Nitrate sources and dynamics in the salinized rivers and estuaries – a &lt;i&gt;δ&lt;/i&gt;&lt;sup&gt;15&lt;/sup&gt;N- and &lt;i&gt;δ&lt;/i&gt;&lt;sup&gt;18&lt;/sup&gt;O-NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;–&lt;/sup&gt; isotope approach

Abstract. To trace NO3– sources and assess NO3– dynamics in the salinized rivers and estuaries, three rivers (HH River, CB River and JY River) and two estuaries (HH Estuary and CJ Estuary) along the Bohai Bay (China) have been selected to determine DIN and δ15N and δ18O-NO3–. Upstream of the HH River NO3– was removed 30.9 ± 22.1% by aerobic 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, respectively. The HH and CY Estuaries behaved mostly conservative excluding the sewage input in the CJ Estuary. Hydrodynamics in estuaries have been changed by the ongoing reclamation projects, aggravating the estuaries losing the attenuation function of NO3–.

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Nitrate sources and dynamics in a salinized river and estuary – a δ15N–NO3− and δ18O–NO3− isotope approach

Biogeosciences ◽

10.5194/bg-11-5957-2014 ◽

2014 ◽

Vol 11 (20) ◽

pp. 5957-5967 ◽

Cited By ~ 7

Author(s):

D. Xue ◽

P. Boeckx ◽

Z. Wang

Keyword(s):

Residence Time ◽

Water Exchange ◽

Inorganic Nitrogen ◽

Bohai Bay ◽

Water Residence Time ◽

Dissolved Inorganic Nitrogen ◽

Haihe River ◽

Nitrate Sources ◽

N Source ◽

Three Rivers

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.

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Water Residence Time in a Typical Tributary Bay of the Three Gorges Reservoir

Water ◽

10.3390/w11081585 ◽

2019 ◽

Vol 11 (8) ◽

pp. 1585 ◽

Cited By ~ 3

Author(s):

Yao Cheng ◽

Zheng Mu ◽

Haiyan Wang ◽

Fengxia Zhao ◽

Yu Li ◽

...

Keyword(s):

Water Level ◽

Residence Time ◽

Three Gorges Reservoir ◽

Water Exchange ◽

Exchange Capacity ◽

Water Residence Time ◽

Three Gorges ◽

Density Currents ◽

The Three Gorges Reservoir ◽

The Three Gorges

Tributary bays of the Three Gorges Reservoir (TGR) are suffering from environmental problems, e.g., eutrophication and algae bloom, which could be related to the limited water exchange capacity of the tributary bays. To understand and quantify the water exchange capacity of a tributary bay, this study investigated the water residence time (RT) in a typical tributary bay of TGR, i.e., the Zhuyi Bay (ZB), using numerical simulation and the adjoint method to obtain the RT. The results show that RT of ZB with an annual mean of 16.7 days increases from the bay mouth to the bay top where the maximum can reach 50 days. There is a significant seasonal variation in RT, with higher RT (average 20 days) in spring and autumn and lower RT (average < 5 days) in the summer. The sensitivity experiments show that the TGR water level regulation has a strong influence on RT. The increase in the water level could increase RT of ZB to some extent. Density currents induced by the temperature difference between the mainstream and tributaries play an important role in the water exchange of ZB, while the impacts of the river discharges and winds on RT are insignificant.

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Simulation of water exchange in Jiaozhou Bay by average residence time approach

Estuarine Coastal and Shelf Science ◽

10.1016/j.ecss.2004.04.009 ◽

2004 ◽

Vol 61 (1) ◽

pp. 25-35 ◽

Cited By ~ 99

Author(s):

Zhe Liu ◽

Hao Wei ◽

Guangshan Liu ◽

Jing Zhang

Keyword(s):

Residence Time ◽

Water Exchange ◽

Jiaozhou Bay ◽

Average Residence Time

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Mapping and Assessing Commercial Fisheries Services in the Lithuanian Part of the Curonian Lagoon

Fishes ◽

10.3390/fishes7010019 ◽

2022 ◽

Vol 7 (1) ◽

pp. 19

Author(s):

Edgaras Ivanauskas ◽

Andrius Skersonas ◽

Vaidotas Andrašūnas ◽

Soukaina Elyaagoubi ◽

Artūras Razinkovas-Baziukas

Keyword(s):

Spatial Distribution ◽

Residence Time ◽

Fish Species ◽

Circulation Model ◽

Curonian Lagoon ◽

Water Residence Time ◽

Total Catch ◽

Catch Per Unit Effort ◽

Commercial Fish ◽

The Impact

The spatial distribution of biomass of main commercial fish species was mapped to estimate the supply of a provisioning fishery service in the Curonian lagoon. Catch per unit effort (CPUE) was used as a proxy to estimate the efficiency of commercial fishing and, subsequently, the potential biomass of fishes. The relationship between distinctive characteristics of the fishing areas and corresponding commercial catches and CPUE was analyzed using multivariate analysis. The total catch values and CPUE used in the analyses were derived from the official commercial fishery records. RDE analysis was used to assess the variation of both catch and CPUE of commercial fish species, while the percentages of bottom sediment type coverage, average depth, annual salinity, and water residence time in each of the fishing squares were used as explanatory variables. This distance e-based redundancy analysis allowed for the use of non-Euclidean dissimilarity indices. Fisheries data spatial distribution map indicated the lack of coherence between the spatial patterns of commercial catches and CPUE distribution in the northern part of the lagoon. Highest CPUE values were estimated in the central-eastern part of the lagoon as compared to the western part of the lagoon where CPUE values were substantially lower. Both total catch and CPUE appeared not to be related to the type of bottom habitats statistically while being spatially correlated in-between. However, the impact of salinity and water residence time calculated using the 3D hydraulic circulation model on the distribution of both CPUE and commercial catches was statistically significant.

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Can reductions in water residence time be used to disrupt seasonal stratification and control internal loading in a eutrophic monomictic lake?

Journal of Environmental Management ◽

10.1016/j.jenvman.2021.114169 ◽

2022 ◽

Vol 304 ◽

pp. 114169

Author(s):

Freya Olsson ◽

Eleanor B. Mackay ◽

Phil Barker ◽

Sian Davies ◽

Ruth Hall ◽

...

Keyword(s):

Residence Time ◽

Internal Loading ◽

Water Residence Time ◽

Seasonal Stratification ◽

And Control

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Coexisting ecosystem states in a tropical coastal lagoon under progressive eutrophication in the northern Cuban keys

Scientia Marina ◽

10.3989/scimar.04682.22a ◽

2018 ◽

Vol 82 (3) ◽

pp. 139 ◽

Cited By ~ 1

Author(s):

Roberto González-De Zayas ◽

Martin Merino-Ibarra ◽

Patricia M. Valdespino-Castillo ◽

Yunier Olivera ◽

Sergio F. Castillo-Sandoval

Keyword(s):

Residence Time ◽

Coastal Lagoon ◽

Spatial And Temporal Variability ◽

Positive Trend ◽

Water Residence Time ◽

Effective Management ◽

Management Options ◽

Trophic Index ◽

Tropical Coastal Lagoon ◽

Mollusc Assemblages

Through a nested suite of methods here we contrast the coexistence of different ecosystem states in a tropical coastal lagoon, the Laguna Larga, with increasing eutrophication stress between 2007 and 2009. Water temperature averaged 27.4°C in the lagoon and showed a slight positive trend during the study period. Salinity averaged 35.0±6.2, exhibiting high spatial and temporal variability, and also a slight positive trend in time. In contrast, dissolved oxygen showed a substantial decreasing trend (–0.83 ml L–1 y–1; –13.3% y–1) over the period, while nutrients increased dramatically, particularly total phosphorus (2.6 µM y–1), in both cases sustaining the progression of eutrophication in the lagoon during the three years we sampled. The Karydis nutrient load-based trophic index showed that the lagoon has a spatial pattern of increasing eutrophication from the sea and the outer sector (oligotrophic-mesotrophic) to the central (mesotrophic) and the inner sector (mesotrophic-eutrophic). Two ecosystem states were found within the lagoon. In the outer oligotrophic sector, the dominant primary producers were macroalgae, seagrasses and benthic diatoms, while mollusc assemblages were highly diverse. In the inner and central sectors (where trophic status increased toward the inner lagoon) a phytoplankton-dominated ecosystem was found where mollusc assemblages are less diverse. In spite of the progression of eutrophication in the lagoon, these two different ecosystems coexisted and remained unchanged during the study period. Apparently, the effect of water residence time, which increases dramatically toward the inner lagoon, dominated over that of nutrient loadings, which is relatively more homogeneously distributed along the lagoon. Therefore, we consider that actions that reduce the water residence time are likely the most effective management options for this and other similarly choked lagoons.

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