In this paper, integrating the Yangtze Estuary with the Hangzhou Bay, a 2-D velocity field model is established. In the model, fine self-adaptive grids are employed to adapt to the complicated coastal shape. The hydro...In this paper, integrating the Yangtze Estuary with the Hangzhou Bay, a 2-D velocity field model is established. In the model, fine self-adaptive grids are employed to adapt to the complicated coastal shape. The hydrodynamic equations satisfied by two contravariant components of velocity vector and surface elevation in non-orthogonal curvilinear coordinates are used. In each momentum equation the coefficients before the two partial derivatives of surface elevation with respect to variables of alternative direction coordinates have different orders of magnitude, i. e., the derivative with the larger coefficient may play a more important role than that with the smaller one. With this advantage, the ADI scheme can be easily employed. The hydrodynamic factors include tidal current, river runoff and wind-induced current. In terms of tidal current, seven main constituents in the area are considered in the open boundaries. The verifications of surface elevation process and current velocity process in the spring tide and in the neap tide show that the model can preferably reflect current fields in the area. Through the simulation of Lagrangian residual current fields in summer and in winter, the paths of the exchange of water and sediment between the Yangtze Estuary and the Hangzhou Bay are elementarily discussed.展开更多
The distributions of partial pressure of carbon dioxide (pCO2) in the surface waters of the Changjiang River Estuary and adjacent Hangzhou Bay were examined in the summer of 2010. Surface water pCO2 ranged from 751-...The distributions of partial pressure of carbon dioxide (pCO2) in the surface waters of the Changjiang River Estuary and adjacent Hangzhou Bay were examined in the summer of 2010. Surface water pCO2 ranged from 751-2 095/zatm (1 atm=101 325 Pa) in the inner estuary, 177-1 036/zatm in the outer estuary, and 498-1 166 μatm in Hangzhou Bay. Overall, surface pCO2 behaved conservatively during the estuary mixing. In the inner estuary, surface pCO2 was relatively high due to urbanized pollution and a high respiration rate. The lowest pCO2 was observed in the outer estuary, which was apparently induced by a phytoplankton bloom because the dissolved oxygen and chlorophyll a were very high. The Changjiang River Estuary was a significant source of atmospheric CO2 and the degassing fluxes were estimated as 0-230 mmol/(m2.d) [61 mmol/(m2.d) on average] in the inner estuary. In contrast, the outer estuary acted as a CO2 sink.展开更多
To explore the distribution and composition of phytoplankton community and their responses to environmental changes, summer net-collected phytoplankton and physicochemical parameters in the Hangzhou Bay during 2004–2...To explore the distribution and composition of phytoplankton community and their responses to environmental changes, summer net-collected phytoplankton and physicochemical parameters in the Hangzhou Bay during 2004–2010 were investigated. A total of four phyla and 84 species were identified, including 67 diatom and 12 dinoflagellate species. The dominant species con- stantly consisted of the diatoms, although the dominance of dinoflagellate and cyanobacteria increased recently. Due to great spa- tio-temporal variations in environmental factors(salinity, suspended solids, and nutrient concentration), significant heterogeneities in community compositions among different years and subregions(inner and middle sections, and bay mouth) were found based on the analyses of multidimensional scaling and similarity. Canonical correspondence analysis showed that salinity and Si/N were the main variables associated with algal assemblage. Compared with the historical data since the 1980 s, eutrophication(N, P, and N/P increased with decreasing Si/N) was exacerbated drastically. Moreover, climatic forcing and human activities resulted in a series of physical alterations, including sediment retention, temperature increase, and salinity decrease as well as reduction in water exchanges. All these changes induced obvious increases in cell density and Chl-a while decreases in species diversity and diatom-dinoflagellate ratio as well as the shifting of dominant species. Therefore, the long-term phytoplankton variations were closely related to anthropogenic and climatic perturbations in the Hangzhou Bay.展开更多
Clay mineral compositions of 199 offshore surface sediment samples collected from the Hangzhou Bay have been analyzed. The clay minerals in the sediments from the Hangzhou Bay are dominated by illite(58.7%, on average...Clay mineral compositions of 199 offshore surface sediment samples collected from the Hangzhou Bay have been analyzed. The clay minerals in the sediments from the Hangzhou Bay are dominated by illite(58.7%, on average), followed by chlorite(20.3%), kaolinite(16.9%) and smectite(4.1%). Two provinces were classified by Q-mode cluster analysis. Class Ⅰ with relatively low amounts of illite and smectite is widely distributed in the Hangzhou Bay, especially concentrated in the top and mouth of the bay, and the northern and southern nearshore areas. Class Ⅱ with comparatively high amounts of illite and smectite is mainly concentrated in the central part of the bay with the water depth of 8–10 m. By comparing clay mineral compositions with the neighbouring regions, we can find that the sediments in the Hangzhou Bay are mainly influenced by the resuspension and repeated deposition of particles from the Yangtze River due to the strong dynamic environment. In particular, the clay fraction of Class Ⅰ is mainly supplied by the Yangtze River, while the sediments of Class Ⅱ are mixture of the clay minerals carried by the Yangtze River and Qiantang River. In general, the distributions of clay minerals in the northern bay are affected by Yangtze River runoff, coastal current and flood tide together, and in the southern they are mainly affected by the Qiantang River runoff and ebb tide.展开更多
This paper presents the sedimentary facies and formation of the Qiantangjiang and Taihu incised valleys, and the characteristics of shallow gas reservoir distribution, based on a large number of data of drilling, stat...This paper presents the sedimentary facies and formation of the Qiantangjiang and Taihu incised valleys, and the characteristics of shallow gas reservoir distribution, based on a large number of data of drilling, static sounding and chemical analysis obtained from the present Hangzhou Bay coastal plain. The incised valleys were formed during the last glacial maximum and were subsequently filled with fluvial facies during the post-glacial period. All commercial gases are stored in the flood plain sand lenses of the incised valleys.展开更多
The Inductively Coupled Plasma Optical Emission Spectrometer was used to analyze sediment samples collected from the Hangzhou Bay to determine major and trace elemental concentrations. Based on these concentrations, t...The Inductively Coupled Plasma Optical Emission Spectrometer was used to analyze sediment samples collected from the Hangzhou Bay to determine major and trace elemental concentrations. Based on these concentrations, the study area can be classified into three geochemical provinces. Province I covers the northern Hangzhou Bay area and contains high concentrations of A120~, Fe203, MgO, Na20, K20, MnO, Cr, Cu, Ni, Pb, V, Co and Zn. Province III is located in the western Hangzhou Bay, near the Qiantang River mouth, and contains high concentrations of SiO~, Na20, P205~ TiO2, Cr, Sr, Zr. Province II is located in the middle and eastern Hangzhou Bay, with the medium concentrations of major and trace elements. The results also demonstrate that the grain size is the dominating factor controlling the spatial variations of elemental concentrations, and the Changjiang River (Yangtze River) and Qiantang River sediments play an important role in the distribution of these elements. Anthropogenic impact on heavy metal concentrations (especially Cr, Sr and Zr) can be detected in the surface sediments near the Qiantang River mouth.展开更多
Land use change plays an important part in the studies of global environmental change and regional sustainable development. The change of soil quality can particularly reflect the impacts of human socio-economic activ...Land use change plays an important part in the studies of global environmental change and regional sustainable development. The change of soil quality can particularly reflect the impacts of human socio-economic activities on environment. Taking the coastal plain of south Hangzhou Bay as a study case, we analyzed the effects of land use changes on organic matter (OM), total nitrogen (TN), total phosphorus (TP), available phosphorus (AP), available potassium (AK), total salinity (TS), pH value in soil genetic layers, and assessed soil quality change related to different land use types from 1982 to 2003. The results show that: (1) The general change tendency of soil quality in the coastal plain of south Hangzhou Bay declined obviously in A layer and slightly rise in B (or P) layer and C (or W) layer. The contents of TP decreased generally in all soil genetic layers, but the variety difference of other soil quality indices was relatively great. (2) The change of soil quality in the areas where land use changed is far more remarkable than that with land use unchanged. The value of quality variety is A layer 〉B (or P) layer 〉C (or W) layer. (3) The changes of soil tillage, cultivation, fertilization, irrigation and drainage activities related to land use may make some soil-forming processes disappeared and bring in other new processes which will affect the soil quality and soil genetic layers directly.展开更多
Based on Landsat TM images in 2005 and urban planning data of 2005-2020 in Hangzhou Bay Industrial Belt, this paper studied the potential risk of the planned urban construction land extension to the wetlands by employ...Based on Landsat TM images in 2005 and urban planning data of 2005-2020 in Hangzhou Bay Industrial Belt, this paper studied the potential risk of the planned urban construction land extension to the wetlands by employing a GIS spatial analysis method. The results show that: (1) The wetland resources are widely distributed and diverse, with a proximal distribution to present urban construction lands spatially. (2) From 2005 to 2020, the urban construction lands will expand vastly and rapidly, and will take over large areas of wetlands that are mostly the ponds and the aquiculture water areas in the reclamation areas of Hangzhou Bay south coast. Moreover, this change will be spatially uneven obviously, e.g., the most serious recessions of the wetlands are concentrated in Ningbo city, Hangzhou city and Cixi city. (3) Overall, the potential risk to wetlands is very high, and will keep increasing with the trend of urbanization. (4) The quantity and spatial pattern of the planning urban construction land have substantial impacts on the wetland loss. Therefore, some policies and regulations are suggested to coordinate the relationship between urban economic development and wetland resource protection such as adjusting the construction land planning, compensating for wetland occupation as well as constructing wetland parks.展开更多
A 3-D numerical model is set up in a large domain covering the Hangzhou Bay and the Changjiang Estuary based on the ECOM model in orthogonal curvilinear coordinates.The numerical schemes for baroclinic pressure gradie...A 3-D numerical model is set up in a large domain covering the Hangzhou Bay and the Changjiang Estuary based on the ECOM model in orthogonal curvilinear coordinates.The numerical schemes for baroclinic pressure gradient (BPG)terms and convective terms are improved in the paper according to the characteristics of velocity field and mass transport in the area.The model is validated by the simulations of residual current and salinity transport in the Hangzhou Bay and the Changjiang Estuary.展开更多
-In order to avoid prescribing open boundary condition on the upstream side of the Hangzhou Bay, in numerical simulation of the tides and residual currents of the Bay, a 1-D model for the Qiantang River is connected t...-In order to avoid prescribing open boundary condition on the upstream side of the Hangzhou Bay, in numerical simulation of the tides and residual currents of the Bay, a 1-D model for the Qiantang River is connected to the 2-D model for the Hangzhou Bay. The harmonic constants of diurnal constituent [ (K1+O1)/2],semidiurnal constituent (M2) and shallow water constituent (M4) are obtained. The results produced by the combined model are in better agreement with the observed ones than those produced solely by the original 2-D model. The combined model gives much more reliable results for tide-induced residual water level and current.展开更多
Based on the historical evolution of the Hangzhou Bay, by making use of the conclusions made by the previous research workers and the integration of concrete data, five distinct impact indicators of the sediment from ...Based on the historical evolution of the Hangzhou Bay, by making use of the conclusions made by the previous research workers and the integration of concrete data, five distinct impact indicators of the sediment from the Changjiang Estuary and the East China Sea to the Hangzhou Bay are summarized. Numerical calculation and analysis indicate that the scouring and deposition of seabed in the Hangzhou Bay are subject to the direct impact of the evolution of the Changjiang Estuary, and the growth and decline and the direction of the sandy bar at Nanhuizui give traces to the sediment transport between the Changjiang Estuary and the Hangzhou Bay. The transport of sediment from the Changjiang Estuary to the Hangzhou Bay occurs mainly in winter and spring seasons and the increase of the Changjiang River runoff and the decrease of sediment charge have caused scouring in the northern coast of the Hangzhou Bay and the seabed erosion along the frontal margin of the Changjiang River Delta.展开更多
The mean sea level, extreme sea level, and astronomical tide in Hangzhou Bay were analyzed using the tide gage data from 1978 to 2017 in Tanxu station, and the effects of rising sea levels on floods were estimated. Th...The mean sea level, extreme sea level, and astronomical tide in Hangzhou Bay were analyzed using the tide gage data from 1978 to 2017 in Tanxu station, and the effects of rising sea levels on floods were estimated. The mean sea level in Hangzhou Bay showed a significant rising trend of 4.6mm per year in 1978-2017. This rate was much higher than the mean sea level of the China seas, and the extreme sea level in Hangzhou Bay increased at the rate of 0.011 m per year. During 1978-2017, the mean tide range increased at the rate of 1.30 cm per year. The amplitude of M2 significantly increased at the rate of 0.57cm per year, whereas the phase lag decreased at the rate of --0.21° per year. The amplitude and phase lag of the K1 tidal component slightly decreased at the rate of --0.03 cm per year and -0.07° per year, respectively. The changes in extreme sea level in Hangzhou Bay were mainly caused by variations in mean sea level. The coastal areas of Hangzhou Bay at risk from flooding due to the 100-year sea level return will increase by about 400 km^2 by 2050.展开更多
Surface sediments from the Changjiang River (Yangtze River) Estuary, Hangzhou Bay, and their adjacent waters were analyzed for their grain size distribution, organic carbon (OC) concentration, and stable carbon is...Surface sediments from the Changjiang River (Yangtze River) Estuary, Hangzhou Bay, and their adjacent waters were analyzed for their grain size distribution, organic carbon (OC) concentration, and stable carbon isotope composition (δ13C). Based on this analysis, about 36 surface sediment samples were selected from various environments and separated into sand (〉0.250 ram, 0.125-0.250 ram, 0.063-0.125 mm) and silt (0.025-0.063 mm) fractions by wet-sieving fractionation methods, and further into silt- (0.004-0.025 mm) and clay-sized (〈0.004 mm) fractions by centrifugal fractionation. Sediments of six grain size categories were analyzed for their OC and 613C contents to explore the grain size composition and transport paths of sedimentary OC in the study area. From fine to coarse fractions, the OC content was 1.18%, 0.51%, 0.46%, 0.42%, 0.99%, and 0.48%, respectively, while the δ13C was -21.64‰, -22.03‰, -22.52‰, -22.46‰, -22.36‰, and -22.28%0, respectively. In each size category, the OC contribution was 42.96%, 26.06%, 9.82%, 5.75%, 7.09%, and 8.33%, respectively. The OC content in clay and fine silt fractions (〈0.025 ram) was about 69.02%. High OC concentrations were mainly found in offshore modern sediments in the northeast of the Changjiang River Estuary, in modern sediments in the lower estuary of the Changjiang River and Hangzhou Bay, and in Cyclonic Eddy modern sediments to the southwest of the Cheju Island. Integrating the distribution of terrestrial OC content of each grain size category with the δ13C of the bulk sediment indicated that the terrestrial organic material in the Changjiang River Estuary was transported seaward and dispersed to the Cyclonic Eddy modern sediments to the southwest of the Cheju Island via two pathways: one was a result of the Changjiang River Diluted Water (CDW) northeastward extending branch driven by the North Jiangsu Coastal Current and the Yellow Sea Coastal Current, while the other one was the result of the CDW southward extending branch driven by the Taiwan Warm Current.展开更多
Time-series InSAR analysis(e.g., permanent scatterers(PSInSAR)) has been proven as an effective technology in monitoring ground deformation over urban areas. However, it is a big challenge to apply this technology...Time-series InSAR analysis(e.g., permanent scatterers(PSInSAR)) has been proven as an effective technology in monitoring ground deformation over urban areas. However, it is a big challenge to apply this technology in coastal regions due to the lack of man-made targets. An distributed scatterers interferometric synthetic aperture radar(DSInSAR) is developed to solve the problem of insufficient samples and low reliability in monitoring coastal lowland subsidence, by applying a spatially adaptive filter and an eigendecomposition algorithm to estimating the optimal phase of statistically homogeneous distributed scatterers(DSs). Twenty-four scenes of COSMO-Sky Med images acquired between 2013 and 2015 are used to retrieve the land subsidence over the Shangyu District on south coast of the Hangzhou Bay, Zhejiang Province, China. The spatial pattern of the land subsidence obtained by the PS-InSAR and the DSInSAR coincides with each other, but the density of the DSs is three point five times higher than the permanent scatterers(PSs). Validated by precise levelling data over the same period, the DSInSAR method achieves an accuracy of ±5.0 mm/a which is superior to the PS-InSAR with±5.5 mm/a. The land subsidence in the Shangyu District is mainly distributed in the urban areas, industrial towns and land reclamation zones, with a maximum subsidence rate -30.2 mm/a. The analysis of geological data, field investigation and historical reclamation data indicates that human activities and natural compaction of reclamation material are major causes of the detected land subsidence. The results demonstrate that the DSInSAR method has a great potential in monitoring the coastal lowland subsidence and can be used to further investigate subsidence-related environmental issues in coastal regions.展开更多
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 ...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.展开更多
-low-frequency sea level fluctuations in the Hangzhou Bay in winter and summer, 1973-1974 are analyzed in this paper. The established multi-spectrum response models effectively identify the different dynamical factors...-low-frequency sea level fluctuations in the Hangzhou Bay in winter and summer, 1973-1974 are analyzed in this paper. The established multi-spectrum response models effectively identify the different dynamical factors and their contributions to the low-frequency sea level fluctuations inside the bay. The results show that the Ekman transport due to longshore winds is the major mechanism to induce the sea level fluctuations, more important than the frictional effect of local winds. There also exists obviously the influental effect of the free fluctuations of the continental shelf. In addition ,a simple estimation suggests that the remarkable sea level fluctuation of 0. 4 d-1 in the bay is related to the resonance of the Huanghai Sea and the Bohai Sea (taken as a single bay).展开更多
This paper deals with the seasonal changes of the tidal flat along the north bank of Hangzhou Bay. Analysis of a one year set of weekly measured tidal flat profiles from Jinhuigang to Caojing shows that the tidal flat...This paper deals with the seasonal changes of the tidal flat along the north bank of Hangzhou Bay. Analysis of a one year set of weekly measured tidal flat profiles from Jinhuigang to Caojing shows that the tidal flat on the north bank of Hangzhou Bay accretes during winter and erodes during summer. To identify the characteristic patterns of the tidal flat spatio-temporal variations, Empirical Orthogonal Function (EOF) is applied on the tidal flat profile data. The results show that most of the variations of the tidal flat profiles can be represented by three eigenfunctions corresponding to the three largest eigenvalues. The first eigenfunction represents the long-term variation of the tidal flat over a year, the second eigenfunction represents the seasonal changes of the tidal flat resulting from the seasonal variations in wave regime, the third eigenfunction indicates sediment exchanges between different parts of the tidal flat associated with the variations of sea level.展开更多
A description is given of the distribution , spacial and temporal variation , mixing and transportation processes about the plume front in the Hangzhou Bay. This front is performed as a group of interfaces among, the ...A description is given of the distribution , spacial and temporal variation , mixing and transportation processes about the plume front in the Hangzhou Bay. This front is performed as a group of interfaces among, the water masses situated in the bay. A discussion is also given of the circulation feature in the frontal zone ence of the front.展开更多
The Holocene environmental evolution in coastal area, including deltas and estuaries, is vital to the Neolithic colonization in the eastern China. A 29-m long sediment core XL was obtained from the region between the ...The Holocene environmental evolution in coastal area, including deltas and estuaries, is vital to the Neolithic colonization in the eastern China. A 29-m long sediment core XL was obtained from the region between the Taihu Lake and Qiantang Estuary, and multiple analyses on the core sediments have been done to investigate the evolution history of the inner coastal zone of Hangzhou Bay during the Holocene. Six sedimentary facies are identified since the late Pleistocene, including the paleosol at the bottom, overlain by tidal-flat-channel complex(TFC), tidal-distributary-channel(TDC), inner estuarine basin(IEB), subtidal-to-intertidal-flat, and fluvial-plain facies. The TFC and TDC facies are dated to be formed before 8500 cal yr BP, featured by relatively coarse sediments, high magnetic properties and less abundant foraminifera, denoting the tide-influenced setting with large terrestrial inputs. The IEB facies characterized by the most abundant foraminifera fossils and the lowest sediment magnetic properties, is inferred to be deposited during the maximum flooding period between 8500 and 7900 cal yr BP. The branch estuary was then infilled by local sediments with a shallowing-upward subtidal-to-intertidal sequence during 7900–4300 cal yr BP. At last the fluvial plain system developed since no later than 4300 cal yr BP, favouring the rapid development of Neolithic cultures in the region.展开更多
On the basis of the time series of AVHRR data from NOAA satellites and the geographical information system PURSIS, fluctuations of the plume front and the turbidity maximum in the Hangzhou Bay, reflected by the distri...On the basis of the time series of AVHRR data from NOAA satellites and the geographical information system PURSIS, fluctuations of the plume front and the turbidity maximum in the Hangzhou Bay, reflected by the distributions of temperature and suspended sediment concentration respectively, are studied in view of long-term behaviors or seasonal and tidal cycles. The data suggest that the effect of front plays an important role in the development of the turbidity maximum close to the Changjiang Estuary > while the effect of tide dominates over the development of another very turbid water situated in the shoal areas in the southern Hangzhou Bay.展开更多
基金National Natural Science Foundation of China under contract No.49776279National Excellent Youth Foundation of China under contract No.49825161
文摘In this paper, integrating the Yangtze Estuary with the Hangzhou Bay, a 2-D velocity field model is established. In the model, fine self-adaptive grids are employed to adapt to the complicated coastal shape. The hydrodynamic equations satisfied by two contravariant components of velocity vector and surface elevation in non-orthogonal curvilinear coordinates are used. In each momentum equation the coefficients before the two partial derivatives of surface elevation with respect to variables of alternative direction coordinates have different orders of magnitude, i. e., the derivative with the larger coefficient may play a more important role than that with the smaller one. With this advantage, the ADI scheme can be easily employed. The hydrodynamic factors include tidal current, river runoff and wind-induced current. In terms of tidal current, seven main constituents in the area are considered in the open boundaries. The verifications of surface elevation process and current velocity process in the spring tide and in the neap tide show that the model can preferably reflect current fields in the area. Through the simulation of Lagrangian residual current fields in summer and in winter, the paths of the exchange of water and sediment between the Yangtze Estuary and the Hangzhou Bay are elementarily discussed.
基金The Marine Public Welfare Project of China under contract Nos200805029,200905012,200905025,and 201005034the Scientific Research Fund of the Second Institute of Oceanography,SOA under contract Nos JG0821 and JG1021
文摘The distributions of partial pressure of carbon dioxide (pCO2) in the surface waters of the Changjiang River Estuary and adjacent Hangzhou Bay were examined in the summer of 2010. Surface water pCO2 ranged from 751-2 095/zatm (1 atm=101 325 Pa) in the inner estuary, 177-1 036/zatm in the outer estuary, and 498-1 166 μatm in Hangzhou Bay. Overall, surface pCO2 behaved conservatively during the estuary mixing. In the inner estuary, surface pCO2 was relatively high due to urbanized pollution and a high respiration rate. The lowest pCO2 was observed in the outer estuary, which was apparently induced by a phytoplankton bloom because the dissolved oxygen and chlorophyll a were very high. The Changjiang River Estuary was a significant source of atmospheric CO2 and the degassing fluxes were estimated as 0-230 mmol/(m2.d) [61 mmol/(m2.d) on average] in the inner estuary. In contrast, the outer estuary acted as a CO2 sink.
基金provided by the Marine Monitoring and Forecasting Center of Zhejiangfunded by the National Basic Research Program of China(2010CB428903)+2 种基金the National Marine Public Welfare Research Project of China(201305009 and 201305043-3)the National Natural Science Foundation of China(41206103)Basic Scientific Research of Second Institute of Oceanography,SOA(JG1222)
文摘To explore the distribution and composition of phytoplankton community and their responses to environmental changes, summer net-collected phytoplankton and physicochemical parameters in the Hangzhou Bay during 2004–2010 were investigated. A total of four phyla and 84 species were identified, including 67 diatom and 12 dinoflagellate species. The dominant species con- stantly consisted of the diatoms, although the dominance of dinoflagellate and cyanobacteria increased recently. Due to great spa- tio-temporal variations in environmental factors(salinity, suspended solids, and nutrient concentration), significant heterogeneities in community compositions among different years and subregions(inner and middle sections, and bay mouth) were found based on the analyses of multidimensional scaling and similarity. Canonical correspondence analysis showed that salinity and Si/N were the main variables associated with algal assemblage. Compared with the historical data since the 1980 s, eutrophication(N, P, and N/P increased with decreasing Si/N) was exacerbated drastically. Moreover, climatic forcing and human activities resulted in a series of physical alterations, including sediment retention, temperature increase, and salinity decrease as well as reduction in water exchanges. All these changes induced obvious increases in cell density and Chl-a while decreases in species diversity and diatom-dinoflagellate ratio as well as the shifting of dominant species. Therefore, the long-term phytoplankton variations were closely related to anthropogenic and climatic perturbations in the Hangzhou Bay.
基金funded by China-ASEAN maritime cooperation fund: Comparative Study of Holocene Sedimentary Evolution of the Yangtze River Delta and the Red River Deltathe National Natural Science Foundation of China (Nos. 4170 6074 and 41506107)+1 种基金the China Geological Survey (No. DD20160145)the Basic Fund of Ministry of Science Foundation of China (No. 2013FY112200)
文摘Clay mineral compositions of 199 offshore surface sediment samples collected from the Hangzhou Bay have been analyzed. The clay minerals in the sediments from the Hangzhou Bay are dominated by illite(58.7%, on average), followed by chlorite(20.3%), kaolinite(16.9%) and smectite(4.1%). Two provinces were classified by Q-mode cluster analysis. Class Ⅰ with relatively low amounts of illite and smectite is widely distributed in the Hangzhou Bay, especially concentrated in the top and mouth of the bay, and the northern and southern nearshore areas. Class Ⅱ with comparatively high amounts of illite and smectite is mainly concentrated in the central part of the bay with the water depth of 8–10 m. By comparing clay mineral compositions with the neighbouring regions, we can find that the sediments in the Hangzhou Bay are mainly influenced by the resuspension and repeated deposition of particles from the Yangtze River due to the strong dynamic environment. In particular, the clay fraction of Class Ⅰ is mainly supplied by the Yangtze River, while the sediments of Class Ⅱ are mixture of the clay minerals carried by the Yangtze River and Qiantang River. In general, the distributions of clay minerals in the northern bay are affected by Yangtze River runoff, coastal current and flood tide together, and in the southern they are mainly affected by the Qiantang River runoff and ebb tide.
基金This research is financially supported by the China National Natural Science Foundation(Project No.40272063)
文摘This paper presents the sedimentary facies and formation of the Qiantangjiang and Taihu incised valleys, and the characteristics of shallow gas reservoir distribution, based on a large number of data of drilling, static sounding and chemical analysis obtained from the present Hangzhou Bay coastal plain. The incised valleys were formed during the last glacial maximum and were subsequently filled with fluvial facies during the post-glacial period. All commercial gases are stored in the flood plain sand lenses of the incised valleys.
基金The National Natural Science Foundation of China under contract No. 41106063China Postdoctoral Science Foundation under contract No. 20100481304+1 种基金Marine Public Welfare Research Project under contract No. 200805063Coastal Investigation and Research Project of China under contract Nos 908-01-CJ09 and 908-ZC-I-05
文摘The Inductively Coupled Plasma Optical Emission Spectrometer was used to analyze sediment samples collected from the Hangzhou Bay to determine major and trace elemental concentrations. Based on these concentrations, the study area can be classified into three geochemical provinces. Province I covers the northern Hangzhou Bay area and contains high concentrations of A120~, Fe203, MgO, Na20, K20, MnO, Cr, Cu, Ni, Pb, V, Co and Zn. Province III is located in the western Hangzhou Bay, near the Qiantang River mouth, and contains high concentrations of SiO~, Na20, P205~ TiO2, Cr, Sr, Zr. Province II is located in the middle and eastern Hangzhou Bay, with the medium concentrations of major and trace elements. The results also demonstrate that the grain size is the dominating factor controlling the spatial variations of elemental concentrations, and the Changjiang River (Yangtze River) and Qiantang River sediments play an important role in the distribution of these elements. Anthropogenic impact on heavy metal concentrations (especially Cr, Sr and Zr) can be detected in the surface sediments near the Qiantang River mouth.
基金National Natural Science Foundation of China, No.40701006 Natural Science Foundation of Zhejiang Province, No.Y505032+2 种基金 Natural Science Foundation of Ningbo, No.2006A610077 No.2002C10026 K. C. Wong Magna Fund in Ningbo University
文摘Land use change plays an important part in the studies of global environmental change and regional sustainable development. The change of soil quality can particularly reflect the impacts of human socio-economic activities on environment. Taking the coastal plain of south Hangzhou Bay as a study case, we analyzed the effects of land use changes on organic matter (OM), total nitrogen (TN), total phosphorus (TP), available phosphorus (AP), available potassium (AK), total salinity (TS), pH value in soil genetic layers, and assessed soil quality change related to different land use types from 1982 to 2003. The results show that: (1) The general change tendency of soil quality in the coastal plain of south Hangzhou Bay declined obviously in A layer and slightly rise in B (or P) layer and C (or W) layer. The contents of TP decreased generally in all soil genetic layers, but the variety difference of other soil quality indices was relatively great. (2) The change of soil quality in the areas where land use changed is far more remarkable than that with land use unchanged. The value of quality variety is A layer 〉B (or P) layer 〉C (or W) layer. (3) The changes of soil tillage, cultivation, fertilization, irrigation and drainage activities related to land use may make some soil-forming processes disappeared and bring in other new processes which will affect the soil quality and soil genetic layers directly.
基金Key Project of Zhejiang Provincial Science and Technology Programs, No.2005C23059 National Key Technology R&D Program of China, No.2006BAJ11B03 National Natural Science Foundation of China, No.40701177 The authors thank Prof. Liu Xinguo from Zhejiang University for his modification of language.
文摘Based on Landsat TM images in 2005 and urban planning data of 2005-2020 in Hangzhou Bay Industrial Belt, this paper studied the potential risk of the planned urban construction land extension to the wetlands by employing a GIS spatial analysis method. The results show that: (1) The wetland resources are widely distributed and diverse, with a proximal distribution to present urban construction lands spatially. (2) From 2005 to 2020, the urban construction lands will expand vastly and rapidly, and will take over large areas of wetlands that are mostly the ponds and the aquiculture water areas in the reclamation areas of Hangzhou Bay south coast. Moreover, this change will be spatially uneven obviously, e.g., the most serious recessions of the wetlands are concentrated in Ningbo city, Hangzhou city and Cixi city. (3) Overall, the potential risk to wetlands is very high, and will keep increasing with the trend of urbanization. (4) The quantity and spatial pattern of the planning urban construction land have substantial impacts on the wetland loss. Therefore, some policies and regulations are suggested to coordinate the relationship between urban economic development and wetland resource protection such as adjusting the construction land planning, compensating for wetland occupation as well as constructing wetland parks.
文摘A 3-D numerical model is set up in a large domain covering the Hangzhou Bay and the Changjiang Estuary based on the ECOM model in orthogonal curvilinear coordinates.The numerical schemes for baroclinic pressure gradient (BPG)terms and convective terms are improved in the paper according to the characteristics of velocity field and mass transport in the area.The model is validated by the simulations of residual current and salinity transport in the Hangzhou Bay and the Changjiang Estuary.
基金This work was sponsored by the National Natural Science Foundation of China
文摘-In order to avoid prescribing open boundary condition on the upstream side of the Hangzhou Bay, in numerical simulation of the tides and residual currents of the Bay, a 1-D model for the Qiantang River is connected to the 2-D model for the Hangzhou Bay. The harmonic constants of diurnal constituent [ (K1+O1)/2],semidiurnal constituent (M2) and shallow water constituent (M4) are obtained. The results produced by the combined model are in better agreement with the observed ones than those produced solely by the original 2-D model. The combined model gives much more reliable results for tide-induced residual water level and current.
文摘Based on the historical evolution of the Hangzhou Bay, by making use of the conclusions made by the previous research workers and the integration of concrete data, five distinct impact indicators of the sediment from the Changjiang Estuary and the East China Sea to the Hangzhou Bay are summarized. Numerical calculation and analysis indicate that the scouring and deposition of seabed in the Hangzhou Bay are subject to the direct impact of the evolution of the Changjiang Estuary, and the growth and decline and the direction of the sandy bar at Nanhuizui give traces to the sediment transport between the Changjiang Estuary and the Hangzhou Bay. The transport of sediment from the Changjiang Estuary to the Hangzhou Bay occurs mainly in winter and spring seasons and the increase of the Changjiang River runoff and the decrease of sediment charge have caused scouring in the northern coast of the Hangzhou Bay and the seabed erosion along the frontal margin of the Changjiang River Delta.
基金National Key Research and Development Program of China (2016YFC1401900, 2017YFC1404200)National Natural Science Foundation of China (41706020, 41406032, 41706019)Open Fund of the Key Laboratory of Research on Marine Hazards Forecasting.
文摘The mean sea level, extreme sea level, and astronomical tide in Hangzhou Bay were analyzed using the tide gage data from 1978 to 2017 in Tanxu station, and the effects of rising sea levels on floods were estimated. The mean sea level in Hangzhou Bay showed a significant rising trend of 4.6mm per year in 1978-2017. This rate was much higher than the mean sea level of the China seas, and the extreme sea level in Hangzhou Bay increased at the rate of 0.011 m per year. During 1978-2017, the mean tide range increased at the rate of 1.30 cm per year. The amplitude of M2 significantly increased at the rate of 0.57cm per year, whereas the phase lag decreased at the rate of --0.21° per year. The amplitude and phase lag of the K1 tidal component slightly decreased at the rate of --0.03 cm per year and -0.07° per year, respectively. The changes in extreme sea level in Hangzhou Bay were mainly caused by variations in mean sea level. The coastal areas of Hangzhou Bay at risk from flooding due to the 100-year sea level return will increase by about 400 km^2 by 2050.
基金The National Basic Research Program(973 Program)of China under contract No.2010CB428903the National Natural Science Foundation of China under contract Nos 41106050,41203085 and 41076036+1 种基金the Public Welfare Industry Research Specific Funding of China under contract Nos 201105014,201105012 and 201205008the Basic Scientific Research Fund of the Second Institute of Oceanography of State Oceanic Administration of China under contract Nos JG1108 and JG1219
文摘Surface sediments from the Changjiang River (Yangtze River) Estuary, Hangzhou Bay, and their adjacent waters were analyzed for their grain size distribution, organic carbon (OC) concentration, and stable carbon isotope composition (δ13C). Based on this analysis, about 36 surface sediment samples were selected from various environments and separated into sand (〉0.250 ram, 0.125-0.250 ram, 0.063-0.125 mm) and silt (0.025-0.063 mm) fractions by wet-sieving fractionation methods, and further into silt- (0.004-0.025 mm) and clay-sized (〈0.004 mm) fractions by centrifugal fractionation. Sediments of six grain size categories were analyzed for their OC and 613C contents to explore the grain size composition and transport paths of sedimentary OC in the study area. From fine to coarse fractions, the OC content was 1.18%, 0.51%, 0.46%, 0.42%, 0.99%, and 0.48%, respectively, while the δ13C was -21.64‰, -22.03‰, -22.52‰, -22.46‰, -22.36‰, and -22.28%0, respectively. In each size category, the OC contribution was 42.96%, 26.06%, 9.82%, 5.75%, 7.09%, and 8.33%, respectively. The OC content in clay and fine silt fractions (〈0.025 ram) was about 69.02%. High OC concentrations were mainly found in offshore modern sediments in the northeast of the Changjiang River Estuary, in modern sediments in the lower estuary of the Changjiang River and Hangzhou Bay, and in Cyclonic Eddy modern sediments to the southwest of the Cheju Island. Integrating the distribution of terrestrial OC content of each grain size category with the δ13C of the bulk sediment indicated that the terrestrial organic material in the Changjiang River Estuary was transported seaward and dispersed to the Cyclonic Eddy modern sediments to the southwest of the Cheju Island via two pathways: one was a result of the Changjiang River Diluted Water (CDW) northeastward extending branch driven by the North Jiangsu Coastal Current and the Yellow Sea Coastal Current, while the other one was the result of the CDW southward extending branch driven by the Taiwan Warm Current.
文摘Time-series InSAR analysis(e.g., permanent scatterers(PSInSAR)) has been proven as an effective technology in monitoring ground deformation over urban areas. However, it is a big challenge to apply this technology in coastal regions due to the lack of man-made targets. An distributed scatterers interferometric synthetic aperture radar(DSInSAR) is developed to solve the problem of insufficient samples and low reliability in monitoring coastal lowland subsidence, by applying a spatially adaptive filter and an eigendecomposition algorithm to estimating the optimal phase of statistically homogeneous distributed scatterers(DSs). Twenty-four scenes of COSMO-Sky Med images acquired between 2013 and 2015 are used to retrieve the land subsidence over the Shangyu District on south coast of the Hangzhou Bay, Zhejiang Province, China. The spatial pattern of the land subsidence obtained by the PS-InSAR and the DSInSAR coincides with each other, but the density of the DSs is three point five times higher than the permanent scatterers(PSs). Validated by precise levelling data over the same period, the DSInSAR method achieves an accuracy of ±5.0 mm/a which is superior to the PS-InSAR with±5.5 mm/a. The land subsidence in the Shangyu District is mainly distributed in the urban areas, industrial towns and land reclamation zones, with a maximum subsidence rate -30.2 mm/a. The analysis of geological data, field investigation and historical reclamation data indicates that human activities and natural compaction of reclamation material are major causes of the detected land subsidence. The results demonstrate that the DSInSAR method has a great potential in monitoring the coastal lowland subsidence and can be used to further investigate subsidence-related environmental issues in coastal regions.
文摘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.
文摘-low-frequency sea level fluctuations in the Hangzhou Bay in winter and summer, 1973-1974 are analyzed in this paper. The established multi-spectrum response models effectively identify the different dynamical factors and their contributions to the low-frequency sea level fluctuations inside the bay. The results show that the Ekman transport due to longshore winds is the major mechanism to induce the sea level fluctuations, more important than the frictional effect of local winds. There also exists obviously the influental effect of the free fluctuations of the continental shelf. In addition ,a simple estimation suggests that the remarkable sea level fluctuation of 0. 4 d-1 in the bay is related to the resonance of the Huanghai Sea and the Bohai Sea (taken as a single bay).
文摘This paper deals with the seasonal changes of the tidal flat along the north bank of Hangzhou Bay. Analysis of a one year set of weekly measured tidal flat profiles from Jinhuigang to Caojing shows that the tidal flat on the north bank of Hangzhou Bay accretes during winter and erodes during summer. To identify the characteristic patterns of the tidal flat spatio-temporal variations, Empirical Orthogonal Function (EOF) is applied on the tidal flat profile data. The results show that most of the variations of the tidal flat profiles can be represented by three eigenfunctions corresponding to the three largest eigenvalues. The first eigenfunction represents the long-term variation of the tidal flat over a year, the second eigenfunction represents the seasonal changes of the tidal flat resulting from the seasonal variations in wave regime, the third eigenfunction indicates sediment exchanges between different parts of the tidal flat associated with the variations of sea level.
文摘A description is given of the distribution , spacial and temporal variation , mixing and transportation processes about the plume front in the Hangzhou Bay. This front is performed as a group of interfaces among, the water masses situated in the bay. A discussion is also given of the circulation feature in the frontal zone ence of the front.
基金financially funded by the National Natural Science Foundation of China (Nos. 41501005, 41476031, 41620104004)supported by China-ASEAN maritime cooperation fund: Comparative study of Holocene Sedimentary Evolution of the Yangtze River Delta and the Red River Delta
文摘The Holocene environmental evolution in coastal area, including deltas and estuaries, is vital to the Neolithic colonization in the eastern China. A 29-m long sediment core XL was obtained from the region between the Taihu Lake and Qiantang Estuary, and multiple analyses on the core sediments have been done to investigate the evolution history of the inner coastal zone of Hangzhou Bay during the Holocene. Six sedimentary facies are identified since the late Pleistocene, including the paleosol at the bottom, overlain by tidal-flat-channel complex(TFC), tidal-distributary-channel(TDC), inner estuarine basin(IEB), subtidal-to-intertidal-flat, and fluvial-plain facies. The TFC and TDC facies are dated to be formed before 8500 cal yr BP, featured by relatively coarse sediments, high magnetic properties and less abundant foraminifera, denoting the tide-influenced setting with large terrestrial inputs. The IEB facies characterized by the most abundant foraminifera fossils and the lowest sediment magnetic properties, is inferred to be deposited during the maximum flooding period between 8500 and 7900 cal yr BP. The branch estuary was then infilled by local sediments with a shallowing-upward subtidal-to-intertidal sequence during 7900–4300 cal yr BP. At last the fluvial plain system developed since no later than 4300 cal yr BP, favouring the rapid development of Neolithic cultures in the region.
基金This work is supported by both Grant-4860244 from the National Natural Science Foundation of China and Grant-188011 from the Zhejiang Provincial Natural Science Foundation
文摘On the basis of the time series of AVHRR data from NOAA satellites and the geographical information system PURSIS, fluctuations of the plume front and the turbidity maximum in the Hangzhou Bay, reflected by the distributions of temperature and suspended sediment concentration respectively, are studied in view of long-term behaviors or seasonal and tidal cycles. The data suggest that the effect of front plays an important role in the development of the turbidity maximum close to the Changjiang Estuary > while the effect of tide dominates over the development of another very turbid water situated in the shoal areas in the southern Hangzhou Bay.