基于潮沟定点观测的潮间带水、沙、盐交换研究     

李鹏  杨世伦 《海洋与湖沼》2014,45(1):126-133

为研究潮间带和潮下带的水、沙、盐交换,于2006年6月25~28日（夏季大潮）和2006年12月29日~2007年1月4日（冬季中-大潮和小潮）在长江口九段沙一典型潮沟的固定点利用OBS-3A和ADP-XR进行了水深、浊度、盐度、流速流向剖面和回声强度观测。结果和结论为：（1）夏季大潮、冬季中-大潮、冬季小潮的潮周期垂向平均流速分别为26.5、15.9和8.4 cm/s,夏、冬季观测到的最大流速分别为84 cm/s和35 cm/s。（2）夏季盐度变化范围为0.65~4.91,平均盐度2.14;冬季盐度变化范围为3.5~10.3,中-大潮和小潮平均盐度分别为6.26和7.98。（3）高悬沙浓度出现在涨潮初期和部分落潮末期的低水位阶段;涨潮阶段的平均悬沙浓度是落潮阶段的1.11~7.0倍。（4）涨、落潮阶段的水体和盐输运量大体上趋于平衡;（5）无论是冬夏季或大小潮,潮沟在潮周期内的净输沙方向均指向陆,即落潮输沙量小于涨潮输沙量（平均小40%）;平均每个潮周期的净输沙量为6102 kg,结合潮盆面积推算的潮周期沉积速率为0.0112 mm/tide,或8.2 mm/a。  相似文献   

2010—2011年东海藻华高发区水体层化对东海原甲藻(Prorocentrum donghaiense Lu)藻华的影响   总被引：1，自引：0，他引：1  

戴鑫烽  陆斗定  夏平  王红霞  何飘霞  李冬融 《海洋与湖沼》2014,45(2):217-224

本文通过2010年和2011年不同时空角度对东海原甲藻藻华进行调查,研究水体层化对藻华发生和发展的影响。结果显示,起初东海原甲藻在50m等深线附近的外海繁殖与聚集,然后随着台湾暖流与长江冲淡水的相互作用,东海区域水体层化现象加剧,其细胞丰度越来越大,直至藻华发生并持续推进到近岸。大部分东海原甲藻细胞位于层化水体上方,而且当水体层化现象明显时,藻华的发展最为迅速且呈大规模爆发状态。结果还显示当出现叶绿素高值层时,总是伴随出现温盐突变现象。本项研究不仅第一次从时间角度记录了东海原甲藻藻华的发展动态,而且还发现了东海水体层化现象为东海原甲藻藻华的发生和发展提供了多种环境因子条件,这为该藻华的监控和预测提供了重要的科学依据。  相似文献   

有孔虫初房特征变化在珠江三角洲晚全新世东亚夏季风降雨研究中的应用     

俞宙菲  李铁刚  南青云  张帅 《海洋与湖沼》2014,45(2):225-232

研究中国降雨格局变化对理解东亚夏季风演化意义重大。本文分析了珠江三角洲柱状样ZJK03-Z中浅水底栖有孔虫常见种Rotalidium annectens的平均初房大小、微球型/显球型比值和壳体δ18O值,以及底栖有孔虫组合中瓷质壳的百分含量,探讨它们对由夏季风降雨引起的河口水体盐度变化的响应,得到了珠江三角洲3114—1260a BP季风降雨的强度变化,识别出了这期间14次季风降雨减少的偏干期。与南美洲Cariaco海盆的钛含量记录对比,二者一致的结果表明,珠江三角洲晚全新世的东亚夏季风降雨与热带辐合带(ITCZ)的南北移动密切相关:夏季风降雨减少,对应于ITCZ纬度位置的南移。  相似文献   

颗粒态有机物在长江口及其邻近海域的夏季分布和影响因素初析   总被引：1，自引：1，他引：0  

邵锡斌  吴莹  胡俊  鲍红艳 《海洋与湖沼》2014,45(6):1288-1294

利用气相色谱法对长江口及其邻近海域的表层颗粒态木质素(p-lignin)进行测定和分析,结合粒度、有机碳(OC%)、叶绿素a(Chl a)、碳稳定同位素(δ13C)等参数研究颗粒态有机物的夏季分布,并对其分布影响因素进行了初步分析。结果表明,悬浮颗粒物粒度组成以粘土和粉砂为主,平均粒径为7.9μm;OC%的值为0.57—7.41%,Chl a的值为0.35—3.71μg/L,δ13C的值为-25.7‰—–16.6‰,在口门外水华站位出现OC%、Chl a和δ13C的最大值,表明浮游生物的现场生产是主要贡献;紫丁香基酚类(S)、香草基酚类(V)和肉桂基酚类(C)8种木质素酚单体的含量Λ8(相对于总有机碳的含量)为0.0406—1.47mg/100mg OC;紫丁香基系列与香草基系列的质量比值(S/V)的分布范围较宽,为0.5—1.6之间,均值为0.8;肉桂基含量与香草基含量比值(C/V)的分布范围为0.02—0.2之间,均值为0.09;香草基酚类的酸醛比值[(Ad/Al)v]在0.24—2.30之间。盐度、总悬浮颗粒物(TSM)浓度是控制长江口内区与邻近海域颗粒态有机物来源与分布差异的重要控制因素,颗粒态木质素在向海输送过程中还会受到矿物组分、生物降解、浮游生物现场生产等各种因素的作用,使其组成成分和性质发生改变。木质素等参数表明最大浑浊带尽管对颗粒态有机物向海输送有改造作用,但是影响区域有限。  相似文献   

Effects of substratum type on fish assemblages in shallow areas of a tropical estuary     

José Amorim Reis‐Filho  Alexandre Clistenes de Alcântara Santos 《Marine Ecology》2014,35(4):456-470

While there is already a comprehensive understanding of the effects of environmental variables, such as dissolved oxygen, temperature and salinity, on the structure, biomass and metabolism of aquatic biota in estuarine habitats, the effect of sedimentation, a harmful underlying factor, remains unclear. The aim of this study was to assess the differences in fish assemblages along the freshwater to salt water gradient of a large tropical estuary, and to evaluate the effects on them of habitat disturbance associated with shallow water sedimentation in the intertidal areas. Fish and environmental variables were recorded in the upper, middle and lower salinity zones of the estuary at ebb tide in both the dry and wet seasons. Sediment samples associated with different levels of habitat disturbance were analysed using granulometry, and their organic content and dissolved oxygen levels were quantified. Water temperature, salinity, pH and dissolved oxygen levels were also measured. Habitat disturbance was found to be correlated with the density, biomass and richness of fish assemblages. A total of 77 species were recorded, forming two distinct fish assemblages, with the Eleotridae family dominating in the upper zone, and Gerreidae, Gobiidae and Tetraodontidae the most common in the middle and lower estuary. Changes in the structure of fish assemblages, including reductions in density, biomass and richness, were associated with disturbance to natural features, where muddy sediment was replaced by sandy sediment and the quantity of organic matter fell. Atherinella brasiliensis was the species which showed a preference for the disturbed areas in the middle and lower zones, while Dormitator maculatus showed a preference for them in the upper estuary. They may be taken as indicators of habitat disturbance due to shallow sedimentation.  相似文献   

Distributional characteristics of grain sizes of surface sediments in the Zhujiang River Estuary   总被引：1，自引：0，他引：1  

JIANG Siyi  XU Fangjian  LI Yan  LIU Xiling  ZHAO Yongfang  XU Wei 《海洋学报(英文版)》2014,33(4):30-36

Distributions of the parameters of sedimentary grain sizes and their correlations were studied to trace the sources of silts and their movement trends in the Zhujiang River Estuary based on the analyses of grain sizes from more than 1080 sedimentary samples. The distributions of the median diameter, public value, quartile deviation, and skewness of sediments were complex in the Zhuiiang River Estuary mainly because of the impact of the matter source regions, distances from the source regions, and hydrodynamic conditions, such as waves, tidal currents, and coastal currents. Analyses of the parameters of the grain sizes for the various types of sediments showed that the distributions of the surface sediments in the Zhujiang River Estuary were controlled by many factors. Their matter sources were mainly the sediments discharged from the runoffs and ebb tidal currents, and from the open sea. The sediments mainly moved by suspension movement. The silts formed a large area of sediments with suspended fine silts in the Zhujiang River Estuary by internal adjustment transportation in the area, and moved toward the western coast of the Zhujiang River Estuary under the effect of Coriolis forces and coastal currents.  相似文献   

Lacustrine basin unconventional resource plays: Key differences     

《Marine and Petroleum Geology》2014

There has been a revival in hydrocarbon source rock characterization and development associated with growing interest in unconventional resources, where these fine-grained organic-rich rocks act as both source and reservoir. To-date, the exploration focus on shale reservoirs has been largely on marine systems. Lacustrine source rocks for conventional resources are geographically important, dominating regions such as China, Indonesia, and Brazil's resource-base. However, they have been generally untested for unconventional resources.There are a number of key differences in the nature of these hydrocarbon systems that should be considered when assessing whether lacustrine systems may represent future unconventional opportunities in areas where the conventional resource-base is dominated by lacustrine-sourced oil. Among the key differences between these depositional systems is the greater sensitivity to high frequency climatic variability within lacustrine systems. Lacustrine systems are highly sensitive to changes in the balance between precipitation and evaporation, which may lead to rapid changes in lake level, potentially exceeding 600 m. These changes in depositional conditions are geologically rapid and may occur over periods of thousands of years. Such changes can reduce the areal extent of potentially thick source rock intervals to only those portions of a basin where a permanent deep lake was present. Thus the core unconventional target area may be geographically limited compared with their marine counterpart. Although potentially areally limited, a review of many lacustrine source rocks suggests that their thicknesses are often significantly greater than marine source rocks. An examination of the more distal portions of lacustrine systems, where better source rock potential is present reveals that there is generally limited connectivity between source and conventional reservoir. In these settings, such as the Wind River basin (Waltman Shale), the hydrocarbons remain trapped within the shales, potentially leading to over-pressured hydrocarbon charged systems. Such conditions suggest that although areally limited, viable unconventional targets may exist, if suitable reservoir conditions are present. Finally, the character of the oils produced is different in these settings, with lacustrine oils being waxy and displaying different hydrocarbon generation and cracking kinetics. High wax oils display distinct flow characteristics, being more viscous, and may offer different production challenges than their non-waxy marine equivalents. Additionally, differences in their cracking kinetics may indicate that the timing of gas generation for shale gas plays may differ significantly from marine systems.  相似文献   

Seismic geomorphology,architecture and genesis of Miocene shelf sand ridges in the Pearl River Mouth Basin,northern South China Sea     

《Marine and Petroleum Geology》2014

Multiple stages of large-scale shelf sand ridges, including the shoreface-attached and the offshore types, have developed in the Miocene successions on the mid-shelf region of the Pear River Mouth Basin, northern South China Sea. Utilizing a high-quality 3D seismic data set, accompanying 2D seismic profiles and well logs, the morphology, architecture and genesis of these shelf sand ridges have been systematically investigated in this study. The ridges are of very large scale, with the largest one having a maximum height of 64 m, a width of more than 20 km and a length of 37 km within the 3D survey area. Being mound-shaped, they also display obvious asymmetry character, with the ridge crest preferentially located on the SE side. Three main internal components, including the ridge front, central ridge and the ridge tail, have been recognized through careful anatomy analysis of the two most well-imaged ridges, each displaying distinct expressions on seismic amplitudes and geometries. In the plan view, most of the shelf sand ridges are generally NE–SW oriented and widening to the SW direction. Scouring features can also be clearly observed along the SW direction, including scour depressions and linear sandy remnants. On well logs, the shelf sand ridges are represented by an overall coarsening-upward pattern. Intervals with blocky sandstones are preferentially present on higher locations due to a differential winnowing process controlled by shelf topography.Plenty of evidence indicates that these ridges were primarily formed by the reworking of forced regressive or lowstand deltaic deposits under a persistent southwesterly flowing current during the subsequent transgression. This very current is a composite one, which is speculated to consist of winter oceanic current, SCSBK (South China Sea Branch of Kuroshio) intrusion onto the shelf and internal waves propagating from the Luzon Strait. Tidal currents might have contributed to the SE growth of the ridge. In response to the reglaciation of Antarctic ice-sheet and the closure of Pacific-Indian ocean seaway in the middle Miocene, the intensification of the North Pacific western boundary current was considered to have potential links to the initiation of the shelf sand ridges at ∼12 Ma. The development of shelf ridges was terminated and replaced by rapid deltaic progradation at ∼5.5 Ma.  相似文献   

Dispersal of the Zhujiang River (Pearl River) derived sediment in the Holocene   总被引：2，自引：1，他引：1  

GE Qian  LIU J. P.  XUE Zuo  CHU Fengyou 《海洋学报(英文版)》2014,33(8):1-9

High-resolution Chirp profiling and coring reveals an elongated(ca. 400 km) Holocene Zhujiang River(Pearl River)-derived mud area(maximum thickness 20 m) extending from the Zhujiang River Delta, southwestward off the Guangdong coast, to the Leizhou Peninsula. Two depo-centers, one proximal and one distal, are identified. On the continental shelf off the west Guangdong Province, the mud is deposited in water depth shallower than 50 m; while to the southeast of the Zhujiang River Estuary, the mud area can extend to the-120 m isobath. A combined analysis with the stratigraphic sequences of other muddy deposits in the Western Pacific marginal seas(mainly Changjiang(Yangtze) and Huanghe(Yellow) Rivers derived) indicates that the initiation of the Zhujiang River muddy deposit can be further divided into two stages: Stage 1 is before the mid-Holocene sea-level highstand(ca. 7.0 cal. ka BP), the proximal mud was mostly deposited after 9.0 cal. ka BP, when the sea-level rose slowly after the Meltwater Pulse-1C; Stage 2, after the mid-Holocene sealevel highstand, clinoform developed on the continental shelf off the west Guangdong Province, extending ca. 400 km from the Zhujiang River Estuary. The proximal clinoform thins offshore, from ca. 10 m thickness around 5–10 m water depth to less than 1–2 m around 20–30 m water depth. In addition, we also find a developed distal clinoform in the east of the Leizhou Peninsula.  相似文献   

九龙江-河口表层水体营养盐含量的时空变化及潜在富营养化评价   总被引：1，自引：0，他引：1  

候丽媛  ;胡安谊  ;于昌平 《台湾海峡》2014,(3):369-378

分别于2012年9月、2013年1、6月,对九龙江两大支流北溪、西溪及河口区开展了3个航次的营养盐监测.研究结果表明,河口区表层水体溶解无机氮（DIN）、总磷（TP）和活性磷酸盐（PO4-P）质量浓度范围分别为0.13-17.35、0.14-1.00和0.00-0.38 mg/dm3,受上游输入和海水稀释作用,营养盐浓度由淡水端至海水端逐渐降低.北溪表层水体的DIN、TP和活性磷酸盐质量浓度范围分别为1.99-24.92、0.12-1.47和0.04-0.68 mg/dm3,受龙岩地区工农业生产及城市进程影响,由上游至下游逐渐降低.西溪表层水体的DIN、TP和活性磷酸盐质量浓度范围分别为2.74-20.61、0.14-0.92和0.02-0.37 mg/dm3,受上游农业生产和下游漳州地区人类活动影响,上下游的DIN质量浓度较高.此外,九龙江沿岸的人类活动可能影响了该地区水体中的溶解无机氮形态组成：北溪和西溪上游的NH4-N和NO3-N占比分别较高.水期分析表明,2013年1月的DIN浓度显著高于其他水期,而不同区域TP和活性磷酸盐的水期波动不尽相同.营养盐结构分析表明,九龙江总体处于磷限制状态,但在河口及北溪部分站位,CDIN/CPO4-P比值已达到适合浮游生物生长繁殖的水平.潜在富营养化程度评价表明,九龙江河口多数站位均处于N或P限制的富营养化级别,但由于N、P营养盐的绝对浓度较高,具有水华暴发的潜在风险.  相似文献