957-5967, 2014
https://doi.org/10.5194/bg-11-5957-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
31 Oct 2014
Nitrate sources and dynamics in a salinized river and estuary – a δ15N–NO3 and δ18O–NO3 isotope approach
D. Xue1, P. Boeckx3, and Z. Wang2,1 1Tianjin Key Laboratory of Water Resources and Environment, Tianjin Normal University, Tianjin 300387, China
2State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China
3Isotope Bioscience Laboratory – ISOFYS, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium
Abstract. To trace NO3 sources and assess NO3 dynamics in salinized rivers and estuaries, three rivers (Haihe River: HH River, Chaobaixin River: CB River and Jiyun River: JY River) and two estuaries (HH Estuary and CJ Estuary) along the Bohai Bay (China) have been selected to determine dissolved inorganic nitrogen (DIN: NH4+, NO2 and NO3. Upstream of the HH River, NO3 was removed 30.9 ± 22.1% by denitrification, resulting from effects of the floodgate: limiting water exchange with downstream and prolonging water residence time to remove NO3. Downstream of the HH River NO3 was removed 2.5 ± 13.3% by NO3 turnover processes. Conversely, NO3 was increased 36.6 ± 25.2% by external N source addition in the CB River and 34.6 ± 35.1% by in-stream nitrification in the JY River. The HH and CY Estuaries behaved mostly conservatively excluding the sewage input in the CJ Estuary. Hydrodynamics in estuaries has been changed by the ongoing reclamation projects, aggravating the loss of the attenuation function of NO3 in the estuary.

Citation: Xue, D., Boeckx, P., and Wang, Z.: Nitrate sources and dynamics in a salinized river and estuary – a δ15N–NO3 and δ18O–NO3 isotope approach, Biogeosciences, 11, 5957-5967, https://doi.org/10.5194/bg-11-5957-2014, 2014.
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