Issue Ebook
cover story
Latest Issue
2020Year38Volume2Issue
- Abstract：Compared with observations, the simulated upper ocean heat content (OHC) determined from climate models shows an underestimation bias. The simulation bias of the average annual water temperature in the upper 300 m is 0.2℃ lower than the observational results. The results from our two numerical experiments, using a CMIP5 model, show that the non-breaking surface wave-induced vertical mixing can reduce this bias. The enhanced vertical mixing increases the OHC in the global upper ocean (65°S-65°N). Using non-breaking surface wave-induced vertical mixing reduced the disparity by 30% to 0.14℃. The heat content increase is not directly induced by air-sea heat fluxes during the simulation period, but is the legacy of temperature increases in the first 150 years. During this period, additional vertical mixing was initially included in the climate model. The non-breaking surface wave-induced vertical mixing improves the OHC by increasing the air-sea heat fluxes in the first 150 years. This increase in air-sea heat fluxes warms the upper ocean by 0.05-0.06℃. The results show that the incorporation of vertical mixing induced by nonbreaking surface waves in our experiments can improve the simulation of OHC in the global upper ocean.Keywords：surface wave-induced;vertical mixing;upper ocean heat content;air-sea heat fluxes;climate model4|3|0Updated：2023-04-27
- Abstract：The impact of typhoon Kujira (2015) on the ocean environment around Yongxing Island in the South China Sea was observed using multiple-satellite sensors and on-site data. A subsurface buoy and Agro float were located to the left and lower right of the track of the typhoon. Satellite observations revealed sea surface cooling of up to 2.5℃, a maximum decrease in sea surface salinity of 2 in the main study area because of heavy rain, and increases in the chlorophyll concentration induced by the slow-moving typhoon with a maximum observed instantaneous wind speed of 35.1 m/s. The sea surface temperature to the right of the typhoon track changed more than that on the left owing to a right bias of the typhoon associated with coupling of the typhoon with wind stress on the sea surface. In the ocean interior, there was obvious downwelling at 24.7 m and upwelling at a depth of 35.7 m with the vertical entrainment and agitation of the typhoon, and the effects extended to different depths of up to more than 1 000 m. When the typhoon passed through the main study area, the maximum flow velocity change at depths of 51 and 660 m was about 0.44 and 0.04 m/s, respectively. The typhoon affected the flow field to a depth of 660 m as it formed and decayed in 11 h, moved at an average speed of 60 m/h, and affected the sea surface over a range exceeding 700 km as it moved slowly and stayed at sea for 2 d. Vertical entrainment and agitation generated by the typhoon, as well as rainfall, cooled the sea surface. This inhibited the strengthening of the typhoon, but the energy transmitted to the ocean led to divergence-convergence flow from a shallow to deep layer.Keywords：typhoon Kujira (2015);downwelling;flow field;wind field4|2|1Updated：2023-04-27
Physics
- Abstract：A metal-dissolved oxygen seawater battery (SWB) uses metal and dissolved oxygen as the reactants, and it is ideal for use as a long-time low-power distributed power supply in deep sea, due to its advantages of open structure in service without electrolyte. However, several simulating deep-sea environmental factors, such as flow rate, dissolved oxygen concentration, and temperature of seawater may affect the oxygen reduction reaction (ORR) rate and the stability of electrochemically modified polyacrylonitrile-based carbon fiber brush (MPAN-CFB) cathode, which was studied by steady-state polarization and galvanostatic discharge methods. In addition, the scales formed on MPAN-CFB surface were characterized by SEM and XRD. Results show that the ORR rate increased quickly with the increase of the seawater flow rate up to 3 cm/s, and then gradually stabilized. Moreover, the ORR rate was largely affected by dissolved oxygen concentration, and the concentration of >3 mg/L was favorable. Compared with surface layer temperature of 15℃, the low temperature of deep sea (4℃) has a negligible effect on ORR rate. When the working current is too high, it will lead to the formation of CaCO3 scales (aragonite) of at the cathodic surface, resulting in the decrease of ORR rate, and consequently the damage to the long-time stability of MPAN-CFB.Keywords：seawater battery (SWB);modified polyacrylonitrile-based carbon fiber brush (MPANCFB);oxygen reduction reaction (ORR);scale formation4|0|2Updated：2023-04-27
- Abstract：To investigate the adsorption characteristics of chitooligosaccharides in solution onto activated charcoal, we studied the optimal adsorption conditions and the adsorption mechanisms of the chitooligosaccharides onto activated charcoal, which will greatly promote the application of activated charcoal in the chitooligosaccharides separation and purification. We studied the effects of particle size of activated charcoal, pH of solution, contact time, temperature, and initial concentration of chitooligosaccharides on the adsorption behavior in batch mode experiments. Activated charcoal in fine particle size showed a high uptake of chitooligosaccharides. Weak alkaline solution (pH 8-9) was the most favorable to the adsorption. The adsorption equilibrium after 60 min was established, which followed a pseudo-second-order kinetic model. The adsorption capacity (Qmax) reached 0.195 g/g (chitooligosaccharides/activated charcoal) at 298 K. The adsorption was temperature-insensitive, and the adsorption isotherms could be best described by the Langmuir equation. Chitooligosaccharides adsorbed on activated charcoal could be desorbed in 50% ethanol solution in combination with an acidic condition (pH 2), reaching desorption efficiency of 96.0%. These findings are of great significance for the production and purification of amino oligosaccharides including chitooligosaccharides using activated charcoal.Keywords：chitooligosaccharide;adsorption;activated charcoal;kinetics;isotherm4|0|0Updated：2023-04-27
Chemistry
- Abstract：Hypoxia, a frequent occurring threat in coastal regions, often results in mass mortalities of marine organisms and brings a serious ecological problem. The commercially important Zhikong scallop Chlamys farreri is being under such a threat as the risks of eutrophication and hypoxia have risen in their culture areas. However, little information has been known concerning their tolerance to hypoxia and their strategy for survival. In the present study, a 20-day experiment was conducted to determine the effects of hypoxia on the survival, behavior, and metabolism of Zhikong scallop. With the LC50 for dissolved oxygen (DO) being estimated as 1.8 mg/L, the survival of Zhikong scallop can be greatly challenged even under the moderate hypoxic condition of around 2.0 mg/L DO. The survival rate ranged from 69% to 59% when DO dropped from 3.0 to 2.0 mg/L, and it was further reduced to 47% at 1.5 mg/L DO. In hypoxic conditions, the scallops became significantly active, which may be explained as escape attempts to avoid hypoxic water. To save energy, Zhikong scallop would depress their respiration. However, when DO dropped from 3.0 to 2.0 mg/L, the oxygen consumption rate hardly changed. The upregulation of lactate dehydrogenase activity and the unrepressed phosphofructokinase activity, which often result in the unbalanced cellular homeostasis and energy budget, may account for the observed increase in the mortality rate of Zhikong scallops. In general, Zhikong scallop is sensitive to hypoxia events, though possible escape attempts, depressed respiration, and oxaloacetate-pathway may increase their survival chance.Keywords：Zhikong scallop;survival;behavior;metabolism4|0|3Updated：2023-04-27
-
-
-
-
Ecology
Biology
Aquaculture and Fisheries
- 联系电话：+86-532-82898754 Email：jol@qdio.ac.cn
- 技术支持由北京北大方正电子有限公司提供 京ICP备09064830号-19
京公网安备11010802024621 - 本系统建议在Chrome、 IE9+ 以上版本浏览器阅读本站内容，360浏览器请切换至极速模式
- Cookies帮助我们提供服务并提供个性化体验。使用本网站，即表示您同意我们使用Cookies
0