scholarly journals Study of the Relation between Sediment Characteristics and Multiphase Flow to the Presence of Sediment Oxygen Demand (SOD) in Open Channels

2018 ◽  
Vol 147 ◽  
pp. 03004
Author(s):  
Dhimas Dwinandha ◽  
Haryo Satriyo Tomo
Keyword(s):  
Multiphase Flow ◽  
Flow Analysis ◽  
Oxygen Demand ◽  
Sediment Oxygen Demand ◽  
Organic Carbon Content ◽  
Silty Clay ◽  
Sediment Characteristics ◽  
Carrier Fluid ◽  
Heterogeneous Flow ◽  
Particle Bed

A laboratory study was conducted with the aim to determine the correlation between sediment characteristics and multiphase flow analysis of carrier fluid to the presence of SOD. Six sediment samples were tested on their physical and chemical characteristics along with particle size distribution of sediments to find the indication of oxygen consumption and to classify the soil sediment class. For multiphase flow analysis, there were two transition velocities calculated: the transition between a pseudo-homogenous flow and a heterogeneous flow and the limit deposit velocities at the onset of solid particle bed. The SOD test was done in laboratory-scale by using a 600-mL reactor. According to tests, the amount of organic carbon content (TOC) in the samples were ranging from 34.58 to 81.27%, with the sediments’ textures categorised as silt loam, silty clay loam, and sand. In the channels, heterogeneous flow occurred in two channel segments, while the other segments’ regime was classified as homogeneous flow. The obtained SOD values were varied from 0.2427 to 0.8487 g/m2/day with K3 values obtained ranged from 8.6537 to 12.4028 m-1. Based on all analysis, the organic characteristic of sediment holds a key role in the presence of SOD value.

scholarly journals Early Diagenesis in Sediments of the Venice Lagoon (Italy) and Its Relationship to Hypoxia

2021 ◽  
Vol 7 ◽  
Author(s):  
Daniele Brigolin ◽  
Christophe Rabouille ◽  
Clément Demasy ◽  
Bruno Bombled ◽  
Gaël Monvoisin ◽  
...  
Keyword(s):  
Water Column ◽  
Heat Waves ◽  
Dissolved Inorganic Carbon ◽  
Multiple Stressors ◽  
Regional Climate ◽  
Oxygen Demand ◽  
Sediment Oxygen Demand ◽  
Total Alkalinity ◽  
Organic Carbon Content ◽  
Climate Conditions

This work focuses on sediments of a shallow water lagoon, located in a densely populated area undergoing multiple stressors, with the goal of increasing the understanding of the links between diagenetic processes occurring in sediments, the dynamics of dissolved oxygen (DO) in the water column, and potential consequences of hypoxia. Sediment data were collected over three consecutive years, from 2015 to 2017, during spring–summer, at five stations. Measured variables included: sediment porosity, grain size and organic carbon content, porewater microprofiles of O2, pH and H2S, porewater profiles of dissolved inorganic carbon (DIC), total alkalinity (TA), NH4+, NO3–, dissolved Fe, and SO42–. In addition, long-term time series of oxygen saturations in the water column (years 2005–2017) were utilized in order to identify the occurrence and duration of hypoxic periods. The results show that the median DO saturation value in summer months was below 50% (around 110 μmol L–1), and that saturation values below 25% (below the hypoxic threshold) can persist for more than 1 week. Sediment stations can be divided in two groups based on their diagenetic intensity: intense and moderate. At these two groups of stations, the average DIC net production rates, estimated trough a steady-state model (Profile) were, respectively, of 2.8 and 1.0 mmol m–2 d–1, SO42– consumption rates were respectively 1.6 and 0.4 mmol m–2 d–1, while diffusive oxygen uptake fluxes, calculated from the sediment microprofile data, were of 28.5 and 17.5 mmol m–2 d–1. At the stations characterized by intense diagenesis, total dissolved sulfide accumulated in porewaters close to the sediment-water interface, reaching values of 0.7 mM at 10 cm. Considering the typical physico-chemical summer conditions, the theoretical time required to consume oxygen down to the hypoxic level by sediment oxygen demand ranges between 5 and 18 days, in absence of mixing and re-oxygenation. This estimation highlights that sediment diagenesis may play a crucial role in triggering and maintaining hypoxia of lagoon waters during the summer season in specific high intensity diagenesis zones. This role of the sediment could be enhanced by changes in regional climate conditions, such as the increase in frequency of summer heat waves.

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.

Non-steady variations of SOD and phosphate release rate due to changes in the quality of the overlying water

2000 ◽  
Vol 42 (3-4) ◽  
pp. 265-272 ◽  
Author(s):  
T. Inoue ◽  
Y. Nakamura ◽  
Y. Adachi
Keyword(s):  
Release Rate ◽  
Oxygen Demand ◽  
Phosphate Concentration ◽  
Sediment Oxygen Demand ◽  
Biochemical Reactions ◽  
Overlying Water ◽  
Phosphate Release ◽  
Do Concentration ◽  
The Difference

A dynamic model, which predicts non-steady variations in the sediment oxygen demand (SOD) and phosphate release rate, has been designed. This theoretical model consists of three diffusion equations with biochemical reactions for dissolved oxygen (DO), phosphate and ferrous iron. According to this model, step changes in the DO concentration and flow velocity produce drastic changes in the SOD and phosphate release rate within 10 minutes. The vigorous response of the SOD and phosphate release rate is caused by the difference in the time scale of diffusion in the water boundary layer and that of the biochemical reactions in the sediment. Secondly, a negative phosphate transfer from water to sediment can even occur under aerobic conditions. This is caused by the decrease in phosphate concentration in the aerobic layer due to adsorption.

scholarly journals Geostatistical modeling of the spatial distribution of sediment oxygen demand within a Coastal Plain blackwater watershed

Geoderma ◽  
2010 ◽  
Vol 159 (1-2) ◽  
pp. 53-62 ◽  
Author(s):  
M. Jason Todd ◽  
R. Richard Lowrance ◽  
Pierre Goovaerts ◽  
George Vellidis ◽  
Catherine M. Pringle
Keyword(s):  
Spatial Distribution ◽  
Coastal Plain ◽  
Oxygen Demand ◽  
Sediment Oxygen Demand ◽  
Geostatistical Modeling

Experimental manipulations of the biomass of introduced carp (Cyprinus carpio) in billabongs. II. Impacts on benthic properties and processes1

1997 ◽  
Vol 48 (5) ◽  
pp. 445 ◽  
Author(s):  
A. I. Robertson ◽  
M. R. Healey ◽  
A. J. King
Keyword(s):  
Algal Biomass ◽  
Solid Phase ◽  
Negative Impact ◽  
Oxygen Demand ◽  
Sediment Oxygen Demand ◽  
Sediment Surface ◽  
Nutrient Concentrations ◽  
Nutrient Ratios ◽  
Biofilm Development ◽  
The Impact

Two billabongs on the floodplain of the Murrumbidgee River, Australia, were partitioned in half with impermeable plastic barriers and the biomass of carp was manipulated to establish high- and low-carp biomass treatments in each billabong. Measurements of benthic variables (rates of particle settlement, biofilm development, sediment respiration, macrophyte detritus decomposition, sediment solid-phase nutrient concentrations and benthic algal biomass) were performed over four months from summer to winter 1995. Rates of particle settlement were greater in the high-carp treatment of each billabong throughout the experiment. High carp biomass had a negative impact on the autotrophic component of the biofilm developing on wood blocks placed at different heights above the sediment surface but the mechanism responsible differed between billabongs. Sediment oxygen demand became greater in the presence of a higher biomass of carp during the experiment but time courses differed between billabongs. Manipulations of carp biomass did not influence algal biomass on the sediment surface, the rate of decomposition of macrophyte detritus or sediment solid-phase nutrients or nutrient ratios. The impact of carp on benthic and surficial processes was significant but the mechanisms of change differed between billabongs.

scholarly journals Baseline biogeochemical data from Australia's continental margin links seabed sediments to water column characteristics

2017 ◽  
Vol 68 (9) ◽  
pp. 1593 ◽  
Author(s):  
Lynda Radke ◽  
Tony Nicholas ◽  
Peter A. Thompson ◽  
Jin Li ◽  
Eric Raes ◽  
...  
Keyword(s):  
Water Column ◽  
Oxygen Demand ◽  
High Water ◽  
Sediment Oxygen Demand ◽  
Continental Margins ◽  
Global Standards ◽  
Moderate Resolution ◽  
Timor Sea ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer

Surficial marine sediments are an important source of nutrients for productivity and biodiversity, yet the biogeochemistry of these sediments is poorly known in Australia. Seabed samples were collected at >350 locations in Australia’s western, northern and eastern continental margins during Federal Government surveys (2007–14). Parameters analysed included measures of organic matter (OM) source (δ13C, δ15N and C:N ratios), concentration (percentage total organic carbon,%TOC, and surface area-normalised TOC, OC:SA) and bioavailability (chlorin indices, total reactive chlorins, total oxygen uptake, total sediment metabolism (TSM), sediment oxygen demand (SOD) and SOD and TSM normalised against TOC). The aim of the present study was to summarise these biogeochemical ‘baseline’ data and make contextualised inferences about processes that govern the observed concentrations. The OM was primarily from marine sources and the OC:SA broadly reflected water column productivity (based on Moderate Resolution Imaging Spectroradiometer, MODIS). Approximately 40% of sediments were organic poor by global standards, reflecting seawater oligotrophy; ~12% were organic rich due to benthic production, high water column productivity and pockmark formation. OM freshness varied due to pigment degradation in water columns and dilution with refractory OM in reworked sediments. δ15N values confirmed the importance of N2 fixation to Timor Sea productivity, and point to recycling of fixed nitrogen within food chains in Western Australia.

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