Anaerobic Respiration in a Cyprinoid Fish Rasbora daniconius (Ham)

UDC 541.15 The neutral water regime with oxygen dosing at a nuclear power plant with a RBMK-1000 reactor has been under discussion now for a long time [1, 2]. A central point of this discussion is estimation of the a priori possible increase in the oxygen concentration in reactor water accompanying the addition of a small, measured quantity of oxygen into the feed water. In [2-4] an attempt was made to solve this problem empirically by examining the oxygen balance in the first loop of the reactor. Although the radiation-chemical process was mentioned as a source of oxygen in reactor water, nothing was said about the mechanisms of the process. At the same time, in our opinion, the problem can be solved by applying the general laws of the radiation chemistry of water to the formation of the products of radiolysis of water in RBMK-1000. From the standpoint of the radiation chemistry of water, an estimate of the change in the stationary concentration of oxygen formed by radiolysis of water accompanying a change in the initial concentration of oxygen can be formulated as follows. Let the reactor feed water contain the regulated concentration of oxygen [O2]feed R. When such water is fed into the multiple forced circulation loop (MFCL), it is mixed with the circulation water, and its concentration at the entrance into the core becomes equal to [O2]iniR. In accordance with this concentration, on passage through the core a stationary hydrogen concentration [H2]st R and oxygen concentration [O2]st R is established in the coolant. If the oxygen concentration in the feed water is increased up to [O2]feea s, then the oxygen concentration in the water at the entrance into the core (we denote it by [O2]iniS ) and the stationary concentration of hydrogen and oxygen in the coolant after passage through the core (we denote them by [H2]st s and [O2]st s) will change. The problem is to determine the extent to which or by how many times the stationary oxgyen concentration in the reactor water will change when its concentration in the feed water fluctuates. To solve this problem we employ the experimental data on the mechanisms leading to the establishment of a stationary concentration of the products of radiolysis of water solutions of oxygen, data on single measurements of the parameters of the water-chemical regime of RBMK reactors and other boiling-water reactors, and the fundamental laws of the radiation chemistry of water. It is known that the stationary concentration of hydrogen, oxgyen, and hydrogen peroxide during -t-radiolysis of water is proportional to the initial concentration of oxygen dissolved in the water prior to irradiation:

In the culture of cranberries it is often necessary to flood the bogs as a protection against frost and certain insects. The length of the flooding period may vary from a few hours to several days. To ascertain the relation between the oxygen content of waters and injuries which had occurred to the vines as a result of flooding, an investigation was begun in I9I8. This work was carried on during the seasons of I9I8 and I919 in the cranberry regions of Massachusetts and Wisconsin. One of the first things that became apparent as a result of the study of flooding water of cranberry bogs was the extent of variation of the oxygen and carbon dioxide content of water from different sources and the correlation of these variations with weather and other conditions. The oxygen and carbon dioxide content of exposed waters under certain conditions varies considerably as between day and night. The extent of this variation is affected by the amount of sunlight during the day as determined by the presence or absence of clouds. The velocity and direction of the wind and the temperature of the water also affect the gas content of flooding waters but are less important than light intensity. The effect of cloudiness on the oxygen and carbon dioxide content of water is indirect, resulting from the action of light on submerged vegetation. When plants are submerged, oxygen and carbon dioxide during respiration or photosynthesis are absorbed from the water or given off into it in solution. Accordingly, the oxygen content of the water is increased during the day in proportion to the amount of vegetation present and to the light intensity, while the carbon dioxide content decreases under the same conditions. The presence of oxidizable organic matter in the water or in the substratum tends to reduce the oxygen and to increase the carbon dioxide content of the water. This effect has been observed in the marshes, used by many Wisconsin cranberry growers for reservoirs, and in the water of cedar swamp reservoirs in Massachusetts. On a clear day the amount of oxygen produced by photosynthesis is much in excess of that used up in respiration or by the oxidation of organic matter. For this reason, when vegetation is present, an accumulation of oxygen occurs. In cloudy weather the accumulation is less. The oxygen content may even decline in densely cloudy weather. A diurnal variation is thus to be expected in ponds with

Results of the annual series of complex measurements of carbon dioxide, oxygen, and biogenic elements in the subglacial water in the littoral zone of the southern area of Lake Baikal, carried out from 2004 to 2016, are analyzed. It was found that the plankton photosynthetic activity significantly decreases the partial pressure of carbon dioxide in water (to 240–350 μatm) as compared to the partial pressure of CO2 in the atmosphere (about 385 μatm) by the end of ice cover season. Hence, the CO2 flux can be directed only from the atmosphere to the water surface during the ice breakup in the littoral zone of Southern Baikal.

The oxygen content in liquid water has been measured in the temperature range between 0°C and −7°C. The measurements have been carried out with an amperometric needle sensor in glass-capillaries with an inner diameter of 1.7 mm. It has been obtained that the oxygen content in water is rapidly increasing as the temperature is lowered below 0°C. At −5°C the concentration of oxygen in water at constant partial pressure of oxygen is by 13% higher than that at +3°C. The increase of oxygen content seems to be related to the unusual temperature dependence of heat capacity, density and isothermal compressibility of supercooled water.

Photosynthesis and cellular respiration are two processes that transform energy and affect concentrations of carbon dioxide and oxygen in air and water. In this lesson, middle school students use graphing calculators and calculator-based laboratory units to measure dissolved oxygen in water and graph their results to gain an under-standing of the relationship between photosynthesis and cellular respiration.

One of the main utilization of bubble columns is for the cultivation of microalgae. Microalgae need carbon dioxide for their growth. The main parameter of bubble column design is the volumetric mass transfer coefficient, kLa. The objective of this study is to determine the kLa of carbon dioxide in an annular bubble column. The kLa of carbon dioxide was formulated from the concentration of dissolved carbon dioxide in water. However, due to the limitation of the measurement of carbon dioxide concentration, the oxygen concentration in water was used. This measurement of oxygen concentration in the annular bubble column was carried out through a dynamic physical method using an oxygen probe. The kLa of carbon dioxide was then formulated from the kLa of oxygen. The effects of the superficial velocity and the water level in the column on the kLa of carbon dioxide were analyzed. The results are that higher superficial velocities and higher water levels yield higher kLa of carbon dioxide. The value of kLa in this study ranges from 0.142 to 0.477 min−1.

Water treatment problems are very relevant in the operation of boiler plants and heating systems, both in small boiler houses, large enterprises, and energy facilities. The main cause of internal corrosion of equipment and pipelines of water heating systems is the presence of corrosive gases (oxygen and carbon dioxide) dissolved in water. This leads to economic costs, disruption of process technology, and also increases the anthropogenic load on the environment. Therefore, high requirements are imposed on these water regimes for desalination and deoxygenation, which allows to reduce the aggressiveness of water, prevent the formation of scale, corrosion of pipes and devices in the water supply system, and reduce the withdrawal of clean water from surface and underground sources. Deoxygenation of water is an important method for reducing metal corrosion, since oxygen is one of the main agents contributing to corrosion processes. Water containing dissolved oxygen can actively interact with metals, causing their oxidation and destruction. Reducing the concentration of oxygen in water helps to significantly slow down these processes. To reduce the oxygen concentration in water, or completely remove it from the system, a fairly large number of methods can be used – physical, chemical, physico-chemical and combined. Hydrazine hydrate is successfully used for water treatment of both drum and direct-flow boilers. The reaction rate depends on the temperature, pH of the medium, excess hydrazine according to the law of mass action, and the presence of catalysts. At temperatures below 30 °C, hydrazine practically does not interact with O2, but at 105 °C, pH 9–9.5, and an excess of hydrazine, the time for almost complete oxygen binding is several seconds. Based on experimental data, dependences were obtained that demonstrate the kinetics of changes in oxygen concentration over one hour. Initially, a study was conducted of the change in oxygen concentration upon addition of hydrazine hydrate when the experimental temperature changed from 15 to 40 °C. Studies of changes in the oxygen concentration in water with the addition of hydrazine hydrate and iron and copper ions and at different temperatures showed that the doses of hydrazine and temperature have the greatest impact on the deoxidation processes, while iron and copper ions almost did not make significant changes to the course of the process. When using iron (II) ions in a composition with hydrazine hydrate at elevated temperatures, an increase in removal efficiency by 30–40 % is noted, and the time to reach zero concentration at maximum doses is reduced by approximately 90 %. Copper (I) ions did not show catalytic properties in compositions with hydrazine hydrate at low temperatures in deoxidation processes and almost did not affect the rate of reaction with oxygen.

New experimental solubility data for carbon dioxide in pure water and in aqueous solution containing sodium hydroxide in the temperature range (293.15 to 393.15) K and pressures up to 5 MPa are presented in this work. A new experimental apparatus based on an equilibrium cell with a constant volume allowing the measurement of carbon dioxide solubility is presented. The liquid phase composition at the thermodynamic equilibrium is determined by an analytical method (ion chromatography) and a static synthetic method. The CO2 + water system is used to validate the experimental apparatus; therefore data obtained are compared with literature data.

This paper presents a way to solve the transfer rate equation of oxygen in water. After running a calculation program, the graph of the function that indicates the increase of the dissolved oxygen concentration in the water as a function of time is plotted. Constructed in an original manner, the experimental installation allows the measurement of the increase of the dissolved oxygen concentration in water. The experimental obtained results are compared with the theoretically obtained data.

Water deoxygenation using hollow fiber membrane module with nitrogen as inert gas

An oxygen-deficient water mass currently impinges along the coast of the eastern tropical north Pacific continental margin. Sediments deposited within this environment (oxygen not measurable in the bottom waters by Winkler titration) typically have organic matter contents that are elevated over similar sediments deposited under more oxic conditions. We evaluated the organic matter content and the amino acid content and composition of sediments from a transect off the Mexican coast near Mazatlan, as well as a gravity core taken in the center of the current oxygen-deficient zone. Organic matter contents in these cores range from 1-11% OC and amino acid contents range from 8-24 mgAA/100 mgOC. Amino acid contents (either carbonor massnormalized) are inversely related to oxygen content of the bottom water and more strongly to the oxygen exposure time of the sediments (calculated as the quantity of time sedimentary organic matter is exposed to oxygen prior to burial: Hartnett et al., 1998). The positive correlations between carbonnormalized amino acid contents and overlying water oxygen content or oxygen exposure time suggests that amino acids undergo diagenesis at an accelerated rate relative to the bulk organic matter in the sediments. Amino acid compositions also correlate with environmental parameters. Within the oxygen-deficient zone, amino acid contents are very similar to that of fresh plankton samples or fecal materials. This suggests that the amino acids present in these sediments have undergone relatively little diagenetic alteration. Conversely, the non-protein amino acids 13-alanine, 7-aminobutyric acid and ornithine, which are not commonly found in planktonic sources, are present in elevated quantities in sediments having higher ambient oxygen concentrations or longer oxygen exposure times. Elevated quantities of nonprotein amino acids in marine sediments result from diagenetic reactions, and thus indicate an increased relative level of diagenesis. Mole percentages of nonprotein amino acids are low (< 2.5%) in sediments taken from within the oxygen-depleted zone, and higher (3-6 mole %) in sediments taken from areas with longer oxygen exposure times. These latter levels (3-6%) are typical of continental margin sediments that are not oxygen-deficient. The correlations of mole percent non-protein amino acids with ambient oxygen levels in overlying water masses or oxygen exposure times suggests that the amino acids present in sediments from under the oxygen-deficient waters have undergone less diagenesis than those deposited under more oxic conditions. Similar trends are inferred in the gravity core sample taken from within the present-day oxygendeficient zone (see also Ganeshram et al., 1996). In sediments deposited during the Holocene, at which time oxygen-deficient waters are thought to have been continuously present, amino acid contents and compositions are consistently elevated and planktonlike in composition. Before the HolocenePleistocene transition, approximately 11,000 years ago, the amino acid contents and compositions were consistent with those observed under the present day oxic conditions (lower yields, altered compositions). These data, along with other (15N isotopic compositions, organic carbon to mineral surface area ratios) suggest that the oxygen minimum zone was not present (or was not as intense) during the last glacial period.

Dissolved oxygen is fundamental for chemical and biochemical processes occurring in natural waters and critical for the life of aquatic organisms. Many organisms are responsible for altering organic matter and oxygen transfers across ecosystem or habitat boundaries and, thus, engineering the oxygen balance of the system. Due to such Lemna features as small size, simple structure, vegetative reproduction and rapid growth, as well as frequent mass occurrence in the form of thick mats, they make them very effective in oxygenating water. The research was undertaken to assess the impact of various species of duckweed (L. minor and L. trisulca) on dissolved oxygen content and detritus production in water and the role of ecological factors (light, atmospheric pressure, conductivity, and temperature) in this process. For this purpose, experiments were carried out with combinations of L. minor and L. trisulca. On this basis, the content of oxygen dissolved in water was determined depending on the growth of duckweed. Linear regression models were developed to assess the dynamics of changes in oxygen content and, consequently, organic matter produced by the Lemna. The research showed that the presence of L. trisulca causes an increase in dissolved oxygen content in water. It was also shown that an increase in atmospheric pressure had a positive effect on the ability of duckweed to produce oxygen, regardless of its type. The negative correlation between conductivity and water oxygenation, obtained in conditions of limited light access, allows us to assume that higher water conductivity limits oxygen production by all combinations of duckweeds when the light supply is low. Based on the developed models, it was shown that the highest increase in organic matter would be observed in the case of mixed duckweed and the lowest in the presence of the L. minor species, regardless of light conditions. Moreover, it was shown that pleustophytes have different heat capacities, and L. trisulca has the highest ability to accumulate heat in water for the tested duckweed combinations. The provided knowledge may help determine the good habitat conditions of duckweed, indicating its role in purifying water reservoirs as an effect of producing organic matter and shaping oxygen conditions with the participation of various Lemna species.

Determination of diffusion coefficients of carbon dioxide in water between 268 and 473 K in a high-pressure capillary optical cell with in situ Raman spectroscopic measurements

The Lunnan Oilfield in the Tarim Basin is known for its abundant oil and gas resources. However, the marine clastic reservoir in this oilfield poses challenges due to its tightness and difficulty in development using conventional water drive methods. To improve the recovery rate, this study focuses on the application of carbon dioxide flooding after a water drive. Indoor experiments were conducted on the formation fluids of the Lunnan Oil Formation, specifically investigating gas injection expansion, thin tube, long core displacement, oil and gas phase permeability, and solubility. By injecting carbon dioxide under the current formation pressure, the study explores the impact of varying amounts of carbon dioxide on crude oil extraction capacity, high-pressure physical parameters of crude oil, and phase characteristics of formation fluids. Additionally, the maximum dissolution capacity of carbon dioxide in formation water is analyzed under different formation temperatures and pressures. The research findings indicate that the crude oil extracted from the Lunnan Oilfield exhibits specific characteristics such as low viscosity, low freezing point, low-medium sulfur content, high wax content, and medium colloid asphaltene. The measured density of carbon dioxide under the conditions of the oil group is 0.74 g/cm3, which closely matches the density of crude oil. Additionally, the viscosity of carbon dioxide is 0.0681 mPa·s, making it well-suited for carbon dioxide flooding. With an increase in the amount of injected carbon dioxide, the saturation pressure and gas-oil ratio of the crude oil also increase. As the pressure rises, carbon dioxide dissolves rapidly into the crude oil, resulting in a gradual increase in the gas-oil ratio, expansion coefficient, and saturation pressure. As the displacement pressure decreases, the degree of carbon dioxide displacement initially decreases slowly, followed by a rapid decrease. Moreover, an increase in the injection rate of carbon dioxide pore volume leads to a rapid initial improvement in oil-displacement efficiency, followed by a slower increase. Simultaneously, the gas-oil ratio exhibits a slow increase initially, followed by a rapid rise. Furthermore, as the displacement pressure increases, the solubility of carbon dioxide in water demonstrates a linear increase. These research findings provide valuable theoretical data to support the use of carbon dioxide flooding techniques for enhancing oil recovery.

Estimated time change of dissolved oxygen and carbon dioxide concentrations in the interstitial water of red sea bream, Pagrus major, egg aggregation