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1.
渤海湾西北岸滨海湖埋藏牡蛎礁古生态环境   总被引:2,自引:0,他引:2  
对渤海湾西北岸沿海平原滨海湖埋藏牡蛎礁的分布形态进行了综合调查,并对位于礁体中央部位的一个垂直剖面上的礁体下伏沉积物、礁体内的泥砂质充填物连续取样。综合研究表明,该埋藏礁体生长于河流入海口处,长轴方向NW—SE、沿古河床分布。礁体开始建造于2445aBP前,基底坐落于当时的潮间带下部。持续建礁约160年后,至2287aBP时,礁体建造至潮间带中部海平面位置。随着岸线的推进,河流携带的大量泥砂逐渐掩埋了平均厚度约2m的滨海湖牡蛎礁。  相似文献   

2.
通过对渤海湾西北岸大吴庄牡蛎礁壳体内部的泥质填充物中硅藻组合的研究,试图探讨该区沉积硅藻组合变化指示的礁体古气候环境变化.分析结果表明,在 7 200~5 600 cal. a BP 整个礁体建造期间,沿岸种 Cyclotella stylorum 是含量最丰富的硅藻种类,其与海水种 Thalassionema nitzschioides 的含量变化指示了礁体生长区河流径流与海水相互作用的强弱波动,主要包括三个阶段:7 200~6 500 cal. a BP,礁体建造初期,礁体受海水影响显著;6 500~5 720 cal. a BP,礁体建造中期,礁体生长区的盐度降低,海水作用减弱,淡水作用增强;5 720~5 600 cal.a BP,礁体建造结束期,礁体生长区的盐度显著降低,礁体受海水影响进一步减弱.  相似文献   

3.
福建深沪湾晚更新世古牡蛎滩的发育与留存古环境   总被引:5,自引:1,他引:5  
徐起浩 《海洋科学》2002,26(4):58-62
福建深沪湾晚更新世古牡蛎滩以牡蛎原生、分布面积大 ,年龄主要在25800±2490aB P~15460±420aB P之间为其主要特征 ,在牡蛎生长期间 ,深沪湾地壳抬升速率与水动型海平面上升速率相当 ,深沪湾海水深度稳定 ,海岸环境稳定 ,古牡蛎繁盛生长 ,其后深沪湾地壳抬升成陆 ,古牡蛎滩脱离海水成为牡蛎滩台地 ,距今7000a和距今2000a的两次强古地震 ,使古牡蛎滩快速下沉到潮下带和潮间带海底 ,这是深沪湾晚更新世古牡蛎滩能留存到今天的重要原因。  相似文献   

4.
环境因子对太平洋牡蛎(Crassostrea gigas)生长的影响   总被引:1,自引:0,他引:1  
前言海洋环境的变化明显地影响着海区太平洋牡蛎(Crassostreagigas)的生长。包括其它的双壳类动物,研究都表明:存活率主要决定于遗传因子,而生长虽然个别种群可以很好的适应于某地的栖息条件,但是受周围环境条件影响很大。水温、盐度、饵料浓度和水深等是影响双壳类动物生长的主要环境因子。试验已证明:四鞭胞藻(Tetraselmissuecica)和角毛藻(Chaetoceroscalcitrans)是太平洋牡蛎和食用牡蛎(Ostreaedulis)获取脂类、碳水化合物和蛋白质的藻类[1]。然而饵料的数量和质量对于天然环境中牡蛎的营养状况也有影响。本文则就环境因…  相似文献   

5.
江苏岸外的小庙洪牡蛎礁在海岸地貌学上是一稀有的生物沉积体。这种位于蚀、淤交替岸段潮间带、古礁体和活体共存的牡蛎礁体是我国所仅见。现场观察了牡蛎礁体的地貌特征,并使用GPS和全站仪进行了主要礁体分布与高程的测量,表明礁区地貌面不是一个水平面,相差可达2m以上。礁体顶高主要分布在两个高程上,一是与平均潮位相当,二是比前者低约30cm,略高于小潮平均低潮位。礁体起伏面高出礁坪面多在0.5—1.5m。小庙洪牡蛎礁正处于退化状态,除物理因素造成的侵蚀外,化学溶蚀及人类活动也是侵蚀退化的主要因素。对于礁区内部的礁体,其退化过程为连片礁→环礁→带礁→斑礁→礁坪的顺序。礁体沉积体有三种:原生礁体、与原生礁体脱离的礁块以及已离开原生地的松散堆积体。浪蚀礁坪分布在礁体的迎浪面上,而溶蚀礁坪则分布在礁体密集区。在礁体稀疏区,则覆盖约20—30cm厚的粉沙或淤泥,形成次生的潮坪。  相似文献   

6.
利用遗传模型分析方法,对长牡蛎生长性状的遗传效应及其与环境互作效应进行研究。结果表明,壳长、壳宽和总重3个性状主要受显性效应控制,显性方差占表型方差的比例分别为0.31、0.23、0.36;壳高性状主要受显性-环境互作效应控制,显性-环境互作方差占表型方差的比例为0.37。4个性状中,壳高的加性效应作用较大,狭义遗传力达到0.10,表明以壳高为目标性状进行选育较容易。但由于总遗传力中互作广义遗传力大于广义遗传力,因此在选育过程中需考虑环境的影响。从遗传效应预测值看,中国和韩国群体杂交子代的效应值最大,表明这2个种群杂交易获得生长性状的杂种优势。  相似文献   

7.
1991年8月~lO月和1992年3月.分别在台湾西部沿海的香山养殖区采集牡蛎以及附近河川溶解态、悬浮态底泥样品进行金属元素的分析,发现牡蛎和溶解态、悬浮态中的铜锌比值一致,显示牡蛎内重金属的累积量和生长环境中金属含量有关,  相似文献   

8.
对位于渤海湾西北岸平原的滨海湖埋藏牡蛎礁中各层牡蛎壳的泥质充填物做硅藻分析,整个牡蛎礁中海水砂质潮间带指标种标志种的Auliscus caelatus含量较高,为19%~42%,表明滨海湖礁体形成于潮间带环境。根据主要硅藻含量的变化,结合14C测年,自下而上将礁体发育期间的古环境分为3个带:I带为2 445~2 327 cal.aBP,礁体在向上建礁的过程中,海水作用逐渐减弱,潮间带特征愈加明显,为受河流影响较强且较为开放的潟湖潮间带环境;Ⅱ带咸水种硅藻Thalassionema nitzschioides的比例急剧增加;外洋指标种的Coscinodiscus spp.和Actinocyclus spp.急剧下降,表明在约2 327 cal.aBP,海岸带砂嘴闭合,形成较为封闭的潟湖内侧潮间带环境,且河流作用减弱导致潟湖的咸度明显增加;Ⅲ带为2 327~2 287 cal.aBP,由封闭的潟湖环境又转向较开放的潟湖潮间带环境。  相似文献   

9.
福建古牡蛎礁与海面、海岸线变动   总被引:1,自引:0,他引:1  
本文研究了福建沿海古牡蛎礁的分布、产状和年代,并据此确定了福建沿岸3000多年以来各有两次明显的上升和下降。两次上升是距今3000年( 2.0m左右)和2000—1500年( 1.5m左右)。两次下降是距今3000—2100年(0m附近)和1500—700年(-0.4m左右)。  相似文献   

10.
竺奇慧  张瑞  纪鹏  许飞  李莉  张国范 《海洋与湖沼》2014,45(6):1264-1271
不规则物体体积测量的传统方法有排液法、称重法和排气法等,不仅操作繁琐,而且准确度及精确度低。本文首次提出了排水称重法,利用该方法能够更加简单、快速、准确地测量出物体的体积和质量。用此法对不同海区26个采样点的1100个牡蛎贝壳密度进行了测定分析,结果表明:大部分牡蛎的左壳密度显著小于右壳密度(P0.05);对于不同海区间的牡蛎,贝壳密度存在极显著的差异(P0.001);分布海区相近的牡蛎间,壳的密度也趋于相近;受环境压力相对较大的潮间带上部的牡蛎,贝壳密度也相对较大。本研究为剖析牡蛎贝壳形成机制以及温度、盐度和海洋酸化等环境因素对牡蛎贝壳形成的影响等研究提供了实验数据和参考。  相似文献   

11.
渤海湾西岸海风时空演变特征观测分析   总被引:2,自引:0,他引:2  
应用2008年全年天津地区14个气象站的逐小时资料和6 h一次的地面常规资料,对渤海湾西岸(天津)海风时空演变特征进行了统计分析,结果表明:2008年全年渤海湾西岸的海风盛行于春夏季的14—17时,海风发生频率的最大值出现在夏季,近海站的海风风速主要集中在2—4 m/s,且春季的海风强度最大,秋季最弱,风向主要以东和南-东南方向为主;海岸带附近建立的海风一半以上都可向内陆传播至30 km远,最大可向内陆传播70 km以远,海风强度的空间分布则呈现出近海站高于远海站,近郊站大于城市站的特点。  相似文献   

12.
Using 110 newly revised Holocene sea level indicators categorized into three types, sediments (67), shelly cheniers (27) and oyster reefs (16), this paper firstly provides a Holocene relative sea level curve, based on multiple approaches of litho- and biostratigraphies and sedimentary faces analysis, for the west coast of Bohai Bay, China. Following considerations, including indicative meaning, the paleo tidal pattern and range and conversion from mean tidal level to mean sea level, an apparent relative mean sea level (RMSL) curve was further reconstructed. After systematical calibration using CALIB, those of the 48 reworked samples were further corrected for the residence-time effect. Similarly, the younger ages for another 35 samples were chosen at the subsample level. These result in a younger-oriented shift for about 0.5 ka. Three local spatial factors, including neotectonic subsidence (average rate about 0.1 mm/a), self-compaction of unconsolidated sediments (between a few decimeters to about 6 m) and subsidence due to groundwater withdrawal (between a few centimeters to about 2.5 m), were quantitatively corrected. Finally, the amended RMSL curve after eliminating all these local temporo-spatial factors is very likely to show non-existence of mid-Holocene highstand and imply potential influences of both ice-volume equivalent sea level and regional glacial isostatic adjustment. Although it is still unable to divide both global and regional factors, the slowdown of sea level rise, in 7.5–6.8 ka with a maximum height less than +1 m, may constrain the model effort in the near future.  相似文献   

13.
对渤海湾西岸CH114 孔岩心全新世沉积硅藻进行了系统研究,发现硅藻17 属28 种。与沉积岩石学、年代学(AMS 14C)研究相结合,将该孔自下而上划分为6 个硅藻组合带,显示研究区全新世以来经历了从陆到海的演化过程:全新世初期 为陆相(组合1带下部) 至受海水影响的盐沼低地环境(组合1带上部);6 646~4 280 cal BP 年间为受风暴强力事件影响的 浅海环境(组合2带);4 280 年以来为水深不断变浅的浅海环境(组合3-6 带)。CH114 孔沉积速率的阶段性变化与河流供 给有较好的对应关系:3.6~2.6 ka cal BP和0.4ka cal BP 以来两个时段相对较高的沉积速率,分别与黄河三角洲超级叶瓣5 的 形成和海河独立入海相对应。由硅藻记录的海洋影响的波动变化与全新世气候变化对比显示:研究区海洋影响的增强与气候 变暖具有一定的正相关性。CH114孔全新世以来陆海环境的演化,总体上是对气候与海面变化的响应。  相似文献   

14.
The geochemical and mineralogical characteristics of pre-Holocene core sediments from Haenam Bay, southwest coast of Korea, were examined for post-depositional diagenetic changes and used to assess the provenance of fine-grained sediments in the region. The geochemical and mineralogical compositions of the sediments vary very little with core depth (Holocene to pre-Holocene age), except for the upper part of the pre-Holocene sedimentary layer. In this case, smectite and chlorite are depleted, presumably due to intensive subaerial weathering and low pH conditions. Highly mobile elements (Ca, Mg, Na and K) were likely removed with the breakdown of labile minerals, such as carbonate minerals, feldspar, and clay minerals, during subaerial exposure of this layer, resulting in low weathering indices. In particular, the low smectite content (<5%) and low V/Al ratio (<13) suggest that the Holocene and pre-Holocene sediments along the southwestern coast of Korea did not originate from mainland China but rather mostly from the Korean Peninsula. This aspect has been a subject of debate since the mid-1970s.  相似文献   

15.
The geochemical and mineralogical characteristics of pre-Holocene core sediments from Haenam Bay, southwest coast of Korea, were examined for post-depositional diagenetic changes and used to assess the provenance of fine-grained sediments in the region. The geochemical and mineralogical compositions of the sediments vary very little with core depth (Holocene to pre-Holocene age), except for the upper part of the pre-Holocene sedimentary layer. In this case, smectite and chlorite are depleted, presumably due to intensive subaerial weathering and low pH conditions. Highly mobile elements (Ca, Mg, Na and K) were likely removed with the breakdown of labile minerals, such as carbonate minerals, feldspar, and clay minerals, during subaerial exposure of this layer, resulting in low weathering indices. In particular, the low smectite content (<5%) and low V/Al ratio (<13) suggest that the Holocene and pre-Holocene sediments along the southwestern coast of Korea did not originate from mainland China but rather mostly from the Korean Peninsula. This aspect has been a subject of debate since the mid-1970s.  相似文献   

16.
Quaternary marine ostracoda on the west coast of the Bohai Sea   总被引:1,自引:0,他引:1  
According to the results of analysis of the marine ostracoda biofacies from over 160 drilled holes on the west coast of the Bohai Sea, i.e. Hebei and Shandong Provinces, Tianjin, and the east part of Beijing, the present paper is a discussion of their palaeoecological and stratigraphigical significance. The investigation of ostracoda thanatocoenoces in the modern coastal zone suggests that the distribution of marine ostracoda has been controlled by the salinity and depth of water. The study of Quaternary marine ostracoda should be concentrated mainly on the determination of their biofacies and palaeogeographigical conditions, so as to provide evidence for the determination of transgression range, palaeoshoreline and sca-leve! changes.  相似文献   

17.
通过对19个观测井2年定期、连续的水位观测,以及水质主要9种离子浓度分析,阐述了辽东湾西部沿岸海水入侵的分布特征。根据海水入侵区地下水中主要离子浓度与地下水的相关关系,总结了随着海水入侵的发展地下水化学类型的变化。地下水化学类型分为5大类型:Na+-Cl-型、Cl-.HCO3-或HCO3-.Cl-型(阳离子为Ca2+.Na+)、HCO3-.Cl-.SO42-或Cl-.HCO3-.SO42-型水(阳离子为Ca2+)、SO42-.HCO3-型(阳离子为Na+.Ca2+)、HCO3-型(阳离子为Ca2+.Na+)。该区地下水水化学类型呈带状分布,类型变化规律明显,反映了海水入侵分布特征。当淡水开采时,水位降深越大,微咸水入侵强度越大。控制淡水开采是防止微咸水入侵的主要措施。  相似文献   

18.
The Pacific oyster Crassostrea gigas was introduced in Europe for commercial purposes in the mid 1960s. It was initially thought that low winter temperatures would restrain this species' reproduction and settlement; however, its present distribution in areas where no introduction has taken place suggests that natural invasion and expansion has occurred. Along the European coast, wild populations of Pacific oysters are already found from northern Germany to southern Portugal. Whether C. gigas will continue to further expand through northern waters will depend on its physiological performance. In this study, the performance of wild oyster populations has been studied in terms of growth and reproduction at three stations: La Rochelle (France; 46°N), Yerseke (Oosterschelde estuary, The Netherlands, 51°N), and Texel (Wadden Sea estuary, The Netherlands, 53°N). The French population had the lowest somatic-shell mass ratio and an increase in maximum shell length, somatic and gonadal mass was observed from France to the Netherlands. In addition, mean oocyte diameter decreased significantly from south to north. The combination of increasing gonadal mass and decreasing oocyte volume suggests an increasing reproductive output in terms of egg numbers from France to The Netherlands. Differences in temperature between locations will at least be partly responsible for the observed patterns; however, other environmental factors (such as food availability, predation pressure, sediment type and/or seston concentration) cannot be excluded. Since smaller eggs (oocytes) are thought to have a longer development time, the environmental conditions along the Dutch coast may result in increased larval dispersal and possibly in further population expansion.  相似文献   

19.
通过对渤海湾西岸BXZK11孔沉积物黏土矿物、地球化学元素组分、粒度分析以及AMS14C年代测定并与研究区周边6个具有较好年龄控制的钻孔剖面对比,结合黏土矿物蒙脱石/(伊利石+绿泥石)比值以及元素Al/Si和Al/Na比值对气候变化的响应,探讨了渤海湾西岸地区全新世以来沉积环境以及气候变化过程.结果表明,末次盛冰期到8...  相似文献   

20.
On the basis of the measurement of ^210Pbcx and ^137Cs activities in the sediment cores taken from the intertidal zone on the west coast of the Bohai Gulf, the average sedimentation rates of modern sediments are calculated. The results indicate that in the sandy area of the intertidal zone (from Daogouzi to the Duliujian River), the sedimentation rate from 1955 to 1963 is 3.43~4.06 cm/a, and is within the range of 0.65~1.59 cm/a since 1963. The average sedimentation rate in the muddy area (around Qikou) is approximately 1.81 cm/a.The results above suggest that the sandy area of the intertidal zone has experienced rapid sedimentation from the 1950s to the 1960s,and the sedimentation slows down after the 1960s, and the sedimentation rates increase from north to south spatially. The rapid sedimentation from the 1950s to the 1960s in the sandy area is due to the fact that North China has plentiful precipitation during this period and the intertidal zone is supplied with abundant matter sources for sedimentation. After the 1960s, the weakened sedimentation may be a result of the reduction of sand transported to the intertidal zone, which is a consequence of diminished rainfall in North China and intensive human activities in the Haihe basin.  相似文献   

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