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Based on the Krig gridding method, 4D space-time terrain models of Lingdingyang estuary were constructed for two years of 1990 and 2008 respectively. And then, the Lingyingyang estuary can be divided into 5 regions of Humen region, Qi’ao island region, Lingdingyang shallow shoal region, Lingding waterway region and marginal region of Tonggu waterway, the shoreline migration and scour-and-fill space-time alternation in all these five regions since 1975 were quantitatively analyzed, combining with ²¹⁰Pb dating method. It had found that the land area of whole region had increased 216. 0 km ² ,the water area had decreased 84.6 km ², and the tidal-flat area had decreased 131. 4 km ²,the holding capacity of water area had reduced 19 783.7X10 ⁴ m ³,the mean annual silting quantity had reached 477. 4 X 10 ⁴ m ³,and the whole estuary was silting and atrophying constantly. The annual silting quantities of the 5 regions were-236.6X10 ⁴,135.3X10 ⁴, 663.7X10 ⁴,-452.7X10 ⁴ and 367.7X 10 ⁴ m ³ respectively, while the mean silting velocity Were-4.46,0.93,1.27,-5.49 and 2.93 cm/a respectively. The total depths in Humen region and Lingding waterway region had increased while those in other regions had decreased. The silting extent in marginal region of Tonggu waterway was significant. The main reason of the increasing water depth in Humen region is natural degradation and manual sand digging while the deepening in Lingding waterway region is the result of artificial desilting. Tonggu waterway is a new digged artificial channel. Influenced by manual dredging mud, water depths at both sides of each channels decreased apparently. But the changes of water depths in other regions were the results of natural evolution of delta. With the fast development of economics at two sides of Lingdingyang estuary, the manual activity had been the main factor for the evolution of seafloor relief and landform in this region.

The characteristics of tropical-cyclone(TC) activities over the western North Pacific during 1951-2016 were analyzed using three TC best track datasets(CMA, JTWC and RSMC). The consistent conclusions in three datasets are as follows: TCs mainly occurred in the latitude of 10°N-25°N. Before 1980, there was a southward latitude shift of TC position points, while it was the opposite after 1980. The TC translation speed was mostly distributed in the 2~6 m/s, and TCs significantly sped up near 25°N. The TC translation speed had a significant decrease trend before 1980. The maximum wind speed was mainly distributed in the range of 10~15 m/s, and it decreased before 1980. The radius of maximum wind speed was relatively smaller in the region with larger maximum wind speed. The radius of maximum wind speed of TCs and typhoons decreased by 0.46 km and 0.54 km per year respectively during 2001-2016. The results of CMA and RSMC were highly consistent, while the results of JTWC were different from them to some extent. The difference between the three datasets had a great influence on the change of TC intensity and the numbers of position points, but had a little influence on the change of the TC location and translation speed.

A knowledge of the effects of major currents, extent of hypoxia, tidal effects, and aquaculture activities on speciation and distribution of particulate phosphorus in surface sediments in the Changjiang Estuary (CJE) and coastal waters of Zhejiang is critical to develop a sustainable strategy for the East China Sea (ECS). Two hypoxic zones are located in this region, one off the CJE in the north and the other in the muddy deposits along the Zhejiang coast of the ECS. Hangzhou Bay is a tide-dominated bay, and Xiangshan Bay is an aquaculture area influenced by tidal mixing. Surface sediments were collected from above four regions during August to September, 2018, and sedimentary phosphorus speciation were quantified using SEDEX method. Under reducing conditions at the mud-water interface in the two hypoxic zones of the ECS, iron bound phosphorus (Fe-P) in the sediments were transformed into exchangeable inorganic phosphorus (Ex-iP) which were immediately bioavailable, as evidenced by low Fe-P and high Ex-iP in the sediments. As the hypoxic zone off the CJE was more oxygen deficit, the contents of Fe-P in the sediments were also lower. Tidal mixing in Hangzhou Bay and Xiangshan Bay led to homogeneous distribution of particulate phosphorus in the surface sediments. All surface sediments in Xiangshan Bay were characterized by very low Fe-P, because tidal mixing caused the hypoxic areal extent, resulted from dense aquacultures, to be further increased to cover the whole bay area. The contents of detrital and refractory phosphorus in the surface sediments in a deserted aquaculture farm were substantially lower than those in non-aquaculture area, most likely due to dilution by biomass accumulated during culturing.

 The temporal and spatial change characters of coastline and tidal flat in the islands with different principle functions in the Zhoushan Archipelago were analyzed, using a coastal remote sensing monitoring dataset with 30 m spatial resolutions at annual interval from 1986 to 2017. The results suggested that the coastlines in Zhoushan Archipelago advanced toward the sea, with many water areas(152 km2) and tidal flats(18 km2) reclaimed into lands and the government policies were the main driven factors. The change characters were various among the islands with different principle functions. In particular, the land reclamation was significant in the islands with the principle functions of comprehensive development, coastal industry, coastal tourism, and harbor and logistics, accounting for 96% of the archipelagos new lands. The land reclamation was slight in the islands with marine science and education and scientific fishery functions, accounting for 4% of the archipelagos total new lands. Meanwhile, the coast was stable and well protected in the islands with ecological conversation and clean energy functions. The results could provide scientific basis for coastal zones ecological protection and restoration projects, as well as the marine principle functional zoning.

The river-estuary-coastal ocean continuum (referred to as the continuum hereinafter) is a transition zone connecting lands and oceans. The carbon budgets in the continuum are dynamic and uncertain components in global carbon budgets. This complex landocean interactive ecosystem can absorb atmospheric CO2 through photosynthesis and dissolution of CO2. Also, the carbon fixed by photosynthesis or chemical weathering in land and watershed can be transported horizontally to the shelf waters and open oceans. In this paper, the progress of carbon cycles in the continuum is reviewed by taking the famous Chesapeake Bay and Changjiang Estuary-East China Sea continuum as typical examples. It is concluded that systematic observation characterized with land-sea coordination, sea-space integration, point-line combination, should be combined with physicalecological numerical simulation to reveal the multiple time-space scale processes. The strategy is generally operable, and the historical retrospective of results is also achievable. Thus, it can be used to clarify the evolution of carbon exchange along the river-estuary-coastal ocean continuum and their influences on carbon budgets under the combined pressures of climate change and anthropogenic activities.

In order to study the deep resistivity structure of intraplate volcanoes and their formation processes, a marine magnetotelluric survey at Suda Seamount in the western Pacific Ocean was conducted. The mainstream data processing method SSMT2000 was used for data processing. The measured data after rotation and the two groups of rotation invariants obtained from the measured data were tested for magnetotelluric response under the assumption of one-dimensional structure, and one-dimensional inversion was conducted for the YX direction data with the best response. Combined with one-dimensional forward modeling and other geological data, the inversion results were comprehensively interpreted. The inversion results show that the thickness of the crust at Suda Seamount is about 21.5 km. The thick volcanic clastic rocks indicate that the formation of Suda Seamount is mainly eruptive and weakly intrusive.

Sea surface temperature (SST) is the critical factor for depicting the marine thermal distribution. Daily global SST data sets support the typhoon elaborated monitoring and other marine disasters forecast. SST products retrieved by the visible infrared radiometers and mediumresolution imagers have high spatial resolution, while the SST products retrieved by infrared remote sensing are affected by clouds, fog and haze, and therefore a large areas under the clouds are lack of value. SST products retrieved by the microwave radiometer have low spatial resolution, while the microwave could penetrate the cloud layer to achieve all-weather sea surface observation. The data interpolation empirical orthogonal function method (DINEOF) was used to reconstructed the global SST products, and FY-3 (Fengyun 3) SST data sets were applied in this study, which included the SST data sets from the FY-3B/FY-3C Visible and Infra-Red Radiometer, FY-3D Medium Resolution Spectral Imager and FY-3D Micro-Wave Radiation Imager. Accuracy of the reconstructed data sets was verified using OISST measurements to demonstrate the validity and reliability of the DINEOF method. The results show that DINEOF reconstructed sea surface temperature (DSST) data are validated reliable. Root mean square error of the original data is ranging from 0.59 ℃ to 0.70 ℃, while the reconstructed data is relatively stable, ranging from 0.10 ℃ to 0.34 ℃. Correlation coefficient obvious raises from 0.33-0.48 to 0.78-0.98. Multi-sensors reconstructed SST products is continuous and credible in spatial distribution and monitor the variation of warm pool from spring to winter. Addition of FY-3D microwave SST products has significantly improved the spatial continuous distribution and temporal resolution of reconstructed SST.

Optical dissolved oxygen sensor based on fluorescence quenching principle can obtain spatiotemporal data of dissolved oxygen in seawater, which is widely used in long-term monitoring of marine environment. However, due to the “storage drift” and “measurement drift” occurring during storage and distribution, it is necessary to calibrate and correct the data drift of the instrument. Existing calibration methods have long cycle and complex operation. In this project, the response characteristics of optical dissolved oxygen sensor in air and water medium were studied, and a field calibration method of optical dissolved oxygen sensor using air medium was proposed, and a two-point calibration model of the instrument was established. Experimental results show that the calibration method can effectively correct the data drift of the dissolved oxygen sensor, and the deviation between the measured value of the sensor and the standard value of Winkler titration is within  ±6 μmol·L-1. This method can realize the convenient and rapid correction of optical dissolved oxygen sensor, avoid the tedious steps of laboratory maintenance, improve the quality of monitoring data, maintain the continuity of monitoring data, and has important application value.

Marine gas hydrate deposits are significant temporal reservoirs for hydrocarbons migrating from deep sources. This is crucial to our understanding of ocean carbon cycling. The cold seep, a geological process regarding gas leakage from deep or shallow sources, is usually linked with gas hydrate decomposition. In this thesis, we reviewed the latest applications of in situ monitoring and detecting methods regarding the leakage plumes, migration pathways, and seafloor geomorphologies associated with gas hydrate and cold seep systems, primarily including vessel-and land-based gas plume measurements, surface ocean-lower atmosphere hydrocarbon emission detections, seafloor visualization techniques, and in situ observation networks. The integrated applications of these in situ observation methods provide a nuanced view of the temporal and spatial variability of hydrate and cold seep systems, facilitate understanding of the fate of hydrocarbons, and expand our knowledge of cold-seep biota in a watery desert.

Based on the measured water level data of Xiuying Station from 1980 to 2017, the distributional characteristics and influencing factors of storm surge in Haikou were studied by using the methods of statistical analysis and numerical model. It is found that Haikou is frequently affected by typhoon storm surge, with an annual average of 2.79 times, which usually occurs from July to October, and the probability of tidal disaster caused by storm surge is high. The horizontal distribution of storm surge shows that the storm surge intensity of Dongzhai Port ranks first, followed by Xiuying Port, Haidian Island and South Port. Influencing factors show that the weight of topography is usually greater than the moving path of tropical cyclone storm surge in Haikou; when the moving speed of tropical cyclone is 14-19 km/h, the storm surge in Haikou is usually the largest.

Based on multi-platform observed data, an unexpected response of a warm mesoscale eddy to bypassed typhoon Megi in the South China Sea in 2010 was observed and investigated. During the passage of typhoon Megi, the SLA maximum of the warm eddy increased from 30 to 36 cm, the radius increased from 78 to 116 km, the eddy kinetic energy increased from 166 to 303 m²/s², and the amplitude increased from 3 to 9 cm. On the right side of the typhoon, the thermocline water at Argo station on the edge of the warm eddy sank by 20 to 40 m. Diagnosis of the wind stress curl alone indicates that the warm eddy should be weaken and the thermocline should be raised, which are inconsistent with the observation results. Diagnosis based on the reanalysis sea surface velocity indicates that during the passage of typhoon Megi, the water diverges below the typhoon path, while the water converges on the right side of the path in the warm eddy region, and the SLA maximum as well as the amplitude of warm eddy are positively correlated with the convergence intensity. Estimation based on the reanalysis sea surface velocity also indicates that the water at Argo station will sink 29 m. Both the warm eddy characteristics and the thermocline depression are consistent with the observation. The case study shows that the response of mesoscale eddy on the edge of typhoon influence to typhoon is constrained not only by wind stress curl but also by the oceanic background conditions, and further attentions are required to explore the corresponding response and mechanism of upper ocean to typhoon.

Combined with the Holland wind fields and the ERA5 wind fields, the mixed wind fields was set up by introducing a weight coefficient varying with the radius of wind speed, and a typhoon wave model in Zhejiang sea area was established using MIKE21 SW. Then, the Holland, the ERA5 and the mixed wind fields were used as the input wind fields to simulate the wind speed and the significant wave height during No.1918 typhoon Mitag, respectively. The verification shows that the simulated results obtained using the Holland wind fields and the ERA5 wind fields cannot agree accurately with the observed data, while the mixed wind fields proposed in this study can improve the simulation accuracy. In order to study whether the above conclusion is universal in Zhejiang sea area, five typical typhoons that have the most serious impact on Zhejiang sea area in the recent 5 years were selected for typhoon wave numerical simulations and the error statistical analysis. The results indicate the wind speed around the typhoon center is relatively good using the Holland wind fields and the average relative errors of the maximum wind speed are 8.62%-10.19%, but the average relative errors of the wind speed below 10 m/s is relatively bigger, reaching 29.76%-44.29%. However, the wind speed around the typhoon center using the ERA5 wind fields is smaller than the observed data, and the average relative errors of the maximum wind speed are 17.64%-25.77%, but the average relative errors of wind speed below 10 m/s are smaller than that using the Holland wind fields, which are 19.64%-32.00%. During the five typhoon processes, the average values of the average relative errors of the significant wave height driven by Holland, the ERA5 and the mixed wind fields are 29.92%, 25.62% and 22.82%, respectively. Correspondingly, the average root mean square errors are 0.46 m, 0.42 m and 0.39 m and the consistency indexes are 0.94, 0.95 and 0.96. The above results shows that the mixed wind fields proposed in this study is universal in Zhejiang sea area and can improve the simulation accuracy of typhoon waves.

Since Spartina alterniflora was transplanted on the Jiangsu coast in 1979, its rapid expansion has a great impact on the native coastal ecosystem. In Rudong, Fistulobalanus albicostatus provides a typical example of the influence by the expansion of Spartina alterniflora. In the present study, 28 quadrates along 5 tidal creeks were sampled during October 2012, to collect the above-ground parts of Spartina alterniflora plants and the barnacles attached to the plants. The maximum elevation at which barnacles attach to the plants were measured. Analyses of the samples reveal that the barnacles are distributed within a narrow zone, on average 5 m wide on both sides of the tidal creek; their landward extension is determined by the size of the tidal creek, i.e. a larger creek is associated with a longer extension. The maximum elevation at which barnacles attach to the plants shows the same level at different sites. Fistulobalanus albicostatus is the only barnacle species in the study area; its average biomass is 273±69 g·m ^-2, and most barnacles have a diameter of 2~10 mm in the autumn. Biomass of Spartina alterniflora is 981±81 g·m ^-2. Plants near the tidal creeks are tall and lower popularity density, while plants far away from the tidal creeks are undersized but higher popularity density. Correlation analysis indicates that although Spartina alterniflora provides the barnacles with an attachment base, its influence on the biomass and spatial distribution pattern is weak. The dominant factor of barnacle attachment-distribution is seawater inundation. The importance of the inundation time implies that the negative topography in relation to tidal creeks is beneficial to the attachment and survival of the barnacles. Meanwhile, higher velocity in tidal creek is advantageous for barnacle attachment, and flooding and ebbing tides in the creek will bring abundant food for barnacles.

Space-borne Synthetic Aperture Radar (SAR) has become one of the new methods for the research of the offshore wind energy resources remote sensing. In this study, progress on the study of offshore wind energy resources remote sensing by space-borne SAR has been reviewed. Especially both the technology and application of the offshore wind energy resources remote sensing, and also the offshore wind turbine wake remote sensing by space-borne SAR are mainly introduced. Meanwhile, we discuss some issues in the present of the studies on the offshore wind energy resources remote sensing by SAR and the research orientation in future.

Based on the main beache quality evaluation systems at home and abroad and combined with the actual situation of island beaches in Zhejiang Province,a suitable quality evaluation system was constructed for Zhejiang Province. The system has 29 factors in number, including 3 large classes and 7 subclasses, which was used to evaluate 63 island beaches in Zhejiang. The result shows that the overall quality of the beach at the middle level, as there are 7 five-star beaches,19 four-star beaches,29 three-star and 8 two-star beaches, which indicates that the evaluation system has better applicability.

Two-phase leaching method can separate hydrogenetic and residual mineral phases of ferromanganese nodules, which will provide valuable information with the research of ferromanganese nodule mineralization and pale-environment. In order to study the applicability of the two-phase leaching method in the nodule mineralization research for different types of nodules compared to the bulk sample results, the ferromanganese nodules samples from six stations were selected, which were collected on the seamounts area of western Pacific Ocean and CC Zone of eastern Pacific Ocean, respectively. Geochemical and mineralogical compositions of the bulk samples were analyzed, and elements compositions of the hydrogenetic and residual mineral phases were analyzed, which were obtained using the two-phase leaching method. The results indicated that the mass ration variation of the residual mineral phases was not obvious with about 14.0%-17.6%, which had high contents of Nb, Rb, Ta, Ti, Zr. Contents and relevant rations of elements such as Co, Ni, Cu, Zn, Sr, REY in the hydrogenetic mineral phase showed similar features with those in the bulk samples. Proportion of elements contents like Ti, Nb, Sr between hydrogenetic and residual mineral phases showed well negative correlation with Mn/Fe values, which probably could be regarded as index for ferromanganese nodule mineralized environment research in the future.

Due to the lack of geological and geophysical data of the Diaoyudao Uplift, the previous studies on this area are unsystematic, so there are many controversies about its tectonic evolution. Based on gravity, magnetic, and multichannel seismic data, the tectonic and sedimentary characteristics of the middle Diaoyudao Uplift were analyzed, which located to the east of the Xihu Depression, East China Sea Basin. The evolution model of the middle Diaoyudao Uplift was further refined. More residual sags are found in the north than in the south of the middle Diaoyudao Uplift. Accordingly, the middle Diaoyudao Uplift can be divided into the north and south segments. The boundary of the two segments is on the extended trace of the Zhoushan-Guotou Fault. In addition, magmatic intrusions are confined below the T20 unconformity in the west, whereas a basement pinnacle caused by magmatic activity exists in the east. It is found that the gradient zone of gravity anomaly corresponds exactly to the western edge of the basement pinnacle. Taking the west edge of the basement pinnacle as the boundary, the middle Diaoyudao Uplift can be divided into two parts from west to east. And the western zone can be further divided into two subzones, including part Ⅰ with magnetic rocks and part Ⅱ with residual sags. The western part of the middle Diaoyudao Uplift is from the strong tectonic and magmatic deformation of the eastern Xihu Depression, whereas the east part retained the original Diaoyudao Uplift. The comprehensive analysis of above features showed that the present-day middle Diaoyudao Uplift was formed by many episodes of tectonic events and magmatic activities around an ancient uplift.

Mangrove is a kind of biological coast composed of salt tolerant mangrove plant communities. Its growth status is of great significance to the coastal zone. Remote sensing technology has become one of the main means for mangrove monitoring. In this study, taking the mangrove in Shankou, Beihai of Guangxi as an example, using the coastal zone imager data of HY-1C satellite, combined with its texture parameters, the mangrove information was extracted, and the mangrove vegetation indexes were analyzed. The results showed that from October to November 2018, the RVI value of mangroves was greater than 1, and this in some areas was greater than 5; the NDVI value of mangroves varied from 0 to 0.01, and the average value was greater than 0.5; the EVI value of mangroves was mainly concentrated between 0.2 and 0.7. The results of different vegetation indexes showed that mangrove in Shankou grew well.

Mangroves, coastal salt marshes and seagrass beds, as the typical coastal blue carbon ecosystems, have been widely recognized for their remarkable capacity in carbon storage. Vegetation carbon pool and sediment (or soil) carbon pool were considered to be the major carbon pools within the coastal blue ecosystems and their variations determined the overall carbon sequestration of the ecosystems. From a perspective of carbon pool interactions, this study summarized the previous research work based on literature review, including the interactions within various vegetation carbon pools and within various sediment carbon pools, as well as the interactions between vegetation and sediment carbon pools. Interspecific competition, allochthonous carbon input and biogeomorphology were found to be the key to understand the carbon pool interactions. Finally, a perspective on the current state-of-the-art of blue carbon pool study is offered, with challenges and suggestions for future directions.

With the increasing saturation of coastal nuclear power plant sites, it is a new idea to select islands as nuclear power plant sites. In view of the problem that the island sites are vulnerable to typhoon disasters, the design basis flood level of the sites is determined by studying astronomical high tide, sea level rise, possible maximum storm surge and maximum typhoon wave. The results show that the astronomical high tide level of 10% superfrequency in this region is 3.14 m and the predicted sea level rise in the next 80 years will be 0.31 m. Based on MIKE21 model, a variety of hypothetical typhoon paths were constructed using tropical cyclone parameters. The northwest moving path of typhoon with 0.5 R (R is the maximum wind speed radius of typhoon) to the left of the site produces the possible maximum storm surge, with the maximum water level of 2.99 m. When the typhoon moves in the direction of west, with R to left of the site, the maximum H _1/100 wave height reaches 8.02 m, especially on the east side of the island, which suffers from severe typhoon wave threats. Considering the superposition of various basis flood factors, the design basis flood level of the island nuclear power plant site reaches 11.25 m. Because the proposed site is located on an island and surrounded by sea waters, compared with other coastal sites, the storm surge level is relatively small, but the impact of waves is more significant.