Speciation and distribution of phosphorus have a direct effect on the primary production and marine biogeochemistry. However, the complex current dynamics in aquatic critical zones such as large river delta and coastal area result in variable characteristics of the phosphorus speciation and distribution that need in depth study. The content, distribution and influence factors of total particulate phosphorus (TPP), particulate inorganic phosphorus (PIP) and particulate organic phosphorus (POP) in the suspended particulate matter (SPM) in the Zhejiang coastal area off Changjiang Estuary were discussed based on the investigation from April to May (spring), July (summer) and September to October (autumn) in 2016. The results showed that the content ranged from 0.13 μmol/L to 66.13 μmol/L, with an average of 3.35 μmol/L for TPP, from 0.03 μmol/L to 34.19 μmol/L with an average of 1.97 μmol/L for PIP, and ranged from 0.06 μmol/L to 31.94 μmol/L with an average of 1.39 μmol/L for POP. PIP was the dominant (52.3%) form of particulate phosphorus in the Zhejiang coastal areas. The percentage of TPP in total phosphorus ranged from 19.3% to 97.7% in spring for surface samples. The spatial distribution patterns of TPP, PIP and POP contents were similar in spring and autumn, decreasing from the inner bay to offshore areas. The content of TPP was higher in areas where the SPM was higher while PIP and POP showed a positive correlation with SPM, indicating an influence from terrestrial input. The regression coefficient and slope between POP and chlorophyll a were significantly higher than that of PIP in the area with salinity above 28 and SPM below 20 mg/L in spring, indicating contributions from phytoplankton to POP accumulation.

Carbon sinking is one of the important ecological services of ocean ecosystems, which acts as a driving force for energy flow and material cycle. Based on the 48th China scientific cruise in the northwest Pacific Ocean, the investigation on the sedimentary environment of intermountain basin was carried out regarding to the characteristics and influencing factors of total organic carbon mass accumulation rate (F_orgc). The results show that the F_orgc in the northwestern Pacific Ocean basin ranges from 1.41 g/(m²·ka) to 1.73 g/(m²·ka), with an average of 1.60 g/(m²·ka). As a whole, about 0.003 1% of the region’s net primary productivity is buried in sediments annually. Both F_orgc and net primary productivity transfer efficiency are lower in the northwestern Pacific intermountain basin in comparison with those in the eastern Pacific Ocean and equatorial Pacific Ocean. Many environmental factors influenced the F_orgc in this area, induding biogeochemical factors in the water column and sediments, such as net primary productivity, sediment mass accumulation rate, organic carbon content, redox potential, and those topographic factors, such as the distance from the nearest seamount and water depth.

Acaudina molpadioides is a low-value sea cucumber. We studied the characteristics and annual variation of gonadal development of A. molpadioides in north coast of Fujian based on histological and morphological observation. We continued to explore its gender ratio, reproductive cycle, spawning pattern and reproductive season. Results showed that the testis and ovary development of A. molpadioides could be divided into six stages: resting stage (I), early developmental stage (II), growing stage (III), mature stage (IV), partly spawned stage (V) and spent stage (VI). The gonadal development of A. molpadioides in males and females were basically synchronous, and it followed an obvious annual development rule. The majority of gonads matured in May. Subsequently, gametes were being released meanwhile with tubules destruction. Then new tubules grew up, which meant the gonad started a new cycle. The gametogenesis initiated in November, and gametes gradually developed till matured in next May. A. molpadioides had a gender ratio close to 1∶1 and an annual reproductive cycle. Its reproductive season was from May to August (summer), when it spawned several times.

Based on the CTD data from the 28th, 29th and 31st Chinese Antarctic Expedition cruises, we calculated dissipation rate of turbulent kinetic energy by using Thrope scale method, and analyzed the distribution characteristics of the dissipation rate and the structure of water masses in the Prydz Bay and its adjacent waters. Results show that the subsurface dissipation rate intensity of turbulent kinetic energy in the first two cruises reach maximum on the shelf break of Prydz Bay. Moreover, we compared the distribution of water masses among the three cruises and found intrusion of the modified circumplar deep water into the shelf happened on the 28th and 29th cruises. The the modified circumplar deep water could reach the depth of 100 m and 200 m on the cruise of 28th and 29th, respectively, and can extend southward to 67.5°S. Furthermore, the distribution of subsurface dissipation rate of turbulent kinetic energy on the shelf break of Prydz Bay are well related to the structure of local water masses. Therefore, the intrusion of the modified circumplar deep water into the shelf could induce instability of the local waters, promote water exchange and finally enhance local turbulent mixing.

In order to study the wave characteristics in the Sanmen Bay, field observation based on AWAC data acquisition equipment was continued for one year, and the statistical analysis, linear regression analysis was done. Moreover, statistics and spectral variations of waves during the typhoon occurrence were investigated, and the reason for the variations was determined on the basis of wave data collected. The results show that the dominant wave direction and the strong wave direction are both E due to the topography of coastal areas; during the wave observation period, H_1/10 is mainly under 0.8 m, and H_max is 2.71 m; the distribution of wave characteristics is a typical Rayleigh distribution in this region; the wave spectra estimated during Typhoon Talim is double-peaked, and the total wave is a combination of swell and wind sea, when the low frequency swell about 0.08 Hz is in a dominant position and the high frequency wind sea about 0.25 Hz is relatively weak. This study will be important as reference in the design of offshore structures as well as for disaster prevention and mitigation.

A series of laboratory experiments is carried out in a wave flume to study the influence of rough reef surface on solitary wave transformation and run-up over coral reefs. The cylinder array is used to model the reef surface with large roughness. The results show that the rough reef surface significantly reduces the leading solitary wave and the secondary wave due to beach-reef beach reflection, as well as the wave speed on the reef flat. The relative cross-shore wave height decreases with the increase of dimensionless incident wave height along the reef. It also increases with the increase of reef-flat wave level. The cross-shore wave height attenuation is more evident with the rough reef surface. The variation of dimensionless reflected wave height with the dimensionless incident wave height depends on the reef-flat wave level. The dimensionless reflected wave height approaches to a constant when the incident wave height is sufficient large. The rough reef surface slightly enhances the wave reflection from the fore-reef slope. The dimensionless transmitted wave height as well as wave run-up decline with the increasing dimensionless incident wave height, particularly for the large reef-flat water level. The dimensionless wave run-up on the back-reef beach with the rough reef surface reduces by an average of 46% compared to that with the smooth surface. An empirical formula is obtained by a regression analysis to predict the wave run-up with both smooth and rough reefs.

Based on the one-layer Boussinesq model with highest spatial derivative being 3, a numerical model is established for focused wave group. The numerical model is solved with predictor-corrector scheme in finite differential method. For time integration, a third-order Adams-Bashforth scheme and a fourth-order Adams-Moulton scheme are separately used in predicting stage and correcting stage. Firstly, the numerical simulations are carried out upon nonlinear regular wave evolution over a constant water-depth in a flume, and the computed results are compared with the semi-analytical solutions. The results demonstrate that the simulated surface elevations, the horizontal velocity and vertical velocity on the free surface can well match the related analytical solutions, while the agreement of the horizontal velocity profile under the crest becomes worse with the increase of water-depth, and the range of the model with respect to nonlinear horizontal velocity profile is for kh<3.5, which is similar to the range of the related linear model with respect to horizontal velocity profile. Secondly, the numerical simulations are conducted upon the nonlinear focused wave group evolution in deep-water. The linear wave groups are used as incident wave conditions. The laboratory experiments conducted by Baldock and Swan (1996) are used to examine the present model. Both the computed surface elevations and the horizontal velocity profile at the focused position are compared with the related experimental data. The results show that the agreement of the surface elevations is pretty good, while the agreement of the horizontal velocity profile is moderate. Finally, with the middle frequency being kept unchanged, the numerical simulations upon the maximum surface elevation and horizontal velocity under the crest are conducted with the variation of the range of focused wave period, the results show that both the crest and the horizontal velocity increase with the increase of the range of the wave periods.

Wind not only drives the surface ocean circulations, but also provides the main source of kinetic energy for deep ocean movements. This study focuses on the wind energy input to the north part of the North Pacific, including wind energy input to surface wave, surface geostrophic currents and surface ageostrophic currents. Results based on SODA3 (2000–2016) data show that there are obvious seasonal wind energy input gateways, which are the Subpolar Gyre for spring and autumn, the Eastern Pacific for summer and the Kuroshio Extension for winter respectively. The winter gateway gains the most wind energy among the four seasonal gateways, which is about 3−5 times higher than others. Since the beginning of the 21st century, wind energy input in winter gateway has weakened significantly, while increased in spring gateway, but has not changed significantly in summer and autumn gateway. For the spatial distribution of the trend in the 17 years, wind energy input to the surface wave is mainly dominated by the wind field, while wind energy input to the surface geostrophic current and ageostrophic current is dominated by the flow field. These mechanical energy input results are important for further understanding the ocean circulations in the North Pacific.

The formation and evolution of the South China Sea is well recorded in the northern continental margin. But the discrepancies of the tectonic and sedimentary evolution between the west and east of the northern margin are still enigmatic. Several drilling and simulation wells with analogous geological setting are chosen from the deep water areas of the Zhujiang River Estuary Basin and the Qiongdongnan Basin. Based on backstripping and previous studies, high resolution sedimentation rates and subsidence rates are constructed. Results show that both two basins are characterized by analogous sedimentation rates and subsidence rates in the syn-rift stage, but significant discrepancies are revealed in the post-rift stage. Episodic sedimentary and tectonic evolution characteristics are revealed in the Zhujiang River Estuary Basin, sedimentation rates are characterized by “two rapid sedimentation periods and three slow sedimentation periods” and subsidence rates are characterized by “two rapid subsidence periods and one slow subsidence period”. But the sedimentation rates are characterized by “graben” style evolution, and the subsidence rates are characterized by “step-up” style evolution in the Qiongdongnan Basin. The “step-up” subsidence rates in the Qiongdongnan Basin might be controlled by activities of the Hainan mantle plume which moved northwestward derived from the dextral strike-slip of the Red River Fault. And it coincided with the magmatism and the subsidence rate in the northwest margin of the South China Sea. The distribution of the rapid deposition and accelerated subsidence in the Qiongdongnan Basin after 1.8 Ma BP could be mainly controlled by the meanwhile dextral strike-slip of the Red River Fault.

In recent years, several deep-water gas fields of Yinggehai Formation have been discovered in ultra-deep water area of Qiongdongnan Basin, showing a broad exploration prospect. However, the reservoir physical property prediction of the Member 2 of Neogene Yinggehai Formation have become increasingly prominent which seriously restricts the further exploration of oil and gas. Based on the regional geological data summarized by predecessors, combined with core, logging and three-dimensional seismic data, the third-order sequence framework of the Member 2 of Neogene Yinggehai Formation is established, and the provenance systems in the sequence framework and the sedimentary characteristics of gravity flow under its control are comprehensively analyzed. The results show that gravity flow sedimentary system mainly developed in Ⅱ2-ygh2c and Ⅱ2-ygh2b, and include three major provenance systems which are the south, the north and the axis. Different rovenance systems control the spatial distribution and sedimentary characteristics of gravity flow reservoirs. (1)The submarine canyons controlled by the south provenance are mainly filled by abyssal mudstone, while the canyons controlled by the north provenance are mainly filled with thick turbidite channel sandstone with fine porosity and permeability, which is a good reservoir. (2) The flood plain deposit affected by axial provenance can also be a good oil and gas reservoir because of its good physical properties. (3) The submarine fans controlled by the south provenance is characterized by thin sandstone with fine grain size and high argillaceous content. While the submarine canyons and fans controlled by the north and the axis provenance formed large scale sandstone with big thickness, coarse grain size and good reservoir physical properties, which are the most important high-quality gas-producing reservoirs of deep water area.