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The transportation capacity of South China Sea mesoscale eddy was studied using Drifter buoys, combined with satellite altimeter data and tracer particles method. Both Drifter buoy data and the flow field showed the existence of the eddy transportation in the real ocean. The Drifter buoy moved into the anticyclonic eddy, and then followed the eddy to make 4 turns, in the end, the Drifter buoy moved towards the east of Hainan Island with arc-shaped trajectory. From the long-term simulation results using tracer particles method, we learned the particles in the eddy moved forwards in the same rotational direction, 93% particles(153) followed the eddy motion, and 7% particles(11) were separated from the eddy in midway. The eddy throwed the particles from inside to edge of eddy, some particles were out of the eddy from the place of the eddy edge, in which the speed turned from large to small. But most particles followed the edge of eddy with arc-shaped trajectory; finally, they were stabled at the very edge of the eddy.

With the statistic results about a total number of 462 heat flow values and geothermal gradient values, the present geothermal field in the northern margin of the South China Sea is characterized with “general higher heat flow values and higher geothermal gradient values”. The heat flow values increase from continental shelf to ocean basin against the trend of the crust thickness and Moho depth. Thermal Curie Point Isotherm (the 575 ℃ isotherm) was obtained according to the static geothermal temperature field calculated from the heat flow and geothermal gradient survey data. Magnetic Curie Point Isotherm was obtained by inversion of the magnetic anomalies. The results show that the two Curie Point Isotherms derived respectively from the prior two methods are inconsistent with significant differences in the middle and lower slope in the northern margin of the South China Sea. The Magnetic Curie Point Isotherm is above the Thermal Curie Point Isotherm between fault F2 and fault F4 in the integrated profiles of OBS93 and ESP-E, which means that some magma under-plating events caused the thermal disequilibrium in this region. Based on the study of the crust structure, crust expansion coefficient, Moho depth, faults and magma activities, the author points out that the variation trend of the heat flow values in the northern margin of the South China Sea is controlled by the magnitude of the lithosphere thinning and Moho uplifting. The magma activities during the Neo-tectonic period might be a factor for the local heat flow anomaly.

The distribution of gas hydrate is affected greatly by the migration of gas fluid. The leakage of gas fluid is common in the slope of northern South China Sea, especially in the Baiyun Sag in the Pearl River Mouth Basin, which implies good prospect of gas hydrate occurrence. According to high resolution seismic data about the Shenhu Area, large numbers of fuzzy zones with different morphological characteristics were recognized. They were considered to be main channel of free gas and could be classified into two types: corolliform and dome-form. The existence of fuzzy zones implied that there was a good condition for the migration of gas hydrate in this area, which could provide a vertical channel for free gas migration. Drilling results showed that gas hydrate zones were related to special distribution of fuzzy zones. The corolliform fuzzy zones connected with a set of middle size faults, which promoted the free gas moving to the flank area. The top might connect the small crack with which the free gas could move upwards to the gas hydrate stability zone to form gas hydrate. The top of dome-form fuzzy zones might connect to seafloor through the gas fluid crack. This kind structure could cause the free gas escape and therefore could not form the gas hydrate. This classification method could provide a new indicator about gas hydrate distribution.

Wetland vegetation biomass is the basic information of wetland ecological assessment, protection and utilization. Remote sensing has become one of the most efficient technologies of wetland biomass monitoring. Utilizing the HJ-1 hyperspectral remote sensing image that acquired in September 2013 and the coinstantaneous field survey data, the biomass estimation capabilities of 7 kinds of narrow-band vegetation indices and 2 kinds of red edge position indices of reeds and suaeda in the Yellow River Estuary have been studied. The results reveal that (1) In single variable estimation model case, for reeds, the SRI index with 635 nm and 827 nm bands and REP_ linear interpolation index get the best R² measures, and for suaeda, the NDVI and SRI indices with 692 nm and 807 nm bands and OSAVI index get the best biomass estimation results. (2) In multiple variable case, for reeds and suaeda, the R² measure get 0.71 and 0.66 respectively.

Using supervised classification method of Landsat satellite sequence remote sensing data, historical changes both cage and longline culture method types of aquaculture farming of Dongshan Bay were identified and analyzed. From 1999 to 2012, the mariculture area expanded ten times while the longline culture-based is 5.6 times the area of cages culture-based. Reasonable mariculture pattern were adjusted year and year to fit the water quality distribution within the bay. Cage culture zones of the bay were mainly concentrated in waters near tidal inlet with strong exchange capacity, while longline culture zones were mainly distributed in the area far away from the bay mouth where the water exchange capacity was a litter poor but nutrient was rich. Massive expansion of seaweed farming dominated aquaculture structure in the bay had played an important role in mitigation eutrophic tendency in bay. However as its nitrogen circulation revealed, excessive intervention process of mariculture may induce instability in the ecosystem.

Aiming at the monitoring requirement of sea area using situation, the extended evidence theory is used to detect reclamation area and the default category space is {reclamation, seawater}. Experimental results show that the extended evidence theory can not only detect the reclamation area with high accuracy, but also identify the underwater sand ridges or small islands in the shallow water as the uncertainty category. That shows the extended evidence theory has the ability to solve the problem of reclamation detection, which provides a new thinking of reclamation monitoring.

According to the special research project of 2011, combined with the red tide and trend monitoring, the existing 50 monitoring stations were optimized for the best 38 monitoring sites by using ordinary Kriging variance analysis method. Then the variance analysis was carried out to test the original and the optimized monitoring data by using the T test method. There was no significant difference between the 2 groups of data. The result show that the amounts of information get from the optimized stations are equivalent to the original ones. So the optimized stations can be used as regular monitoring stations in the future.

Scour and siltation are the forms of riverbed evolution in the vertical direction, which have some impacts on river flood control and drainage, safety of wading engineering, shipping and natural landscape. So it is important practical and theoretical significance to research the riverbed evolution. Taking the engineering of Ningbo Subway Line 2 undercrossing the Yaojiang River as an example, the method of 2-D mathematical model of tidal flow and sediment combined with the method of empirical formula calculation were used to research the greatest scour depth of riverbed near subway line under different flood and tide conditions. The research results show that the flood frequency become smaller, the maximum scour depth of riverbed near the engineering line become deeper, and riverbed scour develops quickly at first, and then slow down gradually.

Based on the multi-year hydrographic and bathyorographical data, the long-term variation of the riverbed width-depth ratio of Jiaojiang Estuary was analyzed and the response of the riverbed width-depth ratio to hydrographic and sediment condition was tried to discuss. The results indicate that the influences of runoff and tidal dynamic on the riverbed configuration are always opposite along the river channel, runoff is more significant on bend reach above Jiangkousha, and tide dynamic is the dominant on the straight reach from the lower reach of Zhapu, which may be the influence factor of regulating difference of riverbed transection configuration between the bend reach and straight reach. The correlation between the width-depth ratio and mean suspended sediment discharge is positive, which indicates that the riverbed configuration has tended to be narrow and deep with the decrease of the suspended sediment discharge. The negative correlation between the width-depth ratio and mean water discharge may indicate that the riverbed configuration of straight reach has tended to be wide and shallow with the decrease of the water discharge. Human being may change the effect of the tidal dynamics to the riverbed configuration for decades, which result in the negative correlation between the width-depth ratio and mean tidal range.

In order to study the level of pollution and impact on ecological environment of polychlorinated biphenyl in surface sediments in the dumping site of Yongjiang Estuary, 8 sites of samples were collected in the dumping site and its nearby area in January, 2014. The contents of polychlorinated biphenyl were detected by a gas chromatography with electron capture detector, and then the ecological risk assessment was studied. The results showed that the content range of polychlorinated biphenyl were varied from 1.310 to 6.538 μg·kg^-1, while the average content was 3.413 μg·kg^-1 in surface sediments in the dumping site of Yongjiang Estuary. The distribution of polychlorinated biphenyl in northwest and southeast was higher than that in dumping site. The types of polychlorinated biphenyl found in the surface sediments were mainly PCB28, PCB 118, PCB 155, and the contents of PCB118 and PCB155 were in relatively high levels, accounting for 26.1% to 93.1% of the total polychlorinated biphenyl in all sites. Compared with other main estuaries, the pollution level of polychlorinated biphenyl in the dumping site of Yongjiang Estuary was lower than that in Yangtze River Estuary, Minjiang River Estuary and Pearl River Estuary, but it was higher than that in Yalu River Estuary, Liao River Estuary and Yellow River Estuary. Furthermore, the Hakanson ecological risk index method, Canadian sediment quality guidelines, ecological risk index method and toxic equivalency factors method were used to conduct an assessment of the pollution of polychlorinated biphenyl. The results were basically the same. It revealed that surface sediments from the dumping site of Yongjiang Estuary were at a lower risk, and it could not cause the negative effects of organisms.

Community characteristics of macrobenthos had been studied in Qinhuangdao Estuary in summer of 2009 and 2012. Multivariate analysis methods were utilized to analyze the characteristics of macrobenthic communities and environmental factors. The result showed that:(1)Polychaeta and Arthropod were the dominant groups. The species and abundance increased from estuary to open sea in 2009 and 2012. Compared with 2009, the species decreased, the dominant species changed obviously, but the dominance of species showed little variation in 2012.(2)The total biomass composition of macrobenthos changed obviously. The dominant groups of macrobenthic community changed distinctly in 2009 and 2012. (3) The species were grouped into three ecotypes in 2009, while the species were grouped into four ecotypes in 2012, and one-way ANOSIM test revealed significant differences from 2009 to 2012. The species which provided main dissimilarity of community structure were significant differences from 2009 to 2012. (4) The results of BIOENV and BVSTEP analysis implied that depth and DIP were the most important factors affecting macrobenthos community in summer of 2009; while depth, salinity, and TOC were the most important factors affecting macrobenthos community in summer of 2012.