杭州湾北岸金山咀—龙泉港岸段近岸滩槽冲淤演变分析          下载免费PDF全文

冯凌旋  季永兴  章馨谣  戴志军 《海洋学研究》2020,38(3):92-98

以杭州湾北岸金山咀—龙泉港岸段边滩及海床为研究区域,利用1989—2014年实测及海图资料分析岸滩断面地形变化和岸段冲淤变化。结果表明:在该研究时段,岸段存在长期稳定的冲刷深槽;近岸海床的冲淤表现出“波动性”,5 m等深线(2014年)以浅区以淤积为主,5 m等深线以深冲淤更迭,1989年以来总体呈现冲刷态势。长江入海泥沙量变化为该岸段发生侵蚀/淤积的影响因子之一,台风大浪及海床侵蚀/淤积波的移动导致海床冲淤复杂化。  相似文献   

台州湾海域表层沉积物中多环芳烃的浓度水平、富集规律及来源   总被引：12，自引：0，他引：12  

江锦花 《海洋通报》2007,26(4):85-90

研究了台州湾海域海水和表层沉积物中15种多环芳烃(PAHs) 的浓度水平,评价了表层沉积物对多环芳烃的富集规律,探讨其可能来源.结果表明,表层沉积物中 PAHs 的浓度范围为85.4～167.6 ng / g,平均值为138.62 ng/g,总多环芳烃的最大值是椒江码头.表层沉积物中二环、三环、四环、五环和六环多环芳烃占总多环芳烃的百分含量平均值分别为7.8 %,42.1 %,33.3 %,9.6 % 和 7.2 %,三环多环芳烃的含量最高;表层沉积物对多环芳烃的富集系数为 532.7～1 068.9,平均值为 807.5,单组分菲的富集系数最高为 122.7,最小的是苯并(a) 芘为 2.7;台州湾表层沉积物中的多环芳烃主要来源于燃煤污染,部分来源于石油烃类物质的直接污染.  相似文献   

大亚湾海洋沉积物的人工放射性核素          下载免费PDF全文

林植青  王建林  郑建禄  吴云华  陈绍勇  周彩芸  陈钧铭 《海洋科学》1993,17(4):61-64

对大亚湾核电站邻近海的海洋沉积物中人工放射性核素~(144)Ce,~(103)Ru,~88Rn,~(85)Sr,~(90)Sr,~(134)Cs,~(137)Cs,~(124)Sb,~(54)Mn,~(60)Co进行了调查研究;得到核素的区域变化规律和与沉积物性质的相互关系,以及获得各核素的分配系数(K_d)。  相似文献   

三门湾的悬沙分布和输移特性     

谷国传  胡方西 《海洋学研究》1991,9(3):1-11

本文根据实测资料,通过悬沙浓度ρ、流速v和水深H的对应分析,得出了三门湾的悬沙浓度分布遵循着ρ∝f(v~2/H)的规律;同时发现湾外海域有着良好的将悬沙输移入湾的动力条件,是三门湾悬沙来源的主要场所;经全潮单宽净输沙量计算表明:进出海域的悬沙净输移量不大,全湾的悬沙输移具有深槽输向边滩、南进北出的趋势,与口外海域的泥沙存在着活跃的交换。通过摩阻流速计算得到三门湾变化的总趋势是:深槽略受冲刷,滩涂缓慢淤涨,入湾通道处于动态平衡中。  相似文献   

Geomorphological control of subsurface hydrology in the creekbank zone of tidal marshes     

Judson W. Harvey  Peter F. Germann  William E. Odum 《Estuarine, Coastal and Shelf Science》1987,25(6)

A combination of field and numerical modeling methods was used to assess porewater movement in a narrow (20 m) Spartina marsh which was flooded regularly by tidal waters. Soil composition and soil hydraulic properties did not vary across the marsh or with depth. Hydraulic head was monitored on a transect perpendicular to the creekbank. During exposure of the marsh surface, hydraulic gradients were predominantly horizontal; vertical gradients were small or zero. Subsurface flow was directed from the marsh interior toward the creekbank. Approximately 141 of pore water were discharged laterally to the adjacent tidal creek per meter of creekbank over a complete tidal cycle.A numerical hydrological model was modified to simulate subsurface hydraulics in the creekbank vicinity of regularly flooded tidal marshes. The model was parameterized to represent soil conditions, tidal fluctuations and topography at the field site. Observed changes in hydraulic head over complete tidal cycles were accurately predicted by the model. Model simulations identified the vertical infiltration of creek water into the marsh surface at the onset of tidal flooding as the primary source (66%) for the replacement of water drained at the creekbank. Significant replacement (31%) also occurred as discharge from the interior marsh. Horizontal recharge at the creekbank was minimal (3%).A sensitivity analysis was conducted with the model to assess the relative importance of geomorphological factors and soil properties in controlling pore water export at the creekbank of tidal marsh soils. Each parameter was varied systematically over a realistic range for field conditions. Changes in marsh elevation exerted greater control over creekbank discharge than changes in soil hydraulic properties. More rapid turnover of pore water near creekbanks of higher elevation marshes is hypothesized.  相似文献   

The phytoplankton bloom response to wind events and upwelled nutrients during the CoOP WEST study     

Frances P. Wilkerson  Adria M. Lassiter  Richard C. Dugdale  Albert Marchi  Victoria E. Hogue 《Deep Sea Research Part II: Topical Studies in Oceanography》2006,53(25-26):3023

In the coastal waters off northern California, seasonal wind-driven upwelling supplies abundant nutrients to be processed by phytoplankton productivity. As part of the Coastal Ocean Processes: Wind Events and Shelf Transport (CoOP WEST) study, nutrients, CO₂, size-fractionated chlorophyll, and phytoplankton community structure were measured in the upwelling region off Bodega Bay, CA, during May–June 2000, 2001 and 2002. The ability of this ecosystem to assimilate nitrate (NO₃) and silicic acid/silicate (Si(OH)₄) and accumulate particulate material (i.e. phytoplankton) was realized in all 3 years, following short events of upwelling-favorable winds, followed by periods of relaxed winds. This was observed as phytoplankton blooms, dominated by chlorophyll in cells greater than 5 μm in diameter, that reduced the ambient nutrients to zero. These communities were located over the near-shore shelf (<100 m depth) and were dominated by diatoms. An optimal window of 3–7 days of relaxed winds, following an upwelling pulse, was required for chlorophyll accumulation. The large-celled phytoplankton that result are likely important players in coastal new production and carbon cycling.  相似文献   

A regional analysis of new production on the northwest European shelf using oxygen fluxes and a ship-of-opportunity     

Charlene P. Bargeron  David J. Hydes  David K. Woolf  Boris A. Kelly-Gerreyn  Mohammed A. Qurban 《Estuarine, Coastal and Shelf Science》2006,69(3-4):478

Seasonal new production (g C m⁻²) estimates obtained from dissolved oxygen and nitrate concentrations in surface waters (5 m depth) along a track between the UK (Portsmouth) and northern Spain (Bilbao) are compared. An oxygen flux method, in combination with a ship of opportunity (SOO), was tested on the northwest European shelf for its value in distinguishing high production in frontal regions. Dissolved oxygen, nitrate and chlorophyll a samples were collected monthly from February to July 2004, alongside continuous autonomous measurements of salinity, temperature and chlorophyll fluorescence. Depth integrated new production estimates for all the individually analysed hydrographic regions of the route were produced.Results from three widely used gas-exchange parameterizations gave seasonal (February–July) new production estimates of 54–68 g C m⁻² for the Ushant region of the western English Channel and 31–40 g C m⁻² for the shelf slope, averaging 24–31 g C m⁻² for the route. This is double the route average obtained using the nitrate assimilation method (17 g C m⁻²) and within the ranges of previous estimates in the same region. The oxygen flux method gave a fivefold enhancement compared to the nitrate method in the Ushant frontal region and a threefold enhancement in the English Channel and shelf break regions. Determining oxygen fluxes to estimate new production may be more reliable than nitrate assimilation in active tidal or frontal regions of shelves where nitrate may be added to the system post-winter through advection or entrainment.  相似文献   

浙江乐清湾现代沉积与悬沙质量浓度分布特征及意义   总被引：2，自引：0，他引：2  

毛龙江  殷勇  郭伟  朱大奎 《海洋科学》2005,29(10):93-96

通过对乐清湾野外考察、表层沉积物的粒度分析和水样的悬沙质量浓度分析，探讨了乐清湾现代沉积和悬沙质量浓度分布特征。研究结果表明，乐清湾现代沉积主要以细颗粒沉降为主，粉沙和粘土总含量占90％以上；悬沙质量浓度具有从湾口向湾内递减的变化趋势，湾口悬沙质量浓度为0．2～0．25kg／m^3，而湾内质量浓度小于0．01kg／m^3。半封闭性海湾和以外海来沙为主的物质来源共同决定沉积物的特征及悬沙质量浓度的空间变化规律，而泥沙来源及沉积过程的研究将为港湾治理工程提供重要的依据参数。  相似文献   

Biogeochemistry of Dimethylsulfoniopropionate (DMSP) in the Surface Microlayer and Subsurface Seawater of Funka Bay,Japan   总被引：1，自引：0，他引：1  

Yang  Gui-Peng  Tsunogai  Shizuo  Watanabe  Shuichi 《Journal of Oceanography》2005,61(1):69-78

Twenty-eight sea surface microlayer samples, along with subsurface bulk water samples were collected in Funka Bay, Japan during October 2000–March 2001 and analyzed for dimethylsulfoniopropionate, dissolved (DMSP_d) and particulate (DMSP_p), and chlorophyll a. The aim of the study was to examine the extent of enrichment of DMSP in the microlayer and its relationship to chlorophyll a, as well as the production rate of dimethylsulfide (DMS) from DMSP and the factors that influence this. The enrichment factor (EF) of DMSP_d in the surface microlayer ranged from 0.81 to 4.6 with a mean of 1.85. In contrast, EF of DMSP_p in the microlayer varied widely from 0.85–10.5 with an average of 3.21. Chlorophyll a also appeared to be enriched in the microlayer relative to the subsurface water. This may be seen as an important cause of the observed enrichment of DMSP in the microlayer. The concentrations of DMSP_p in the surface microlayer showed a strong temporal variation, basically following the change in chlorophyll a levels. Moreover, the microlayer concentrations of DMSP_p were, on average, 3-fold higher than the microlayer concentrations of DMSP_d and there was a significant correlation between them. Additionally, there was a great variability in the ratios of DMSP_p to chlorophyll a over the study period, reflecting seasonal variation in the proportion of DMSP producers in the total phytoplankton assemblage. It is interesting that the production rate of DMS was enhanced in the microlayer and this rate was closely correlated with the microlayer DMSP_d concentration. Microlayer enrichment of chlorophyll a and higher DMS production rate in the microlayer provide favorable evidence supporting the view that the sea surface microlayer has a greater biological activity than the underlying water.  相似文献   

台湾南湾区秋末冬初海樽类的种类组成和数量分布   总被引：6，自引：0，他引：6  

张金标  黄将修  连光山 《海洋通报》2003,22(6):9-16

根据2001年11月2--3日和12月8--10日在台湾南湾12个测站分别用2种圆锥形浮游生物网(长180cm，网口直径45cm，网目333μm或200μm)采集表层和底层的浮游动物样品，分析了南湾浮游海樽类的种类组成和数量分布，其鉴定海樽类16利，其中7种为台湾周围海域新记录。东方双尾纽鳃樽和小齿海樽为优势种。南湾海樽类的种类数及个体数量均以12月多于11月。讨论了水文条件与海樽类时空分布的关系，认为外海高盐水团足南湾冬季海樽类生态特征的主要制约因子。典型的高温高盐种大西洋火体虫、长吻纽鳃樽、安纽鳃樽、多手纽鳃樽、书氏纽鳃樽、羽环纽鳃樽和斑点纽鳃樽等可以作为外海高温高盐水入侵南湾的指标种。与邻近海域比较，秋冬季南湾与台湾岛以东海域海樽类的区系特征比与台湾海峡和南海北部更加相似。  相似文献