Water mass of the northward throughflow in the Bering Strait in the summer of 2003

The temperature and salinity data obtained by the Chinese national arctic research expedition （CHINARE2003） are used to study the water structure in the Bering Strait and ambient regions. Four water masses appeared in the research region： the intermediate Bering Sea water mass （IBWM）, the Alaska coastal water （ACW）, the Anadyr water （AW） and the Bering shelf water （BSW）. The AW originates from the IBWM, but the upper layer water has been greatly altered. In the cruise on 28/29 July 2003, there were only the BSW and ACW in a section across the Bering Strait （BS section）, but in the September 12/13 cruise, the AW, BSW and ACW flowed parallelly into the Bering Strait. The upper waters of these water masses were all altered due to ice melting, runoff, solar radiation, and wind mixing. The waters in the central and northern parts of Bering Strait stratified by two uniform layers,were expressed as the typical feature of the water masses originating from the pacific. A two-layer structure also dominated the vertical stratification in most part of the Chukchi Sea. An obvious subseasonal variation was observed in the BS section, which caused varying transportation of fresh water, heat, and substance, and produced a long-term and extensive impact on the Arctic Ocean.

The release behavior of inorganic nitrogen and phosphorus in sediment during disturbance

Sediments and surface water were sampled in a tide flat in the Huiquan Bay, Qingdao, China in January 2004 to simulate the exchange of NH4-N/NO3-N/ PO 43- between sediments and surface water. A working system was designed with which samples were shaken at 60, 120 and 150 revolutions per minute (r/min). Experiment results show that NH4-N concentration in water at shaking rate of 60r/min decreased gradually, while at 120r/min increased gradually. In resuspension, fine-grained sediments contributed most NH4-N to the seawater, followed by medium-grained and coarse-grained sediments. The NO3-N concentration in water had a negative relation with the shaking rate; the medium-grained sediments contributed more NO3-N to seawater than the coarse-and fine-grained sediments. The PO 43- concentration is positively related with the shaking rate, the fine-grained sediments were the main N and P contributor to the seawater, followed by medium-and coarse-grained sediments.

Observed and modelled snow and ice thickness in the Arctic Ocean with CHINARE buoy data

Sea ice and the snow pack on top of it were investigated using Chinese National Arctic Research Expedition （CHINARE） buoy data. Two polar hydrometeorological drifters, known as Zeno ice stations, were deployed during CHINARE 2003. A new type of high-resolution Snow and Ice Mass Balance Arrays, known as SIMBA buoys, were deployed during CHINARE 2014. Data from those buoys were applied to investigate the thickness of sea ice and snow in the CHINARE domain. A simple approach was applied to estimate the average snow thickness on the basis of Zeno temperature data. Snow and ice thicknesses were also derived from vertical temperature profile data based on the SIMBA buoys. A one-dimensional snow and ice thermodynamic model （HIGHTSI） was applied to calculate the snow and ice thickness along the buoy drift trajectories. The model forcing was based on forecasts and analyses of the European Centre for Medium-Range Weather Forecasts （ECMWF）. The Zeno buoys drifted in a confined area during 2003-2004. The snow thickness modelled applying HIGHTSI was consistent with results based on Zeno buoy data. The SIMBA buoys drifted from 81. 1°N, 157.4°W to 73.5°N, 134.9°W in 15 months during 2014-2015. The total ice thickness increased from an initial August 2014 value of 1.97 m to a maximum value of 2.45 in before the onset of snow melt in May 2015; the last observation was approximately 1 m in late November 2015. The ice thickness based on HIGHTSI agreed with SIMBA measurements, in particular when the seasonal variation of oceanic heat flux was taken into account, but the modelled snow thickness differed from the observed one. Sea ice thickness derived from SIMBA data was reasonably good in cold conditions, but challenges remain in both snow and ice thickness in summer.

Change in Sediment Provenance Near the Current Estuary of Yellow River Since the Holocene Transgression

Sedimentary sequence and sediment provenance are important factors when it comes to the studies on marine sedimentation. This paper studies grain size distribution, lithological characteristics, major and rare earth elemental compositions, micropaleontological features and ^(14)C ages in order to examine sedimentary sequence and sediment provenance of the core BH6 drilled at the mouth of the Yellow River in Bohai Sea. According to the grain size and the micropaleontological compositions, 4 sedimentary units have been identified. Unit 1(0–8.08 mbsf) is of the delta sedimentary facies, Unit 2(8.08–12.08 mbsf) is of the neritic shelf facies, Unit 3(12.08–23.85 mbsf) is of near-estuary beach-tidal facies, and Unit 4(23.85 mbsf–) is of the continental lake facies. The deposits from Unit 1 to Unit 3 have been found to be marine strata formed after the Holocene transgression at about 10 ka BP, while Unit 4 is continental lacustrine deposit formed before 10 ka BP. The provenances of core BH6 sediments show properties of the continental crust and vary in different sedimentary periods. For Unit 4 sediments, the source regions are dispersed while the main provenance is not clear, although the parent rock characteristics of a few samples are similar to the Luanhe River sediments. For Unit 3, sediments at 21.1–23.85 mbsf have been mainly transported from the Liaohe River, while sediments above 21.1 mbsf are mainly from the Yellow River and partially from the Liaohe River. For Unit 2, the sediments have been mainly transported from the Yellow River, with a small amount from other rivers. For Unit 1, the provenance is mainly the Yellow River catchment. These results help in better understanding the evolution of the Yellow River Delta.

Geochemical characteristics of the fluid inclusions in the Gangxi Fault Belt, Huanghua Depression, Bohai Bay Basin, China

We studied the geochemical characteristics of the fluid inclusions in the Ordovician carbonates and the Oligocene Shahejie Formation sandstones from 15 wells in the Gangxi Fault Belt, Huanghua Depression. The fluid inclusions are all sec- ondary with gas/liquid ratio of 5%~10%. Base on Raman they are mainly composed of H2O, CO2 and CH4. The homogenization temperatures, combined with burial and geothermal history of the host rock, indicate that the fluid flows in the Shahejie Formation and the Ordovician carbonates were trapped in Neocene. Using a VG5400 mass spectrometer, the helium isotopic compositions were analyzed. Interpretation of results suggested a significant amount of mantle-derived helium mainly accumulating in the intersections of the NWW trending Xuzhuangzi and NE trending Gangxi faults. The maturity of hydrocarbon decreases from the intersection to the outside pointing out that the fluid related to the NWW trending Xuzhuangzi and NE trending Gangxi faults. These factors implied the fluid inclusions have a close relationship to the local tectonic setting. Gangxi Fault Belt experienced intensive Neo-tectonic activities in Cenozoic. Widespread faulted-depressions and strong volcanic eruptions manifested its tec- tonic status of extensional stress field. Mantle uplift caused the movement of magma that carried mantle-derived gases and deep heat flows, the deep-rooted tension faults provided the passages for the gases and heat flows to shallow crust levels.

Effects of Salinity Fluctuation Frequency on the Growth, Molting Rate and Hemolymph 20-Hydroxyecdysone Concentration in Juvenile Chinese shrimp, Fenneropenaeus chinensis

This experiment was conducted to examine the effects of salinity fluctuation frequency on the growth, molting rate and hemolymph 20-hydroxyecdysone （20-HE） concentration for juvenile Fenneropenaeus chinensis with an initial wet body weight of 1.115 g±0.012 g. The salinity of the control treatment （represented by DO） was 28 throughout the experiment, whereas treatments D2, D4, D6 and D8 were subjected to different salinity fluctuation frequencies of 2, 4, 6 and 8 d, respectively. The range of salinity fluctuation was 4. The salinity in treatments D2, D4, D6 and D8 was kept at 28 for 2, 4, 6 and 8d, respectively; each original salinity was decreased abruptly to salinity 24, which first lasted for another 2 d and was then raised to its initial value 28. This constituted a salinity fluctuation cycle and afterwards the cycle repeated. It was found that： 1） The weight gain of shrimp in treatment D4 was 202.9% and significantly higher than that in treatment DO （P〈0.05）. The molting rate in treatment D2 was the lowest, while that in treatment D6 was the highest and significantly higher than those in treatments DO and D2 （P〈0.05）. 2） The hemolymph 20-HE concentration of shrimps in all treatments was at low levels and increased first gradually during the inter-molt period and then increased sharply. It reached a peak value during the pre-molt stage, and then decreased abruptly during the post-molt stage when the lowest level occurred. 3） During the post-molt stage, the hemolymph 20-HE concentration in treatment D2 was 7.47pg μL^-1 and significantly higher than that in treatment DO （P〈0.05）. There were, however, no significant differences in hemolymph 20-HE concentration among all five treatments during the inter-molt stage （P〉0.05）. During the pre-molt stage, the hemolymph 20-HE concentration in treatment D6 was significantly higher than that in treatment DO （P〈0.05）, whereas the hemolymph 20-HE concentration in treatment D2 was significantly lower than that in other treatments （P〈0.05）. Adequate salinity fluctuation promoted the molting rate through increasing hemolymph 20-HE concentration at the pre-molt stage.

Analysis of the inter-annual variability and southward expansion of red tides in the Zhejiang coastal waters from 1981 to 2018

A time series dataset spanning 39 years(1981-2018) on red tide events in Zhejiang coastal waters was used to study the characteristics of inter-annual spatial and temporal variations. A distinct inter-annual pattern characterized by low frequency, explosive growth and fluctuating decline stages was found over the studied time scale. Most red tide events occurred in parallel to the bathymetric contour, and 95.4% were located to the west of the 50 m isobath. Additionally, the high-incidence area of red tides is expanding southward. In this paper, local sea surface temperature(SST), mariculture area and secondary industry growth rate are introduced and identified as the main factors influencing the nutrient and hydrometeorological conditions. A multivariate nonlinear regression equation based on these factors was constructed, and the goodness of fit coefficient was 0.907. The causes of the annual variation and high-frequency area in the southward expansion were quantitatively analyzed based on the proposed regression model. Finally, the results indicated that 68.7% of the annual occurrence variation of red tide was due to the SST and mariculture area, which are the main impact factors;however,secondary industry growth could compensate for the nutrient deficiency caused by the sharp mariculture area reduction and decreased SST. The background nutrient level, which is elevated by coastal economic development, especially secondary industry, is the main determinant of the southward expansion. Although the trend of the southward expansion of high-frequency areas has not changed, the red tide frequency in coastal cities has decreased by half and remained at a stable level after 2010 due to substantial economic restructuring and environmental protection.

Impact of Assimilation of Radiosonde and UAV Observations from the Southern Ocean in the Polar WRF Model

Weather forecasting in the Southern Ocean and Antarctica is a challenge above all due to the rarity of observations to be assimilated in numerical weather prediction(NWP)models.As observations are expensive and logistically challenging,it is important to evaluate the benefit that additional observations could bring to NWP.Atmospheric soundings applying unmanned aerial vehicles(UAVs)have a large potential to supplement conventional radiosonde sounding observations.Here,we applied UAV and radiosonde sounding observations from an RV Polarstern cruise in the ice-covered Weddell Sea in austral winter 2013 to evaluate the impact of their assimilation in the Polar version of the Weather Research and Forecasting(Polar WRF)model.Our experiments revealed small to moderate impacts of radiosonde and UAV data assimilation.In any case,the assimilation of sounding data from both radiosondes and UAVs improved the analyses of air temperature,wind speed,and humidity at the observation site for most of the time.Further,the impact on the results of 5-day-long Polar WRF experiments was often felt over distances of at least 300 km from the observation site.All experiments succeeded in capturing the main features of the evolution of near-surface variables,but the effects of data assimilation varied between different cases.Due to the limited vertical extent of the UAV observations,the impact of their assimilation was limited to the lowermost 1?2-km layer,and assimilation of radiosonde data was more beneficial for modeled sea level pressure and near-surface wind speed.

Sediment Transport in the Nearshore Area of Phoenix Island

Based on the measured data, suspended sediment concentration, surface sediment grain size, current and waves, the sediment transport mechanisms and pathways in the Phoenix Island area were analyzed using methods of flux decomposition and Grain Size Trend Analysis(GSTA). The results show that net suspended sediment is mainly transported by average current, Stokes drift, and gravitational circulation. The transport direction of suspended sediment is varying and basically following the direction of residual tidal currents. Surface sediment transport pathways are primarily parallel to the coastline along with two convergent centers. Waves and longshore currents have a significant influence on sediment transport, but the influence is limited due to a steep and deep underwater bank. Tidal current is the main controlling factor for sediment transport, especially in the deep water area. Neither suspended nor surface sediment is transported towards the southwest. The South Shandong Coastal Current(SSCC) has little effect on sediment transport processes in the nearshore area of Phoenix Island.

Reflections on Maritime Parmership： Building the 21st Century Maritime Silk Road

The ＂Silk Road＂ is a general term used to geographically describe ancient Chinese exchanges between Asia, Europe and Africa in the areas of politics, economics and culture. Starting on land and developing on sea, the ＂Silk Road＂ is a vehicle of historic importance for the dissemination of culture. The ancient maritime Silk Road was developed under political and economic backgrounds and was the result of cooperative efforts from ancestors of both the East and West. China＇s proposal to build a 21st Century Maritime Silk Road is aimed at exploring the unique values and concepts of the ancient road, enriching it with new meaning for the present era and actively developing economic partnerships with countries situated along the route. Specifically, the proposal seeks to further integrate current cooperation in order to achieve positive effects.

The Distribution of Sedimentary Organic Matter and Implication of Its Transfer from Changjiang Estuary to Hangzhou Bay, China

In this study, a comparison was made between the Changjiang Estuary and the Hanghzou Bay, in terms of the sources and diagenesis of the sedimentary organic matter (OM). To achieve this purpose, surface sediments from the estuary and bay were analyzed for lignin-derived phenols, stable carbon isotope and TOC/TN (total organic carbon/total nitrogen) molar ratio. The signal of land-derived OM decreased, and the vanillic acid to vanillin ratio, (Ad/Al)v, increased with increasing distance from the Changjiang Estuary and the Hangzhou Bay. These results corresponded with the contribution of the terrigenous OM from the rivers to the coastal zone, and the predominance of marine OM farther offshore, and that the land-derived OM underwent decomposition during transport along the estuary and bay. It should be noted that besides the Qiantang River, Hangzhou Bay is also receiving more than half of its materials from Changjiang Estuary, which flows into the Hangzhou Bay at the north, and leaves via the southern part of the bay. This important aspect of the hydrological cycle in Hangzhou Bay corresponded to higher Λ (total lignin in mg/100 mg OC), higher TOC and C/N ratios and more elevated (Ad/Al)v and (Ad/Al)s values in the bay than the Changjiang Estuary, thus, rendering the bay as a site for the accumulation and rapid cycling of terrigenous OM.

A high-quality genome provides insights into the new taxonomic status and genomic characteristics of Cladopus chinensis(Podostemaceae)

The Podostemaceae are ecologically and morphologically unusual aquatic angiosperms that survive only in rivers with pristine hydrology and high water quality and are at a relatively high risk of extinction.The taxonomic status of Podostemaceae has always been controversial.Here,we report the first high-quality genome assembly for Cladopus chinensis of Podostemaceae,obtained by incorporating Hi-C,Illumina and PacBio sequencing.We generated an 827.92 Mb genome with a contig N50 of 1.42 Mb and 27,370 annotated protein-coding genes.The assembled genome size was close to the estimated size,and 659.42 Mb of the assembly was assigned to 29 superscaffolds(scaffold N5021.22 Mb).A total of 59.20%repetitive sequences were identified,among which long terminal repeats(LTRs)were the most abundant class(28.97%of the genome).Genome evolution analysis suggested that the divergence time of Cladopus chinensis(106 Mya)was earlier than that of Malpighiales(82 Mya)and that this taxon diverged into an independent branch of Podestemales.A recent whole-genome duplication(WGD)event occurred 4.43 million years ago.Comparative genomic analysis revealed that the expansion and contraction of oxidative phosphorylation,photosynthesis and isoflavonoid metabolism genes in Cladopus chinensis are probably related to the genomic characteristics of this growing submerged species.Transcriptome analysis revealed that upregulated genes in the shoot group compared to the root group were enriched in the NAC gene family and transcription factors associated with shoot development and defense responses,including WUSCHEL(WUS),ASYMMETRIC LEAVES(ASL),SHOOT MERISTEMLESS(STM),NAC2,NAC8,NAC29,NAC47,NAC73,NAC83 and NAC102.These findings provide new insights into the genomic diversity of unusual aquatic angiosperms and serve as a valuable reference for the taxonomic status and unusual shoot apical meristem of Podostemaceae.

Seasonal changes in sea ice conditions along the Northeast Passage in 2007 and 2012

Remote sensing data from passive microwave and satellite-based altimeters, associated with the data measured underway, were used to characterize seasonal and spatial changes in sea ice conditions along the Arctic Northeast Passage （NEP） and the high-latitude sea route （HSR） north of the island groups in the eastern Arctic Ocean in 2007 and 2012. In both years, summer Arctic sea ice extent reached minima since satellite records began in 1979. However, there were large differences in spatial distribution of sea ice between the two years. Sea ice conditions in the eastern sections of the sea routes were relatively slight in the 2007 summer, because of the remarkable decline of sea ice in the Pacific sector. A belt of sea ice that blocked sections from the western Laptev Sea to the eastern Kara Sea resulted in both sea routes not completely opening through the 2007 summer. The combination of a great storm in early August causing sea ice to be sheared from the Arctic pack ice and the thick ice surviving the winter delayed the summer opening of the eastern parts of the sea routes in 2012. However, the average open period, defined by 50% ice concentration for the entire NEP and HSR, reached 82 d and 55 d, respectively. Thus, 2012 was the most accessible year since the satellite era began in 1979. The distinct decrease in sea ice in the western parts of the HSR in the 2012 summer can be attributed to the thinning preconditions of sea ice prior to the melt season. The HSR opening can benefit Arctic shipping of deeper-draft vessels.

The adaptability of three Arctic microalgae to different low temperatures

In order to study the adaptability of Arctic microalgae to different environmental temperatures,the growth curves and antioxidase system of three microalgae （Skeletonema marinoi.Chlorella sp.and Chlamydomonas sp.） that were separated from the Ny-（？）lesund,the high Arctic,at different low temperatures （0℃,4℃and 8℃） were determined.The result showed that the adaptability of the microalgae to temperatures depended on the species.The growth rate,SOD and CAT activities of Skeletonema marinoi were the highest at 4℃, but MDA content was the lowest.The growth rate and enzyme activity of Chlorella sp.were the highest at 8℃,while the lowest MDA content presented at 0℃.The growth of Chlamydomonas sp.at the different temperatures was not so significant,the lowest MDA content presented at 8℃.The change of antioxidase system also depended on species and temperatures.Three indexes of antioxidase system of Skeletonema marinoi between 0℃and 4℃showed extremely significant difference（p0.01）.SOD activity of Skeletonema marinoi and Chlorella sp.between 0℃and 8℃showed significant difference（p0.05）, and the other two indexes of them differed insignificantly.Antioxidase systems of Chlamydomonas sp.at the three temperatures differed insignificantly.In conclusion, the three microalgae had good adaptability to the three temperatures; their MDA content presented a low level,and had unique physiological mechanism to adapt to the environment with different low temperatures.

Optimization of fluorescence in situ hybridization (FISH) for the identification of two polar coccoid green algae species

Standard FISH protocols using fluorochrome-labeled oligonucleotide probes have been successfully applied for in situ detection.However,optimized protocols of FISH for specific eukaryotes in marine environments are often not developed.This study optimized the conditions of fluorescence in situ hybridization （FISH） by using two polar isolated microalgae.The modified conditions were as follows：（1） 10 mg·mL^（-1） lysozyme solution pretreatment at 37℃for 30 min;（2） the hybridization buffer including 20%formamide;（3） the hybridization condition was 47℃for 6 h.The cells enumerated by FISH were compared with those enumerated by flow cytometry（FCM） and DAPI to confirm the cell loss and hybridization efficiency.The optimized protocol was also successfully applied to Arctic Ocean samples,which were found to be dominated by Micromonas sp.The modified protocol showed a high relative efficiency and could be successfully applied for the detection of specific microbial eukaryotes in environmental samples.

发展海洋合作伙伴关系 推进21世纪海上丝绸之路建设的若干思考（英文）

China's proposal to build a 21 st Century Maritime Silk Road is aimed at exploring the unique values and concepts of the ancient road, enriching it with new meaning for the present era and actively developing economic partnerships with countries situated along the route. Specifically, the partnerships the proposal seeks to further integrate current cooperation in order to achieve positive effects.

Numerical Modeling on Hydrodynamic Performance of A Bottom-Hinged Flap Wave Energy Converter

The hydrodynamic performance of a bottom-hinged flap wave energy converter （WEC） is investigated through a frequency domain numerical model. The numerical model is verified through a two-dimensional analytic solution, as well as the qualitative analysis on the dynamic response of avibrating system. The concept of ＂optimum density＂ of the bottom-hinged flap is proposed, and its analytic expression is derived as well. The frequency interval in which the optimum density exists is also obtained. The analytic expression of the optimum linear damping coefficient is obtained by a bottom-hinged WEC. Some basic dynamic properties involving natural period, excitation moment, pitch amplitude, and optimum damping coefficient are analyzed and discussed in detail. In addition, this paper highlights the analysis of effects on the conversion performance of the device exerted by some important parameters. The results indicate that ＂the optimum linear damping period of 5.0 s＂ is the most ideal option in the short wave sea states with the wave period below 6.0 s. Shallow water depth, large flap thickness and low flap density are advised in the practical design of the device in short wave sea states in order to maximize power capture. In the sea state with water depth of 5.0 m and wave period of 5.0 s, the results of parametric optimization suggest a flap with the width of 8.0 m, thickness of 1.6 m, and with the density as little as possible when the optimum power take-off （PTO） damping coefficient is adopted.

Assimilation of High Frequency Radar Data into a Shelf Sea Circulation Model

High Frequency(HF) radar current data is assimilated into a shelf sea circulation model based on optimal interpolation(OI) method. The purpose of this work is to develop a real-time computationally highly efficient assimilation method to improve the forecast of shelf current. Since the true state of the ocean is not known, the specification of background error covariance is arduous. Usually, it is assumed or calculated from an ensemble of model states and is kept in constant. In our method, the spatial covariances of model forecast errors are derived from differences between the adjacent model forecast fields, which serve as the forecast tendencies. The assumption behind this is that forecast errors can resemble forecast tendencies, since variances are large when fields change quickly and small when fields change slowly. The implementation of HF radar data assimilation is found to yield good information for analyses. After assimilation, the root-mean-square error of model decreases significantly. Besides, three assimilation runs with variational observation density are implemented. The comparison of them indicates that the pattern described by observations is much more important than the amount of observations. It is more useful to expand the scope of observations than to increase the spatial interval. From our tests, the spatial interval of observation can be 5 times bigger than that of model grid.

Translation-invariant wavelet denoising of full-tensor gravity-gradiometer data

Denoising of full-tensor gravity-gradiometer data involves detailed information from field sources, especially the data mixed with high-frequency random noise. We present a denoising method based on the translation-invariant wavelet with mixed thresholding and adaptive threshold to remove the random noise and retain the data details. The novel mixed thresholding approach is devised to filter the random noise based on the energy distribution of the wavelet coefficients corresponding to the signal and random noise. The translation- invariant wavelet suppresses pseudo-Gibbs phenomena, and the mixed thresholding better separates the wavelet coefficients than traditional thresholding. Adaptive Bayesian threshold is used to process the wavelet coefficients according to the specific characteristics of the wavelet coefficients at each decomposition scale. A two-dimensional discrete wavelet transform is used to denoise gridded data for better computational efficiency. The results of denoising model and real data suggest that compared with Gaussian regional filter, the proposed method suppresses the white Gaussian noise and preserves the high-frequency information in gravity-gradiometer data. Satisfactory denoising is achieved with the translation-invariant wavelet.

Neottia wuyishanensis(Orchidaceae:Neottieae),a new species from Fujian,China

A new species,Neottia wuyishanensis(Neottieae,Orchidaceae),is described and illustrated from Wuyishan,Fujian,eastern China,based on morphological characters and molecular data.Molecular phylogenetics indicate that N.wuyishanensis is nested within the clade formed by Neottia fugongensis and Neottia nujiangensis.Morphologically,N.wuyishanensis is similar to N.fugongensis and N.pseudonipponica,but differs from them by having indistinct auricles at the base,and in the shape and size of lobelets.