scholarly journals Factors Controlling Hypoxia Occurrence in Estuaries, Chester River, Chesapeake Bay

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1961 ◽  
Author(s):  
Richard Tian
Keyword(s):  
Chesapeake Bay ◽  
Interannual Variability ◽  
Nutrient Loading ◽  
Nutrient Management ◽  
River Estuary ◽  
Ocean Model ◽  
Quality Model ◽  
Oyster Aquaculture ◽  
Living Species ◽  
Predominant Factor

The Chester River, a tributary of Chesapeake Bay, provides critical habitats for numerous living species and oyster aquaculture, but faces increasing anthropogenic stresses due to excessive nutrient loading and hypoxia occurrence. An application of the Integrated Compartment Water Quality Model (ICM), coupled with the Finite-Volume Community Ocean Model (FVCOM), was carried out to study the controlling mechanisms and interannual variability in hypoxia occurrence from 2002 to 2011. Our study shows that hypoxia occurs mostly in the main stem in July, followed by August and June. On an interannual scale, 2005 had the highest hypoxia occurrence with an accumulative hypoxia volume of about 10 km3-days, whereas 2008 had the lowest occurrence with an accumulative hypoxia volume of about 1 km3-days. Nutrient loading is the predominant factor in determining the intensity and interannual variability in hypoxia in the Chester River estuary, followed by stratification and saltwater intrusion. Phosphorus has been found to be more efficient in controlling hypoxia occurrence than nitrogen due to their different limiting extent. On a local scale, the Chester River estuary is characterized by several meanders, and at certain curvatures helical circulation is formed due to centrifugal forces, leading to better reaeration and dissolved oxygen (DO) supply to the deeper layers. Our study provides valuable information for nutrient management and restoration efforts in the Chester River.

scholarly journals What drives interannual variability of hypoxia in Chesapeake Bay: Climate forcing versus nutrient loading?

2016 ◽  
Vol 43 (5) ◽  
pp. 2127-2134 ◽  
Author(s):  
Ming Li ◽  
Younjoo J. Lee ◽  
Jeremy M. Testa ◽  
Yun Li ◽  
Wenfei Ni ◽  
...  
Keyword(s):  
Chesapeake Bay ◽  
Interannual Variability ◽  
Nutrient Loading ◽  
Climate Forcing

scholarly journals Numerical Study on the Expansion and Variation of Changjiang Diluted Water in Summer and Autumn

2021 ◽  
Vol 9 (3) ◽  
pp. 317
Author(s):  
Wanli Hou ◽  
Menglin Ba ◽  
Jie Bai ◽  
Jianghua Yu
Keyword(s):  
Yangtze River ◽  
Sea Water ◽  
Numerical Study ◽  
River Estuary ◽  
Ocean Model ◽  
Theoretical Research ◽  
Yangtze River Estuary ◽  
Hydrodynamic Characteristics ◽  
Changjiang Diluted Water ◽  
Transportation Route

In view of the expansion and directional change mechanisms of Yangtze River water diluted with sea water in the shelf region (also known as Changjiang diluted water [CDW]) during summer and autumn, a three-dimensional hydrodynamic model of the Yangtze River Estuary (YRE) and its adjacent waters was established based on the Finite Volume Community Ocean Model (FVCOM). Compared with the measured data, the model accurately simulates the hydrodynamic characteristics of the YRE. On that basis, the influence of the expansion patterns of the CDW in both summer and autumn was studied. It was found that, in 2019, the CDW expanded to the northeast in the summer and to the southeast in the autumn, and that the route of the CDW is mainly controlled by the wind, not the runoff. Current seasonal winds also change the transportation route of the CDW by affecting its hydrodynamic field. Typhoons are frequent in both summer and autumn, causing abnormalities in both the transportation route and expansion of the CDW. During a typhoon, a large amount of the CDW is transported in a continuous and abnormal manner, accelerating the path turning of the CDW. This paper enhances the existing theoretical research of the CDW and provides a reference with respect to the expansion of diluted water all over the world.

scholarly journals The Response of Turbidity Maximum to Peak River Discharge in a Macrotidal Estuary

Water ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 106
Author(s):  
Yuhan Yan ◽  
Dehai Song ◽  
Xianwen Bao ◽  
Nan Wang
Keyword(s):  
River Discharge ◽  
Recovery Time ◽  
Morphological Evolution ◽  
Spring Tide ◽  
River Estuary ◽  
Sediment Concentration ◽  
Ocean Model ◽  
Turbidity Maximum ◽  
Sediment Supply ◽  
Three Dimensional Model

The Ou River, a medium-sized river in the southeastern China, is examined to study the estuarine turbidity maximum (ETM) response to rapidly varied river discharge, i.e., peak river discharge (PRD). This study analyzes the difference in ETM and sediment transport mechanisms between low-discharge and PRD during neap and spring tides by using the Finite-Volume Community Ocean Model. The three-dimensional model is validated by in-situ measurements from 23 April to 22 May 2007. In the Ou River Estuary (ORE), ETM is generally induced by the convergence between river runoff and density-driven flow. The position of ETM for neap and spring tides is similar, but the suspended sediment concentration during spring tide is stronger than that during neap tide. The sediment source of ETM is mainly derived from the resuspension of the seabed. PRD, compared with low-discharge, can dilute the ETM, but cause more sediment to be resuspended from the seabed. The ETM is more seaward during PRD. After PRD, the larger the peak discharge, the longer the recovery time will be. Moreover, the river sediment supply helps shorten ETM recovery time. Mechanisms for this ETM during a PRD can contribute to studies of morphological evolution and pollutant flushing.

Contributions of external nutrient loading and internal cycling to cyanobacterial bloom dynamics in Lake Taihu, China: Implications for nutrient management

2021 ◽  
Vol 66 (4) ◽  
pp. 1492-1509
Author(s):  
Hai Xu ◽  
Mark J. McCarthy ◽  
Hans W. Paerl ◽  
Justin D. Brookes ◽  
Guangwei Zhu ◽  
...  
Keyword(s):  
Nutrient Loading ◽  
Nutrient Management ◽  
Lake Taihu ◽  
Cyanobacterial Bloom ◽  
External Nutrient ◽  
Internal Cycling

scholarly journals Climate-induced interannual variability and projected change of two harmful algal bloom taxa in Chesapeake Bay, USA

2020 ◽  
Vol 744 ◽  
pp. 140947
Author(s):  
Ming Li ◽  
Wenfei Ni ◽  
Fan Zhang ◽  
Patricia M. Glibert ◽  
Chih-Hsien (Michelle) Lin
Keyword(s):  
Chesapeake Bay ◽  
Interannual Variability ◽  
Algal Bloom ◽  
Harmful Algal Bloom ◽  
Projected Change

Nitrogen-Fixing Phylotypes of Chesapeake Bay and Neuse River Estuary Sediments

2002 ◽  
Vol 44 (4) ◽  
pp. 336-343 ◽  
Author(s):  
J.A. Burns ◽  
J.P. Zehr ◽  
D.G. Capone
Keyword(s):  
Chesapeake Bay ◽  
River Estuary ◽  
Neuse River Estuary ◽  
Nitrogen Fixing ◽  
Neuse River

Numerical Models as Enabling Tools for Tidal-Stream Energy Extraction and Environmental Impact Assessment

2016 ◽  
Author(s):  
Zhaoqing Yang ◽  
Taiping Wang
Keyword(s):  
Water Quality ◽  
Unstructured Grid ◽  
Puget Sound ◽  
Tidal Energy ◽  
Ocean Model ◽  
Energy Extraction ◽  
Volume Flux ◽  
Quality Model ◽  
Flushing Time ◽  
Tidal Turbine

This paper presents a modeling study conducted to evaluate tidal-stream energy extraction and its associated potential environmental impacts using a three-dimensional unstructured-grid coastal ocean model, which was coupled with a water-quality model and a tidal-turbine module. The unstructured-grid tidal-turbine model was first applied to investigate the effects of different tidal farm configurations on tidal energy extraction and the effects on the system flow field as well as biogeochemical transport processes in an idealized bay with a narrow channel connecting to the coastal ocean. Model results indicated that a large number of turbines are required to extract the maximum tidal energy and cause significant reduction in the volume flux. Model results also showed that tidal energy extraction has a greater effect on flushing time than on volume flux reduction. In the idealized tidal channel, a 10% reduction of volume flux caused by tidal energy extraction would result in an approximately 50% increase in flushing time in the bay. The flushing time increases exponentially as a function of flow reduction. A water-quality model simulation was conducted to investigate the dynamic effect of tidal energy extraction on water quality in a stratified tidal channel and estuary system. Model results showed that deployment of tidal turbines in the channel would increase vertical mixing in the bay. However, extraction of tidal energy also would result in a decrease in bottom dissolved oxygen in the bay during summer, which may cause hypoxia in fish. Finally, the tidal-turbine model was applied to a real-world site in Puget Sound — a highly energetic estuary on the US Pacific Northwest coast. The model application of tidal energy extraction in Puget Sound demonstrated the advantage of using an unstructured-grid modeling approach with high grid resolution near the tidal-turbine farm within a large model domain. This study showed that a numerical model can be a useful tool for assessing tidal energy extraction and its environmental impacts and for informing regulatory and policy processes for tidal energy development.

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