Journal of Ocean University of Qingdao

In shallow-water areas, the marine magnetotelluric (MT) method faces a challenge in the investigation of seabed conductivity structures due to electrical and magnetic noises induced by ocean waves, which seriously contaminate MT data. Ocean waves can affect electric and magnetic fields to different extents. In general, their influence on magnetic fields is considerably greater than that on electric fields. In this paper, a complex adaptive filter is adopted to reduce wave-induced magnetic noises in the frequency domain. The processing results of synthetic and measured MT data indicate that the proposed method can effectively reduce wave-induced magnetic noises and provide reliable apparent resistivity and phase data.

Based on the simulation with SWAN wave model and data of ERA-Interim from 1979 to 2016, how the waves propagate globally and why swell pools distribute in the eastern ocean were investigated in this study. The simulation results show that waves from North Pacific and North Atlantic mainly propagate southeastward or southward and swells generated in Southern Ocean spread northeastward. The waves from high latitude regions spread along the east coast and encounter in the tropical Pacific and Atlantic to form swell fronts around equator and then turn eastward. As the weak wind field with numerous swell inflows, swell pools are generally located on the eastern side of the ocean basin, where the swell index S are greater than 0.9 calculated using ERA-20C data for the period of 1981–2010. Another remarkable feature is that swell pools move southward and split into two parts in winter, while they move northward and merge together in summer.

Polybrominated diphenyl ethers (PBDEs) are a kind of serious pollutants in the ocean. Biodegradation is considered as an economical and safe way for PBDEs removal and reductive debromination dominates the initial pathway of anaerobic degradation. On the basis of experimental study, Octa-BDE 197, Hepta-BDE 183, Hexa-BDE 153, Penta-BDE 99 and Tetra-BDE 47 were selected as the initial degradation objects, and their debromination degradation were studied using density functional theory. The structures were optimized by Gaussian 09 program. Furthermore, the molecular orbitals and charge distribution were analyzed. All C-Br bond dissociation energies at different positions including ortho, meta and para bromine atoms were calculated and the sequence of debromination was obtained. There is a close relationship between molecular structure, charge, molecular orbital and C-Br bond. All PBDEs exhibited similar debromination pathways with preferential removal of meta and para bromines.

The advantage of lidar over other wind sensors is presented in this paper. With more than 20 years research, the development of the space-borne wind lidar is reviewed. Longer-term investigation has made many technologies suitable for the wind lidar measurement from an orbital platform become mature. However, there are still some problems to be solved. In order to obtain the optimal performance in wind detection, great importance is being attached to the simulation of a virtual space-borne wind lidar system on computer as developed by NASA and ESA.

This study was carried out explore the mechanism underlying the inhibition of platelet activation by kelp fucoidans in deep venous thrombosis (DVT) mouse. In the control and sham mice, the walls of deep vein were regular and smooth with intact intima, myometrium and adventitia. The blood vessel was wrapped with the tissue and there was no thrombosis in the lumen. In the DVT model, the wall was uneven with thicken intima, myometrium and adventitia. After treated with fucoidans LF1 and LF2, the thrombus was dissolved and the blood vessel was recanalized. Compared with the control group, the ROS content, ET-1 and VWF content and the expression of PKC-β and NF-κB in the model were significantly higher (P < 0.05); these levels were significantly reduced following treatments with LF2 and LF1. Compared with H2O2 treated-HUVECs, combined LF1 and LF2 treatment resulted in significant decrease in the expression of PKC-β, NF-κB, VWF and TM protein (P < 0.05). It is clear that LF1 and LF2 reduces DVT-induced ET-1, VWF and TM expressions and production of ROS, thus inhibiting the activation of PKC-β/NF-κB signal pathway and the activation of coagulation system and ultimately reducing the formation of venous thrombus.

Coastal and estuarine protists are frequently exposed to salinity undulation. While the tolerance and stress responses of microalgae to salinity have been extensively studied, there have been scarce studies on the physiological response of heterotrophic protists to salinity stressing. In this study, we investigated the physiological response of the heterotrophic ciliate Gastrostyla setifera to a salinity of 3, via a transcriptomic approach. The first transcriptome of genus Gastrostyla was obtained utilizing a group of manually isolated ciliate individuals (cells) and RNA-seq technique. The completeness of the transcriptome was verified. Differentially expressed gene (DEG) analysis was performed among the transcriptomes of G setifera acclimated in saline water (salinity 3) and those cultured in fresh water. The results demonstrated a significant alternation in gene transcription, in which the ciliate exhibits a transcripttomic acclimation in responding salinity stressing. The up-regulated DEGs were enriched in the pathways of cytoskeleton proteins, membrane trafficking, protein kinases and protein phosphatases. These may represent enhanced functions of ion transport, stress response and cell protections. Pathways involved in energy metabolism and biosynthesis were markedly down-regulated, reflecting decreased cell activity. Particularly, we detected significantly down-regulated genes involved in several pathways of amino acid catabolism, which may lead to accumulation of amino acids in the ciliate cell. Amino acid could act as compatible solutes in the cytoplasm to maintain the osmotic balance in saline water. Overall, this work is an initial exploration to the molecular basis of the heterotrophic protist responding to salinity stressing. The result sheds light on the mechanisms of enhancement of cell protection, reduction of cell activity, and osmotic pressure regulation in ciliates acclimated to salinity.

A three-dimensional ecosystem model, using a PIC (Particle-In-Cell) method, is developed to reproduce the annual cycle and seasonal variation of nutrients and phytoplankton biomass in Laizhou Bay. Eight state variables, i.e., DIN (dissolved inorganic nitrogen), phosphate, DON (dissolved organic nitrogen), DOP (dissolved organic phosphorus), COD (chemical oxygen demand), chlorophyll-a (Chl-a), detritus and the zooplankton biomass, are included in the model. The model successfully reproduces the observed temporal and spatial variations of nutrients and Chl-a biomass distributions in the bay. The nutrient concentrations are at high level in winter and at low level in summer. Double-peak structure of the phytoplankton (PPT) biomass exists in Laizhou Bay, corresponding to a spring and an autumn bloom respectively. Several numerical experiments are carried out to examine the nutrient limitation, and the importance of the discharges of the Yellow River and Xiaoqinghe River. Both DIN limitation and phosphate limitation exist in some areas of the bay, with the former being more significant than the latter. The Yellow River and Xiaoqinghe River are the main pollution sources of nutrients in Laizhou Bay. During the flood season, the algal growth is inhibited in the bay with the Yellow River discharges being excluded in the experiment, while in spring, the algal growth is enhanced with the Xiaoqinghe River excluded.

Pituitary adenylate cyclase activating polypeptide (PACAP) and growth hormone-releasing hormone (GHRH) play important roles in the GH/IGF growth axis in fishes. To determine whether epigenetic change is involved in the regulation of pacap and ghrh responses to low salinity stress in Cynoglossus semilaevis, the correlation between growth traits, DNA methylation status and gene expression level in low salinity (15, S15) and optimal salinity (30, S30) at day 7 (D7) and day 60 (D60) were analyzed. Results showed that exposure to low salinity for 60 days attenuated C. semilaevis growth rate. Under low salinity, DNA methylation level of pacap promoter increased in females and decreased in males at day 7, but inverted at day 60. Additionally, pacap expression was up-regulated in both males and females. The pacap promoter methylation level was higher and expression level was lower in female than in male. The results suggest that pacap promoter methylation level is negatively correlated to mRNA level and positively correlated to body weight, while gene expression level is negatively related with body weight. With the decrease of salinity, DNA methylation level of ghrh promoter and exon1, as well as its gene expression displayed minor changes. Overall, pacap gene seems to play an important role in fish growth, contributing to female growth superiority, while ghrh gene seems not pertinent under salinity stress. The results indicate that low salinity potentially affects fish growth through regulating DNA methylation in pacap promoter. This study expands the understanding of the molecular mechanism of how salinity modulates fish growth from the epigenetic perspective.

Shallow water flow (SWF), a disastrous geohazard in the continental margin, has threatened deepwater drilling operations. Under overpressure conditions, continual flow delivering unconsolidated sands upward in the shallow layer below the seafloor may cause large and long-lasting uncontrolled flows; these flows may lead to control problems and cause well damage and foundation failure. Eruptions from over-pressured sands may result in seafloor craters, mounds, and cracks. Detailed studies of 2D/3D seismic data from a slope basin of the South China Sea (SCS) indicated the potential presence of SWF. It is commonly characterized by lower elastic impedance, a higher Vp/Vs ratio, and a higher Poisson’s ratio than that for the surrounding sediments. Analysis of geological data indicated the SWF zone originated from a deepwater channel system with gas bearing over-pressured fluid flow and a high sedimentation rate. We proposed a fluid flow model for SWF that clearly identifies its stress and pressure changes. The rupture of previous SWF zones caused the fluid flow that occurred in the Baiyun Sag of the northern SCS.

The Nordic Seas have a significant impact on the climate system. Here 23-day air-sea heat fluxes were analyzed from an in situ air-sea coupled buoy deployed in the Lofoten Basin from 5 August 2012 to 27 August 2012. The buoy captured two stages of strong south and north winds. The observations indicate that warm and wet air transported by the south wind can lead to decreased sensible and latent heat fluxes and net longwave radiation. The total oceanic heat loss was 50–60 W m−2. Thus, this stage was called the heat insulation process. By contrast, the heat dissipation process occurred with the north wind condition during advection of the cold and dry air. During this process, sensible and latent heat fluxes and net longwave radiation notably increased. The total oceanic heat loss during the heat dissipation process reached 240 W m−2, which was four-fold greater than that in the heat insulation process. Given that the heat insulation process is dominant in summertime, the ocean lost minimal heat but absorbed strong solar energy. Thus, a large quantity of energy was stored in the ocean. Heat was transported to the Arctic Ocean and accelerated Arctic warming. The heat dissipation process is dominant in autumn and winter when the ocean releases considerably more energy. The two processes revealed in this paper can be applied to warm-water areas in high latitudes.