The Organic Metabolism of Sea-water with Special Reference to the Ultimate Food Cycle in the Sea
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Studies are reported of the behaviour of stored sea-water with regard to oxygen, ammonia, and bacteria content in relation to the conditions of storage and to the effect of various filtration procedures. When sea-water is sterilised by filtration and stored in the dark, the oxygen content remains constant or diminishes only by less than 0·07c.c. per litre in several hundred hours. In non-sterile experiments there is always an oxygen consumption roughly parallel to a bacterial multiplication which begins very suddenly after collection of the water. These effects are greatest in “raw” water, less in paper-filtered water and least in water which is doubly filtered.Keywords:
Filtration (mathematics)
Cracks are inevitable in concrete structures, and the deterioration of concrete crack interfaces in intertidal zones is often accelerated due to seawater dry–wet cycles. This paper aims to analyze the morphology and deterioration of crack interfaces under seawater dry–wet cycles. First, concrete crack surface specimens were obtained through splitting tests. Then, the specimens were placed in seawater solutions of different concentrations to undergo seawater dry–wet cycles. Furthermore, three-dimensional (3D) laser surface profile scanning was performed on the specimens after 0, 10, 30, and 60 seawater dry–wet cycles. Finally, the changes in morphological parameters were analyzed and calculated to derive the effect patterns of seawater dry–wet cycles on the 3D morphology of concrete crack interfaces. The results showed that the crack surface deterioration of the specimens in clear water was only affected by the dry–wet cycles, while that in seawater was jointly affected by seawater erosion and dry–wet cycles. The crack surface deterioration of the specimens in seawater can be divided into two stages. In the first 10 seawater dry–wet cycles, the chemical products generated by seawater erosion played a dominant role. The 3D morphological parameters and 3D fractal dimension changes of the specimens in seawater showed opposite trends to those in clear water. From the 10th seawater dry–wet cycle, erosion and flaking by the dry–wet cycles were dominant. The changes in the 3D morphological parameters and 3D fractal dimension of the specimens in seawater were consistent with those in clear water. Moreover, higher seawater concentrations led to more significant trends in the crack surface 3D morphological parameter and 3D fractal dimension changes.
Artificial seawater
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Abstract Seawater for water flooding has been in use for many years. It is obviously the fluid of choice in coastal or offshore locations. Seawater differs from surface waters in the concentration of dissolved salts and trace metals. shows a typical seawater analysis. The total dissolved solids (salinity) is high (38,000 ppm) compared to most surface waters which usually have salinities ranging from 500 – 1000 ppm. This paper addresses the analysis and treatment requirements for seawater for water injection as well as provide operating conditions for some seawater treatment plants around the world particularly with respect to scale control.
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Based on hydrochemical data of 31 surficial seawater samples collected along the coast of Shenzhen,scatter diagrams of major ions(Ca~(2+),Mg~(2+),Na~+,K~+,SO~(2-)_4 and HCO~-_3) vs Cl~-,and Br~-vs Cl~-are analyzed.On the western coast,the Ca~(2+),K~+,SO~(2-)_4 and HCO~-_3 vs Cl~-of surficial seawater deviate from the seawater dilution lines,which are confirmed by the mixture of seawater with river water in different ratios under the influence of the Pearl River.On the eastern coast,the Ca~(2+),K~+ and HCO~-_3 vs Cl~-of surficial seawater fluctuate around the seawater dilution lines,which are resulted from progressively effect by slow flow and evaporation of the surficial seawater and the discharge of local polluted river waters.The compositions of 5 seawater samples on the western coast near the Shenzhen Bay are similar to those of surficial seawater samples on the eastern coast.
Dilution
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Highly polished coupons (25 by 25 by 1.5 mm) sourced from the same steel sheet were continuously immersion-exposed either to natural coastal seawater or to seawater from the same source subjected to filtration and UV irradiation to eliminate microbiologically influenced corrosion as much as possible. This was continued for 943 days (2.6 years). Dissolved oxygen levels were very similar in both environments. On average the UV-treated seawater was 2°C warmer, but all coupons exposed to it showed less localized corrosion than those exposed to natural seawater. The typical topographical difference was about 60% as measured by surface roughness parameter Sa. Mass losses in UV-treated seawater were about 10% higher than in natural seawater, but after temperature correction were similar to natural seawater for the first year and tended to be lower subsequently. At all exposure periods the rusts in UV-treated seawater were less voluminous than the rusts in natural seawater. Eventually they also contained a higher proportion of magnetite.
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The multi-outlets were installed on the existing seawater exchange breakwater in order to improve seawater exchange rate at Jumunjin harbor. Physical and numerical model system were fulfilled for 4 cases to evaluate seawater exchange system which is able to discharge water remotely. The seawater circulation pattern and seawater exchange rate in the harbor were compared and analyzed. Consequently, total seawater exchange rate for CASE 1 was calculated 48% due to the dead zones which hinder seawater circulation in the harbor. Otherwise, the seawater exchange rates of CASE 2, CASE 3, and CASE 4 with the installation of the system were enhanced 19%, 15% and 17%, respectively compare to CASE 1.
Circulation (fluid dynamics)
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Determination of Li, Rb, B and Sr in seawater does not need to use complicated methods used for determination of trace elements in seawater such as chelation-separation and standard addition calibration. It can be performed briefly by diluting seawater by 50 times directly, tuning the sensitivity of Inductively Coupled Plasma Mass Spectrometry(ICP-MS) and adding internal standard Re on line. The examination limit(3σ) for Li, Rb, B and Sr was 0.75, 0.25, 14.0 and 0.10 μg/L respectively. After 10 times continuous determination of seawater samples, the relative standard deviation(RSD) was calculated: the RSD of Li was 1.47%, B was 3.13%, Rb was 2.05% and Sr was 2.01%. The standard was added to assess the recovery of experimentand the recovery rate was from 96.5% to 105%. The results show that this method is simple, fast, and the data is stable, accurate and reliable, which well met the requirement for determination of these elements in seawater. We have measured these four elements in Atlantic bottom water(from the Underwater at 200 meters). The data deviation was less than 2.65%, which was lower than the standard deviation of the method. The seawater in this layer is steady and there is no change.
Relative standard deviation
Standard solution
Standard addition
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This paper proposes a kind of seawater pH standard material more suitable for the measurement of pH in seawater,and studies the methods of preparation and setting method of small batch process for the preparation of the standard material. The pH value in seawater reference material determined by spectrophotometry is carried out to evaluate the homogeneity and stability of the seawater pH standard material prepared by F test and t test method. The experimental results show that both homogeneity and stability,in six month at room temperature,of this seawater pH standard material in artificial seawater are good.
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Water multi-utilization pattern system is of great significance for seawater utilization and the reduction of waste seawater discharge of aquaculture. However, the change analysis of seawater quality in the water multi-utilization pattern system is little reported. The water multi-utilization pattern system of Cynoglossus semilaevis-Penaeus vannamei-Artemia-ocean chemical industry was employed to determine the changes of seawater quality. Results showed that with seawater utilized continuously, pH, inorganic N and P, organic N, total N and COD concentrations were all increased significantly(p0.05),which indicated that aqua-cultivation can lowering seawater quality significantly. Compared with continuous increase of organic N, total N and COD concentrations, inorganic N and P concentrations of seawater changed in the wave-shaped patterns,showing significantly higher than those of un-utilized seawater(p0.01). Wave-shaped patterns probably resulted from the organic N and P utilization by living beings in seawater. With seawater salinity increasing, the increase of organic N, total N and COD concentrations boosted greatly, which suggested that self-cleaning capacity of seawater was inhibited obviously.Compared with un-utilized seawater, organic N, total N and COD concentrations of seawater in Artemia cultivating pond increased by 6.27, 6.15 and 3.90 times respectively. Based on change rules of seawater, the seawater quality demands of components in water multi-utilization pattern systems should decrease in turn. At the same time, high efficient cultivating and cleaning technologies are also needed to improve seawater quality.
Artificial seawater
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The influences of the composition of seawater to the seawater direct electrolysis were discussed. The composition of seawater varies from season to season and from place to place. While the concentration of Cl~- decreases, the electrochemical potential in creases and the current efficiency decreases. The current efficiency increases progressively as the concentration of Mg~(2+) (or Ca~(2+)) concentration does.
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