Isotopic evidence for the turnover of biological reactive nitrogen in the Pearl River Estuary, south China

Ye, Feng; Ni, Zhixin; Xie, Luhua; Wei, Gangjian; Jia, Guodong

doi:10.1002/2014jg002842

Cited by 56 publications

(52 citation statements)

References 60 publications

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“…It is likely that DIN would behave in different biogeochemical processes. It is agreement with the previous study32. They found the east and west PRE might be associated with different degrees of active internal N cycling.…”

Section: Discussionsupporting

confidence: 94%

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Evolution of the sink and source of dissolved inorganic nitrogen with salinity as a tracer during summer in the Pearl River Estuary

Hong

Yin

et al. 2016

Sci Rep

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In this study, we evaluated the sink and source of the surface water along the PRE using a mixing model method with salinity as tracer. The observational data showed that the decreasing of dissolved inorganic nitrogen (DIN) did not closely follow the physical mixing lines of freshwater and modified seawater. In the western part, DIN consumption by phytoplankton and bacteria uptake (ΔDIN)varied from 15.81 μmol L−1 to 88.53 μmol L−1. On the contrary, in the eastern part, ΔDIN varied from −63.66 μmol L−1 to −10.45 μmol L−1. DIN source in the eastern part may be mainly caused by organic matter decomposition, while DIN remove is strongly associated with phytoplankton growth and bacteria consumption. These differential behaviors of the estuary with respect to DIN are largely due to varying degrees of hydrodynamics due to different topography in the two areas. Sensitivity analysis indicated reduction strategies of DIN inputs to coastal waters may improve environment quality in the PRE, due to DIN changes in the freshwater end-member having a determined influence on biological activities (R). Our results indicate that the model may be a valuable way to address the sources and sink of DIN in the river-dominated estuaries.

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Section: Discussionsupporting

confidence: 94%

“…The suspended particulate matter (up to 40 mg L −1 ) was higher in low salinity. It is disagreement with previous study32. They found that phytoplankton growth can be limited by high turbidity in low-salinity waters (up to 30~150 mg L −1 at near-zero salinity in the Pearl River Estuary3334.…”

Section: Discussioncontrasting

confidence: 64%

Evolution of the sink and source of dissolved inorganic nitrogen with salinity as a tracer during summer in the Pearl River Estuary

Hong

Yin

et al. 2016

Sci Rep

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“…The mixing behavior of N species in estuaries is often assessed using a two end‐member mixing model (Fry, ; Officer, ), and this approach has been widely applied in the tidal estuaries, such as the Scheldt estuary (Middelburg & Nieuwenhuize, ), the Elbe estuary (Dähnke et al, ), and the Pearl River estuary (Ye et al, ).

f_{1} + f_{2} = 1,

f_{1} \times S_{1} + f_{2} \times S_{2} = S_{obs},

f_{1} \times C_{1} + f_{2} \times C_{2} = C_{ex},

f_{1} \times C_{1} \times δ_{1} + f_{2} \times C_{2} \times δ_{2} = C_{ex} \times δ_{ex},

where C and δ denote, respectively, the concentration and isotopic composition of N species, the subscripts 1 and 2 indicate the two end‐members.…”

Section: Methodsmentioning

confidence: 99%

Biogeochemical Dynamics in a Eutrophic Tidal Estuary Revealed by Isotopic Compositions of Multiple Nitrogen Species

et al. 2019

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Estuaries sit at the land‐ocean boundary and act as natural reactors for nitrogen (N) transformations among numerous forms. Superimposing onto physical mixing, biological processes lead to nonconservative N behavior in estuaries. Under the coinfluences of biological alteration and multiple end‐members, however, some N species can exhibit apparent conservation. To explore N dynamics and potential mechanisms that modulate the mixing behaviors, we measured concentrations and natural isotopic compositions of multiple N species (nitrate: NO3−, nitrite: NO2−, ammonium: NH4+, and particulate nitrogen) in a typical eutrophic estuary in southern China. Additionally, N uptake and oxidation rates were measured by using isotope labelling techniques to evaluate processes potentially offsetting the conservative mixing of specific N pools. We found that NO3− followed conservative two end‐member mixing with dual isotopes varying in a narrow range (<1–2‰) due to low microbial preferences. Moreover, δ15N‐NO2− revealed a nonconservative pattern with an involvement of multiple end‐members. The dominant N transformation processes shifted downstream. In the upper estuary, ammonia oxidation (~20 μmol L−1 day−1) dominated NH4+ removal and was accompanied by NO2− accumulation. In the middle‐lower estuary, NH4+ uptake became dominant, with phytoplankton showing strong preference for it over NO3− and NO2−. Based on measured NH4+ uptake rates (9.1–12.5 μmol L−1 day−1 in the light and 0.9 μmol L−1 day−1 in the dark), short water residence time (<1 day) was required to maintain the conservative mixing. Coupling N isotopes in multiple nitrogen species with measurements of N uptake and nitrification, we successfully uncovered N dynamics and distinguished biological processes from physical mixing.

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“…Recent work (Chang et al, 2002;Kaushal et al, 2011;Panno et al, 2008;Ye et al, 2015) shows that denitrification also increases δ …”

mentioning

confidence: 99%

“…Denitrification can be differentiated from sewage contamination if both δ 15 N and δ 18 O isotopes are measured in NO 3 À (Chang et al, 2002;Kaushal et al, 2011;Panno et al, 2008;Ye et al, 2015). In dissolved NO 3 À subjected to denitrification, both δ 15 N and δ…”

mentioning

confidence: 99%

Tracking Change in the Illinois River using Stable Isotopes in Modern and Ancient Fishes

et al. 2016

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The Illinois River has been heavily modified by human activities. We examined the nitrogen and carbon stable isotope composition of collagen from fish bones in two Native American middens comparing them to modern fishes in the River today. We also compared ancient and modern fishes to three reference samples-(i) Illinois River phytoplankton; (ii) backwater lake sediment; and (iii) tissue from riverside trees. We found a large increase in δ 15 N values in modern fish bone collagen relative to ancient collagen. However, there is little change in δ 13 C between ancient and modern samples. Bone collagen from invasive carp species (Hypopthalmichthys and Cyprinus) are similar to modern phytoplankton. All fishes are different from riverside trees and backwater lake sediment. The large shift in δ 15N values between ancient and modern fishes is probably caused by contamination of the river by Chicago treated wastewater and by denitrified fertilizer run-off. Our results indicate a major change in nitrogen biogeochemistry in the modern river. Comparisons between ancient and modern δ 13 C values suggest little change in feeding behaviour of fishes between ancient and modern times. However, our data for invasive carp suggest strong competition with native planktivores.

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Isotopic evidence for the turnover of biological reactive nitrogen in the Pearl River Estuary, south China

Cited by 56 publications

References 60 publications

Evolution of the sink and source of dissolved inorganic nitrogen with salinity as a tracer during summer in the Pearl River Estuary

Evolution of the sink and source of dissolved inorganic nitrogen with salinity as a tracer during summer in the Pearl River Estuary

Biogeochemical Dynamics in a Eutrophic Tidal Estuary Revealed by Isotopic Compositions of Multiple Nitrogen Species

Tracking Change in the Illinois River using Stable Isotopes in Modern and Ancient Fishes

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