scholarly journals On the oxygenation of the Archaean and Proterozoic oceans

2020 ◽  
pp. 1-8
Author(s):  
Amlan Banerjee ◽  
Mirosław Słowakiewicz ◽  
Dilip Saha
Keyword(s):  
Dissolved Oxygen ◽  
Water Temperature ◽  
Ocean Circulation ◽  
Oxygen Demand ◽  
Global Scale ◽  
Convective System ◽  
Water Density ◽  
Ocean Water ◽  
Density Profiles ◽  
Secondary Instabilities

Abstract Modern-day ocean circulation behaves as a complex forced convective system that is characterized by the decrease in water temperature but increase in water density with depth. The dissolved oxygen content – which initially decreases due to biological oxygen demand – also increases with depth. In contrast to the present-day scenario, we propose that during the Archaean and Proterozoic eons inverted profiles could have developed such that, with depth, ocean water temperature increased and density and dissolved oxygen decreased. These inverted temperature and density profiles resulted in palaeo-ocean circulation behaving as a free convective system. It is proposed that this free convection, which may have been stable, or chaotic and subject to secondary instabilities, hindered the deep oxygenation of the palaeo-ocean. It may not be coincidental that the great oxygenation event (GOE) and Huronian glaciations are contemporaneous, in a similar way that the Neoproterozoic oxygenation event (NOE) is known to have been associated with glaciations. The global-scale external forcing required to switch the natural convective system to its present-day configuration is suggested to have been associated with Neoproterozoic glaciations and the subsequent lowering of ocean water salinity that accompanied them. We propose that this inverted the ocean water density gradient, allowing the oxygenation of the oceans for the first time. It is beyond the scope of this work to model the complex natural convection system, but we hope that geophysicists and numerical modellers will quantitatively evaluate the hypothesis proposed here to validate or refute our proposition.

Impact of net pen aquaculture on lake water quality

2003 ◽  
Vol 47 (12) ◽  
pp. 293-300 ◽  
Author(s):  
J. Veenstra ◽  
S. Nolen ◽  
J. Carroll ◽  
C. Ruiz
Keyword(s):  
Water Quality ◽  
Organic Carbon ◽  
Dissolved Oxygen ◽  
Water Temperature ◽  
Ictalurus Punctatus ◽  
Oxygen Demand ◽  
Total Alkalinity ◽  
Total Hardness ◽  
Army Corps ◽  
Lake Water Quality

A 3-year study was conducted by the U.S. Army Corps of Engineers assessing water quality related impacts of aquaculture of 250,000 channel catfish (Ictalurus punctatus) in floating net pens in the Rock Creek Arm of Lake Texoma, Oklahoma/Texas. Five large nylon nets suspended from a floating framework of galvanized metal anchored in open water 100 m offshore made up the net pens with fish stocking densities varying from 88 to 219 fish/m3. Water quality sampling was conducted biweekly from April to September and monthly from October to March at three locations. On all sampling dates field measurements of water temperature, pH, dissolved oxygen, and conductivity were recorded at 1 m depth intervals and water samples were collected at a depth of 0.5 m and near the bottom of the water column at each site. Sample analyses included: total alkalinity, total hardness, turbidity, chloride, sulfate, orthophosphate, total phosphorus, nitrate-N, nitrite-N, total Kjeldahl nitrogen, total organic carbon, dissolved organic carbon, biochemical oxygen demand, and chlorophyll a. The results showed statistically significant decreases in water temperature and dissolved oxygen and significant increases in field conductivity in surface waters near the net pens relative to other sampling sites. The most dramatic water quality effect observed during the study was decrease in dissolved oxygen levels near the net pens following lake turnover in the second year.

scholarly journals Physico-chemical Parameters of Koshi River at Kushaha Area of Koshi Tappu Wildlife Reserve

Our Nature ◽  
1970 ◽  
Vol 9 (1) ◽  
pp. 156-167 ◽  
Author(s):  
D. Thapa Chhetry ◽  
J. Pal
Keyword(s):  
Dissolved Oxygen ◽  
Water Temperature ◽  
Air Temperature ◽  
Oxygen Demand ◽  
Summer Season ◽  
Biological Oxygen Demand ◽  
Total Alkalinity ◽  
Total Hardness ◽  
Chemical Parameters ◽  
Wildlife Reserve

The Koshi river is the major tributaries of the Ganges which originates from the snowy peaks of Tibetan plateau in the central Himalayas. Its total catchment area is 60,400 km2, of which 28,140 km2 lies in Nepal, while the remainder is situated in Tibet. It passes from Nepal to India via the Koshi Tappu Wildlife Reserve area of Nepal. It destroys large area through floods, especially in India. This paper deals with the air temperature and phyco-chemical parameters like temperature, transparency, pH, oxygen, carbondioxide, alkalinity, hardness, chloride and biological oxygen demand of water of Koshi river at Kushaha area of Koshi Tappu Wildlife Reserve. The water temperature was recorded maximum in summer season but the transparency, pH, dissolved oxygen, total alkalinity and total hardness were recorded maximum in winter season. Similarly, free carbondioxide was maximum in rainy season and chloride and biological oxygen demand were recorded maximum in summer season. The air temperature and water temperature had positive and significant correlation with free carbondioxide and biological oxygen demand. Dissolved oxygen had positive and significant correlation with pH, total alkalinity and total hardness. Similarly, total alkalinity had positive and significant correlation with transparency, total hardness, chloride etc.DOI: http://dx.doi.org/10.3126/on.v9i1.5746

Influence of Seasonal Temperature Variation on pH, Dissolved Oxygen and Biological Oxygen Demand in Tamdil Lake, Mizoram, India

2018 ◽  
Vol 6 (2) ◽  
pp. 59-63
Author(s):  
Lalzahawmi Chenkual ◽  
◽  
B.P Mishra ◽  
Laltan puia ◽  
Mary Lalthansangi ◽  
...  
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Water Temperature ◽  
Significant Relationship ◽  
Water Samples ◽  
Oxygen Demand ◽  
Ecological Factors ◽  
Quality Parameters ◽  
Biological Oxygen Demand ◽  
Seasonal Temperature

Temperature is one of the most important ecological factors which play a significant role on the earth, and all the living organisms have evolved various methods to meet extremes of temperature. Seasonal temperature variations are quite significant in freshwater lakes and ponds. The present study deals with the effect of seasonal variations of water temperature on different water quality parameters of Tamdil lake, Mizoram, India, for a period of two years, i.e., from March, 2014 to February, 2016. The water samples were collected from five sampling sites, and the average reading was calculated for each of the water quality attributes namely, temperature, pH, Dissolved Oxygen (DO) and Biological Oxygen Demand (BOD). The water samples were analyzed monthly, and the results are computed on seasonal basis, i.e., pre-monsoon, monsoon, post- monsoon and winter seasons. Statistically, there was a positive and significant relationship between water temperature and pH, and negative significant relationship between temperature and DO. A negative correlation was observed between temperature and BOD. The result shows that there is a significant seasonal variation in physico-chemical parameters. The lake has not reached the polluted stage yet.

scholarly journals New record of three species of Leeches (Annelida:Hirudinea) in Al-Hindyia River / Babil Province / Iraq

2019 ◽  
Vol 16 (3(Suppl.)) ◽  
pp. 0677
Author(s):  
AL-Ameen Et al.
Keyword(s):  
Electrical Conductivity ◽  
Dissolved Oxygen ◽  
Water Temperature ◽  
New Record ◽  
Oxygen Demand ◽  
Biological Oxygen Demand ◽  
Temperature Potential ◽  
Total Dissolved Solid ◽  
Physical And Chemical ◽  
Chemical Water

In this study, a total of 209 individuals of leeches were collected from Al-Hindyia River / Babil Province. 116 individuals were identified as Erpobdella octaculata (Linnaeus, 1758), 50 individuals as Erpobdella punctata (Leidy,1870) and  43 individuals as Hemiclepsis marginata (Müller, 1774).  Four samples were collected monthly during a period from February to June 2018. Some physical and chemical water properties were also examined, including air and water temperature, potential of hydrogen pH, Electrical Conductivity EC, Total Dissolved Solid TDS, Dissolved Oxygen DO, and the Biological Oxygen Demand BOD₅.  Air and water temperature were ranged 19.5-29, & 14.6-23.2 °C respectively. The values of pH ranged 6.2-7.6. EC ranged 1104-1581 μs/cm². The TDS recorded 669- 767 mg/l, while the DO reached 1.3- 8.5 mg / l, the BOD₅ ranged 3.5- 5.7 mg/l.

scholarly journals Environmental Flow for Sungai Johor Estuary

2018 ◽  
Vol 34 ◽  
pp. 02041
Author(s):  
A.Kadir Adilah ◽  
Yusop Zulkifli ◽  
Z. Noor Zainura ◽  
Baharim N. Bakhiah
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Water Temperature ◽  
Oxygen Demand ◽  
Correlation Coefficients ◽  
Water Quality Model ◽  
Surface Elevation ◽  
Quality Model ◽  
Quality Models ◽  
Water Quality Models

Sungai Johor estuary is a vital water body in the south of Johor and greatly affects the water quality in the Johor Straits. In the development of the hydrodynamic and water quality models for Sungai Johor estuary, the Environmental Fluid Dynamics Code (EFDC) model was selected. In this application, the EFDC hydrodynamic model was configured to simulate time varying surface elevation, velocity, salinity, and water temperature. The EFDC water quality model was configured to simulate dissolved oxygen (DO), dissolved organic carbon (DOC), chemical oxygen demand (COD), ammoniacal nitrogen (NH3-N), nitrate nitrogen (NO3-N), phosphate (PO4), and Chlorophyll a. The hydrodynamic and water quality model calibration was performed utilizing a set of site specific data acquired in January 2008. The simulated water temperature, salinity and DO showed good and fairly good agreement with observations. The calculated correlation coefficients between computed and observed temperature and salinity were lower compared with the water level. Sensitivity analysis was performed on hydrodynamic and water quality models input parameters to quantify their impact on modeling results such as water surface elevation, salinity and dissolved oxygen concentration. It is anticipated and recommended that the development of this model be continued to synthesize additional field data into the modeling process.

scholarly journals Results of monitoring of Lake Khanka in 2016–2018

2020 ◽  
Author(s):  
В.И. МАТВЕЕВ ◽  
А.С. КУРНОСОВА ◽  
О.И. КАТАЙКИНА
Keyword(s):  
Dissolved Oxygen ◽  
Water Temperature ◽  
Phytoplankton Bloom ◽  
Water Discharge ◽  
Oxygen Demand ◽  
Maximum Level ◽  
Household Waste ◽  
Nitrogen And Phosphorus ◽  
Suspended Substances ◽  
Lake Khanka

Представлены результаты гидрохимических исследований озера Ханка в 2016–2018 гг. В 2015–2016 гг. съемки проводились в период максимального уровня озера. С 2017 г. наблюдалось снижение его уровня. Пространственное распределение температуры воды в целом не менялось из года в год, но при этом изменялись значения температуры. Так, температура воды в 2018 г. в течение всего сезона была выше на 1–2°. Содержание питательных веществ и растворенного кислорода во многом зависело от стока бытовых отходов пос. Камень-Рыболов, стока вод с рисовых чеков, от интенсивности стока впадающих в озеро рек и продукционных процессов. Цветение фитопланктона происходило даже зимой подо льдом, что подтверждалось высоким содержанием растворенного кислорода (до 180 %) под слоем льда. Вместе с тем содержание кислорода зимой в 2016 г., когда уровень озера был самым высоким, было несколько ниже, чем в последующие годы. Подобные межгодовые изменения отмечались и в колебаниях концентрации кремния. Зимой биологическое потребление кислорода (БПК5) также было высоким (6.53 мл/л), что указывало на активное разрушение органических веществ. Питательные вещества меняли свое соотношение в течение года из-за различных источников их поступления в определенные сезоны. Но в целом их значения и соотношение не имели значительных межгодовых колебаний. Наибольшие концентрации минерального азота и фосфора наблюдались осенью, вероятно, из-за сброса воды с рисовых плантаций. Сделан вывод о том, что высокие значения концентрации питательных веществ, БПК5 и содержания взвешенных веществ характерны для озера Ханка и не были обусловлены повышением его уровня. The results of the hydrochemical investigations of the Lake Khanka in 2016–2018 are presented. In 2015–2016, the surveys were carried out in the period of maximum level of the Lake. From 2017, its level recession was observed. The spatial distribution of the water temperature has generally remained the same each and every year but, at that time, the temperature values have changed. So, for example, the water temperature for the entire length of season in 2018 was higher by 1–2°. The content of nutrients and dissolved oxygen has largely depended on the household waste flow of the Kamen-Rybolov settlement, water flows from the rice checks as well as on flow intensity of the rivers falling into the Lake and production processes. The phytoplankton bloom was observed even in winter under the ice which was confirmed by the high content of the dissolved oxygen (up to 180‰) under the ice layer. At the same time, in winter of 2016 when the Lake level was highest the content of oxygen was slightly lower than in the subsequent years. The similar interannual changes were also noted in the silicon concentrations. In winter, the biological oxygen demand (BOD5) was also high (6.53 ml/l), which has pointed to the active destruction of the organic matter. The nutrients have changed their proportions throughout the year due to different sources of their entry during particular seasons. However, their values and proportions had basically no considerable interannual fluctuations. The highest concentrations of the mineral nitrogen and phosphorus were observed in autumn, probably, due to water discharge from the rice paddies. The conclusion was drawn that the high concentrations of nutrients, BOD5 and content of the suspended substances are characteristic of the Lake Khanka and were not caused by rise in its level.

scholarly journals How Might the Ocean Change in the Future?

2021 ◽  
Vol 9 ◽  
Author(s):  
Denise Tyemi Fukai ◽  
Anna Beatriz Jones Oaquim ◽  
Mauro Cirano
Keyword(s):  
Climate Change ◽  
Time Scales ◽  
Ocean Circulation ◽  
Thermohaline Circulation ◽  
Water Density ◽  
Ocean Water ◽  
The World ◽  
Main Components ◽  
Circulation Changes ◽  
Different Time Scales

The ocean is one of the main components of the climate system. It distributes and absorbs heat to regulate climate at different time scales. Temperature and salinity (saltiness) control the density of ocean water. Differences in water density are important for ocean circulation—they are responsible for generating some currents of water that move through the ocean. An important part of ocean circulation is called thermohaline circulation. Thermohaline circulation absorbs, stores, and transfers heat around the world. Changes in the temperature or salinity of ocean waters can affect thermohaline circulation, so climate change may also alter this circulation. Changes in water circulation also impact the ocean’s chemistry and the organisms that live in the ocean. First, we will explain how ocean circulation happens, and then we will look at how climate change can affect it.

scholarly journals Modeling Spatial Patterns of Dissolved Oxygen and the Impact Mechanisms in a Cascade River

2021 ◽  
Vol 9 ◽  
Author(s):  
Ming Zhong ◽  
Shanxia Liu ◽  
Kun Li ◽  
Huabo Jiang ◽  
Tao Jiang ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Dissolved Oxygen ◽  
Water Temperature ◽  
Water Environment ◽  
Oxygen Demand ◽  
Organic Contamination ◽  
Reservoir Regulation ◽  
Do Concentration ◽  
Hydro Project ◽  
The Impact

Dissolved oxygen (DO) concentration is an essential indicator for assessment of river ecosystems. A hydrodynamic and water quality mathematical model coupling one-dimensional and two-dimensional models is developed in this study. The characteristics of study area, flow velocity, temperature, and organic contamination are taken as consideration in the scenario setting. The changing processes of DO concentration are simulated in different scenarios, and the effects on DO concentration are discussed. Results indicate that: 1) A negative relation was present between DO concentration in Yongjiang River and releasing discharge of the Laokou hydro-project, since reoxygenation is greater than oxygen consumption along the river, DO concentration increases from upstream to downstream. 2) DO concentration increases with the releasing of DO in the water, which also varies along with the releasing of biochemical oxygen demand (BOD) concentration. Laokou exhibits the greatest increase of BOD, which ranges from 0.1 mg/L to 0.75 mg/L 3) The increasing of water temperature results in increased reoxygenation and a decrease in oxygen consumption. Our study shows that the water temperature increased from 19°C to 29 °C, and correspondingly saturated DO decreased from 9.25 mg/L to 7.54 mg/L. The study provides scientific support for ecology operation in the cascade river, and is expected to improve the water environment by reservoir regulation.

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