scholarly journals Modeling hypolimnetic dissolved oxygen depletion using monitoring data

2020 ◽  
Vol 77 (5) ◽  
pp. 814-823 ◽  
Author(s):  
Lester L. Yuan ◽  
John R. Jones
Keyword(s):  
Dissolved Oxygen ◽  
Chlorophyll Concentration ◽  
Oxygen Demand ◽  
Oxygen Depletion ◽  
The United States ◽  
Biological Communities ◽  
Effective Strategies ◽  
Organic Carbon Concentration ◽  
Lakes And Reservoirs ◽  
Oxygen Profiles

Eutrophication increases hypoxia in lakes and reservoirs, causing deleterious effects on biological communities. Quantitative models would help managers develop effective strategies to address hypoxia issues, but most existing models are limited in their applicability to lakes with temporally resolved dissolved oxygen data. We describe a hierarchical Bayesian model that predicts dissolved oxygen in lakes based on a mechanistic understanding of the factors that influence the development of hypoxia during summer stratification. These factors include the days elapsed since stratification, dissolved organic carbon concentration, lake depth, and chlorophyll concentration. We demonstrate that the model can be fit to two datasets: one in which temporally resolved dissolved oxygen profiles were collected from 20 lakes in a single state and one in which single profiles were collected from 381 lakes across the United States. Analyses of these two datasets yielded similar relationships between volumetric oxygen demand and chlorophyll concentration, suggesting that the model structure appropriately represented the effects of eutrophication on oxygen depletion. Combining both datasets in a single model further improved the precision of predictions.

Investigation of the Contribution of Natural Organic Runoff to Dissolved Oxygen Depletion in the Red Deer River

1979 ◽  
Vol 14 (1) ◽  
pp. 71-88
Author(s):  
S.E. Penttinen ◽  
P.H. Bouthillier ◽  
S.E. Hrudey
Keyword(s):  
Dissolved Oxygen ◽  
Red Deer ◽  
Stream Water ◽  
Oxygen Demand ◽  
Oxygen Depletion ◽  
Experimental Program ◽  
Nitrogen Budgets ◽  
Carbon And Nitrogen ◽  
Tributary Stream ◽  
Small Tributary

Abstract Studies on the chronic low dissolved oxygen problems encountered under winter ice in the Red Deer River have generally been unable to account for dissolved oxygen depletion in terms of known manmade inputs. An experimental program was developed to assess the possible nature and approximate bounds of oxygen demand due to natural organic runoff carried to the Red Deer River by a small tributary stream, the Blindman River. The study employed an electrolytic respirometer on stream water samples subjected to prior concentration by vacuum evaporation. Evaluation of carbon and nitrogen budgets in conjunction with the measured oxygen demand indicate that biochemical oxygen demand is originating with natural organic runoff in tributaries of the Red Deer River. The results provide a basis for estimation of the possible contribution to the observed oxygen demand in the Red Deer River originating from natural organic runoff.

scholarly journals Impact of Global Warming on Dissolved Oxygen and BOD Assimilative Capacity of the World’s Rivers: Modeling Analysis

Water ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2408
Author(s):  
Steven C. Chapra ◽  
Luis A. Camacho ◽  
Graham B. McBride
Keyword(s):  
Dissolved Oxygen ◽  
Natural Waters ◽  
Cold Water ◽  
Oxygen Demand ◽  
Oxygen Depletion ◽  
Assimilative Capacity ◽  
Mountainous Regions ◽  
Modeling Analysis ◽  
Lower Oxygen ◽  
The Impact

For rivers and streams, the impact of rising water temperature on biochemical oxygen demand (BOD) assimilative capacity depends on the interplay of two independent factors: the waterbody’s dissolved oxygen (DO) saturation and its self-purification rate (i.e., the balance between BOD oxidation and reaeration). Although both processes increase with rising water temperatures, oxygen depletion due to BOD oxidation increases faster than reaeration. The net result is that rising temperatures will decrease the ability of the world’s natural waters to assimilate oxygen-demanding wastes beyond the damage due to reduced saturation alone. This effect should be worse for nitrogenous BOD than for carbonaceous BOD because of the former’s higher sensitivity to rising water temperatures. Focusing on streams and rivers, the classic Streeter–Phelps model was used to determine the magnitude of the maximum or “critical” DO deficit that can be calculated analytically as a function of the mixing-point BOD concentration, DO saturation, and the self-purification rate. The results indicate that high-velocity streams will be the most sensitive to rising temperatures. This is significant because such systems typically occur in mountainous regions where they are also subject to lower oxygen saturation due to decreased oxygen partial pressure. Further, they are dominated by salmonids and other cold-water fish that require higher oxygen levels than warm-water species. Due to their high reaeration rates, such systems typically exhibit high self-purification constants and consequently have higher assimilation capacities than slower moving lowland rivers. For slow-moving rivers, the total sustainable mixing-point concentration for CBOD is primarily dictated by saturation reductions. For faster flowing streams, the sensitivity of the total sustainable load is more equally dependent on temperature-induced reductions in both saturation and self-purification.

scholarly journals Quantified Hypoxia and Anoxia in Lakes and Reservoirs

2004 ◽  
Vol 4 ◽  
pp. 42-54 ◽  
Author(s):  
Gertrud K. Nürnberg
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Depletion ◽  
Phosphorus Loading ◽  
Lake Water Quality ◽  
Specific Level ◽  
Custom Made ◽  
Potential Applicability ◽  
Lakes And Reservoirs ◽  
Internal Phosphorus Loading ◽  
Polymictic Lakes

Hypoxia and anoxia occur frequently in freshwater systems and have biological and chemical implications.Anoxiacan be expressed and quantified as the anoxic factor;hypoxia, for a specific level of oxygen depletion, can be expressed as the hypoxic factor in lakes, reservoirs, and river sections. These methods summarize information of individual dissolved oxygen profiles as annual values or factors that facilitate comparison between and within lakes. Therefore, these factors are useful in the formulation and testing of hypotheses related to the dissolved oxygen status in water bodies. Methods of calculating different factors for different oxygen levels and water layers, including those applying separately to the epilimnion and hypolimnion, are presented in detail. Proven and potential applicability include: (1) the quantification of relationships with lake water quality variables and lake classification (trophic state), (2) the evaluation of restoration techniques with respect to their effects on hypolimnetic oxygen depletion, (3) the determination of internal phosphorus loading in stratified and polymictic lakes, (4) the exploration of habitat constraints due to hypoxia (e.g., fish species richness and winterkill), (5) forecasting potential effects of climatic change on oxygen content and internal phosphorus loading, and (6) the establishment and examination of criteria and guidelines with respect to hypoxia by custom-made definitions.

The Unquiet Frontier

2017 ◽  
Author(s):  
Jakub J. Grygiel ◽  
A. Wess Mitchell ◽  
Jakub J. Grygiel ◽  
A. Wess Mitchell
Keyword(s):  
United States ◽  
The United States ◽  
Great Powers ◽  
Global Order ◽  
American Power ◽  
Alliance Networks ◽  
Effective Strategies ◽  
The World ◽  
The Baltic ◽  
Critical Regions

From the Baltic to the South China Sea, newly assertive authoritarian states sense an opportunity to resurrect old empires or build new ones at America's expense. Hoping that U.S. decline is real, nations such as Russia, Iran, and China are testing Washington's resolve by targeting vulnerable allies at the frontiers of American power. This book explains why the United States needs a new grand strategy that uses strong frontier alliance networks to raise the costs of military aggression in the new century. The book describes the aggressive methods which rival nations are using to test American power in strategically critical regions throughout the world. It shows how rising and revisionist powers are putting pressure on our frontier allies—countries like Poland, Israel, and Taiwan—to gauge our leaders' commitment to upholding the American-led global order. To cope with these dangerous dynamics, nervous U.S. allies are diversifying their national-security “menu cards” by beefing up their militaries or even aligning with their aggressors. The book reveals how numerous would-be great powers use an arsenal of asymmetric techniques to probe and sift American strength across several regions simultaneously, and how rivals and allies alike are learning from America's management of increasingly interlinked global crises to hone effective strategies of their own. The book demonstrates why the United States must strengthen the international order that has provided greater benefits to the world than any in history.

Survey of the Ecological State of Eight Man-Made Lakes Within the City Limits of Freiburg, Germany

1992 ◽  
Vol 27 (2) ◽  
pp. 301-310
Author(s):  
Agnes G. Pulvermüller ◽  
Heidulf E. Müller
Keyword(s):  
Escherichia Coli ◽  
Water Quality ◽  
Biochemical Oxygen Demand ◽  
Secchi Depth ◽  
Oxygen Demand ◽  
Ecological Condition ◽  
Ecological State ◽  
Biological Parameters ◽  
The City ◽  
Oxygen Profiles

Abstract The survey of the ecological condition of eight lakes within the city limits of Freiburg included hydrochemical measurements and analyses (oxygen profiles, Secchi depth, pH, biochemical oxygen demand) together with biological parameters (chlorophyll a, phytoplanktonbiomass, Escherichia coli counts), as well as parasitic examinations. Only some of the investigated parameters are presented here. Seven of the eight lakes were found to be eutrophic. The process of eutrophication appears to be still in progress. One lake can be considered to be hypertrophic. Schistosome dermatitis was observed. The water quality in general was considered to be acceptable; suggestions to maintain or improve the water quality are made.

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.

Revealing Safety Risks of Unmanned Aerial Vehicles in Construction

2021 ◽  
pp. 036119812110171
Author(s):  
Mostafa Namian ◽  
Mohammad Khalid ◽  
George Wang ◽  
Yelda Turkan
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Construction Projects ◽  
The United States ◽  
Extensive Literature ◽  
Effective Strategies ◽  
Aerial Vehicles ◽  
Safety Risks ◽  
Potential Safety ◽  
Post Hoc

Unmanned aerial vehicles (UAVs) have gained their prevalent recognition in construction because of their exceptional advantages. Despite the increasing use of UAVs in the industry and their remarkable benefits, there are serious potential safety risks associated that have been overlooked. Construction is one of the most hazardous industries in the United States. In addition to the ordinary hazards normally present in dynamic construction workplaces, UAVs can expose workers to a wider range of never-before-seen safety risks that must be recognized and controlled. The industry is not equipped with safety measures to prevent potential accidents, because of scarce research on drone-associated hazards and risks. The aim of this research was to (1) identify the UAV-associated hazards in construction that may expose personnel and property to potential harms, and (2) study the relative impact of each hazard and the associated safety risks. In Phase I, the researchers conducted an extensive literature review and consulted with a construction UAV expert. In Phase II, the researchers obtained data from 54 construction experts validating and evaluating the identified hazards and risks. The results revealed that adopting UAVs can expose construction projects to a variety of hazards that the industry is not familiar with. “Collision with properties,”“collision with humans,” and “distraction” were identified as the top three safety risks. Moreover, the study introduces effective strategies, such as having qualified crew members, proper drone model selection, and drone maintenance, to mitigate the safety risks. Finally, a post-hoc case study was investigated and presented in this article.

Study of the Oxygen Transfer Efficiencies in the Different Methods Used in the Technique of Hypolimnetic Aeration

2012 ◽  
Vol 452-453 ◽  
pp. 1014-1019 ◽  
Author(s):  
Gafsi Mostefa ◽  
Kettab Ahmed ◽  
Abdelkader Djehiche
Keyword(s):  
Oxygen Transfer ◽  
Thermal Stratification ◽  
Cold Water ◽  
Negative Impact ◽  
Drinking Water Treatment ◽  
Oxygen Depletion ◽  
Bubble Plume ◽  
Water Treatment Process ◽  
Aeration System ◽  
Lakes And Reservoirs

Thermal stratification of lakes and reservoirs can result in substantial hypolimnetic oxygen depletion, which may have a negative impact on the cold-water fisheries, the drinking water treatment process, and water quality downstream of hydropower reservoirs. Several techniques of aeration are presented in this study, to describe their effectiveness in control of physical and chemical parameters, that compromising the balance ecological and the thermal stratification in water supplies. As a result, we demonstrate that the most efficient hypolimnetic aeration system is the bubble plume diffuser; although an accidental destratification may occur. In hypolimnetic aeration systems, the aeration system by bubble plume appears to be the most economic and perhaps the simplest among the systems used in Stanley lake (Colorado, U.S.A), even as other researches select Speece Cone aeration system, or the full airlift systems, or the TVA line diffuser. The purpose of this study is to show the oxygen transfer efficiencies in the different methods used in the technique of hypolimnetic aeration, and their effect on the preservation of the thermal stratification. As well, this study concentrate on the economic and technical sides associated to these aeration systems.

Sign in / Sign up

Export Citation Format

Share Document