Measurement of Sediment Oxygen Demand to Simulate Dissolved Oxygen Distribution: Case Study in the Main Danshuei River Estuary

2009 ◽  
Vol 26 (12) ◽  
pp. 1701-1711 ◽  
Author(s):  
Wen-Cheng Liu ◽  
Wei-Bo Chen ◽  
Nobuaki Kimura
Keyword(s):  
Dissolved Oxygen ◽  
River Estuary ◽  
Oxygen Demand ◽  
Sediment Oxygen Demand ◽  
Oxygen Distribution

Considering the impact of intermittent discharges when modelling overflows

1998 ◽  
Vol 38 (10) ◽  
pp. 23-30
Author(s):  
Sarah Jubb ◽  
Philip Hulme ◽  
Ian Guymer ◽  
John Martin
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Preliminary Investigation ◽  
Oxygen Demand ◽  
Sediment Oxygen Demand ◽  
Combined Sewer Overflows ◽  
River Hydraulics ◽  
Combined Sewer ◽  
The Impact ◽  
Curve Equation

This paper describes a preliminary investigation that identified factors important in the prediction of river water quality, especially regarding dissolved oxygen (DO) concentration. Intermittent discharges from combined sewer overflows (CSOs) within the sewerage, and overflows at water reclamation works (WRW) cause dynamic conditions with respect to both river hydraulics and water quality. The impact of such discharges has been investigated under both wet and dry weather flow conditions. Data collected from the River Maun, UK, has shown that an immediate, transient oxygen demand exists downstream of an outfall during storm conditions. The presence of a delayed oxygen demand has also been identified. With regard to modelling, initial investigations used a simplified channel and the Streeter-Phelps (1925) dissolved oxygen sag curve equation. Later, a model taking into account hydrodynamic, transport and dispersion processes was used. This suggested that processes other than water phase degradation of organic matter significantly affect the dissolved oxygen concentration downstream of the location of an intermittent discharge. It is proposed that the dynamic rate of reaeration and the sediment oxygen demand should be the focus of further investigation.

scholarly journals Biotope Determinants of EPT Assamblages Structure – Târnava Watershed (Transylvania, Romania) Case Study

2015 ◽  
Vol 17 (2) ◽  
pp. 95-104
Author(s):  
Angela Curtean-Bănăduc
Keyword(s):  
Dissolved Oxygen ◽  
Total Nitrogen ◽  
Biochemical Oxygen Demand ◽  
Oxygen Demand ◽  
Total Hardness ◽  
Factors Affecting ◽  
Average Flow ◽  
Heterogeneous Structures ◽  
High Diversity

Abstract This study aims to analyze the biotopic factors affecting the EPT assemblage diversity in the rivers of the Târnava Watershed. Our research revealed that the high diversity of the Plecoptera communities is associated with river reaches with boulder and cobble lithological substrate, accentuated slope and natural bank dynamics, and also it is directly correlated with dissolved oxygen and inversely correlated with chemical and biochemical oxygen demand, total hardness, nitrates and total nitrogen in the water. The high diversity of the Trichoptera communities is associated with water which presents moderate quantities of nutrients (total phosphorus, phosphates) and with river reaches with heterogeneous structures (where runs and bends were present). The diversity of the Ephemeroptera communities is positively correlated with the multiannual average flow and riverbed width.

scholarly journals Sediment-associated organic matter sources and sediment oxygen demand in a Special Area of Conservation (SAC): A case study of the River Axe, UK

2017 ◽  
Vol 33 (10) ◽  
pp. 1539-1552 ◽  
Author(s):  
A. L. Collins ◽  
Y. Zhang ◽  
S. McMillan ◽  
E. R. Dixon ◽  
A. Stringfellow ◽  
...  
Keyword(s):  
Organic Matter ◽  
Oxygen Demand ◽  
Sediment Oxygen Demand ◽  
Organic Matter Sources ◽  
Special Area

scholarly journals A numerical analysis of biogeochemical controls with physical modulation on hypoxia during summer in the Pearl River Estuary

2016 ◽  
Author(s):  
Bin Wang ◽  
Jiatang Hu ◽  
Shiyu Li ◽  
Dehong Liu
Keyword(s):  
River Estuary ◽  
Oxygen Demand ◽  
Pearl River Estuary ◽  
Sediment Oxygen Demand ◽  
Biogeochemical Processes ◽  
Lower Estuary ◽  
Vertical Diffusion ◽  
The West ◽  
Hypoxic Area ◽  
The Pearl River

Abstract. As an important biogeochemical indicator of aquatic ecosystem, dissolved oxygen (DO) is affected by the boundary conditions and biogeochemical processes. Biogeochemical processes can affect DO concentrations by directly consuming or generating oxygen locally, or through changing the DO fluxes from the ambient water bodies. However, the latter mechanism is still unclear. In this study, a novel method named physical modulation of biogeochemical terms is therefore proposed and coupled to a physical-biogeochemical model to investigate their contributions to the hypoxia during the summer of the Pearl River Estuary (PRE). According to the result of modulation method, re-aeration and sediment oxygen demand are the most important biogeochemical processes, and determine the distribution, the spatial extent, and the duration of hypoxia in the PRE. A DO balance analysis is conducted and reveals that although the re-aeration occurs on the air-sea interface, the reoxygenation leads to a strong DO gradient form between the surface and lower layers. As a result, the majority (89 %) of oxygen entering the surface layer from the atmosphere will be transported to the lower layer through the vertical diffusion, and 28 % eventually reach the bottom layer. Similarly, after consuming the bottom DO, sediment oxygen demand facilitates the downward DO flux of vertical diffusion and decreases the upward DO flux of vertical advection. Under the modulation of physical processes, sediment oxygen demand causes a most significant decrease in DO concentration by 4.31 mg L−1 in the bottom of the HFZ (a high frequency zone of hypoxia located off the Modaomen sub-estuary) and the west of lower estuary. However, the re-aeration supplements an average of 4.84 mg L−1 DO on the west of lower estuary, which leads to hypoxia only occur in HFZ. Numerical experiments show that turning off the re-aeration leads to an expansion of hypoxic area from 237 km2 to 2203 km2 and results in a shift of hypoxic center to the west of lower estuary. Moreover, a persistent hypoxia (hypoxic frequency > 80 %) is observed in the west of lower estuary. When compared with re-aeration and sediment oxygen demand, photosynthesis and water column respiration have fewer effects on DO conditions. In the bottom of the HFZ, photosynthesis exceeds the water column respiration and eventually supplements DO concentration by 0.98 mg L−1, causing an increase of hypoxic area to 591 km2.

scholarly journals Impacts of anthropogenic inputs on the hypoxia and oxygen dynamics in the Pearl River Estuary

2018 ◽  
Author(s):  
Bin Wang ◽  
Jiatang Hu ◽  
Shiyu Li ◽  
Liuqian Yu ◽  
Jia Huang
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
River Estuary ◽  
Oxygen Demand ◽  
Pearl River Estuary ◽  
Sediment Oxygen Demand ◽  
Pearl River ◽  
The Pearl River Estuary ◽  
Anthropogenic Inputs ◽  
The Pearl River

Abstract. In summer, the Pearl River Estuary experiences hypoxia, largely driven by the high input of freshwater with low dissolved oxygen (DO) and abundant nutrients and particulate organic carbon from the Pearl River network. In this study, we used a well-validated coupled physical-biogeochemical model to study the response of hypoxia and oxygen dynamics to variations of anthropogenic inputs (i.e. DO, nutrients, and particulate organic carbon). Model results showed that hypoxia in the Pearl River Estuary was confined to the shelf off the Modaomen sub-estuary with a hypoxic area of ~ 200 km2 mainly due to the combined effect of re-aeration and sediment oxygen demand. Numerical experiments suggested that hypoxia in the Pearl River Estuary was most sensitive to riverine inputs of particulate organic carbon , followed by DO concentrations and nutrients. Specifically, a 50 % decrease (increase) in riverine input of particulate organic carbon led to a 47 % decrease (64 % increase) in hypoxic area, with the sediment oxygen demand and water column production being the two most important processes contributing to the changes in DO concentration and hypoxic extent. Changes in the riverine inputs of DO and nutrients had little impact on the simulated hypoxia because of the buffering effects of re-aeration, i.e. the re-aeration compensated the changes in surface apparent oxygen utilization (AOU) associated with river-induced variations of oxygen source and sink processes. The Pearl River Estuary features shallow waters (with averaged depth of 10 m) where oxygen provided by the re-aeration could penetrate to bottom waters via vertical diffusion that largely offset the changes in DO contributed by other oxygen source and sink processes. This study highlights the importance of re-aeration in determining the hypoxic extent and the buffering effects of re-aeration in reducing hypoxia variability in shallow estuary.

scholarly journals How Physicochemical Parameters of Water Change with Distance in a Lake: Case Study Lake Bunyonyiinkigezi

2021 ◽  
Vol 7 (4) ◽  
pp. 1-22
Author(s):  
Mukasa Tebandeke I.Z ◽  
Karume I ◽  
Ssebuwufu J ◽  
Wasajja H.Z ◽  
Nankinga R ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Dissolved Oxygen ◽  
Oxygen Demand ◽  
Agricultural Practices ◽  
Aquatic Organisms ◽  
Total Hardness ◽  
Ambient Temperatures ◽  
High Chemical Oxygen Demand ◽  
Whatman Paper

Pollution resulting from unsustainable agricultural and urbanization activities in the Ruhezamyenda and Bunyonyi catchments are threatening lake Bunyonyi. These have led to high chemical oxygen demand (COD), electrical conductivity, turbidity, pH, iron (II) concentration and low dissolved oxygen (DO5). In this study we have investigated the how COD, turbidity, pH, concentration of iron, total suspended solids, total nutrients and DO5 of water changed with distance in lake. Water sampled from different distances in the lake filtered using Whatman paper at ambient temperatures was tested for COD, electrical conductivity, turbidity, total nutrients, iron, hardness and DO5. COD was 20.8±.0.03mg/L to 16 ± 0.03mg/L; total hardness was 16.5±0.2 mg/L to 18.6 ± 0.3 mg/L total nitrate was 103.5± 2 mg/L to 88 ± 3 mg/L; total phosphate was 100.8 ±.2.5 to 87± 3 mg/L; high TSS values from 3.4 ± 0.1 mg/L to 2.5 ± 0.1 mg/L showed contamination of water. As pH decreased from 8.3 ± 0.03 to 7.6 ± 0.04 revealed that bases were getting removed. The turbidity dropped from 25.7 ± 0.3 NTU to 20 ± 2 NTU due settling down of sediments. Iron (II) concentration ranging from 1.1± 0.1 to 0.8± 0.1 mgL-1 . Dissolved oxygen decreased from 7.9 ±0.3 mg/L to 4.8 ± 0.2 mg/L indicating surface water can uphold life of aquatic organisms. Total hardness ranged from 0.22± 0.05 to 0.19± 0.05 mg/L Electrical conductivity was high and ranged from 130± 5 to 150± 5 µS/cm indicating presence of electrolytes. Lake Bunyonyi water is not greatly polluted, but requires to be safe guarded against poor unsustainable agricultural practices, sewage draining from towns, schools and hotels in nearby settlements.

Sign in / Sign up

Export Citation Format

Share Document