Net subterranean estuarine export fluxes of dissolved inorganic C, N, P, Si, and total alkalinity into the Jiulong River estuary, China

Wang, Guizhi; Wang, Zhangyong; Zhai, Weidong; Moore, Willard S.; Li, Qing; Yan, Xiuli; Qi, Di; Jiang, Yuwu

doi:10.1016/j.gca.2014.11.001

Cited by 86 publications

(50 citation statements)

References 20 publications

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“…Unfortunately, the variation ranges of δ 15 N‐NO 3 − and δ 18 O‐NO 3 − in the JRE were narrow (<1‰–2‰) and thus made it difficult to effectively trace NO 3 − sources. Of course, a plausible explanation of this is that the NO 3 – pool in the JRE was too large to be altered by biological processes since τ w in the JRE is as short as <1 day in summer (Wang et al, ). The low impact of biological transformations in rapidly flushed estuary has been noted before in the Tweed estuary (Ahad et al, ).…”

Section: Discussionmentioning

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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Section: Discussionmentioning

confidence: 99%

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

et al. 2019

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“…Seasonal variations are present in the river discharge as inferred from precipitation (Wang et al, 2005) and there might be increase in the groundwater discharge and associated nutrient fluxes in summer as in other coastal systems (e.g., Lewis, 1987;Costa et al, 2006;Kelly and Moran, 2012;Wang et al, 2015). However, the relative changes in the groundwater discharge and associated nutrient fluxes would be much smaller than those of the river.…”

Section: Seasonal and Regional Extrapolations And Expectationsmentioning

confidence: 99%

Tidal variability of nutrients in a coastal coral reef system influenced by groundwater

Wang¹,

Wang²,

Wang³

et al. 2017

Preprint

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Abstract. To investigate variations in nitrite, nitrate, phosphate and silicate in a spring-neap tide in a coral reef system influenced by groundwater discharge, we carried out a time-series observation of these nutrients and and 2.68 M, respectively. Nitrate and phosphate were negatively correlated with water depth during the spring tide, but showed no correlation during the neap tide. Nitrite was positively correlated with water depth in the spring and neap tide.They were also significantly correlated with salinity at the ebb flow of the spring tide. We quantified variations in oxidized nitrogen (NO x ) and phosphate contributed by biological processes based on mixing lines of these nutrients. During both the spring and neap tide biologically contributed NO x and phosphate were significantly correlated with regression slopes of 4.60 20 in the spring tide and 13.37 in the neap tide, similar to the composition of these nutrients in the water column, 5.43 and 14.18, respectively. This similarity indicates that the composition of nutrients in the water column of the reef system was closely related with biological processes during both tidal periods, but the biological influence appeared to be less as inferred from the less significant correlations during the spring tide when groundwater discharge was more prominent.

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“…SGD‐derived nutrients have been shown to be a major component and indisputable source in some estuarine systems (Liu et al, ; Rengarajan & Sarma, ; Su et al, ). The estimation of net export SGD nutrient fluxes could be derived from the difference between total SGD‐associated nutrient fluxes and the return fluxes from the KRE surface layer to the groundwater (G. Z. Wang, Wang, et al, ). In this study, the total SGD‐associated nutrient fluxes were calculated by multiplying the total SGD flux by its nutrient concentrations (126, 0.57, and 120 μmol/L for DIN, DIP, and DSi, respectively).…”

Section: Discussionmentioning

confidence: 99%

Net Submarine Groundwater‐Derived Dissolved Inorganic Nutrients and Carbon Input to the Oligotrophic Stratified Karstic Estuary of the Krka River (Adriatic Sea, Croatia)

Liu

Hrustić

et al. 2019

JGR Oceans

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Submarine groundwater discharge (SGD) is a significant source of biogenic elements in estuaries, and relevant studies in karstic estuaries are scarce. Krka River Estuary (KRE), located on the eastern Adriatic Sea (Croatia), is a typical oligotrophic stratified karstic estuary. In this study, based on 226Ra and 228Ra, the total SGD flux into the KRE surface layer was estimated to be (12.8–16.2) × 105 m3/day. A conservative estimation of the fresh groundwater flux was (5.0–8.3) × 105 m3/day, which accounts for 10–17% of the Krka River discharge into the estuary. By establishing water and nutrient budgets in the KRE surface layer, we found that SGD dominated the nutrient sources, although it accounted for a small portion of the total inflow water. Specifically, net SGD‐derived dissolved inorganic nitrogen (DIN) and silicates contributed 58–90% and 24–64%, respectively, to the total input fluxes. These results indicate that SGD was a major external nutrient source, in which net SGD‐derived high DIN flux and high DIN to dissolved inorganic phosphorus ratio may affect productivity in the KRE ecosystem and nearby Adriatic Sea. Additionally, net SGD‐derived dissolved inorganic carbon (DIC) flux in the KRE (1.53 mol · m2 · day) was much higher than those in most estuaries worldwide, suggesting that the DIC‐enriched karst aquifers are important sources for global carbon cycle. Therefore, the impact of net SGD‐derived DIC from karst aquifers on coastal seas will likely become more evident and substantial with further development of global climate change, such as sea level rise.

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Net subterranean estuarine export fluxes of dissolved inorganic C, N, P, Si, and total alkalinity into the Jiulong River estuary, China

Cited by 86 publications

References 20 publications

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

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

Tidal variability of nutrients in a coastal coral reef system influenced by groundwater

Net Submarine Groundwater‐Derived Dissolved Inorganic Nutrients and Carbon Input to the Oligotrophic Stratified Karstic Estuary of the Krka River (Adriatic Sea, Croatia)

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