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771.
2009年和2013年对北戴河中海滩二浴场进行了一期治理工程和二期治理工程,通过对2次养滩前后的监测剖面数据的研究和2次养滩工程效果对比分析得出:①2009年的一期治理工程后,海滩经过了近4年的自然演化,至2013年3月,海滩侵蚀后退较大,必需开展二期的整治工程;②2次工程都为成功的养滩实例,从养滩后的3个月以及6个月的剩余填沙体积(一期:91.9%、77.5%;二期:95.9%、86.8%)对比可以看出,二期整治工程效果更加理想。为进一步查看二期工程效果,探索影响养滩效果的因素,需继续进行工程后的养滩监测。  相似文献   
772.
对洋中脊研究的国际研究战略与计划进行分析,具体包括综合大洋钻探计划(IODP)、国际洋中脊协会(InterRidge)和国际海洋研究委员会(SCOR)的相关研究规划和资助项目。此外,结合洋中脊研究论文的文献计量学研究,使用社会网络分析法、VOSviewer和Histcite软件综合分析了洋中脊研究的国际发展趋势及研究热点。美国的洋中脊研究实力最强。中国近3年的发文比例非常高,表明越来越关注该领域的研究。中国洋中脊研究的主要合作对象是美国。热液生态系统与洋中脊岩石地球化学研究目前是该领域的研究热点。本分析结果可以为我国的洋中脊研究和相关决策提供参考依据。  相似文献   
773.
Samples of simple ascidians of the genera Asterocarpa, Cnemidocarpa, Corella, and Pyura were collected from Wellington Harbour, New Zealand (41°16'S, 174° 51'E) and three species of the crustacean family Notodelphyidae were recovered, all from the branchial baskets of the ascidians.

Pygodelphys novaeseelandiae (Schellenberg), and two new species of Doropygus, are described and illustrated.  相似文献   
774.
根据美国TOGA水位中心所提供的1975—1988年水位月平均资料,分析、讨论了热带西太平洋水位的年际变化特征,特别是与ENSO事件有关的低水位现象。此外,还重点叙述了1986—1987年ENSO事件中水位沿经向和赤道剖面的变化,以及与此有关的赤道流系的变化。文中还定性地讨论了赤道开尔文波沿赤道剖面的传播特性。  相似文献   
775.
The Australian-Antarctic Discordance (AAD) is an anomalously deep and rugged zone of the Southeast Indian Ridge (SEIR) between 120° E and 128° E. The AAD contains the boundary between the Indian Ocean and Pacific Ocean isotopic provinces. We have analyzed SeaMarc II bathymetric and sidescan sonar data along the SEIR between 123° E and 128° E. The spreading center in the AAD, previously known to be divided into several transform-bounded sections, is further segmented by nontransform discontinuities which separate distinct spreading cells. Near the transform which bounds the AAD to the east, there is a marked change in the morphology of the spreading center, as well as in virtually every measured geochemical parameter. The spreading axis within the Discordance lies in a prominent rift valley similar to that observed along the Mid-Atlantic Ridge, although the full spreading rate within the AAD is somewhat faster than that of slow-spreading centers (~ 74 mm a–1 vs. 0–40 mm a–1). The AAD rift valleys show a marked contrast with the axial high that characterizes the SEIR east of the AAD. This change in axial morphology is coincident with a large (~ 1 km) deepening of the spreading axis. The segmentation characteristics of the AAD are analogous to those of the slow-spreading Mid-Atlantic Ridge, as opposed to the SEIR east of the AAD, which exhibits segmentation characteristics typical of fast-spreading centers. Thus, the spreading center within and east of the AAD contains much of the range of global variability in accretionary processes, yet it is a region free from spreading rate variations and the volumetric and chemical influences of hotspots. We suggest that the axial morphology and segmentation characteristics of the AAD spreading centers are the result of the presence of cooler than normal mantle. The presence of a cool mantle and the subsequent diminution of magma supply at a constant spreading rate may engender the creation of anomalously thick brittle lithosphere within the AAD, a condition which favor, the creation of an axial rift valley and of thin oceanic crust, in agreement with petrologic studies. The morphologies of transform and non-transform discontinuities within the Discordance also possess characteristics consistent with the creation of anomalously thick lithosphere in the region. The upper mantle viscosity structure which results from lower mantle temperatures and melt production rates may account for the similarity in segmentation characteristics between the AAD and slow-spreading centers. The section of the AAD which overlies the isotopic boundary is associated with chaotic seafloor which may be caused by an erratic pattern of magmatism and/or complex deformation associated with mantle convergence. Finally, the pattern of abyssal hill terrain within a portion of the AAD supports previous models for the formation of abyssal hills at intermediate- and slow-spreading ridges, and provides insights into how asymmetric spreading is achieved in this region.  相似文献   
776.
于2015年和2016年对三亚大东海砂质潮间带进行了季节性的调查,对小型底栖生物及其所处的沉积环境进行了研究,探讨了小型底栖生物的丰度、生物量和群落的时空变化及其与环境变量的关系。共鉴定小型底栖生物类群11个,优势类群为海洋线虫类与桡足类(二者占总丰度83.13%);小型底栖生物年平均丰度为(595.77±442.72)ind·10cm~(–2),小型底栖生物2015年12月的平均丰度为(768.70±533.22) ind·10cm~(–2), 2016年6月平均丰度为(422.85±236.42) ind·10cm~(–2)。丰度分布呈现明显的季节和潮区差异。相关分析结果表明pH、偏态系数与小型底栖生物的丰度呈极显著的负相关,分选系数、中值粒径与之呈极显著的正相关性。小型底栖生物的丰度随季节变化趋势为冬季夏季。食物丰度、溶氧量升高与沉积物粒径的变化是冬季桡足类丰度的大幅增加的主要原因。TWO-WAY ANOVA与ANOSIM结果显示,潮带对小型底栖生物丰度和群落结构的影响在冬季显著。SIMPER分析结果显示,此差异主要来源为桡足类和线虫类。BIOENV分析结果显示,溶氧量和分选系数的组合最能解释这种差异。这一结果可能是由于高、中潮带的人为干扰与砂滩的清理作用导致。夏季潮带间丰度与群落结构差异不显著,pH、盐度、叶绿素含量是影响其分布的主要原因。研究结果可为砂质滩小型底栖生物的研究提供基础数据,也可为全球气候变化背景下砂质潮间带的保护、开发和利用提供科学依据。  相似文献   
777.
于2015年和2016年对大连金沙滩砂质潮间带进行了季节性的调查,对小型底栖生物及其所处的沉积环境进行了研究,探讨了小型底栖的丰度、生物量和群落的时空变化及其与环境变量的关系。结果表明,金沙滩砂质潮间带沉积物主要成分为极粗砂和粗砂,年平均叶绿素a (Chl-a)质量比为0.99μg/g±1.44μg/g,年平均有机碳质量分数为0.38%±0.56%;共鉴定小型底栖生物类群15个,优势类群为海洋线虫类与底栖桡足类(二者占总丰度72.82%);小型底栖生物年平均丰度为42.52个/cm~2±42.91个/cm~2,呈现明显的季节变化和潮区差异,季节变化趋势为3月10月7月12月,潮区变化趋势为高潮带中潮带低潮带;年平均生物量为87.00μg/cm2±85.32μg/cm~2,季节变化趋势为10月7月3月12月,潮区间也存在显著差异。小型底栖生物的类群组成在季节间具有极显著差异。BIOENV分析表明,间隙水盐度、极粗砂质量比和有机碳质量分数的组合能最好地解释金沙滩小型底栖生物群落的时空分布。研究结果可为砂质滩小型底栖生物的研究提供基础数据,也可为全球气候变化背景下砂质潮间带的保护、开发和利用提供科学依据。  相似文献   
778.
The equilibrium planform concept (EPC) for bayed beaches has achieved wide currency in coastal morphodynamics. The north coast of Ireland comprises a series of discrete headland-embayment beaches within which waves and currents recycle a finite sediment volume. It is therefore an ideal setting in which to explore the applicability of the concept. Application of the approach to 9 embayment beaches on the north coast of Ireland provides some insights into the application of the concept. The planform of some beaches does correspond to that predicted while others do not. Those whose measured planform does not correspond to the predicted planform can be interpreted through, (a) difficulty in identifying the wave diffraction point, (b) disequilibrium on the beach (sediment scarcity or excess), (c) geological control of beach morphology. The subjectivity in selecting the diffraction point renders alternative explanations difficult and reduces the utility of the approach on natural shorelines, where significant irregularities render identification of such points difficult.  相似文献   
779.
The impacts of a beach seine fishery on macroinvertebrate communities and sediment characteristics were investigated in the Southwest Caspian Sea. Samples from a single impacted site that was regularly seined were compared with two control sites outside the fishing area. Benthic macroinvertebrates were sampled on four occasions: 6 months prior to the opening of the beach seine fishery (Time 1), 1 day immediately after the closing of beach seining (Time 2), 1 week after closing (Time 3), and 1 month after closing (Time 4). No significant differences were detected in total density, Shannon diversity, or evenness of the macroinvertebrate assemblages between impact and control sites. Unlike density, species richness increased significantly immediately after fishery closure at all sites. A significant difference was detected in the number of species between Time 2 and Time 3 at all sites and the number of species was reduced at Time 4 in all sites. Pontogammarids increased by twofold in the impact site 1 day immediately after closing beach seine fishery and leveled off toward the end of the closed season. The amplified density of pontogammarids 1 day after fishery closing at the impact site might be driven in part by an increase in sediment oxygen content resulting from disturbance of the sea floor. An alternative explanation is that the effect of fish predation on pontogammarids has largely been minimized at the impact site after 6 months of continuous fishing activity. No significant changes in the sedimentary organic content and chlorophyll‐a between the impact and control sites were observed during the courses of sampling; however, a significant change occurred between the average sedimentary pheopigment content of the control sites and that of the impact site. The conclusion from the present study is that beach seine fishery does not harm to benthic communities. The closed season also seemed to allow recovery to pre‐season levels of macroinvertebrate richness and sedimentary chlorophyll‐a.  相似文献   
780.
本文选取了辽宁省盘锦市红海滩6个采样点的沉积物,通过测定其中重金属和石油各组分的含量,调查盘锦红海滩的重金属和石油的污染情况。结果表明,各采样点中除退化区的Cu和茂盛区的Pb含量高于《海洋沉积物质量标准》(GB18668-2002)Ⅰ类标准外,其他各区域重金属含量均低于(GB 18668-2002)Ⅰ类标准。茂盛区的植物必需金属Fe、Mg、K含量在36.9~46.1 g/kg之间,高于退化区和光滩区的30.7~38.0 g/kg;退化区和茂盛区的土壤样品含油浓度较高,在1.6~5.2 mg/kg之间,光滩区的土壤样品含油浓度较低,为2.5mg/kg,均远低于(GB18668-2002)Ⅰ类标准500mg/kg;退化区的土壤中多环芳烃各组分含量在0.4~51.8ng/g之间,相比于其他地区的0.2~25.0ng/g较高,而光滩区土壤中多环芳烃各组分含量在0.2~3.8 ng/g之间,相比于其他地区的0.3~51.8 ng/g较低;不同区域土壤正构烃的组成(C10~C35)基本相同,但是分布特征存在较大差别。  相似文献   
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